Motion Control for Hydraulic Steel Grab Excavator Based on Contour Compensation

Hydraulic steel grab excavators are widely used in steel handling tasks. However, due to nonlinear characteristics, large inertia, and hydraulic circuit coupling, achieving precise contour control is challenging, making steel grabbing and unloading tasks more complex. To address this issue, this paper proposes a contour compensation-based motion control method for hydraulic steel grab excavators. By analyzing the contour error characteristics across different operational stages, we design a contour compensation method to achieve precise trajectory tracking control of the end-actuator. Experimental results show that the proposed method limits the maximum tracking error in the horizontal direction within 3.72 cm, with an average error of 1.04 cm during the entire steel-grabbing process. Compared to traditional PID control, the proposed method reduces the maximum tracking error and average error by 76% and 66%, respectively, demonstrating its effectiveness.