Research On Adaptive Fuzzy Vibration Control For Flexible Manipulator Based On Pneumatic Driving

The characteristics of flexible manipulators are light weight, high speed; low energyconsumption and low launch costs, widely used in industrial applications and space robots.Because the flexible manipulator in the process of movement will produce distorted, shear theelastic deformation, causing the robot end elastic deformation error, thus affecting theaccuracy of the robot’s movement. Flexible manipulator has low modal damping, inmovement or positioning was prone to produce elastic vibration, which affects the smoothmotion and positioning accuracy. High frequency small amplitude vibration can be more rapiddecay, but its low frequency large amplitude vibration will last a very long time. Consequently,it will not only affect the control accuracy and stability of the system, but also cause structuralfatigue of flexible manipulators. In order to meet the requirements of high stability and highpositioning accuracy, active control must be applied for suppressing structural vibrations offlexible manipulators.A rodless cylinder based pneumatic driving scheme was proposed to suppress thevibrations of flexible beam. Pulse code modulation (PCM) method was employed to controlthe motion of piston rod for simultaneous positioning and vibration control. The positionsignal of the piston is measured by the linear grating sensors, while the vibration of the beamwas measured by a piece of piezoelectric ceramic patch (lead Zirconate Titanate, PZT)bonded on the beam’s surface. Mathematic modeling, simulation and experimental researchusing control algorithms have been carried out.Firstly, the pneumatic drive based flexible beam system was proposed. It comprised thepneumatic circuit constructed by means of PCM method, signal acquisition circuit andcontroller system. Then, the dynamic model of the system was obtained by using Hamiltonprinciple and Lagrange principle, and its standard state space form was provided forcharacteristic analysis, control algorithms simulation and controller design.Secondly, the adaptive fuzzy control algorithms for mathematical simulation wereconducted. PD controller, fuzzy controller, the variable universe fuzzy controller and directadaptive fuzzy controller were designed, and the closed-loop stability analysis wrer carriedout. Conducted a simulation study of the pneumatic positioning and vibration control, providea reference for the control experiments.Finally, in order to verify the feasibility of the proposed pneumatic driving scheme andthe adopted intelligent control algorithms, an experimental setup of a flexible beam driven bya pneumatic rodless cylinder was constructed. The mechanical structure of the system, hardware circuit and system software of the electrical control were designed, which includethe Quadruplicated Frequency of the grating signal, and distinguish the pulse counting circuit,data acquisition A/D conversion circuit, the D/A conversion and signal conditioning circuitand its driver softwares and real-time control system. The experimental research forsuppressing vibrations of the flexible beam and positioning based on the rodless cylinder andthe piezoelectric actuators was conducted.The theoretical analysis, numerical simulation and experimental results demonstratedthat the proposed pneumatic drive control program and the algorithms can suppress thevibration of the flexible beam and achieve the positioning of the cylinder base simultaneously.