A Real-time and Parameterized Optimal Torque Distribution Strategy for 4WID Electric Vehicle without Road Adhesion Information

The straight-ahead torque distribution strategies of four-wheel independently driving (4WID) electric vehicles greatly impact on the vehicle's economy, traction and braking performance. Many adhesion-coefficient-dependent strategies have been put forward to improve the energy efficiency. To avoid the challenge to precisely estimate the road adhesion in practice, this paper proposes an energy-and-adhesion optimal torque distribution strategy with combination of online and offline methods. Both the workload utilization ratio and the energy efficiency are optimized. For the purpose of real-time application, the analytical solution of the optimal problem has been derived which is expressed by structure and experimental parameters. The simulation results reveal that the proposed strategy can obtain the equivalent economy performance under WLTP test cycle as the energy-oriented torque distribution strategy does. In addition, the traction capability and the brake safety can be better guaranteed.