New skid avoidance method for electric vehicle with independently controlled 4 in-wheel motors

Novel skid detection method for electric vehicle (EV) with independently controlled four in-wheel motors is proposed. This proposed method can detect the skidding of wheels with only the values of current and rotating velocity of each motor. Estimation of vehicle chassis velocity or wheel absolute velocity is not required any more, and this is remarkable advantage over conventional methods. In this proposed method, skid is detected with the dependence of traction force on motor torque. Traction force is estimated with simple disturbance observer, thus, the exact value of shaft input torque is required. It is quite easy for EVs, but not so for internal combustion vehicles (ICVs). The proposed algorithm is examined with experimental results with a laboratory-made electric vehicle "UOT Electric March". These experimental data show the effectiveness of the authors' new skid detection method. They also carried out a simulation to show how to prevent skidding with the proposed skid detection method.