Qualities in Öllöv SoftStep Analysis of Öllöv SoftStep’s shock absorbing and vibration damping qualities compared with a steel shoe and unshod hoof, using an accelerometer Analys av Öllöv SoftStep’s stöt- och vibrationsdämpande egen- skaper jämfört med en stålsko och oskodd hov med hjälp av en accelerometer Bachelor’s thesis in Mechanical engineering, 15hp FRIDA JÖNSSON AMANDA SALFJORD Department of Physics CHALMERS UNIVERSITY OF TECHNOLOGY Gothenburg, Sweden 2018 BACHELOR’S THESIS 2018 Qualities in Öllöv SoftStep Analysis of Öllöv SoftStep’s shock absorbing and vibration damping qualities compared with a steel shoe and unshod hoof, using an accelerometer FRIDA JÖNSSON AMANDA SALFJORD Department of Physics TIFX04 CHALMERS UNIVERSITY OF TECHNOLOGY Gothenburg, Sweden 2018 Qualities in Öllöv SoftStep FRIDA JÖNSSON, AMANDA SALFJORD © FRIDA JÖNSSON, AMANDA SALFJORD, 2018. Supervisor: Magnus Karlsteen, Department of Physics Examiner: Magnus Karlsteen, Department of Physics Bachelor’s Thesis 2018 Department of Physics TIFX04 Chalmers University of Technology SE-412 96 Gothenburg Telephone +46 31 772 1000 Cover: Shows a 3D picture of an Öllöv Softstep with the outer layer of rubber peeled of to reveal the inner steel core. Typeset in LATEX Printed by Chalmers University of Technology Gothenburg, Sweden 2018 iv Qualities in Öllöv SoftStep FRIDA JÖNSSON, AMANDA SALFJORD Department of Physics Chalmers University of Technology Abstract The study is commissioned by AB Halmstad Gummi Fabrik/Öllöv and is in collaboration with Chalmers Sports and Technology. The study concerns the rubber shoe Öllöv Soft- Step, which is a result of a development done on the former shoe, Öllöv Original. Öllöv SoftStep has a forged shoe inside the rubber enclosure and a change in the friction surface to provide a grip similar to the unshod hoof. Former studies have shown that rubber shoes and synthetic shoes have a better impact on the hoof’s shock absorbing and expansion qualities. To measure the shock absorbing and vibration damping qualities, a test including two horses wearing Öllöv SoftStep, steel shoes and unshod hooves was made. The test was designed to be able to measure the qualities on two different grounds, concrete and fibre sand, using an accelerometer attached to the horse’s hoof. A logger was attached to the accelerometer with a sampling rate at 7161 points/sec and an associated application con- nected to an Ipad could process the data during the measurements. The logger provided with raw data which was analyzed in MatLab. The amplitude values was collected in the five steps in the range of 10 m. Every step had maximum and minimum peak which showed the highest amplitude. Average values for each measurements were calculated in Excel. To be able to analyze the visible oscillations, every step in the measurements had to be taken into account to be able to find a pattern in every combination of ground and shoe. When the analysis of the vibrations was conducted, the focus was to find characteristics in the oscillations between the steel shoe, Öllöv SoftStep and an unshod hoof in the impact phase of the step. The analysis of the amplitude showed that Öllöv SoftStep has better shock absorbing qual- ities than the steel shoe on concrete. Dora’s measurements showed a decrease between 12%-28% and for Empe’s measurements 69%-76% when comparison with the unshod hoof. On fibre sand there were no significant difference between the shoe types. The analysis showed that Öllöv SoftStep has better vibration damping qualities than the steel shoe. Öllöv SoftStep has better vibration damping qualities than the unshod hoof, but significance of the differ is not concluded. Öllöv SoftStep has according to the analysis similar vibration damping qualities in fibre sand as an unshod hoof and a hoof wearing steel shoe. Keywords: Öllöv, vibration, rubber, SoftStep, shock absorbing, damping, horseshoe v Sammanfattning Denna studien är på uppdrag av AB Halmstad Gummi Fabrik/Öllöv och är ett samarbete med Chalmers Sport och teknologi. Studien handlar om gummiskon Öllöv SoftStep, som är ett resultat av utvecklingen av deras tidigare sko, Öllöv Original. Öllöv SoftStep har en smidd stålsko som omsluts av ett gummihölje med en förändring i friktionsytorna som ska efterlikna greppet på en oskodd hov. Tidigare studier har visat att gummi-och syntetskor har en bättre inverkan på hovens stötdämpning och expansion. För att mäta de stötdämpande och vibrationsdämpande egenskaperna utfördes ett test med två hästar som var skodda med Öllöv SoftStep, stålskor och då de var oskodda. Testet var designat så att mätningar var utförningsbara på två olika underlag, betong och fibresand, men hjälp av en accelerometer som var fäst på hästens hov. En datalogg var fäst till ac- celerometern och hade en insamlingshastighet på 7161 punkter/sekund och en tillhörande applikation som var ansluten till en Ipad kunde processa datan direkt. Dataloggen lagrade data som analyserades i Matlab. Amplitudvärderna var insamlade under de fem stegen hästen tog på den 10 m långa mät- ningabanan. Varje steg hade ett maximum och minimum värde som visade sig som den högsta amplituden. Medelvärden för alla de olika mätningar räknads ut i Excel för att sedan kunna analysera resultatet. För att analysera de synliga svängningarna, var varje steg i varje mätning tvungen att tas i beaktning för att kunna urskilja mönster i varje kombination av underlag och sko. När analysen av vibrationerna genomfördes låg fokuset på att se karaktäristiken i svängningarna mellan de två skorna och den oskodda hoven. Analysen av amplituden visade att Öllöv SoftStep hade bättre stötdämpande egenskaper jämfört med stålskon på betong. Doras mätningar visade en minskning av 12%-28% och för Empes mätningar 69%-76% när Öllöv SoftStep jämfördes med den oskodda hoven. På fibersand var den ingen betydande skillnad mellan de olika skorna. Analysen av vibrationerna visade att Öllöv SoftStep har en bättre förmåga att dämpa vibrationerna jämfört med stålskon. Öllöv SoftStep hade en något bättre vibrationsdämp- ning än den oskodda hoven, men exakt hur mycket kunde inte fastslås. Öllöv Softstep har enligt analysen liknande vibrationsdämpande egenskaper på fibersand som en oskodd hov och en stålsko. Nyckelord: Öllöv, vibration, gummi, SoftStep, stötdämpande, vibrationsdämpande, häst- sko vii Acknowledgements It’s been very pleasant and educational to been able to work close to Öllöv and share their passion for the horses well-being. We will send our warmest thanks to Sofie Sandhagen, development manager at HGF who’s been our mentor. She has been an important guide and source of knowledge. We will also thank Beate-Sofie Fredriksson, intl. Sales and marketing manager at Öllöv for her support and providing us with necessary means. The cooperation with Chalmers sports and technology has given us the opportunity to meet many inspiring people. We would like to send a special thank to Magnus Karlsteen, he has been our mentor at Chalmers University. We are very grateful for his support and knowledge. We would like to thank farrier Lars Kärvestedt for the help with the ferrule, Anna Kär- vestedt for all the help with the horses and Victoria Kärvestedt for her great riding abilities and Emma Sjölin for your involvement in the pre-test. Our study has been conducted together with another project at Öllöv and Chalmers Uni- versity. We therefor want to thank Charlotta Elvind and Martin Soffronow for a great collaboration. Frida Jönsson & Amanda Salfjord, Gothenburg, May 2018 ix Contents List of Tables xiii List of Figures xiii 1 Introduction 1 1.1 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Delimitation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.3 Clarification of question . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 Background 3 2.1 Hoof-mechanism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2.2 Vibration damage for humans . . . . . . . . . . . . . . . . . . . . . . . . 4 2.3 Problems with current solution . . . . . . . . . . . . . . . . . . . . . . . 5 2.4 Rubber properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.5 Öllöv and Halmstad Gummifabrik . . . . . . . . . . . . . . . . . . . . . 5 2.5.1 Öllöv SoftStep and differences from Öllöv Original . . . . . . . . 6 2.6 Former studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3 Method 9 3.0.1 Measuring equipment . . . . . . . . . . . . . . . . . . . . . . . . 9 3.0.1.1 Accelerometer SEN040F . . . . . . . . . . . . . . . . 9 3.0.1.2 Data logger HVM200 . . . . . . . . . . . . . . . . . . 10 3.0.1.3 Metal bracket . . . . . . . . . . . . . . . . . . . . . . 10 3.0.2 Pre-test at riding cite in Kullavik . . . . . . . . . . . . . . . . . 10 3.0.3 Implementation plan for the test day . . . . . . . . . . . . . . . . 11 3.0.4 Test site in Vallda . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.0.5 Horses used during testing day . . . . . . . . . . . . . . . . . . . 11 3.1 Method for analyzing measurements from testing day . . . . . . . . . . . 12 3.1.1 Approved measurements . . . . . . . . . . . . . . . . . . . . . . 12 3.1.2 Processing of data . . . . . . . . . . . . . . . . . . . . . . . . . 12 4 Results 13 4.1 Pre-test at riding stable in Kullavik . . . . . . . . . . . . . . . . . . . . . 13 4.1.1 Experiences from the pre-test . . . . . . . . . . . . . . . . . . . 14 4.2 Testing day in Vallda . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 4.3 Results and analysis of the testing day . . . . . . . . . . . . . . . . . . . 19 4.3.1 Approved measurements . . . . . . . . . . . . . . . . . . . . . . 19 xi Contents 4.3.2 Processing of raw data in Matlab and Excel . . . . . . . . . . . . 19 4.3.3 Amplitude values to analyze shock absorption . . . . . . . . . . . 21 4.3.4 Vibrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 4.3.4.1 Steel shoe . . . . . . . . . . . . . . . . . . . . . . . . 25 4.3.4.2 Öllöv SoftStep . . . . . . . . . . . . . . . . . . . . . . 28 4.3.4.3 Unshod hoof . . . . . . . . . . . . . . . . . . . . . . . 