Research On Trajectory Tracking Electro-hydraulic Servo Control System Of Robotic Excavator

Robotic excavator is a mechatronics product concentrated in many fields of technology. Research on robotic excavator, to replace conventional hydraulic excavator, can reduce labor costs, improve working environment, increase quality of task and expand the application of excavators to a greater extent. Research on the servo control system of trajectory tracking is one of the preconditions for robotic excavator to realize autonomous mining. This thesis focuses on robotic excavator’s joint trajectory servo control. Mathematical modeling of robotic excavator’s working device and hydraulic system was carried out, electro-hydraulic servo controller based on sliding mode variable structure and flow-saturated resistant controller were designed, the whole modeling for simulation was established, robotic excavator experiment platform was built, and then trajectory tracking control experiments were completed.Overall, this paper is mainly about the following aspects:1. Kinematics analysis of spatial variables of robotic excavator and mathematical modeling of hydraulic systems. The conversion method between joint space and drive mechanism space were proposed. Hydraulic system components were analyzed, and the mathematical model of hydraulic system was established.2. Robotic excavator servo control system based on sliding mode variable Structure. To track the desired joint trajectory accurately, sliding mode variable structure control based electro-hydraulic servo system was designed. Proposed flow-saturated resistant control strategy is an effective solution for flow saturation of robotic excavators.3. Robotic excavator modeling and experimental study on trajectory tracking simulation. Simulation model of the robotic excavator based on AMESim was built. Simulation of joint trajectory tracking electro-hydraulic servo control was carried out, and trajectory tracking simulation results of sliding mode variable structure controller were compared with PID controller. Trajectory tracking simulation of multi-joint composite motion was completed. The results show that sliding mode variable structure controller and flow-saturated resistant controller can ensure all the joints trajectory tracking requirements and improve their trajectory tracking accuracy.4. Robotic excavator platform design and experimental study. Based on the slewing platform, boom, stick and bucket joints from a small hydraulic excavator, the robotic excavator experiment platform was developed. Experimental study of trajectory tracking mining was conducted, testing the function of robotic excavator platform.