Collaborative tracking control strategy for autonomous excavation of a hydraulic excavator

A hydraulic excavator consists of multiple electrohydraulic actuators (EHA) to control the movement of its manipulator. However, uncertainties and nonlinear behaviors of its hydraulic components always make it challenging to design a proper control strategy for successful excavation. This paper proposes a collaborative tracking control strategy to overcome these difficulties and minimize tracking errors of the bucket tip for autonomous excavation.

The proposed control strategy has two decoupled layers to tackle the complex problem of tracking control of a hydraulic excavator. As the first component, a PID controller was used to compensate for misplacement of the bucket tip on the working plane, and thus can contribute to minimizing tracking errors. Meanwhile, three separate fuzzy controllers as the second component were adopted to maintain the desired stroke of each EHA by adjusting the position of servo valves, which allows for tracking control during excavation operations due to its capability dealing with highly nonlinear and uncertain dynamics of the hydraulic components.

To validate the performance of the developed controllers, a multi-domain simulation model was created for co-simulations, which includes the control algorithms and the excavator’s mechanical and hydraulic system designed in Matlab and Amesim, respectively. Simulations indicate that the proposed method enables achieving accurate tracking control for autonomous excavation with small tracking errors despite the nonlinear characteristics of the hydraulic excavator system.