Implementation of FPGA-based high performance joint servo controller

A fully digitized design scheme of joint servo controller is proposed through NIOS II processor, in which the vector control of PM motor, M/T speed measurement algorithm and SPWM generation were achieved, and so the trajectory plan in the joint, space joint position control and torque control. CAN controller was embedded in the FPGA. The CAN Bus communication interface to the host computer could be implemented to adjust the control parameters on the line. The sample rate of the current control loop was 20 kHz, while the sample rate of the position loop and torque loop could be set at least 1 kHz. Experimental results indicate that the precision of the joint quiescence is smaller than 0.01 degree. The Chinese Space Robotic Arm (the length is 1.8 m) was composed of six identical joints, the end precision of which was reach ±2.7 mm and meets the requirement of the space robotic.