31 5 Discussion 35 5.1 Recommendations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 6 Conclusion 39 Bibliography 39 A Documentation of testing day I B Matlab code V C Amplitude results VII D Spread of steps XI E Empe’s vibration measurements XIII E.1 Empe’s measurements with steel shoe on concrete . . . . . . . . . . . . . XIII E.2 Empe’s measurements with steel shoe on fibre sand . . . . . . . . . . . . XIV E.3 Empe’s measurements with Öllöv Softstep on concrete . . . . . . . . . . XV E.4 Empe’s measurements with Öllöv Softstep on fibre sand . . . . . . . . . XVI E.5 Empe’s measurements on unshod hoof on concrete . . . . . . . . . . . . XVII E.6 Empe’s measurements on unshod hoof on fibre sand . . . . . . . . . . . . XVIII xii List of Tables 4.1 Amplitude for Dora on concrete . . . . . . . . . . . . . . . . . . . . . . 21 4.2 Amplitude for Empe on concrete . . . . . . . . . . . . . . . . . . . . . . 21 4.3 Comparison between Öllöv SoftStep and steel shoe . . . . . . . . . . . . 22 4.4 Amplitude for Dora on fibre sand . . . . . . . . . . . . . . . . . . . . . . 22 4.5 Amplitude for Empe on fibre sand . . . . . . . . . . . . . . . . . . . . . 22 xiii List of Tables xiv List of Figures 2.1 A typical horseshoe made of steel. [1] . . . . . . . . . . . . . . . . . . . 3 2.2 The division of the main parts of the hooves bottom [3]. . . . . . . . . . . 4 2.3 Öllöv SoftStep i partly section view. . . . . . . . . . . . . . . . . . . . . 6 3.1 The accelerometer SEN040F which are used during the measurements. . . 10 4.1 The metal plate attached on the hoof. . . . . . . . . . . . . . . . . . . . . 13 4.2 The cord’s attachment along the horse’s leg from the accelerometer to the logger. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 4.3 The metal bracket attached with two different types of adhesive. . . . . . . 16 4.4 How the accelerometer is screwed into the metal bracket and how the cord is fixed alongside the leg and into the logger. . . . . . . . . . . . . . . . . 16 4.5 The horse passes through the 10 m track where the measurements take place in the riding hall. Light beam visible on the ground from the high speed camera. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 4.6 Measuring track in stable with concrete as ground and light beam from the high speed camera visible on the ground. . . . . . . . . . . . . . . . . 18 4.7 The farrier attaches Öllöv SoftStep on the hoof in between the measure- ments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 4.8 How measurements differ from concrete to sand. . . . . . . . . . . . . . . 20 4.9 How the middle pulse’s amplitude is higher than the rest at concrete for Dora. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 4.10 How the pulses are more even at sand for Dora. . . . . . . . . . . . . . . 24 4.11 How the middle pulse amplitude is higher than the rest at concrete for Empe. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 4.12 How the pulses are more even at sand for Empe. . . . . . . . . . . . . . . 24 4.13 The characteristics of the oscillations in x-direction of the hoof wearing a steel shoe on concrete. . . . . . . . . . . . . . . . . . . . . . . . . . . 26 4.14 The left show the character of the oscillation in y-direction and the right in z-direction, in combination of steel and concrete. . . . . . . . . . . . . 27 4.15 The oscillations in x-direction of the hoof wearing a steel shoe on fibre sand. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 4.16 The left show the character of the oscillation in y-direction and the right in z-direction, in combination of steel and fibre sand. . . . . . . . . . . . 28 4.17 The characteristics of the oscillations in x-direction of the hoof wearing a Öllöv SoftStep on concrete. . . . . . . . . . . . . . . . . . . . . . . . . 29 xv List of Figures 4.18 The left shows the character of the oscillation in y-direction and the right in z-direction, in combination of Öllöv SoftStep and concrete. . . . . . . . 30 4.19 The oscillations in x-direction of the hoof wearing Öllöv SoftStep on fibre sand. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 4.20 The left shows the character of the oscillations in y-direction and the right in z-direction, in combination of Öllöv SoftStep and fibre sand. . . . . . . 31 4.21 The characteristics of the oscillations in x-direction of the unshod hoof on concrete. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 4.22 The left shows the character of the oscialltion in y-direction and the right in z-direction, in combination of unshod hoof and concrete. . . . . . . . . 33 4.23 The oscillations in x-direction of the unshod hoof on fibre sand. . . . . . . 33 4.24 The left shows the character of the oscillation in y-direction and the right in z-direction, in combination of rubber and fibre sand. . . . . . . . . . . 34 5.1 The left show oscillations with steel and the right with Öllöv SoftStep, both on concrete. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 E.1.1 The oscillations in x-direction of the steel shoe hoof on concrete. . . . . . XIII E.1.2 The left shows the character of the oscillation in y-direction and the right in z-direction, in combination of steel and concrete. . . . . . . . . . . . . XIV E.2.1 The oscillations in x-direction of the steel shoe on fibre sand. . . . . . . . XIV E.2.2 The left shows the character of the oscillation in y-direction and the right in z-direction, in combination of steel and fibre sand. . . . . . . . . . . . XV E.3.1 The oscillations in x-direction of Öllöv SoftStep on concrete. . . . . . . . XV E.3.2 The left shows the character of the oscillation in y-direction and the right in z-direction, in combination of Öllöv SoftStep and concrete. . . . . . . . XVI E.4.1 The oscillations in x-direction of Öllöv SoftStep on fibre sand. . . . . . . XVI E.4.2 The left shows the character of the oscillation in y-direction and the right in z-direction, in combination of Öllöv SoftStep and fibre sand. . . . . . . XVII E.5.1 The oscillations in x-direction of the unshod hoof on concrete. . . . . . . XVII E.5.2 The left shows the character of the oscillation in y-direction and the right in z-direction, in combination of the unshod hoof and concrete. . . . . . . XVIII E.6.1 The oscillations in x-direction of the unshod hoof on fibre sand. . . . . . . XVIII E.6.2 The left shows the character of the oscillation in y-direction and the right in z-direction, in combination of the unshod hoof and fibre sand. . . . . . XIX xvi 1 Introduction For several thousands of years horses have played an important part in the history of everything from agriculture to warfare, but the more the society developed, the horses part changed. Nowadays the horses are mostly used for equestrian sport and in some cases forestry. The use of the horses exposes them to more strain than they were initially build for. For centuries the horses have been shod with different types of steel shoes, but newer shoes with more developed materials and functions are trying to enter the market against the more established steel shoe. 1.1 Purpose The purpose of this task is to analyze and evaluate how Öllöv SoftStep behaves during use. The importance of the task lies on the shock absorbing and the vibration damping qualities in Öllöv SoftStep and if it’s a better option compared with the classic steel shoe or the unshod hoof based on the analyze. This study is the first one made on Öllöv SoftStep, therefore the study is going to be the foundation of the future measurements done by AB Halmstad Gummifabrik. 1.2 Delimitation The assignment will not include working with the development of the shoes construction or any re-design. The measurement will compare a steel shoe, Öllöv SoftStep and a unshod hoof on the ground of concrete and fibre sand. The measurement will be taken on two different horses using the steel shoe, Öllöv Soft- Step and an unshod hoof. In this study two horses are used in the measurement and the results from the measurements will be what the conclusions are being based on. Due to time- and logistics limitations there will be no more tests done during this study. During the measurement the horses will be tested in trot. The measurements will be done in the course of one day. Long term impact on the horses health, particularly the long term well-being of their hooves and in consequence of wearing the different types of shoes is not going to be included in this project due to that is a long-term study, and therefore out of the time range. 1 1. Introduction 1.3 Clarification of question Questions that will be answered within the end of the project are: • How good is Öllöv SoftStep shock absorbing qualities? • How well can Öllöv SoftStep attenuate vibration? • Is Öllöv SoftStep a better option than the steel shoe according to the analysis? The results will be compared with the results of a steel shoe and an unshod hoof. 2 2 Background To minimize the wear on the hoof, the horse is provided with shoes. The majority of these shoes are made out of steel. Öllöv has developed a shoe with a core of steel and a enclosure of rubber. Rubber is known for its shock absorbing and vibration damping qualities. Horses in all kinds of disciplines is subjected to strain on hooves, joints and back. A shock absorbing shoe can contribute to that the horse is subjected to less strain, which can have positive effects during the horses entire life span. Figure 2.1 shows a typical horse shoe made out of steel. In the slit are four square holes are placed, this is where the farrier attaches the seams. The seams attached the shoe on the horse’s hoof. On both ends of the shoe, two round threads are drilled. These holes are used to screw in studs that give the shoes attachment on slippery grounds. Figure 2.1: A typical horseshoe made of steel. [1] 2.1 Hoof-mechanism The hooves carry the horses weight and is therefore constantly exposed to strain. The part that embraces the core of the hoof is called horn and consists of dead tissue. The horse shoe is attached with seams around the hoof in the horn because there isn’t any nerve fibres in the horn and therefore no unpleasant pain for the horse. 3 2. Background The bottom of the hoof is divided in such way as figure 2.2 shows. The hoof works as a natural shock absorbing system and provides the horses blood circulation. When the hoof is pressed against the ground it gives a pressure against the frog, which press against the digital cushion inside the frog and it starts the pumping of the blood. The digital cushion gives a pressure on the cartilage which make the hoof expand [2]. Figure 2.2: The division of the main parts of the hooves bottom [3]. 