Kinematics and trajectory planning of a cucumber harvesting robot manipulator

In order to reduce cucumber harvesting cost and improve economic benefits, a cucumber harvesting robot was developed. The cucumber harvesting robot consists of a vehicle, a 4-DOF articulated manipulator, an end-effector, an upper monitor, a vision system and four DC servo drive systems. The Kinematics of the cucumber harvesting robot manipulator was constructed using D-H coordinate frame model. And the inverse kinematics which provides a foundation for trajectory planning has been solved with inverse transform technique. The cycloidal motion, which has properties of continuity and zero velocity and acceleration at the ports of the bounded interval, was adopted as a feasible approach to plan trajectory in joint space of the cucumber harvesting robot manipulator. Moreover, hardware and software based on CAN-bus communication between the upper monitor and the joint controllers have been designed. Experimental results show that the upper monitor communicates with the four joint controllers efficiently by CAN-bus, and the integrated errors of four joint angles do not exceed four degrees. Probable factors resulting in the errors were analyzed and the corresponding solutions for improving precision are proposed.