The Critical Theory Study Of 3SPS+SP Parallel Mechanism

With the development of parallel mechanism research, lower-mobility parallel mechanism have attracted much attention due to their simple in structure, easy control, and low cost, ect. Moreover,they have much more wider apply foreground in production and manufacturing. Based on the analyses of the current situation of the lower-mobility parallel mechanism home and abroad, A novel 3SPS+SP parallel mechanism with 4-DOF is put forward in this dissertation. This mechanism which has a compound spherical joint can perform three rotational DOF and one translational DOF. Some important theoretical issues on the spatial parallel mechanisms are investigated systematically and the analytic results are verified.Based on the existence of geometry constraints, the inverse position quations of the parallel mechanism are derived by using vector method. Through the dissolution of the Coupling relationship between position, a jabobian matrix and a Hessian matrix without the partial differentiation are derived. By means of CAD variation geometry approach,the simulation mechnisms of the 3SPS+SP parallel mechanism are built and the analytic results are verified.MATLAB-based programmming, eitht groups solution of forward position and its corresponding errors are obtained throuth the numerical algorithm which combines gradient descent method and Newton's method, fast and effectively.The reachable workspces and sub-workspces of the parallel mechanism are solved via double extremum method and Envelope method, respectively. The impact of independent parameters, limbs length and the scope of spherical joint on the work space'section was analysis qualitatively,with consteaint-based inverse kinematcs equations MATLAB independent variables. The static analysis of the parallel mechanism is studied by using virtual work theory. The model of dynamics is set up by Lagrange method and the system state-space equation is drived,which laid the foundation for the design of system.The analysis platform of 4-DOF is developed through graphical user interface in MATLAB. The feature of this platform is easy applicability and simple operation. The parameters analysis of parallel mechanism is achieved by the anslysis platform.In order to ensure validity of dynamics analysis, the entity modeling is built in Proe sorfware, then dynamic simulation and analog processing are carried out by ADAMS software, and the simulative results provides a reference for the design of actual prototype.