2.2 Vibration damage for humans The damage of vibrations for humans is a common issue in jobs including vibration tools. These damages are separated in hand-and arm vibrations (HAV), which includes tools that’s been used by the hands and body vibrations (HKV) which includes working with vehicles such as trucks, buses, excavator etc. The vibrations damage the capillaries and is hurting the nervous system. Vibration damages doesn’t appear immediately, but occurs several years later. These in- juries may occur for example as pain in hands and fingers, muscles weakness and numb- ness in body parts exposed to the vibration[4]. To avoid these types of vibration damages the work environment authority in Sweden have identified the requirements which has to be met by the machines in use. Require- ments are stated as limit values and input values. The limit value for HAV of 5 m/s2 if it’s 4 2. Background exceeded it implies immediate action by the employer. The input values for HAV of 2.5 m/s2, if this value is to be exceeded it implies a demand of medical controls and a demand that action is taken to reduce the vibration in the tool or vehicle. These values are seen as the maximum daily exposure to vibration [5]. 2.3 Problems with current solution The problem with a steel shoe is that it’s impairs the hooves natural shock absorbing sys- tem by assisting the hoof with the stiffer material. If it’s to thick it also impairs the blood circulation from the hoof, due to that the frog do not get in touched with the ground. Re- search has been made to produce shock absorbing ground for riding halls and paddocks, but it still remains that the natural shock absorbing quality in the hoof is still reduced due to wearing shoes [6]. Today, infrastructure is built around a society which is depending on vehicles, and there- fore roads are intended for vehicles. This means that the roads are hard and stiff. The natural habitat of the horses does not include asphalt or concrete, which contributes to more strain on the horses joints and ligaments than they are made for. The classic steel shoe protects the hoof from unnatural wear, but does not contribute to any shock absorp- tion against these harder grounds. 2.4 Rubber properties Rubber is a viscoelastic material [7] with many desirable properties. Before the synthetic rubber materials could be fabricated, rubber was synonymous with natural rubber which is usually made from latex, the gum tree’s milk juice. The latex is treated and then mixed with a variety of additives to achieve the desired properties, when added together they have formed a rubber material. [8]. Rubber is a very elastic material that has many uses. Rubber is commonly known for use as vibration-and shock absorbers. 2.5 Öllöv and Halmstad Gummifabrik This study is in collaboration with Öllöv which are a part of AB Halmstad Gummifabrik, from now on is going to be recalled as HGF. HGF are a company that specializes in pro- duction in rubber and thermoplastics. They have their head office and production facility in Halmstad, Sweden and another production facility in Riga. Öllöv is a brand belonging to HGF. The brand was founded around the same time as the first shoe was launched, Öllöv Original. Before this, there had been some studies that were based on the patent [9] that were bought 1993 of its owner Lone Pedersen. 5 2. Background 2.5.1 Öllöv SoftStep and differences from Öllöv Original Öllöv SoftStep is a horseshoe with a steel core with a rubber enclosure as can be seen in figure 2.3. The idea of the shoe is that it will optimize shock absorbing, minimize vibra- tions and mimic the movement pattern of an unshod hoof and therefore be a better option than the steel shoe. Figure 2.3: Öllöv SoftStep i partly section view. Öllöv SoftStep has been developed after several years of studying the previous one, Öllöv Original. The friction surface has been changed to provide a grip more similar to an unshod hoof. In Öllöv Orginal the core was cut out from steel, therefore it was harder to shape and process the shoe for farriers, to do this they needed special tools. This is changed in Öllöv SoftStep to be a forged shoe inside a rubber enclosure. To shape and progress SoftStep is the same as to shape and progress a traditional steel shoe. 2.6 Former studies In a study from 2006 [10], measurement were made on unshod hooves, steel shoes and synthetic shoes made by polyurethane. The study contained 12 horses, two geldings and two mares in ages between 5-20 years old. The horses were Dutch warm-blood horses with a height between 160-171 cm. 6 2. Background A hypothesis was established that synthetic materials can have a positive impact on the horses joints and prevent lameness and then too chronic articular. According to the au- thor, there is not enough research to ensure this hypothesis. They explain that when the hoof is in direct contact with the ground, the speed is reduced and the distal phalanx, the lower part of the legs bone, is almost zero. This is known for the most critical part of the horse movement when it comes to injuries of the musculoskeletal system of the horse and is called the impact phase. The group who preformed the measurements chose to convey the horses in trot. They considered that it would minimize the risk of interference in the vibration. The length of the track that preformed the measurements on were 10 m and in a successful test the horse held a mean speed of 3.5 m/s. They calculated the time by the length of the track by the time it took for the horse to get between start and finish. A minimum of six successful trials was collected for each horse wearing each shoe and unshod, so it was 72 trials alto- gether. They used a triaxial piezoelectric accelerometer which they attach on the lateral side of the hoof on the horses left feet. To attached the accelerometer they first cleaned the area on the hoof with ethanol an than fixed an aluminum bracket with fast-drying adhesive. To be able to attach the bracket in a similar position on all horses, they attached the brackets lowest part 7-8 mm to the hooves bottom in a perpendicular position towards the ground. The total mass of the equipment was 19.9 g. The result of the measurements showed that the different in an unshod hoof and the steel shoe were not significant, but the mean relative frequency in the steel shoe was significant higher. The synthetic shoe had a significant lowering of the deceleration amplitudes in the mean maximum values. During a two year period, 1996-1998, Swedish Agricultural University in Uppsala and HGF made a research about the Öllöv original [11]. These studies included a total of measurements on 32 different horses spread over three different test occasions. Measure- ments have been made on steel shoes, rubber shoes and unshod hooves. A lot of focus was on measuring the sliding-phase between hoof and ground in the different combinations of shoes and surfaces. The study reported on how the hoof is given the opportunity to expand, which in itself is a shock-absorbing function in the horse’s anatomy. In general, it can be said that the unshod hoof always has a lager expansion than a shod hoof. It is because of the fact that when a hoof is shod, the walls of the hoof will be fixed in the shoe to some extent. The study showed that a hoof shod with Öllöv original increases expansion compared with the traditional steel shoe. In walk, expansion increases by 44 percent and at trot by 19 percent. Expansion of the hoof is important to keep the hoof in a good condition due to blood circulation among other things. In U. Yxklintens report from 1996 [12] he summarizes measurements done by S. Drevemo and C. Jonhston 1992 [13]. The study was done on three horses shod with steel shoes, 7 2. Background without any shoes and rubber shoes -Öllöv original. The horses was led by hand forward with a velocity of 3 m/s. In the study the acceleration in vertical direction was measured in contact with concrete and also on an dirt track. The results of the study shows that the rubber shoe completely attenuated the shock and the vibrations that occurs in contact with hard ground while the steel shoe and the unshod hoof does not, and therefore the vibrations will spread up to the horses leg and tissues. 8 3 Method The tests will be held at a riding cite with two different horses and each will be tested with Öllöv SoftStep, steel shoes and unshod hooves on concrete and fibre sand. To measure shock absorbing and vibrations during the test, an accelerometer will be used. The ac- celerometer will be attached on the lateral side of the hoof by a metal bracket and a cord will connect the accelerometer to the logger. 3.0.1 Measuring equipment To be able to measure the acceleration, there will be a need of certain equipment. To sample the acceleration values and to store the data that is sampled there will be a need of an accelerometer, a logger and a metal bracket to attach the accelerometer on the hoof. The testing day is going to be conducted in collaboration with an other project group, which task is to measure and analyze the sliding phase in the same combinations. Due to this they are going to use a high speed camera which is going to be placed in the middle of the 10 m measuring range. 3.0.1.1 Accelerometer SEN040F The accelerometer is called SEN040F and has the ability to measure accelerations in three directions, x, y and z. Dimensions of the accelerometer is 10,2 x 19,6 x 10,2 mm and weight 5.3 g, see figure 3.1. The dimensions are small and the weight is low compared to the hoof so the perception is that it will not affect the horse and the measurements noticeably [14]. 9 3. Method Figure 3.1: The accelerometer SEN040F which are used during the measurements. 