Performance Analysis And Research On Hybird Force/position Control Of A5-DOF Parallel Mechanism With Actuation Redundancy

Parallel mechanisms (PMs) and serial mechanisms form a complementaryrelationship in practical application. Compared with serial mechanisms, PMs performbetter in terms of rigidity, accuracy and carrying capacity, etc． However, itspracticalization and commercialization are restricted for small workspace, singularconfigurations existed in workspace, less flexibility of end-effector and great performancedegradation, uncontrollability, poor rigidity, low carrying capacity, decreased movementaccuracy near the singular configurations. As a new hot topic in the field of PMs,redundant actuation could reduce or eliminate the singular configurations, enlargeeffective workspace, improve structural rigidity, optimize load distribution betweenactuations, balance internal forces of PMs, eliminate the hinge gap and improve themovement precision to reach the practical level in velocity, rigidity, accuracy and carryingcapacity.The dissertation puts forward a novel6-PUS/UPU redundantly actuated PM andresearches the relevant issues in-depth aimed at the PM. The main contributions are asfollows:Firstly, the degree of freedom(DOF) and main parameters of6-PUS/UPUredundantly actuated PM are determined, and its kinematics model is established.Meanwhile, its work space is analyzed.Secondly, based on the detailed analysis of the intermediate constrained limb, forceequilibrium equation of the6-PUS/UPU redundantly actuated PM is established. Inaddition, the driving force of redundant actuation limb is created by using norm minimumto optimize redundant driving force, which provides theoretical basis to improve themechanical performance of other driving limbs. Moreover, the dynamics model isestablished by Kane.Thirdly, on the basis of the kinematics and dynamics analysis, the control system ofthe redundantly actuated PM is studied. And the motion control, force/position hybridcontrol, force/position synchronization control and zero-returning strategy are developed in condition of the movement unrestricted/restricted. Moreover, the virtual prototype ofthe PM is built by ADAMS software and the driving model by MATLAB software tocomplete the co-simulation. Besides, the simulation and the theoretical calculations areanalyzed comparatively and verify mutual model accuracy.Fourthly, based on analyzing6-PUS/UPU demand, the open SOA(Service-OrientedArchitecture)/MVC(Model View Controller) control system architecture is proposed.Moreover, the control system of6-PUS/UPU PM is designed and implemented based onthe framework.Finally, a series of experimental investigations for the redundantly actuated PM areconducted, including PID parameter tuning, calibration, control strategy verification, etc.The experimental results show that the redundantly actuated PM operates smoothly andmeet the needs of complex tasks. What’s more, it also verifies that the redundant drivinglimb improves the positioning accuracy and dynamic performance of the moving platform.The theoretical and experimental researches of the dissertation lay the foundation offurther study and engineering applications of redundantly actuated PMs, and also offer agood reference for theoretical and experimental studies of other types of PMs. At the sametime, this work will be complicated surface precision machining, spacecraft docking thenational economy and national defense industrial development has important theoreticalsignificance and practical value.