Chalmers Open Digital Repository

Welcome to Chalmers Open Digital Repository!

Here you can find:

Student theses and papers
Digital special collections, such as Chalmers modellkammare
Selected project reports

Research publications, reports and dissertations can be found in research.chalmers.se

Communities in Chalmers ODR

Select a community to browse its collections.

Now showing 1 - 2 of 2

Recent Submissions

The effects of natural aging, stress relief & ferritic nitrocarburizing treatment on the damping development of ventilated grey cast iron brake discs
(2026) Dittmer, Albin
This report investigates the change in Q-factor that ventilated grey cast iron brake discs with different treatments applied experience over time to analyse the impact of natural aging, stress relief treatment and ferritic nitrocarburizing treatment (FNC). Eighty grey cast iron brake discs in groups of twenty, each group having a different combination of material treatments applied to them, were measured with a standard damping measuring tool equipped with an excitation hammer and a microphone. Coupled with a microstructural analysis, thorough literally review and additional analysis, in-depth conclusions have been made regarding natural aging, stress relief treatment and ferritic nitrocarburizing treatment (FNC), and much more. The results show that stress relief treatment and ferritic nitrocarburizing treatment (FNC) have significant initial negative effects on the Q-factor, however they are also perceivably self-repairing this initial damage over time. The rate of self-repair is considerably slow, not being close to fully undoing the initial damage after 82 days but considering that the self-repairing trend shows no signs of stopping in its tracks there is a real possibility that it will give time. Other results include natural aging improving the Q-factor over time, geometric design having an impact on the Q-factor of the point measured and ferritic nitrocarburizing treatment (FNC) increasing the hardness of the grey cast iron material.
Flödesanalys och kontroll av ett Job-shopproduktionssystem
(2026) Hedenberg, Emil; Ebrahimi, Yusuf
Today’s industry is changing rapidly, and the demand for customized products with shorter lead times is growing. This bachelor thesis aims to analyze a company’s production system in order to identify bottlenecks and provide improvements in the production flow. The study was carried out through proved methods within lean, layout planning, and discrete event simulation. The data was modeled in Tecnomatix Plant Simulation, where the simulated model was verified and validated against the real production data to ensure accuracy. The results show that the sawing station creates significant bottlenecks and causes blocking, which prevents the whole system from working effectively. The analysis also demonstrates that machine placement and transport distances play an important role in lead time. An alternative layout was developed according to lean philosophy and the SSLP-method to improve production rate, utilize space, and create an efficient flow. The findings show that optimizing layout design and balancing cycle times can improve the overall performance and efficiency of the production system.
Utformning av produktionssystem och försörjningskedjan för tillverkning av mätinstrument
(2026) Boulos, Josef; Elia, David
This thesis aims to optimize the production at RanLOS AB and help them move from building one prototype at a time to producing in larger series. The goal is to create a cost effective, quality ensured and scalable production that focuses on reducing waste and ensuring a good material flow. The work is limited to the production side and logistics only, design and product development are not included in this project. The research questions addressed are how bottlenecks can be avoided by optimizing the flow of materials in production, and what safety stock levels are needed to reduce risk of longer lead times. A literature review was conducted to build knowledge in lean philosophy, value stream mapping, systematic layout planning (SLP) and safety stock. The value stream mapping was used to document the current production and identify areas for improvement. SLP helped plan where workstations should be placed, based on their relationship and material flow. The type of layout was discussed based on product volume and the variety of RanLOS products, comparing job shop, project line and cell layouts. A safety stock estimate was developed through calculations and reasonableness assessment done together with RanLOS. Observations and interviews with assembly workers and production managers were conducted throughout the project to collect data from the existing production. A simulation model was made in Siemens Plant Simulation after all mapping and data collection was completed. It recreated how the real system would work in the new layout. Several experiments were run on the digital model to evaluate the optimized flow
Cobot + Vision to remove plastic straps from pallets
(2026) Lokku, Roger; Gustafsson, Alexander
This thesis aims at assisting Volvo Trucks to automate the de-strapping of the incoming pallets on a conveyor line using a vision-based robotic solution. Volvo provides a UR10e cobot, a Photoneo 3D-scanner and Aurora Design Assistant (ADA) to carry out this thesis. In return, Volvo requires the answer to the question whether this robot, camera, and software configuration is satisfactory to get the job done. The solution, however, needs to be divided into two main parts - building the system architecture along with integration of the given equipments and development of methods for de-strapping of the pallets. This thesis proposes the system architecture along with integration of the given equipments and the three methods that have been developed for de-strapping of the pallets. Each method is a combination of the force mode functionality of the robot and the image processing functionality via ADA after image acquisition via the camera. A python script is used to act as the middle man between the robot’s controller and ADA, facilitating data exchange and logging of data. The methods will be judged on the ability of the camera to identify and localize the strap, the ability of the UR controller to form a valid robot path to grab the straps and the cycle time. The accuracy and dependability of the robot, camera and software is judged by doing 30 cycles of grabbing the straps at various pallet offset and/or rotated from/at a fixed point. This will give quantitative data. Thus, answering Volvo’s question of "Can a UR10e cobot, a Photoneo 3D-scanner and ADA be used to de-strap their pallets?". The calibration error of the estimated homogeneous transformation matrix was found to be 3.5 mm. The fastest method was Method 3 with an average cycle time of 39.24 s. The camera, when deployed on the production line, was able to correctly determine the presence of straps with a success rate of 76.79% and the success rate of the colour identification of the straps was 75.00%. The camera was found to be able to solve the strap identification and colour identification but having a 3D camera is deemed excessive, and the image quality could be the limitation of the robustness of strap identification and colour identification.
Robotic Phantom Knee and Digital Twin Platform for Early-Stage Exoskeleton Validation: Nonlinear Stiffness and Tuneable Soft-Tissue Compliance
(2026) Habrah, Wajih
Testing wearable exoskeletons and rehabilitation devices directly on human subjects is often expensive, time-consuming, and ethically challenging, especially during early-stage development when designs and control strategies are frequently updated. In addition, human trials introduce variability that complicates systematic benchmarking and controller verification. This thesis presents the design and development of a robotic phantom knee (RPK) testbed and a real-time Unity-based digital twin (DT) intended to provide a controlled bench-top platform for evaluating exoskeleton controllers. The developed system combines a single-degree-of-freedom knee hinge with antagonistic actuation using two Koala BEAR linear actuators coupled through an elastic linkage to shape the joint’s passive resistance. To emulate tuneable soft-tissue and interface compliance, the platform integrates inflatable chambers whose stiffness is adjusted via closed-loop pressure regulation using solenoid valves, a pump and reservoir, and pressure sensing. A modular ROS 2 (Jazzy) software stack on a Raspberry Pi 5 handles hardware communication, pressure control, and safety functions (including E-STOP and release-air). A Unity-based DT connects via ROS–TCP to visualize system state in real time and support interactive parameter tuning and experiment execution. Subsystem validation demonstrated stable ROS–TCP streaming, safety handling (ESTOP and release-air), and closed-loop pressure tracking suitable for bench-top trials. The platform supports systematic controller development and validation before human testing by enabling controlled experiments under configurable compliance conditions.