Optimal Distribution Control Of Non‐Linear Tire Force Of Electric Vehicles With In‐Wheel Motors

Abstract

An over‐actuated control system has the advantage of being able to use redundant actuators to reconfigure the control system and it can realize fault tolerant control. In order to achieve improved vehicle stability and handling performance for electric vehicles with in‐wheel steering and driving motors, the control of the vehicle body slip angle and yaw rate is actually an over‐actuated control problem. To obtain the optimal solution for this control problem, this study proposes a two‐level tire force distribution control method, where the upper level controller calculates the desired lateral and longitudinal forces generated by friction on the tire of each wheel according to the driver's steering and driving inputs. The lower level controller maps the desired tire forces into the input of each steering actuator and driving actuator. Unlike the linear mapping method applied in most of the current research, this study develops a proportional‐integral (PI) controller for each actuator so that the non‐linear tire characteristics can be counteracted. In addition, since the PI controllers for eight actuators (four steering actuators and four driving actuators) have a total of 16 control gains to be determined, a genetic algorithm is applied to accurately determine these control gains. The simulation results are presented to validate the control performance of the proposed tire force allocation method.

Radial pole path approach for fast response of affine constrained nonlinear systems with matched uncertainties

“…Remark The first constraint in the optimization problem of Step 3 aims the stability of the VSC scheme by limiting the feedback gain amplitude while the second and third constraints are due to the control limitations . This scalar nonlinear programming problem can be solved by heuristic and artificial intelligence methods like Genetic Algorithms, Tabu search, Bees Algorithm, and Particle Swarm Optimization . Sometimes, due to the problem simplicity, finding the feasible set of the variable v according to the constraints is suggested.…”

Continuous Steering Stability Control Based on an Energy-Saving Torque Distribution Algorithm for a Four in-Wheel-Motor Independent-Drive Electric Vehicle

“…(2) In the second-hierarchy torque distribution algorithm, the equality constraint Bu = v is converted to min W v (Bu − v) 2 and introduced into (20) as a penalty item to reduce the constraint intensity of the control error. The optimization problem can be reformulated as:…”

“…For example, Zhai et al [4] and Kang et al [19] separately developed a stability judgment controller and a supervisory controller to determine the control mode, in order to control both yaw rate and sideslip angle after judging whether the vehicle tends to be unstable. This kind of upper-level controller with stability judgement turns out to improve the steering stability to a certain degree, but may cause instability in extreme conditions because of the delayed control [20]. At the same time, compared with a control mode working continuously, a larger torque is also required for this control mode to restrain the tendency of the vehicle to lose its stability, which is not conducive to energy saving.…”

Vehicle Stability Enhancement through Hierarchical Control for a Four-Wheel-Independently-Actuated Electric Vehicle

“…Alipour et al [19] presented a three-level controller with a novel reference speed generation system to improve the vehicle lateral stability on slippery tracks. Li et al [20] proposed a two-level tire force distribution control method to improve vehicle stability and handling performance. PI controllers were leveraged for each actuator so that the nonlinearities of tires could be counteracted.…”