Theoritical Study Of Limited-DOF Parallel Manipulators And Serial-Parallel Manipulators Based On Constrained Force/Torque

Recently, the theoretical and applied research for various novel limited-DOF parallel manipulators(PMs) becomes a very important research direction and a front technology. The essential differences between limited-DOF PMs and 6 DOF PMs lie in the structure constraints appear in this class PMs and thus the constrained forces/torques appear in the sub chains of this class PMs. The terminal of limited DOF PMs is restrained and the kinematics of the terminal is coupling. Due to the different structure constraints, the limited DOF PMs possess various kinematical characteristic. In fact, many properties of this class PMs are related to constraints. This dissertation focuses on the research of limited-DOF PMs and serial-PMs from constraint point of view and aims at establishing some models in basal theory which fit the characteristics of limit-DOF PMs and serial-PMs. The research of this dissertation mainly includes:The kinematics study of limit-DOF PMs are carried out based on constraint point of views. The constraints of this class PMs mainly represented by constrained forces/torques and constrained equations. Based on the arrangement of joints in the sub chains, the constrained force/torques which universally exist in limited-DOF PMs are determined. A novel method for establishing Jabobian for limited-DOF PMs is proposed based on the characteristic of constrained force/torques. The Hessian matrix of this class PMs is established. Based on the constrained equations of this class PMs, the coupling relation of moving platform is derived. The research aims at establishing simple and unified kinematics model for limit-DOF PMs.The novel analytical expression of statics mapping matrix is derived. The relation between this matrix and traditional velocity mapping matrix are studied. Combine the established statics model with the generalized coordinates derived from constrained equations, the stiffness model which reflects the relation between the generalized forces and generalized coordinates is studied. The constrained force/torques greatly affect the stiffness and elastic deformation of limit-DOF PMs. However, they are often neglected in previous studies. The stiffness with the constrained forces/torques considered is systematically studied in this paper. The dynamic model containing constrained force/torques for limit-DOF PMs are studied. The kinematics for the legs which have different structures are analyzed. The research aims at establishing simple and unified dynamics model with constrained force/torques contained for this class PMs.Some novel limited-DOF PMs with different kinematical characteristics are synthesized. The proposed novel PMs are analyzed by the established theoretical model and some corresponding theories are established.The research for serial-PMs formed by 2 limited-DOF PMs connected in series is developed. The unified kinematics, statics and stiffness models for serial-PMs are established.Novel methods are proposed for solving the kinematics, statics and determining singularity and quasi-singularity for mechanisms by CAD variation geometry approach. The proposed methods are used in the analysis of kinematics, statics, singularity, quasi-singularity and workspace for serial-PMs.Some limited DOF PMs are obtained based on the adjustable PM model. A 4-DOF 4UPS/SP prototype and the control systems are established. This prototype has been applied for kinematical experimentation successfully.