Robotic excavator motion control using a nonlinear proportional-integral controller and cross-coupled pre-compensation

•A nonlinear proportional integral controller with pre-compensation is designed.•Performance of proportional integral controller and the new one is compared.•Cross-coupled pre-compensation will reduce tracking error of bucket tip.•Tracking error can be reduced to 2-9 cm according to the planned trajectory.

For a robotic excavator, there is no operator in the cab while it is working, so the moving trajectory of the bucket teeth is planned in advance. For such a multi-joint machine, the coordinate motion control algorithm must be properly designed to achieve high tracking precision. However, due to uncertainty of the load and fluctuation of the speed, the multi-actuator system cannot work stably, resulting in tracking errors. To improve tracking performance, a cross-coupled pre-compensation algorithm is put forward in this paper. It is combined with nonlinear proportional-integral controllers to optimize the control parameters of the actuators. Experiments are performed on a 3.5-ton exactor. The results show that the proposed control algorithm is effective for improving the tracking accuracy.