3.0.1.2 Data logger HVM200 To be able to view and store the results from the accelerometer, the logger HVM200 [15] is used. It can be used to measure hand-arm, whole body and general vibration. In this study it is going to be used to store vibration and shock absorbing values on the hoof. To be able to see the measurements directly there is an application to HVM200. The logger supports a removable micro SD memory, so it’s possible to store received data into 24-bit format and files can be read with tools as Matlab [16]. The sampling rate in the combination of accelerometer and logger is 7161 points/sec. 3.0.1.3 Metal bracket The metal bracket will be constructed with measurements similar to the accelerometer. The accelerometer has the dimensions 10 x 10 mm, and therefore the metal plate will be 15 x 15 mm. The metal bracket dimension is limited due to the hooves shape. A hoof is arched all the way around and the larger the dimensions are, the bigger risk there is that the space between the metal bracket and the hoof creates vibration which can interfere will the actual vibration the group is interested in. 3.0.2 Pre-test at riding cite in Kullavik Before the actual test the student group will preform a pre-test on the accelerometer and logger that will be used during the test day, as a preparatory measure. The metal bracket that is constructed to be attached to the horses hooves and concatenate the accelerometer will also be tested. The metal bracket will be fixed on the horses hoof using adhesive. The pre-test will be done on one horse and the purpose of this is to understand the accelerom- eters function, the best way to attach the metal bracket and to see how the logger stores the data. 10 3. Method 3.0.3 Implementation plan for the test day The test day is estimated to take a whole workday, approximately eight hours. The farrier and the horses have a travelling time in over two hours, therefore the preparations of the tests will start at 9:00 AM. The preparations include measure out a track of exactly 10 m. There is of highest importance that the horses keep similar speed during this length range, else the data from the accelerometer will not be comparable between the different shoes and grounds. The horses will arrive wearing steel shoes, therefore the first tests will be done on the steel shoe. When the first measurements are done on both steel shoe and unshod hoof, the farrier will attach Öllöv SoftStep. If the day goes according to the implementation plan there will always be a horse available for measurements. During the whole day there will be five people which monitors the tests. The first one is in charge of the timing, this is carried out by a stopwatch which will start when the equestrians passes the first mark and stops when the equestrians passes the finish line of 10 m. The second one monitors the application, so the data is transmitted correctly to the logger. The third one stores the time range and the accelerometers start time. The fourth monitors the assembly of the equipment between the different horses. The fifth monitors the high speed camera, the data from the high speed camera will not be presented in this study. 3.0.4 Test site in Vallda The facility is located in Vallda, south of Gothenburg. The facility is a horse farm equipped with a riding hall and stable where the floors are made of concrete. These boxes will be used as store a desk with a computer which controls high speed camera. They will also be used as protection towards the horse who will trot along the corridor. The riding hall is 30 x 60 m where the long side of the hall will be used for the 10 m track. The riding hall is equipped with cones, which will be used to mark the length of the tracks. Fibre sand is an underlay used in riding halls and paddocks. It is a micro-fibre reinforced, sand based underlay with shock absorbing properties [17]. The fibre sand that were being used had 21 kg fibres/ton mixed sand and consisted of 1.8 % water. 3.0.5 Horses used during testing day The horses which will be used during the test were brought to the location by its owner on the testing day. The owner is also the farrier which will be in charge of the ferrule. During the test an equestrian will control the horses gaits, direction and speed. The horses will be equipped with saddle and trans. Due to the fact that the tests will take a full day and that living animals are involved, the horses welfare will always come first and how the horses react to the environment can not be controlled. Both horses are of the breed P.R.E. P.R.E. derived from Spain and is imported to Sweden. The breed is trained in a variable of disciplines and is a very benevolence horse. The 11 3. Method P.R.E. has tactile motion patterns with energetic and forward moving movements. [18] The horses involved in the test are Emperador and Emparadora. Emperador, from now on is going to be referred to as Empe, is a gelding, 14 years old, weighs around 600 kg and is 1.66 m high. Emparadora, from now on going to be referred to as Dora is a 14 year old mare, weighs around 500 kg and is 1.52 m high. The height of the horse is measured from the ground up to the withers. 3.1 Method for analyzing measurements from testing day This section describes which tools that are going to be used when analyzing the sampled data from the testing day. 3.1.1 Approved measurements For the measurements to result in a correct analyze, it is important that the speed during the tests are similar to each other on both of the grounds. The time it takes for the horse get from one side to the other in trot is being measured by a stopwatch and stored into a document. Five measurements for each horse will be analyzed and those which differ the most are not included in the analyze. 3.1.2 Processing of data When all measurements are done the raw data is going to be stored and be analyzed in Matlab and Excel. There is accompanied program to the logger that can be used for analyzing the measure- ments, but accuracy in that program is only 1 point/sec and when using Matlab there can be 7161 points/sec and therefore that is preferred. To the logger a Matlab code is accompanied for creating graphs over the measurements. This code is in need of some modification to reach this analysis purpose. The measurements that are inside the 10 m track, are the ones that are going to be ana- lyzed, but the total measurement length is longer and includes values before and after the 10 m track. Due to this it is important to be able to choose which interval that is going to be analyzed. The measurements are going to be presented as graphs with impulses, one impulse for each step of the horse. Maximum value of these impulses are what’s going to be analyzed in deciding how well the shock absorbing is. The comparison between the different horses wearing the different shoes will result in the analysis of the best shock absorbing choice. The vibrations damping will be analyzed by observing the different graphs for the diverse combination of horse, shoe and ground. The comparison between the different horses wearing the different shoes will result in the analysis of the best vibration damping choice. 12 4 Results In this section, the results are presented. In how the the pre-test resulted in and the experi- ence that were needed to the testing day. Results from the measurements and the analyze of these. 4.1 Pre-test at riding stable in Kullavik The group arrived to the stable in Kullavik to do the pre-test on the accelerometer, the logger and how well the adhesive attached on the hoof. Sofie Sandhagen from HGF par- ticipated in the test and brought all the equipment as needed to the pre-test. The horse Carpe Vita and his equestrian Emma Sjölin participated during the whole time. The hoof’s lateral side was cleaned with water and a cloth to make sure that the adhe- sive attached properly. The first adhesive which was tested was a quick drying adhesive, which was produced to fit rubber and plastic. This adhesive turned out not to meet the requirements, thus the metal bracket fell of quite easy. The same surface was once again cleaned to remove residual adhesive before the second adhesive was applied. The second adhesive which was used was a partly flexible with a slightly longer curing time. This adhesive was stronger and easily removed by acetone after the test. The position of the metal bracket is shown in figure 4.1. Dimensions of the metal bracket were 15 x 15 mm and had a threading that went all through its width. Figure 4.1: The metal plate attached on the hoof. 13 4. Results The accelerometer was screwed into the metallic brackets threading and the cord was at- tached. The cord is 1.5 m long and the idea is that it’s long enough to attach the logger somewhere on the horses body. During this pre-test the cord was fixed along the horses leg with two velcro straps. The logger was put in a accompanied arm pocket that was attached around the rider’s calf. The cord could be led trough the stirrup and finally be attached to the logger as can be seen i figure 4.2. Figure 4.2: The cord’s attachment along the horse’s leg from the accelerometer to the logger. After a couple of runs the equipment was up running together with the application and in real time showed how the shocks varied in the different directions. Due to a slightly loose fixed cord only walking was tested to avoid the horse getting tangled up. 4.1.1 Experiences from the pre-test The group quickly notice that the horse lost patience, so the first learning was to bring some snacks for the horses. Water and a cloth for cleaning the hoof worked for the short time of the pre-test but for the testing day there will be needed some more accurate clean- ing method. The horse that were involved was 1,63 m high and to that the cord’s length was long enough to be attached to the equestrian’s boot, but that can be changed due to the horses size on the testing day. 14 4. Results To prevent that the horses will be affected or to get tangled up in the cord it is important that the cord socket on the accelerometer is pointed upwards, in contrast to this time when it was pointed forward. Due to this it is important how the metallic bracket is fixed on the hoof in the start of the tests. For the cord to be held in place alongside the leg of the horses we will be in need of a flexible sling. While the horses are moving it’s important that the cord never gets completely stretched to protect the accelerometer, the logger and to retain the horses natural movement pattern. The attachment of the logger can differ on different horses and from this method used in the pre-test. After dismantling the equipment from the horse and the analyze of the sampled values in the accompanied computer program we realized that it was problematic to understand in which direction the sampled valued belonged to. The