Configuration And Kinematics Analysis Of Two Kinds Decoupled Parallel Mechanism And Their Choas Identification

Compared to the coupled parallel mechanism, there exists a one to onecorrespondence between the input and output kinematic variables of the decoupled parallelmechanisms, which will be more likely to realize a better performance improvement of themechanism. With a series of decoupling mechanisms appearing, it is more and more worthto search for the reasonable performance evaluation indices, which are the bases for theoptimal selection and optimization. Analysis of dynamic characteristics and their chaosidentification is also a prerequisite for decoupled parallel mechanism to adapt tohigh-speed, high-reliability requirements and thus can be applied in the field ofengineering. Aiming at two typical decoupled parallel mechanisms, this paper will carryout the kinematics analysis and chaos identification. The main contents are as follows:Through investigation on research status and development trend of the decouplingparallel mechanism, it is taken as the research object of the decoupled parallel mechanismswith RU-RPR and PU-RCRR-CRRR, and the kinematical equations are established.Based on the given mechanisms, the forward and reverse position kinematics is analyzed,and then, velocity and singularity are analyzed.Based on the kinematic transmission property indicators of the existing generalparallel mechanisms, the paper analyzes the structures of Jacobian matrix of suchmechanisms as RU-RPR, PU-RCRR-CRRR,3-CPR and3-CUR systematically, as well asindicators based on it. And in the meantime, the paper makes a preliminary research forselecting what property indicators to evaluate the decoupled parallel mechanisms.In view of questions of pair clearance during operation, the paper establishes thevirtual prototype model for RU-RPR with clearance and makes simulation to thedecoupled parallel mechanism at the basis of ADAMS dynamics simulation software.Then, influence of the gap on the displacement, velocity, acceleration, and contact forceare analyzed. And the paper also discusses the difference of the dynamic performancewhen different pair clearance or driving velocity is given.Aiming at chaos phenomena in nonlinear dynamics of the space parallel mechanism, dynamic differential equation of RU-RPR with clearance is established by Lagrangeequations. By combination of the mechanism and chaos theory, Poincare map is set up toidentify phenomena of chaos in dynamic behavior. And then, the effects of clearance sizeon chaotic motion are investigated.