Optimal motion generation for heavy duty industrial robots—control scheme and algorithm

In this paper an optimal motion generation approach for a heavy duty industrial robot, including both the control scheme and algorithm, was designed and tested. Aiming for the main defects in data sampling interpolation process of traditional motion control scheme, a FC based control scheme is proposed, An industrial computer with a TwinCAT real-time system was chosen as the motion control unit,and EtherCAT was used for command transmission. With the bask requirements of motion generation, a navel time and power optimal motion generation algorithm based on modified cubic spline interpolation is proposed. The execution time and work were chosen as the objective function. The constraints are the limits of torque, velocity and jerk. The position and velocity of the optimized motion were smooth. Acceleration was continuous throughout the execution period, including at the start point and end point Then the proposed control scheme and motion generation algorithm was applied for control of heavy duty material handling robots. The final experimental results showed that after obtaining motion parameters in an off-line stage, the computation of interpolation in Cartesian space could be finished very rapidly, within a short sample time (about four times the sample time of the position control loop). And the motion generation algorithm has a great effect on energy saving and production efficiency improvement.