Design of an Adaptive FO-PID Controller for an In-Wheel-Motor Driven Electric Vehicle 2017-01-0427

An EV prototype, with all the wheels respectively driven by 4 inwheel motors, is developed, and undergoes a series of practical measurements and road tests. Based on the obtained vehicle parameters, a multi-body dynamics model is built by using SolidWorks and Adams/Car, and then validated by track test data. The virtual prototype is served as the control plant in simulation. An adaptive fractional order PID (A-FO-PID) controller is designed to enhance the handling and stability performance of the EV. Considering the model uncertainties, e.g. the variation in body mass distribution and the consequent change in yaw moment of inertial, a Parameter Self-Adjusting Differential Evolution (PSA-DE) algorithm is adopted for tuning the controller parameters, i.e. K_P, K_I, K_D, λ and μ. As a modification of traditional DE algorithm, the so-called Variance of Population’s Fitness is utilized to evaluate the diversity of the population. In order to avoid the premature convergence problem, a random disturbance is applied on the scaling factor in each iteration step, until the optimal solution is resolved. The simulation tests under some typical handling cases are carried out, and the results show that the proposed A-FO-PID controller is feasible and effective to enhance the handling and stability performance of the vehicle.