The Innovative Design Of The New Three Degrees Of Freedom Controllable Mechanism

The research of mechanisms had significant changes with the development of technology. Because of the crossing, adding and penetrating of mutli-disciplinary and mechanisms, the range and content of the mechanism research were expanding. Multi-degree of freedom controllable mechanism was a new generalized mechanism, which had good flexibility output, high carrying capacity, high accuracy and fast running speed. Many domestic and foreign scholars got more achievement about research of controllable mechanism, but the results were still relatively fragmented, contents of the research about the controllable structural synthesis was still very small compared with the research of controllable mechanism kinematics characteristics, while it was more uncommon for the research about the mechanism configuration of the practical application of engineering.Now, excavator has mechanical transmission and hydraulic transmission. It is single of the traditional single-degree-of-freedom mechanical excavator and many actions can not be achieved. While, hydraulic excavator can achieve flexible tracks, but there are also some problems for high precision parts manufacturing of hydraulic, low life and oil spills. This paper combined the multi-DOF controllable mechanism with excavator, this controllable excavator not only overcame defects in short precision, single function and controlling complex, but also there are advantages with good rigidity, strong bearing and good flexible. Because the research about the controllable structural synthesis was still very small, this paper launched the type synthesis from the perspective of controllable mining mechanism, and it provided the basis for innovative. This is a thorny problem of the field of mechanical engineering, which is a long-term and impossible breakthrough.In response to these problems, this paper studied theory and methods of innovative design for the planar multi-degree of freedom controllable mechanism. This paper would serve excavators of construction machinery as an example, the main work of this paper for mining mechanism was the following aspects:Firstly, the structural analysis of the existing mechanical excavator with controllable mechanism was presented, it combined the regenerated kinematic chain method with number synthesis method, and the innovative design of the mechanism was completed. The original mechanism was generalized to a kinematic chain, then the ninety-eight motion chains were obtained by using number synthesis method. Through the specialized kinematic chains with design constraints, sixty-five acceptable specialized kinematic chains were attained. And sixty-two new mechanisms were synthesized with the particularization and getting rid of the existing mechanisms. Secondly, the degree of freedom was calculated by the theory of screw, when selecting a typical controllable mechanism and establishing a mathematical model of the new mechanism. The vector equation was established by the method of the closed-loop vector, forward kinematics and inverse kinematics of the mechanism were solved and the numerical analysis was completed.Thirdly, this chapter got Jacobian matrix and Hessian array of the mechanism on the basis of the position model, and the analysis of singularity combined splitting method and module method. The condition of workspace boundary of the mechanism was derived with using the implicit function theorem, the theoretical workspace was getting with simulation analysis.Finally, the virtual prototype model of the controllable mechanism was established. The result of the kinematics and dynamics simulation was analyzed. Compared excavating trajectory of simulation with the actual excavation trajectory, it was proved that the feasibility of the new excavation mechanism.