most accurate would be a function in the accelerometer, to reset the directions to zero, but it seems like there is no such function. Therefore the attachment of the metallic bracket is of highest importance, the accelerometer has to be perpendicular to the ground. Consequently the aim is that the cord socket of the accelerometer is pointed straight up so that shocks and vibrations will be sampled in an optional way. 4.2 Testing day in Vallda The two students groups which will preform the tests met with Sofie Sandhagen and Beate Sofie Fredriksson at the horse cite in Vallda. One student group started with the assem- bling of the high speed camera and the other group started preparing the accelerometer and the attachments of the accelerometer. The 10 m track were also measured and marked by cones in both the riding hall and the stable hall. The equipment was first installed in the riding hall were the first measurement took place. Unlike from the pre-test, metal brackets were used which were a bit thicker. The reason for this was to not risk to get glue in the threading and the accelerometer to get stuck. The dimensions of the metal brackets are 15 x 15 x 8 mm and had a weight of 13.5 g and the threading does not go all way through. The group made a decision to use a another adhesive than the one at the pre-test, which was an adhesive constructed for metal, plastic and rubber. The problem with this adhesive was that the surface on the hoof was to slippery, which made the metal bracket to fall of when the accelerometer was attached. The group decided to use the initially adhesive and to strengthen the attachment with a special hoof glue around the edges of the bracket, see figure 4.3. The lateral side of the hoof was grinded to get a flatter surface to make sure the metal bracket would stay in place. 15 4. Results Figure 4.3: The metal bracket attached with two different types of adhesive. The cord between the accelerometer and the logger was attached in three places along the horses leg with elastic bandage. The bandage was attached to the horses during the whole day. When changing horse between the measurements, the cord could easily be pulled through. The logger was attached in another way than during the pre-test. The accompanying arm socket were still being used, but it was attached onto the webbing, as can be seen in figure 4.4, where also the way the accelerometer was screwed into the metal bracket can be seen. Figure 4.4: How the accelerometer is screwed into the metal bracket and how the cord is fixed alongside the leg and into the logger. 16 4. Results Figure 4.5 shows when the horse passes through the measuring track in the riding hall with fibre sand as ground. In figure 4.6 there can be seen what the measuring site looked like in the stables when measurements were done on concrete as ground. In the both pic- tures it can be seen a light beam that hits the ground. The light beam is part of the high speed cameras equipment. Figure 4.5: The horse passes through the 10 m track where the measurements take place in the riding hall. Light beam visible on the ground from the high speed camera. 17 4. Results Figure 4.6: Measuring track in stable with concrete as ground and light beam from the high speed camera visible on the ground. When the steel shoe had been tested on fibre sand and concrete, the farrier removed the shoes so the tests could be made on an unshod hoof and later on the farrier attached Öllöv SoftStep, see figure 4.7 Figure 4.7: The farrier attaches Öllöv SoftStep on the hoof in between the measurements. 18 4. Results During the first measurements in the riding hall, the high speed camera processed the images slowly and the memory on the computer was soon filled, so the files from the camera had to be transferred to other computers. This was unfortunately very time con- suming. The original plan was to measure on three horses but this were where the decision was made to only proceed the rest of the measurements with two horses. The following measurement went as planned and a total of 103 measurements were sampled with the accelerometer. 4.3 Results and analysis of the testing day The approved measurements were calculated and processed in MatLab and Excel. The results of the measurements will be presented in the analysis of the amplitude and the analysis of the vibration damping. 4.3.1 Approved measurements With a stopwatch the time for each measurement was stored in a document alongside with measuring number, the type of ground, which horse and shoe type. Number of measure- ments sampled for each ground, horse and shoe type varied between 6-13, depended on there had been a successfully photo taken by the high speed camera or not. The sampled values of the times it took to trot the 10 m long track were converted to a average time and speed for each horse. Dora had a average time om 3.4 s and Empe 3.6 s, that is equivalent to a speed of 2.9 m/s for Dora and 2.8 m/s for Empe. Average time for both horses were 3.5 sec and speed were 2.8 m/s. Five measurements that differed the least from the average time for each horse was se- lected for each ground. horse and shoe type. The documentation of the measurements can be seen in appendix A. The measurements that were approved are marked with green colour and the measurements there were not approved are marked with red colour and the letter ’d’ i the second column. This screening of the measurements resulted in that the maximum deviation for all the measurements was 0.31 and the average deviation was 0.10 sec on the 10 m track. These measurements proceeded into the analysis, a total of 60 measurements. 4.3.2 Processing of raw data in Matlab and Excel Maximum and minimum of the impulses in the graphs can be seen quite clearly in the Matlab code accompanying the logger. To choose and be able to store the values for fur- ther analysis, a self-composed code was added to the initial code. Since every measurement started the sampling before the 10 m interval, there was im- portant to be able to choose interval in the graphs. Sampling time for the measurements were around 30 sec and in this graph the interval of 3.5 s were interesting for the analysis. The 3.5 s of the measurement represent approximately 25x103 number of points on the graphs x-axis. When the measurements were taken place on the fibre sand the right inter- val occurred around 20 seconds into the measurement, which on the x-axis in the figure 19 4. Results is approximately 14.3x104 number of points. On concrete the time into the right interval is around 5 s, which is around 3.5x104 number of points at the x-axis of the graphs. Ex- ample of how the different measurement looks like without having zoomed in is shown in figure 4.8 with a graph from a concrete measurement on the left side and a graph from a fibre sand measurement on the right side. The scaling on the y-axis of the both graph differ a lot between the measurements. Figure 4.8: How measurements differ from concrete to sand. During the 10 m track and the average time of 3.5 s the horses take 5 steps with each leg, that is five impulses on the graph. Maximum and minimum values was collected from the graph using ’ginput’ in Matlab and to be able to zoom and choose the right interval, the Matlab function ’waitforbutton- press’ were used. The modified Matlab code can be found in appendix B. Maximum and minimum values for each impulse were stored in vectors that later got transferred to Excel to better clarity over the results and to a continuously analysis. In Matlab, a Z-vector of five maximum and five minimum values was created and trans- ferred to Excel, they were converted to absolute values and stored in a S-vector. Of these an average and a median were calculated for every measurement. In an F-vector, the highest absolute values for each impulse were stored in Matlab and transferred to Excel, five values for each measurement. In the same way as for the Z- vector an average and an median were calculated to be compared with the other measure- ments. For each measurement, a maximum value was stored, that is the highest absolute value for all five impulses for each measurement. This was compared with the same values for the other measurements. The entire document of all the sampled values can be found in appendix C. 20 4. Results 4.3.3 Amplitude values to analyze shock absorption From the analysis that can be seen in appendix C, it had been summarized into four tables, one for each horse and ground. The average values of the measurements can be viewed in the tables. Last row is the maximum amplitude over all the measurements. In the columns for steel shoe and Öllöv SoftStep there is also a percentage within brackets and is the difference from the unshod hoof. Calculated according to: unshod − (steel/rubber) unshod = (%) I table 4.1 and 4.2 the the concluded results from concrete as ground for both Dora and Empe. Table 4.1: Amplitude for Dora on concrete Dora on concrete [m/s2] Steel Unshod Öllöv SoftStep Average max and min values 4286 (+71%) 2500 2194 (-12%) Average absolute values 6219 (+88%) 3307 2643 (-20%) Average maximal values 8066 (+46%) 5531 4039(-27%) Max of maximal values 11046 (+52%) 7290 5238 (-28%) Table 4.2: Amplitude for Empe on concrete Empe on concrete [m/s2] Steel Unshod Öllöv SoftStep Average max and min values 4110 (+28%) 3215 1005(-69%) Average absolute values 4963 (+9%) 4562 1371 (-70%) Average maximal values 6451 (-4%) 6741 1649 (-76%) Max of maximal values 7636 (+7%) 7165 2125 (-70%) The values show that Empe has a more powerful downturn than Dora. Despite this, Dora has the highest sampled maximum values from all the 600 sampled values of 11 046 m/s2. On concrete it’s quite clear that the amplitude values is lower in every aspect wearing Öllöv SoftStep compared to the two other options, steel shoe and unshod hoof. For Dora the decrease is between 12% to 28% and for Empe the decrease is considerably higher, between 69% to 76%. The increase from unshod to steel shoe in almost the opposite. The increase for Dora is big, it lies between the percentage of 46% to 88% while Empe has a smaller increase from 7% till 28% and on the average of maximum values he has a decrease of 4 percent from the unshod hoof. 21 4. Results Due to that the percentage is quite different for the two horses