| In the paper, a kind of 3UPS-PU parallel mechanism was regarded as the research object, which was used for attitude adjustment experiment apparatus. Moreover, the kinematics, dynamics, error analysis and compensation and the reliability of the mechanism was further studied. The research findings were mainly as follows:(1)The structure of 3UPS-PU parallel mechanism was firstly explained for analyzing the possible freedom. And the branch’s inverse solution equation was constructed by the closed vector theoretical formula of parallel mechanism based on the input and output characteristics of parallel mechanism. The complete inverse kinematics of parallel mechanism has been deduced. Meanwhile, three legs’ length has been also obtained by inverse solution data.The inverse kinematics of typical working condition was subsequently simulated by the ADAMS software. Compared with mechanism’s kinematic theoretical results by MATLAB software, the correctness of inverse kinematics model has been verified. Based on the first-order influence coefficient method, the 3 x 3 jacobian matrix was constructed for the Euler angle form of rotation speed as the certification of one to one correspondence relation between 3UPS-PU parallel mechanism’s joint space speed and workspace speed, which could realize the plan and control of moving platform’s speed. The forward kinematics of the mechanism was further analyzed by the numerical method and the rule of attitude changing with rod has been obtained. Then the forward kinematics simulation of the mechanism was carried out through MATLAB software to obtain the forward kinematics curve. As a result, the correctness of forward kinematics was verified according to the case analysis compared with inverse kinematics data.(2)The dynamics of this mechanism was analyzed based on the principle of virtual work. And the dynamic relationship model between driving force and output kinematic parameters has been created. In addition, the change tendency of driving force and length have been revealed based on the simulation of typical working condition by MATLAB and ADAMS software. Due to the slightly error of the simulation results, it effectively verified the correctness and feasibility of the analysis method.(3)The basic concept of error and its source was firstly explained. Besides, the error model of 3UPS-PU parallel mechanism was established by using matrix differential method, which verified the correctness of the error model from the macro to micro accordance with the volume error and single element of the pose error. And based on the results of single error analysis through the error model, the main error terms were analyzed, which could afford the reliable foundations for determinations of parts manufacturing tolerances and its assembly levels. Then institutional hinge gap error was analyzed and calculated. Meanwhile, the parallel mechanism’s error compensation method of software and hardware theory were discussed and compared laying the foundation for error compensation and accuracy improvement.(4)The dynamics model of 3UPS-PU parallel mechanism was firstly established for revealing the movement reliability. Then the basic concept of reliability engineering and significance of motion reliability were discussed. And the various factors affecting reliability of mechanism were also expounded with a variety of methods of the reliability calculation. The advantages and disadvantages of each method were further analyzed. Finally, the mechanism’s motion reliability dynamics model r was obtained by Monte Carlo method considering size error and joint clearance error. |
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