Acceleration Noise Suppression for Geared In-Wheel-Motor Vehicles Using Double Encoder

In-wheel-motor type electric vehicles (IWM-EVs), which have independent motors inside each of the four wheels, are expected to be the next power-trains because they have quite good motion-control performance. From the viewpoint of commercial use, a reduction gear must be inserted between the motor and the wheels to increase the driving torque of the wheels, but doing so drastically declines the control performance because of gear elasticity and backlash. Moreover, the reduction gear not only obstructs the smooth transmission of the driving torque but also leads to unpleasant noise or ride-comfort deterioration. Here, we propose the gear-collision-free backlash-compensation and the joint-torque-control method for geared IWM-EVs by using a double encoder. Currently, the concepts of the double-encoder system are prevailing as an effective control method for the two-inertia systems in the motion-control societies. We have introduced these schemes skillfully and constructed a simple and practical control strategy. The suitable mechanical system of IWM and angular sensor resolution are also discussed, and its effectiveness is demonstrated via some simulations and experiments. We anticipate this research to solve the critical problem of the gear noise and facilitate the practical realization of IWM-EVs.