The distributed control system of a fruit and vegetable picking robot based on CAN bus

A distributed control system based on controller area network (CAN) bus is presented for an articulated picking robot with four degrees of freedom. The system is composed of one motion controller node and four joint servo controller nodes. The inverse kinematics transform, trajectory planning, and the end effector control are implemented on the motion controller. And joint servo controllers take charge of motor driving, position controlling, angle acquiring of AS5045. Moreover, the hardware circuits and programs are designed for the control system. In order to verify the reliability of CAN bus communication and feasibility of the control system, experiments on measuring motor rotating angles of the robot have been carried out. Results show that the motion controller can communicate with the four joint controllers efficiently through CAN bus, and the maximum measuring error of joint angles is about 2.03°, which could basically satisfy the request of the control system.