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, determines the feasibility of using in electric vehicles independent drives for two or more wheels. The
configuration of pure electric vehicles with 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 by the low-level of control, a
number of additional functions at the high-level of 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 vehicles cornering. The article considers a seven-degree of freedom
mathematical model of dynamics of a four-wheeled vehicle and shows how this model can be simplified to a two-degree of freedom
model describing the dynamics of an two-wheeled vehicle. This model is sufficient to assess the lateral stability of electric vehicles in
cornering and for formation the reference of additional yaw-moment, which would regulate the yaw-rate to prevent the electric
vehicles skidding. On this basis, the structure of the lateral vehicle stability system was developed, which corrects the
electromagnetic torques of the drive motors of the front wheels 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 vehicles speed 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 two
independent motors electric vehicles with 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 vehicle was built and simulation studies were
conducted, which demonstrate the operation of the proposed lateral vehicle stability system