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This article investigates the impact of Hall errors on the speed, rotor position, and current of joint motors in robots, focusing on brushless dc torque motors. On introducing the sensing principle of the Hall sensor in the torque motor system, the influence of circumferential installation errors and axial offset errors on the rotor position and current of the motor is derived analytically on the basis of the Hall vector signals. The results show that the Hall errors generate rotor position errors characterized by the occurrence of specific harmonics with inherent deviations in rotor position, which in turn introduce the ( ${2}{n}-{1}$ )th current harmonics. The study proceeds to conduct simulations for a comparative evaluation of the degrees of influence exerted by circumferential installation errors and by axial offset errors on the motor speed, rotor position, and current. These findings are then validated through experiments, wherein the characteristics of Hall errors’ influence are elucidated via analysis of speed and current harmonics. This study provides a fresh methodology for analyzing errors in Hall sensors.

In this article, a multicoil wireless power transmission (WPT) model is presented. The model is applied to the multi-degree-of-freedom (multi-DOF) motor rotor position detection system. The WPT system is evenly distributed on the upper part of the rotor, and the receiving coil is placed on the rotor shaft. When the motor rotor rotates along the three motion states of pitch, spin, and tilt, the receiving coil and multitransmit coil will produce angle deviation. The precise mutual inductance estimation method can be used to obtain the rotor position quickly and avoid complicated finite element calculation. The system can not only realize the pose estimation of the multi-DOF motor, but also provide flexible energy supplement for the manipulator. The WPT position measurement method is used for PID control of multi-DOF motor, and it is compared with the micro-electro-mechanical-system attitude measurement method. The mechanical sliding measurement method of the encoder is taken as a reference. The results show that the position detection method of WPT has high accuracy, and the estimation error is less than 2%.