Research On The Kinematic Characteristics Of 3-pcr Parallel Robot

Compared with serial robot, parallel robot has more advantages as simple configuration, low cost, strong carrying capacity, high precise, easy control and so on. Parallel robots with six DOF have been widely researched since the Stewart platform had been proposed. However, limited-DOF parallel robots with fewer than six DOF which maintain the inherent advantages of parallel mechanisms, but also possess several other advantages including the reduction of total cost of the device and control, are attracting attentions of various researchers.The research on the 3-PCR parallel robot is introduced in this thesis after referring to the related documents and materials both at home and abroad. The following four aspects are discussed in this thesis:Firstly, the kinematics analysis of a novel 3-DOF parallel manipulator was investigated. Based on the motion constraint equation of the 3-PCR parallel manipulator, the inverse displacement solutions of the parallel manipulator were presented. Then the forward displacement solutions were obtained via Bezout's elimination method, and some numerical examples were given in order to prove the correctness of the inverse and forward displacement solutions. The models of velocity and acceleration relationships between three output motions and three input parameters were discussed; the forward and inverse solutions of velocity and acceleration were given. At last, the planning trajectory was verified through solution examples and simulation.Secondly, this paper analyzes the motion and force transmission on the basis of a particular 3-DOF parallel mechanism—3-PCR parallel robot. First of all, the kinematic equation for 3-PCR parallel robot has been established. Besides, the manipulability of velocity and force has been defined in line with the Jacobian matrix for the robot mechanism. Moreover, the relevant evaluation indices for the velocity and force transmission of the robot mechanism have been specified. Finally, the capability of the velocity and force transmission of the mechanism, under designated postures within the workspace, have been measured by considering the velocity and force manipulability as performance indices.Thirdly, based on Lagrange's equation, the dynamic equation of 3-PCR parallel robot was established and the drive force acted on the mechanism was given. Computer simulation was established to investigate the driving forces variation when the platform moves along planning trajectory. The relation between system parameters and drive force of the mechanism was obtained.Additionally, the 3-PCR parallel mechanism is used to settle the question of multi-dimensional vibration damping. The dynamics equation is established by using the Lagrange method, and the formula of free frequency is deduced. The free frequency of the system is validated in ADAMS software.