Research Of Control Strategies For PSS 3-2-1 Orthogonal Parallel Mechanism Platform

Parallel robots are widely used in the operating sections of spaceflight, navigation,medical treatment and numeric-controlled manufacture. Meanwhile, the PSS 3-2-1orthogonal parallel mechanism platform is a new type of 6-DOF orthogonal parallelmechanism platform, and it meets the similar technical issues with the parallel robot in theoperating process. In this paper, a new type of orthogonal parallel mechanism is discussed.How to apply this new mechanism to the parallel robot technique is a hot issue in presentresearches, as well as the key point of the theoretical investigation and practicalapplication of parallel robot technique.Taking the PSS 3-2-1 orthogonal parallel mechanism platform as the research subject,two kinds of algorithms are proposed in the paper: the Fuzzy PID Algorithm and theRobust Control Algorithm. And the specific works are as follows:Firstly, the analytic expression is derivated for the position inverse solution of thePSS 3-2-1 orthogonal parallel mechanism platform, and put forward the Fuzzy PIDControlling Method, the progress is as follows: on one hand, expected trajectory will betransferred to the Motion Control Card through the IPC; on the other hand, depending onthe Inverse Kinematics Formula, the Motion Control Card will calculate the theoreticaldisplacement vector of each branched chain, and input them into the Fuzzy AdaptationController as expected figures, at the same time, the controlling outputs of the BranchedChain Servo System Transmission-Mechanism will be input into the Fuzzy AdaptionController as virtual figures, then the deviations between the expected figures and virtualfigures of the servo branched chains will be input into the PID controller, and thus realizethe Deviation Close-Loop Motion Control to the bionic robot horse’s motion branchedchains. The simulation experiments have shown that the Fuzzy PID Self-Tuning Controlcan achieve more satisfactory results.Secondly, this paper refers to the model errors raised from the PSS 3-2-1 motionplatform and the interferences from the outside environment, and puts forward the RobustTracking Control Algorithm. Based on the physical characteristics of dynamics model forthe orthogonal parallel mechanism confirm the expectations trajectory of controlled object. Designing a robust feedback controller is moving platform to track tends to be desiredtrajectory. This algorithm can reduce the instability of the system in a great range, andimprove the transient state performance of the system. It has a short response time, a shortregulation time, a great stability and a strong anti-interference ability, which makes itcapable to promptly trace the real-time changes of the six axes. This control algorithm hasalso been proved to be effective in simulation experiments.As a conclusion, the research results of this paper can be widely used in flightsimulators, the Astronomical Telescope Tracing-and-Locating System, the MobileEntertainment Platform and some other systems. They are also of great reference value toachieve simple, easy, high-speed and high-precision control.