there is a comparison just between steel shoe and Öllöv SoftStep. This was done in a simple way just to see how large part the Öllöv SoftStep values is of the steel shoe values according to: rubber steel = (%) The results can be seen in table 4.3 where the percentage is presented in the right column. Table 4.3: Comparison between Öllöv SoftStep and steel shoe Concrete [m/s2] Dora Steel Öllöv SoftStep % Average max and min values 4286 2194 51 Average absolute values 6219 2643 42 Average maximal values 8066 4039 50 Max of maximal values 11046 5238 49 Empe Average max and min values 4110 1005 24 Average absolute values 4963 1371 28 Average maximal values 6451 1649 26 Max of maximal values 7636 2125 28 In comparison just between Öllöv SoftStep and the steel shoe there is more similarities between the two horses results. For Dora the results lie between 42% to 51% and for Empe it’s more even and lies between 24% to 28%. In table 4.4 and 4.5 the results from fibre sand as ground can be seen. Table 4.4: Amplitude for Dora on fibre sand Dora on fibre sand [m/s2] Steel Unshod Öllöv SoftStep Average max and min values 191 (+1%) 189 184 (-3%) Average absolute values 260 (+11%) 235 265 (+13%) Average maximal values 293 (+6%) 277 288 (+4%) Max of maximal values 327 (-13%) 375 347 (-7%) Table 4.5: Amplitude for Empe on fibre sand Empe on fibre sand [m/s2] Steel Unshod Öllöv SoftStep Average max and min values 112(+5%) 107 92 (-14%) Average absolute values 156 (+13%) 138 120 (-13%) Average maximal values 177 (+11%) 160 141 (-12%) Max of maximal values 209 (+8%) 194 162 (-16%) 22 4. Results In the measurements done on fibre sand as ground is it a big difference in amplitudes from the measurements being done on concrete as ground. On fibre sand the highest average maximum value from all the measurements is 293 m/s2, which only is 4% of the highest average maximum value for concrete at 8066 m/s2. This proofs that the fibre sand as ground is absorbing shocks. The differences between steel, unshod and Öllöv SoftStep is not distinct as it was on concrete for the fibre sand measurements. For Dora the results is unclear thus they vary between -7% to +13% from the unshod to Öllöv SoftStep and from unshod to steel shoe it varies from -13% to +11%. For Empe the differences between the shoe type is clearer thus the amplitude is lower in all aspects for Öllöv SoftStep and higher in all aspects for steel shoe. It is a small variation and the decrease lies between -12% to -16% and the increase lies between +5% to +13%. The differences between the shoe types on the fibre sand as ground are to small and follow no clear pattern so therefore there is no comparison just between Öllöv SoftStep and steel shoe as in table 4.3 for concrete as ground. In the measurements done in the stables, on the concrete, there is a pattern that there is increase in amplitude in the middle of the interval, in the measurements done at the fibre sand there is not the same pattern. In figure 4.9 measurements on Dora on concrete can be seen and the increase of amplitude in the middle of the interval. The maximum value is printed in the figure where it occurs. In figure 4.10 measurements for Dora on fibre sand can be seen and the increase of amplitude in the middle can’t be seen. Figure 4.9: How the middle pulse’s amplitude is higher than the rest at concrete for Dora. 23 4. Results Figure 4.10: How the pulses are more even at sand for Dora. In the same way as the figures above can be seen for Empe, on concrete with the increase in amplitude in the middle in figure 4.11 and on fibre sand in figure 4.12. Figure 4.11: How the middle pulse amplitude is higher than the rest at concrete for Empe. Figure 4.12: How the pulses are more even at sand for Empe. At a more accurate analysis of the sampled values the results weren’t the same. Each absolute value of the impulses was compared with that measurements average to see how much higher or lower it was. In that way that spread of the more powerful steps could be seen. It resulted in that there was no significant difference in were the most powerful step were in the interval between measurements done on concrete compared with fibre sand. What the comparison did show was that the steps were more even on fibre sand than on concrete. On concrete the average maximum value was 148% higher than the average step for Dora, on fibre sand the same value were 113%. For Empe the same results was 134% and 115%. All the results can be seen in appendix D. That is that both the horses take more irregular steps in the stables on concrete than in the riding site on fibre sand. 24 4. Results 4.3.4 Vibrations According to the Nyquist sampling theorem the maximum frequency is half of the sam- pling rate [19]. In this logger the sampling rate is 7161 points/sec and therefore the highest frequency the measurements can read is 3581 hertz. This leads to the fact that the frequen- cies above this can not be presented in a representative way. To be able to analyze the visible oscillations, every step in the measurements had to be taken into account to be able to see a pattern in every combination of ground and shoe. Every approved measurement on the 10 m track included five steps with the hoof wearing the accelerometer, every step was analyzed with the same value on the graphs axes to give a result that was as representative as possible. When the analysis of the vibrations was conducted, the focus was to find characteristics patterns in the oscillations between the steel shoe, Öllöv Original and an unshod hoof in the impact phase of the step. The hoof impact is the phase where the hoof interacts with the ground. In the impact phase is where the largest amplitude was collected and where the most intense oscillations during the step occurred. 4.3.4.1 Steel shoe In the analysis of the steel shoes oscillations for Dora there had a characteristic pattern in the most intensive oscillations in the hoof impact. The interval of the vibrations starts off with intense oscillations and then decreases gradually during the interval, see figure 4.13. The oscillations in the x-direction for the steel shoe on the measurements done on the horse Empe shows the similar characteristic pattern as the oscillations in Dora’s mea- surements. The oscillations intense part gradually decreases from the highest collected amplitude, see appendix E.1 25 4. Results Figure 4.13: The characteristics of the oscillations in x-direction of the hoof wearing a steel shoe on concrete. It was a decrease of oscillations in the y-and x-direction for Dora’s measurements, and the y-direction follows the same characteristic pattern as the x-direction. The z-direction had a different pattern compared to the other directions, where the oscillations did not decrease in the same way and kept more intense oscillations during the whole interval. In figure 4.14 you can see the different between the y-direction and the z-direction. The appearance of the oscillations in Empe’s measurement has the same intense charac- teristic pattern as the y-direction and the z-direction in Dora’s measurements. Where the highest amplitude occurred, so did the most intense oscillations occurred, see appendix E.1. 26 4. Results Figure 4.14: The left show the character of the oscillation in y-direction and the right in z-direction, in combination of steel and concrete. In the combination of steel and fibre sand there was considerably less oscillations where the highest amplitude was collected. There was difficulties to find a characteristic pattern for the steel shoe. This shows that the fibre sand has a large impact on the oscillations in the hoof while wearing a steel shoe. In figure 4.15 the oscillations for Dora’s measure- ments of the x-direction in the combination of steel and fibre sand is shown. The same oscillation pattern was shown when analyzing Empe’s measurements, see appendix E.2. Figure 4.15: The oscillations in x-direction of the hoof wearing a steel shoe on fibre sand. 27 4. Results The analysis in the combination of steel and fibre sand shows that fibre sand also reduces the oscillations in the y-direction and the z-direction in Dora’s measurements, see figure 4.16. Appendix E.2 shows how the fibre sand also attenuate the oscillations in Empe’s measurements. Figure 4.16: The left show the character of the oscillation in y-direction and the right in z-direction, in combination of steel and fibre sand. 4.3.4.2 Öllöv SoftStep The most significant difference between Öllöv SoftStep and the steel shoe was that Öllöv SoftStep showed a different pattern, where the part with the intense oscillations decreased radically until total attenuation. The qualities in Öllöv SoftStep was able to attenuate the oscillations in the same time range, but less intense oscillations occurred, see figure 4.17. Just like the analysis of the steel the intense oscillations appeared where the highest am- plitude is collected, but the oscillations is sparser. Empe’s measurements the same characteristics oscillations pattern as Dora’s measure- ments, see appendix E.3 28 4. Results Figure 4.17: The characteristics of the oscillations in x-direction of the hoof wearing a Öllöv SoftStep on concrete. The same applies in the y-direction and the z-direction in Doras’s measurements, where the oscillations were significantly less during the hoof impact and the highest amplitude. As the analysis of the x-direction, the oscillations attenuation more in Öllöv SoftStep than in the steel shoe, see figure 4.18. Empe’s measurements in the y-direction followed the same pattern as Dora, although you could see a slightly intense oscillation which decreased radically in the z-direction, see appendix E.3 29 4. Results Figure 4.18: The left shows the character of the oscillation in y-direction and the right in z-direction, in combination of Öllöv SoftStep and concrete. In the same way as with steel shoe on fibre sand, it was difficult to see a clear pattern in the combination of Öllöv SoftStep and fibre sand in Dora’s measurements. The oscillations kept the same characteristic pattern as the steel shoe during the hoof impact, but there were a certain differences in the number of oscillation, see figure 4.19. The oscillation in the combination of Öllöv SoftStep and fibre sand is still less than steel, but the differences are not as significant as on concrete. The same similarities occurred in Empe’s measure- ments for Öllöv SoftStep on fibre sand, see appendix E.4. Figure 4.19: The oscillations in x-direction of the hoof wearing Öllöv SoftStep on fibre sand. 30 4. Results In y-direction and z-direction, Öllöv SoftStep has the same characteristic as the steel shoe in Dora’s measurements, it’s the fibre sand that contributes to the most of the damping qualities, see figure 4.20. Empe’s measurements follows the same pattern, see appendix E.4 Figure 4.20: The left shows the character of the oscillations in y-direction and the right in z-direction, in combination of Öllöv SoftStep and fibre sand. 4.3.4.3 Unshod hoof The unshod hoof’s most intense oscillations also occurred during the hoof impact in Dora’s measurements, where the largest amplitude occurred. The unshod hoof had a similar characteristic pattern as Öllöv SoftStep on concrete, where the part with intense oscillations decreased radically until total attenuation, see figure 4.21. In Empe’s measurements the x-directions was more similar to the steel shoe, than to Öllöv SoftStep. This was the characteristic pattern typical for the analysis of the oscillations in the combination of the unshod hoof and concrete for Empe, see appendix E.5 The intense of the oscillation was still lower than the oscillations in the combination of steel shoe and concrete. 