Lateral stability control system for front two-wheel independent driving electric vehicle

Abstract

High specific indicators of power and torque of modern electric motors, as well as the relative ease of implementation of electric drive system,determinesthe feasibility of using in electric vehicles independentdrives fortwo or more wheels. The configuration of pure electric vehicleswith two driving front wheels, which is considered in this paper, is still uncommon, but it has the advantage of a radical simplification of transmission and steering mechanism. A specific feature of this configuration is the ability to perform by front-wheel drive systems, in addition to the main function of traction and braking bythe low-level of control, a number of additional functions atthe high-levelof control. In addition to the previously developed functions of the electronic differential, electric strengthening of steering and damping of spring oscillations of the steering mechanism, this paper also adds the function of lateral vehicle stability control in electric vehiclescornering. The article considers a seven-degreeof freedom mathematical model of dynamics of a four-wheeledvehicle and shows how this model can be simplified to a two-degree of freedom model describing the dynamics of antwo-wheeled vehicle. This model is sufficient to assess the lateral stabilityof electric vehiclesin cornering and forformation the reference ofadditional yaw-moment, which would regulate the yaw-rate to prevent the electric vehiclesskidding. On this basis, the structure of the lateral vehicle stabilitysystem was developed, which corrects the electromagnetic torques of the drive motors of the frontwheels to form the desired yaw-moment. For the studied electric vehicles with the set parameters, the dependences of the allowable yaw-rate on the set by a driver electric vehiclesspeed and angle of wheels turn in different traction conditions of wheels with a roadway are calculated. A general functional model of a front driving by twoindependentmotorselectric vehicleswith a two-level control system that performs all the above functions has been developed. In the Matlab/Simulink environment, a computer mathematical model of this electric vehiclewas built and simulation studies were conducted, which demonstrate the operation of the proposed lateral vehicle stabilitysystem.