Research On Virtual Prototyping Of Mechanical-Electrical-Hydraulic Coupling Manipulator

Nuclear radiation does harm to the human deadly, but we have to depend on nuclear energy to meet our great demands for energy resource. Remote handling manipulator is a good solution to solve the contradiction between radiation and needs, so the research and development of remote handling manipulator and automatic transfer vehicle under nuclear environment are regarded as a key technology by many countries in the world. The most typical example is the ITER (International Thermonuclear Experimental Reactor) program launched by seven sides including China, America, Japan, Russia, Korea, India and Europe union. The seven sides will invest about fifty hundred million euros to construct a large-scale reactor of nuclear fusion, and further to explore the technique approach of generating electricity by nuclear fusion of magnetism restriction. Fifteen kinds of automatic transfer vehicles will be employed in the ITER. These vehicles are air cushion vehicles with 8-meter length, 5-meter height and 3-meter width. Their main function is to transport heavy parts between the vacuum vessel of ITER building and hot cell (maintaining room). There is a manipulator inside the vehicle to realize the operations of installation, uninstallation and transit of the seal plug at the port of vacuum vessel and hot cell.The study object of this dissertation is just the manipulator driven by hydraulic cylinders. The deadweight of the manipulator is about 5 tons, and weight of the manipulated object is about 45 tons. The accurate orientation of the manipulator is the precondition to operate the heavy-load seal plug precisely, safely and reliably. The accurate orientation is based on the adjustment of position and pose, trajectory planning, friction compensation and track control, so these points are the key research topics to manipulat the 45-ton seal plug successfully. Since the manipulator is heavy and expensive, virtual prototyping of the manipulator is developed to verify the design. The research content of this thesis includes the modeling of virtual prototyping, the analysis and modeling of kinematics and dynamics, the adjusting of position and post, trajectory planning, friction compensation of hydraulic joints, trajectory track control, the establishment of co-simulation experimental platform of mechanical-electrical-hydraulic coupling system, the co-simulation of the manipulator, the dynamic finite element analysis of the manipulator. The main research achievements of the dissertation are as follows:1. The analysis and modeling of kinematics and dynamics of manipulator Tilting and lifting mechanism of manipulator is the most important movement component, so it is very necessary to research and analyze the movement trait of this mechanism. At first a model of 7-linkage complicated plane mechanism is built, and then the mathematic relations between the tilting angle 9 of tilting and lifting frame and the displacement of hydraulic cylinders, between the lifting heightΔh of frame and the displacement of hydraulic cylinders, between the lifting heightΔh and horizontal displacementΔs of frame are all concluded by a series of close deducing and calculation, finally the above established mathematical models were proved to be accurate and valid by comparing the calculated results with kinematics simulation resuluts of mechanism. Besides the dynamics characteristic and dynamic statics analysis of the tilting and lifting mechanism were also studied. All these analysis and modeling will provide theoretic guidance and numerical basis for the intelligent control of hydraulic cylinders of manipulator.2. The implementation of the trajectory planning of manipulatorIn view of the disadvantage of traditional trajectory planning method such as no only kinematics converse solution, the great computation, and the bad characteristic of real time, a new method of trajectory planning was proposed by using converse simulation idea and combining the modeling and simulation technology of virtual prototyping, moreover the definition rule of the driving, passive, or virtual joints was also recited in the dissertation. Not only were some shortcomings of the traditional planning method conquered, but also the continuity of displacement, velocity and acceleration of the end trajectory and each joint was guaranteed. Finally the validity and accuracy of this method were confirmed by the converse kinematics simulation of manipulator. In addition the complicated adjustment of position and pose of manipulator was translated to the reposition of hydraulic cylinders by comprehensive analysis and accurate geometrical constructing. Not only was the control system simplified, but also the precise orientation of manipulator was guaranteed easily by this method. At last the accurate trajectory planning and precise orientation of manipulator were both obtained.3. Joint friction compensation and accurate trajectory track of thr manipulatorJoint friction is one of the major limitations to make manipulator perform high precision tasks. Friction compensation of hydraulic joint is particularly important for manipulator driven by hydraulic cylinders to implement the accurate position and speed control. So in order to eliminate the friction made by the hydraulic joints, a friction compensation method based on fuzzy and sliding intelligent control was proposed after analyzing the complicated friction phenomena, friction modeling, traditional friction compensation method and its excellence and shortcoming. This method integrating the fuzzy control with sliding mode control not only keeps the merit of sliding mode control such as the speediness response, the characteristic of strong anti-jamming, but also can eliminate the high frequency input by the fuzzy rule. At last system simulation model of manipulator was established by the MATLAB/Simulink according to the actual parameter of hydraulic system, and the LuGre model of friction was also built. The results of simulation proved the efficacy of control algorithm based on fuzzy and sliding mode control, and that the friction of hydraulic joints of manipulator can be compensated perfectly, and the accurate trajectory track can be achieved.4. The strategy and implementing of co-simulation of manipulatorThe integration interfaces among CATIA, ADAMS and MATLAB were studied and explored in the dissertation, and the virtual experimental platform of co-simulation of mechanical-electrical-hydraulic complicated coupling system was established by the integration interfaces between different software, moreover the co-simulation of manipulator was carried out under this virtual platform. The validity of proposed control algorithm was proved, and the accurate trajectory track and the synchronization control of parallel hydraulic cylinders of manipulator were also implemented by the co-simulation of manipulator. A new method was presented in the mechanical-hydraulic coupling aspect. This method made use of the ability of automatic computation of ADAMS and the accurate virtual prototyping models to simulate the load change of piston rod of hydraulic cylinder during the movement process beforehand, and then the load change curve was input to the hydraulic cylinder while performing the hydraulic simulation to get the actual motion parameters of hydraulic cylinder. In this way the consistency between the change of the position and poise of manipulator and the hydraulic simulation of manipulator was guaranteed, and the mechanical-hydraulic coupling was achieved indeed.