Kinematical And Dynamic Analyses Of A Two-degree-of-freedom Closed-loop Mechanism And Research On Its Mechanical Characteristics

This paper is mainly concerned with a closed-loop mechanism that lies betweenparallel mechanism and parallel robotics. The analysis of kinematical and dynamicalmodel and mechanical characteristics are involved, and the emulation of the motion anddynamic is put into reality. The motion performance of the output varies because of thedifferently applied actuations. Two-degree-of-freedom parallel mechanism is dealt withby the definition of topology. Three ordinary types of parallel mechanism 5R,4RP and3RPR are analyzed. And the sufficient condition of full crank is derived. Then withimplicit function theorem the flexible workspace is dealt with. By using the Jacobianmatrix of the hybrid input mechanism, the sensitivity of output is obtained. Then thecondition number of Jacobian matrix is derived. According to the discussion of theJacobian matrix, we find out the dual instantaneous self-motion singularities of themanipulators. The feasibility of its avoidance from the actuating-singularity by means ofstep motors and mutation of mechanism is proven with the help of the condition numberof the Jacobian matrix. Based on the stochastic clearance model, the outputdisplacement error of the plane closed-loop mechanism is analyzed. By means of thedifferentiation of the Jacobian matrix, the velocity error caused by the tolerance of thebar is derived. Considering the influence of the velocity error on the output trajectory'scurvature, we interpolate and fit the curve between two given points of calculation.Finally, the theory of control is applied to the parallel mechanism, which including theprinciple theory of auto control, position control, coordination control and force control.With flexible joints and 4RP mechanism, a vibrating micro-robotic mechanism isinvited.