31 4. Results Figure 4.21: The characteristics of the oscillations in x-direction of the unshod hoof on concrete. As shown in figure 4.22, the oscillations occurred more in the y-direction and the z- direction in the unshod hoof than the hoof wearing Öllöv SoftStep on the concrete. The unshod hoof had a poorer ability to attenuate the oscillations on concrete in these di- rections. The same pattern with a slightly increase of oscillations occurred in Empe’s measurements, see appendix E.5. 32 4. Results Figure 4.22: The left shows the character of the oscialltion in y-direction and the right in z-direction, in combination of unshod hoof and concrete. The analysis of the unshod hoof on fibre sand showed a similar pattern as both the steel shoe and Öllöv SoftStep did for Dora’s measurements. The fibre sand attenuate the os- cillation in the unshod hoof, and only sparse oscillation occurred. Figure 4.23 shows the unshod hooves oscillations on fibre sand in x-direction for Dora’s measurements and has the same characteristics as well as the hoof wearing steel shoe and Öllöv SoftStep. The same pattern is shown in appendix E.6 for Empe’s measurements Figure 4.23: The oscillations in x-direction of the unshod hoof on fibre sand. Figure 4.24 shows the unshod hoof’s oscillations on fibre sand in y-direction and z- direction in Dora’s measurements. The left picture in the figure is over a larger range 33 4. Results to show that the most intense oscillations occurred by -30 m/s2. It still has the same char- acteristics as the steel shoe and Öllöv SoftStep, but a displacement by the most intense oscillations position. The displacement did not occurred in Empe’s measurements, see appendix E.6. Figure 4.24: The left shows the character of the oscillation in y-direction and the right in z-direction, in combination of rubber and fibre sand. 34 5 Discussion The result shows that Öllöv SoftStep is a clearly better option than the steel shoe in shock absorbing on hard grounds. On hard grounds it absorbs shocks better than an unshod hoof as well. On the soft ground, fibre sand, there is no significant difference between the steel shoe, unshod and Öllöv SoftStep. In this study there has only been measurements done on concrete and fibre sand as grounds, which can be seen as two extremes. Concrete is a very hard ground and is mainly used in stables for shorter transports, and then only while the horse is walking. Fibre sand is developed to be an absorbing ground for the horses, so the results show that there are no significant differences between the different shoes on fibre sand. It confirms that it is a shock absorbing ground. How Öllöv SoftStep works on concrete can be compared how it would be to trotting on asphalt, which is a more common ground for horses. Although, measurements on asphalt must be done to determine it. The measurements have only been done in trotting and with an average speed of 2.8 m/s. The movement pattern for the horses differ between the different gaits, therefore can this study only determine the qualities in trot. In future testing walking and gallop should be tested to realize how they differ from each other in shock and vibrations that occur in different shoes. The results from the amplitude measurements shows that the steel shoe has higher values than the unshod hoof on concrete, and that Öllöv SoftStep has lower values than the un- shod hoof. It is hard to see some clearly similar percentage in table 4.1 and table 4.2, that is very likely because it is two different horses with their own movement pattern. When in table 4.3 not to compare Öllöv SoftStep and the steel shoe with the unshod hoof but to each other instead gives a more aggregated value. In this comparison the highest ampli- tude value for Dora wearing Öllöv SoftStep is 50% of the highest value wearing the steel shoe. The same comparison for Empe is at 26%. Due to time limitations there has only been comparison i x-direction for the shock ab- sorbing analysis, that is the vertical direction and there the highest and most decisive amplitude values can be found. The fact that both the horses had more uneven steps during measurements on concrete than on the fibre sand can have some different factors. A simple explanation is that the horses felt more at ease at the much bigger riding cite than in the stable and therefore had more even steps. On the fibre sand they had quite a long reach to get into the right speed. At the concrete it was a more abrupt start. Due to that is no difference between the shoeing types in the spread of steps, it is not likely that the grip of the shoes has affected the horses to more or less even steps at the grounds. Another possible reason to the irregularly of 35 5. Discussion the horses steps is the light beam was from the high speed camera. In the stables the light beam were clearer than in the riding cite. It is possible that the horses reacted to the light and therefore had irregular steps, and more irregular on the concrete than on the fibre sand. In the analyze of the vibration, the mainly difficulty was that the logger had a sampling rate at 7161 points/s, so the highest frequency we would be able to calculate would be 3581 hertz according to the Nyquist sampling theorem. The new method we had to apply was a time consuming analytic method, where every five steps in every measurement had to be analyzed. There is always a human factor that has to be taken in to account, this means that there is always a certain percentage risk of making mistakes. To ensure that this human factor won’t have any significant impact on the final result, we saved over 400 pictures of graphs from the different combinations of shoe and ground. This to be able to compare as many of the oscillations as possible to give a representative result. The human error is still a factor that has to be taken in to account, when not using a numerical method. A logger with a higher sampling rate would provide the test a more accurate frequency analysis. The two grounds the measurements were preformed on have two different characteristics. It was easier to see a characteristic pattern of the oscillations on the hoof when they were performed on concrete. The concrete is a hard, tightly packed ground, and after every measurement the ground surface was unchanged. The fibre sand on the other hand, has an airier top layer. This allows the surface of the ground to change between each mea- surement and depending on where the horse places it’s hoof the accelerometer may have an interference between the different directions. This may be a reason why it is easier to find the pattern on the measurements made on concrete. In Dora’s measurements with an unshod hoof on fibre sand, the most intense oscillations occurred by -30 m/s2. This was not similar to Empe’s measurements with the same com- bination. This may be a consequence of the accelerometers position on the hoof. The possibility that the accelerometer had been dislocated between the test was not taken in to account. Dora’s and Empe’s oscillations with unshod hoof on concrete, was the largest differential in the characteristic oscillation pattern analysis. Empe’s measurements showed character- istic similar to the steel shoe, while Dora showed characteristic similar to Öllöv SoftStep. As mentioned earlier in the study, the hoof works as a part of a shock absorbing-system. The hooves quality differs from one to another and Dora may have a better attenuate qual- ity in the hooves. In figure 5.1 we placed the graph from a measurement with steel shoe on concrete, beside a measurement with Öllöv SoftStep on concrete in the x-direction. This was the char- acteristics of the oscillations in the analyze that showed how Öllöv SoftStep was able to attenuate the oscillations in a much more effective way than the steel shoe could. The steel shoe has what is called a typical decreasing sinusoidal curve, where the intense oscilla- tions gradually decreases. As a former study had showed, the quality in synthetics have a vibration damping properties and a lower frequency during the hoof impact. According 36 5. Discussion to this analysis Öllöv SoftStep has similar properties. Figure 5.1: The left show oscillations with steel and the right with Öllöv SoftStep, both on concrete. The horses used in the tests was used to wearing steel shoes, this could have an impact on the result. It all comes down to that the horses are living animals. If a horse is used to wearing steel shoe, they adjust to their ability to their movements. If the horses affected their movements while wearing the rubber shoe is hard to say. Therefore would also measurements on horses used to Öllöv SoftStep be interesting to analyze. 