End-Effector Position Estimation and Control of Hydraulic Excavators with Total Stations

This paper presents an end-effector position esti-mator for excavators with total stations and joint angle sensors. The total stations are external sensors for measuring positions in the world coordinates and have high measurement accuracy, but the sampling interval is long, typically about
$0.3 s$
or longer. The structure of the estimator is a simple integrator of the end-effector velocity and acceleration obtained from the angle sensors with a high sampling frequency. To combine the information from the total stations and the angle sensors, which have different sampling intervals, the estimator resets its output by the total-station measurement with the lower sampling interval. Moreover, this paper presents an end-effector position controller employing the estimator. The estimator and the controller are validated by employing a real-time simulator of a hydraulic excavator.