Research On Hydraulic Robotic Excavator Servo Control System

This paper studies on the servo control system of the hydraulic robotic excavator. After addressing and analyzing the problems of the servo control system in hydraulic excavator, a control strategy that the servo control effect can not only depend on the servo control of each link but also depend on the coordinate control between three links is proposed. Experiments are carried out on an experimental excavator (WY3. 5 Hydraulic Excavator) produced by Mechanical Design Institute of Zhejiang University. Relative experiment results have been gathered up and analyzed to demonstrate the feasibility and promise of that control method. More detail will be discussed in the following:(1) Establishment and analysis of the servo control system. This paper divides the servo control system into two parts: mechanical part and hydraulic part. Each part has been mathematically modeled. And the nonlinearity and time-variety of each part has been analyzed according to the servo control system.(2)Study on servo control method of each link. A nonlinear proportional-integral(NPI) controller has firstly been introduced and then been improved according to the experimental excavator. Simulation has been carried out to analyze the capability of the controller.(3)Study on coordinate control method between three links. In robotic excavator servo control system, the uncoordinated speeds between links always make quite trajectory errors no matter how well each link performs. This paper put forward a coordinate control method based on cross-coupled precompensation(CCP) method to solve the above problem. Simulation has also been carried out to analyze the capability of the control method.(4)Experiments and result analysis. Two experimental schemes are proposed for NPI and CCP respectively. Results have been analyzed and evaluated to demonstrate the feasibility and promise of the two control methods.