Study On Shimmy Control Method For Electric Vehicle Driven By Four In-wheel Motors With Unknown Sensor Sensitivity

The past few years have witnessed significant advancements in the development of electric vehicles,which have emerged as a crucial mode of transportation for individuals.However,with the proliferation of options available,the safety and stability of electric vehicles have gained prominence.Of particular concern is the occurrence of shimmy,which has a detrimental impact on vehicle ride comfort,stability,and safety.This paper focuses on the development of a non-linear four-degree-of-freedom(4-DOF)independent suspension shimmy model to mitigate or eliminate the shimmy phenomenon in electric vehicles powered by four in-wheel motors.The study proposes a sampled-data output feedback controller based on the constructed model to suppress shimmy effectively and enhance vehicle handling stability and ride comfort.The main research content of this paper is divided into five parts as follows:1.A 4-DOF active shimmy model is constructed.In light of the issue of front wheel shimmy in electric vehicles propelled by four in-wheel motors with independent suspension,which arises from various sources including utilization,external perturbations,and design and fabrication,the stability and smoothness of vehicle handling are adversely impacted.To address this challenge,a nonlinear 4-DOF model for front wheel shimmy has been developed via Lagrange equation,which incorporates the electric wheel model,the independent suspension model and the steering system model.2.Design an active shimmy sampled-data output feedback controller.To address the challenges posed by unknown sensor sensitivity error,environmental temperature,external interference and other factors that affect the accuracy of the dynamic model,as well as the difficulty in designing state observers and controllers due to nonlinear and unknown interference,we propose a sampled-data output feedback front wheel shimmy controller.The controller aims to mitigate front wheel shimmy during vehicle operation,and can effectively reduce or eliminate the phenomenon,which may cause large measured data error,poor system control effect and possible failure to work properly.To verify the effectiveness of the designed sampled-data output feedback controller in reducing front wheel shimmy,we also develop a sliding mode controller using sliding mode control method and compare its anti-shimmy performance with the former.3.MATLAB simulation analysis.To validate the accuracy of the established dynamic model and the effectiveness of the designed controller,we perform MATLAB simulation analysis under various speeds and excitation signals.The simulation analysis enables us to refine the established dynamic model and controller accordingly.We carry out separate simulation analyses of the sampled-data output feedback controller and the sliding mode controller and compare the simulation results to assess the effectiveness of the designed controller.4.Co-simulation of Simulink and Car Sim.To further validate the effectiveness of the designed control law in a practical environment,we conduct a co-simulation using Simulink and Car Sim.We select a class C-Type vehicle model in Car Sim as the simulation object,subjecting it to convergent sine input signal,sine input signal and step input signal at speeds of 20km/h and 100km/h.The swing angle of the left and right front wheels and the output force of the controller serve as evaluation indexes to verify the control effect of the designed sampled-data output feedback control method.We compare the performance of the sampled-data output feedback controller with that of the sliding mode controller.The simulation results demonstrate that the sampled-data output feedback controller outperforms the sliding mode controller in terms of convergence performance.Furthermore,it significantly improves the handling stability and ride comfort of the vehicle.5.Experiment verification.Experiment verification.Designing and building the front wheel active shimmy test platform.Carrying out the shimmy reduction experiment of the sampled-data output feedback controller at different vehicle speeds on the experiment platform to verify the effectiveness of the designed controller in this paper in practical engineering applications.