|M.Sc Student||Selig Ilan|
|Subject||Steering Control and Stability Prediction of Off-road|
|Department||Department of Agricultural Engineering||Supervisor||Professor Emeritus Itzhak Shmulevich|
|Full Thesis text - in Hebrew|
The aim of this research is to develop a path tracking and stability control planning for an off-road vehicle. A simulation of the car performance and control model was built by integrating Simulink (simulation-software for models and control) with DADS (software for building and simulation of dynamic multi-bodies models). The control system includes the following compensated loops: Steering angle loop; Vehicle angle loop (Yaw); Vehicle's distance-from-the-path loop. A frequency response of the models was presented at varied working points, by identifying the simulation model response of each loop to a sinusoidal input at a constant range of frequencies. The working points differ by vehicle's speed and amplitude of the input. An analytic analysis of the reference signal influence on the vehicle angle loop was preformed. The reference signal was computed using the known Look-Ahead method.
The analysis shows the influence of the Look-Ahead Distance on the control loop stability. Linear compensators were planned with QFT (method for control planning for uncertain systems with known limits) from the identified frequency responses. A stability-predicting-model was integrated in the simulation for keeping the vehicle's stability during maneuvering. The model computes the desirable speed for safe maneuvering. The computation of the safe speed was based on a roll-over criterion, and a steering limitation criterion. The main achievements of the research are: a. Developing a comprehensive simulation model for controlling the maneuvering of an off-road vehicle. b. Good agreement at low frequencies was found between the simulation results and research listed in literature which used simple vehicle models. c. An improvement to the stability of the vehicle-angle control was achieved by performing an analytic analysis. d. Preventing specific roll over situations by integrating a simple stability predicting model with the vehicle simulation.