Research On A Hydraulic-mechanical Joint Model Simulation And Control Of A Demolition Robot's Working Equipment

A hydraulic demolition robot is a kind of special engineering robots. Researchers combine machinery and electronics, communication, control, hydraulic technology into an organic whole. When it is equipped with all kinds of instruments, it is able to complete the corresponding work such as demolishment and shearing under the high dangerous working conditions of inflaming and explosion. The characteristics of this kind of equipments are that the multi-bar mechanical arm's working stroke is long and its weight is also large, the equipments are driven in a hydraulic manner and better control performance of the system is needed. In order to explore the influence of the change of the quality of its working equipment on the dynamic performance of the system, by taking the main arm of one company's GTRC-15-type demolition robot as research object, dynamics equations of a hydraulic system are combined with those of a mechanical arm into a set of nonlinear time-varying state equations. Then a hydraulic- mechanical joint model of the main arm is established. The model can reflect the influence of time-varying parameters(e.g. the quality and dynamics equations' coefficients) on the dynamic performance of the system real-timely. Furthermore, the prototype experiment system based on the control and testing of the CANopen fieldbus is built to accomplish relevant experiments. Compared simulation results with experiments, the system model is proved to be accurate and reasonable, and the influence of closed- loop PID control on the system is explored by experiments. The main work is as follows:(1). A research object of this paper is introduced briefly. Then, the domestic and foreign research development of the motion control of working device of the demolition robot is summarized.(2). The principle of the working device's hydraulic system is analyzed. Through the study of the flow equations of the hydraulic system, the flow continuous equations of the asymmetric hydraulic cylinder and the balance equation between output force of the hydraulic cylinder and load force, the open- loop transfer function of the hydraulic system is established and the equivalent mass M of the working device has a direct influence on the dynamic performance of the whole system. In order to analyze time-varying parameter M conveniently, the state equations of the hydraulic system are deduced.(3).Taking the main arm as an example, the formula of load equivalent mass M1 of the main arm is deduced by the theory of mechanics knowledge. For achieving the transformation between the demolition points and joint spaces and fullfiling the transformation between joint spaces and the drive spaces, the kinematics model of the demolition robot's work device is established. The extremums of equivalent mass M1 are estimated by 1stopt, and the change relationship between M1 and the joint angle ?1 is analyzed by Matlab.(4).The dynamic mathematical model of the demolition robot's working device is established by the method of Lagrange. Considering the coupling of joints among mechanical arms and the application of engineering, the system model in the most unstable state of the main arm is analyzed on the basis of the previous chapter, then the dynamics equation of the main arm is concluded.(5).In the most unstable state of the demolition robot's main arm, dynamics equations of a hydraulic system are combined with those of a mechanical arm into a set of nonlinear time-varying state equations. Then a hydraulic- mechanical joint model of the main arm is established. The model is simulated by open- loop control and closed- loop control. Compared simulation results with experiments, the system model is proved to be accurate and reasonable.(6). Furthermore, the prototype experiment system based on the control and testing of the CANopen fieldbus is built to accomplish relevant experiments and the analysis of dates. Experiment One, the influence of P, I, D on the PID closed- loop control system is studied on the basis of the hydraulic- mechanical joint model being correct, and the robustness of PID closed- loop control is tested. Experiment Two, based on the Experiment One, the actual tracks of the hydraulic hammer are tested under different control conditions, and the influence of the open-loop and closed- loop PID control on the motion of hydraulic cylinder and the track of hammer's top is studied.