Traction Control for Off-Road Full Electric Vehicle

Abstract

In this Master thesis a traction control for the construction equipment wheel loader is developed and analysed for the vehicle motion control system. The wheel loader is a articulated vehicle used for different application in various environmental terrains. The machine was undergoing some drawbacks with the current system, this lead to study and development of the new system. There are many research work performed in this industry related to this subject, by considering them as reference the work was initiated. The vehicle considered and studied in the work is an under development vehicle in Volvo Construction Equipment. The tire is the contact patch of the complete vehicle with the ground. The tire characteristics and the dynamics are very important for the vehicle performance. Study and analysis on tire shows, the tire power efficiency is directly connected with the slip ratio. The slip should be maintained with the optimal value irrespective of the environmental conditions. This optimal value should be maintained in all the wheels to keep the vehicle stable and energy efficient. The input signals are used to maintain the optimal slip value according to the ground condition and the application performed. Study shows that, controlling these values results in the stability and better performance in the vehicle. During the study of controller it is noticed that, torque and wheel speed at individual wheel plays a major role in the process of control action. By using both the signal together in the PID controller the control strategy to the proposed controller is developed. In this action individual torque and wheel speed controller are designed. They are connected in series. The working cycle of the wheel loader are divided into torque and speed mode depending on the type of driver request. The working of the both the controller also depends on the mode of operation.The simulation are performed in both the modes in different environmental condition on wheel loader model. These results are compared with the current or baseline controller used in the vehicle. Finally along with the development of new controller strategy, it is compared with current controller to obtain the drawbacks during its performance. The comparison includes some limitations considered throughout the project. Hence future work is required to tune the controller for the wheel loader productivity.