5.1 Recommendations In this study we made a good foundation for testing and analyze measurements with an accelerometer but our belief is that there is still much to examine. Our recommendations for future testing is following: To do measurements on more horses and on different kind of breeds for a more precise value how the qualities of Öllöv SoftStep are. This study was only done on concrete and fibre sand and more commonly used grounds for horses should be tested on, such as grass, gravel and soil. For future measurements it should be more prioritized to have similar terms for the dif- ferent measuring cites and that there are no disturbances on the measuring track that can affect the horses, such as the light from the high speed camera. A recommendation for future test, is to verify the accelerometers location on the hoof between every measurement to get as similar initial value as possible in every graph. If the horses affected their movements while wearing the rubber shoe is hard to say. There- fore would also measurements on horses used to Öllöv SoftStep be of a recommendation. 37 5. Discussion 38 6 Conclusion As previous measurements have shown that the rubber shoe is a better option than steel shoe for hard grounds. On soft grounds as fibre sand there is no significant difference. In this study it is proven that Öllöv SoftStep is a better than both unshod hoof and a steel shoe at absorbing shocks that occur when trotting on a hard ground such as concrete. By the analysis of the vibration damping, significant differences were shown between Öllöv SoftStep and the steel shoe on concrete. Öllöv SoftStep was able to attenuate the resulting oscillations significantly better than the steel shoe during the same interval. It occurred more oscillation in the steel shoe during the impact phase, than in Öllöv Soft- Step during the same interval. Öllöv SoftStep has better vibration damping qualities than the steel shoe. The analysis between the unshod hoof och Öllöv SoftStep showed two different patterns. Öllöv SoftStep had in both cases better vibration damping, but in one case significantly better and in the other case slightly better. Öllöv SoftStep has better vibration damping qualities than the unshod hoof, but the significance of the differ is not concluded. The analysis between steel shoe, Öllöv SoftStep and the unshod hoof on fibre sand showed that the characteristics was similar and the vibration damping qualities in Öllöv SoftStep had a lower impact on the vibrations in the fibre sand. Öllöv SoftStep has according to the analysis similar vibration damping qualities in fibre sand as an unshod hoof and a hoof wearing steel shoe. This study has given results on two different grounds, on two different horses. A more extensive study, which includes different grounds and more different horses, needs to be done to evaluate Öllöv SoftStep full quality. 39 6. Conclusion 40 Bibliography [1] Creative Commons CC0 (2017)Horse shoe (Retrieved 2018-05-15) https://pxhere.com/en/photo/1200456 [2] Yngve Anki (2016) Hovvård del 1: Så fungerar hästens hovar (Retrieved 2018-03- 10) https://www.hippson.se/artikelarkivet/hasthantering/ hovvard-del-1-sa-fungerar-hasthoven.htm [3] Judy Sandra (2012) Healthy hoof photos (Retrieved 2018-03-10) https://www.hosshoofho.com/healthy-hoof-photos.html [4] Internetmedicin (2018)Vibrationsskador i arm och hand (Retrieved 2018-05-02) https://www.internetmedicin.se/page.aspx?id=3393 [5] Arbetsmiljöverket (2015) Vibrationer(Retrieved 2018-05-02) www.av.se/globalassets/filer/publikationer/foreskrifter/ vibrationer-foreskrifter-afs2005-15.pdf [6] Johansson Eva (2017) Barfota versus skodd(Retrieved 2018-03-12) https://stud.epsilon.slu.se/10476/11/johansson_e_170717.pdf [7] S. Sandhagen, Personal communication, 25 april 2018. [8] Nationalencyklopedinm. Gummi. (Retrieved 2018-05-03) www.ne.se.proxy.lib.chalmers.se/uppslagsverk/encyklopedi/lång/ gummi [9] Patent- och registreringsverket (n.d) Gummiskor för hästars hälsa (Retrieved 2018-04-26) www.prv.se/sv/patent/varfor-patent/exempel-pa-patent/ gummisko-for-hastars-halsa/ [10] W. Back, M. HM van Schie, J. N Pol (2006) Synthetic shoes attenuate hoof im- pact in the trotting warmblood horse Departement of Equine Sciences, Faculty of Veterinary Medicin, Utrecht University. [11] U. Yxklintenm C. Johnston, L. Roepstorff, S. Drevemo (1996-1998) Öllöv orginal and the biomechanics in horses Swedish Agricultural University, Uppsala [12] U. Yxklinten (1996) Evaluation of the sliding-phase between the hoof and ground for horses with rubbershoes [13] S. Drevemo, C. Johnston (1992) Utvärdering av glidning mellan hov och underlag hos hästar med gummiskor Sveriges Lantbruksuniversitet, Inst. för Anatomi och histologi, Uppsala [14] Larson Davis (n.d) Triaxial Shear ICP Accelerometer (Retrieved 2018-05-02) www.larsondavis.com/Portals/LD/SEN040F.pdf [15] Larsson Davis (2017) Human Vibration Meter: for Workers safety Product testing (Retrieved 2018-04-25) 41 https://pxhere.com/en/photo/1200456 https://www.hippson.se/artikelarkivet/hasthantering/hovvard-del-1-sa-fungerar-hasthoven.htm https://www.hippson.se/artikelarkivet/hasthantering/hovvard-del-1-sa-fungerar-hasthoven.htm https://www.hosshoofho.com/healthy-hoof-photos.html https://www.internetmedicin.se/page.aspx?id=3393 www.av.se/globalassets/filer/publikationer/foreskrifter/vibrationer-foreskrifter-afs2005-15.pdf www.av.se/globalassets/filer/publikationer/foreskrifter/vibrationer-foreskrifter-afs2005-15.pdf https://stud.epsilon.slu.se/10476/11/johansson_e_170717.pdf www.ne.se.proxy.lib.chalmers.se/uppslagsverk/encyklopedi/l�ng/gummi www.ne.se.proxy.lib.chalmers.se/uppslagsverk/encyklopedi/l�ng/gummi www.prv.se/sv/patent/varfor-patent/exempel-pa-patent/gummisko-for-hastars-halsa/ www.prv.se/sv/patent/varfor-patent/exempel-pa-patent/gummisko-for-hastars-halsa/ www.larsondavis.com/Portals/LD/SEN040F.pdf Bibliography www.larsondavis.com/contentstore/mktgcontent/LD_Brochures/LD_ HVM200_Lowres.pdf [16] MATLAB R2017b academic use. The MathWorks, Inc., Natick, Massachusetts, United States. [17] Svenska Ridsportförbundet och SLU (2014)Ridunderlag, en guide (Retrieved 2018-05-08) http://www.ridsport.se/ImageVaultFiles/id_35816/cf_559/SvRF_ Ridunderlag_Mars_2014_LR.PDF [18] Svenska PRE-föreningen (2017-2018)Om Pura Raza Española (Retrieved 2018-05- 12) http://www.presverige.se/avel/om-rasen-37045398 [19] WhatIs.com (2005)Nyquist Theorem (Retrieved 2018-05-15) https://whatis.techtarget.com/definition/Nyquist-Theorem 42 www.larsondavis.com/contentstore/mktgcontent/LD_Brochures/LD_HVM200_Lowres.pdf www.larsondavis.com/contentstore/mktgcontent/LD_Brochures/LD_HVM200_Lowres.pdf http://www.ridsport.se/ImageVaultFiles/id_35816/cf_559/SvRF_Ridunderlag_Mars_2014_LR.PDF http://www.ridsport.se/ImageVaultFiles/id_35816/cf_559/SvRF_Ridunderlag_Mars_2014_LR.PDF http://www.presverige.se/avel/om-rasen-37045398 https://whatis.techtarget.com/definition/Nyquist-Theorem I A. Documentation of testing day A Documentation of testing day II A. Documentation of testing day III A. Documentation of testing day IV V B. Matlab code B Matlab code VI VII C. Amplitude results C Amplitude results VIII C. Amplitude results IX C. Amplitude results X XI D. Spread of steps D Spread of steps XII E Empe’s vibration measurements E.1 Empe’s measurements with steel shoe on concrete Figure E.1.1: The oscillations in x-direction of the steel shoe hoof on concrete. XIII E. Empe’s vibration measurements Figure E.1.2: The left shows the character of the oscillation in y-direction and the right in z-direction, in combination of steel and concrete. E.2 Empe’s measurements with steel shoe on fibre sand Figure E.2.1: The oscillations in x-direction of the steel shoe on fibre sand. XIV E. Empe’s vibration measurements Figure E.2.2: The left shows the character of the oscillation in y-direction and the right in z-direction, in combination of steel and fibre sand. E.3 Empe’s measurements with Öllöv Softstep on concrete Figure E.3.1: The oscillations in x-direction of Öllöv SoftStep on concrete. XV E. Empe’s vibration measurements Figure E.3.2: The left shows the character of the oscillation in y-direction and the right in z-direction, in combination of Öllöv SoftStep and concrete. E.4 Empe’s measurements with Öllöv Softstep on fibre sand Figure E.4.1: The oscillations in x-direction of Öllöv SoftStep on fibre sand. XVI E. Empe’s vibration measurements Figure E.4.2: The left shows the character of the oscillation in y-direction and the right in z-direction, in combination of Öllöv SoftStep and fibre sand. E.5 Empe’s measurements on unshod hoof on concrete Figure E.5.1: The oscillations in x-direction of the unshod hoof on concrete. XVII E. Empe’s vibration measurements Figure E.5.2: The left shows the character of the oscillation in y-direction and the right in z-direction, in combination of the unshod hoof and concrete. E.6 Empe’s measurements on unshod hoof on fibre sand Figure E.6.1: The oscillations in x-direction of the unshod hoof on fibre sand. XVIII E. Empe’s vibration measurements Figure E.6.2: The left shows the character of the oscillation in y-direction and the right in z-direction, in combination of the unshod hoof and fibre sand. XIX List of Tables List of Figures Introduction Purpose Delimitation Clarification of question Background Hoof-mechanism Vibration damage for humans Problems with current solution Rubber properties Öllöv and Halmstad Gummifabrik Öllöv SoftStep and differences from Öllöv Original Former studies Method Measuring equipment Accelerometer SEN040F Data logger HVM200 Metal bracket Pre-test at riding cite in Kullavik Implementation plan for the test day Test site in Vallda Horses used during testing day Method for analyzing measurements from testing day Approved measurements Processing of data Results Pre-test at riding stable in Kullavik Experiences from the pre-test Testing day in Vallda Results and analysis of the testing day Approved measurements Processing of raw data in Matlab and Excel Amplitude values to analyze shock absorption Vibrations Steel shoe Öllöv SoftStep Unshod hoof Discussion Recommendations Conclusion Bibliography Documentation of testing day Matlab code Amplitude results Spread of steps Empe's vibration measurements Empe's measurements with steel shoe on concrete Empe's measurements with steel shoe on fibre sand Empe's measurements with Öllöv Softstep on concrete Empe's measurements with Öllöv Softstep on fibre sand Empe's measurements on unshod hoof on concrete Empe's measurements on unshod hoof on fibre sand