Study On Error In Hybrid Mechanism Based On Tripod Universal Wrist & Biglide Parallel Mechanism

The parallel mechanism has a series of advantages, such as, high stiffness, high carrying capacity, excellent dynamic character, quick moving, simple frame etc, which has attracted the comprehensive attention of the international academic and engineering communities. Although the parallel mechanism's appearance can cover the shortages of the traditional series mechanism, the parallel mechanism itself has lots of drawbacks, like in capacious workplace, movement coupling, low contact stiffness, complex mathematic model, difficult to control and so on, which make the application of parallel mechanism fall into confinement. To improve the foregoing disadvantage efficiently, it's better to adopt series-parallel and hybrid structure when designing the structure of mechanism. In this article, a novel hybrid mechanism based on the successfully developed tripod parallel universal wrist and biglide parallel transition machine is proposed and its spatial mechanism theory is detailedly studied. Its error is analyzed.Firstly, based on large quantities of literatures from civil and overseas, the history, advantages, shortcomings and development of parallel kinematics machine were summarized. The significance of this thesis is illuminated.Secondly, there are many factors affected biglide parallel transition mechanism, such as: the length of poles and rotation gap. In this article, mathematical model of biglide parallel transition mechanism is established and the simulation of errors is carried on in MATLAB. Experiment is designed to modify the accuracy of mathematical model. The results show that theoretical calculation is correct. Error compensation program is given out to minimize the affection of biglide parallel transition mechanism accuracy.Thirdly, analysis of factors affect tripod universal wrist error is done, including:two expansion poles, main axle and terminal actuator. Error's mathematical model has been established, the corresponding simulation is given out using MATLAB. Lastly, the error analysis to hybrid mechanism has been carried on. The position analysis is calculated. Error mathematical model is established. There are many factors which affect the error in hybrid mechanism, including:the length of poles in parallel transition mechanism, two expansion poles and main axle and the terminal actuator in tripod universal wrist and so on. The corresponding simulation has been carried on by using MATLAB.