Research On Control Methods For A High-speed And Light-weight Parallel Manipulator

Aimed at a two DOF light-weight parallel manipulator with high speed, severalcontrol strategies to enhance its speed and precise are presented. The following workshave been accomplished.With the aid of vector method, the inverse kinematic model has been developed.And the inverse dynamic model has also been formulated by the means of virtualwork principle. This provides necessary theory foundation for the path planningand control strategy research.An effective path planning method for high-speed parallel manipulator has beenproposed, taking the minimum pick-and-place time as the objective and at thesame time considering its affection on servo control system. The path planning iscarried out in the working space firstly and then through inverse kinematic modeltransformed into joint space to contrast sine, polynomial and trapezoid patterns.Based on this, a flexible arc trajectory planning method is presented, whichmakes the higher speed and higher precise possible.A new method on parameter tuning for the fixed-parameter PID controller hasbeen presented. Taking the elect-mechanical coupling and the whole workingspace performance into account, together with the aid of the kinematic model,dynamic model and the designed paths with coefficients, the tuning scheme isbuilt up, which takes the mean square root error as the objective. It solves theproblem of optimum results difficult to get in the traditional way since it takesthe interactional indexes as objective. As a result, the high performance of themanipulator is successfully guaranteed.A self-adaptive control strategy based on BP neural network has been broughtforward. The real-time capability and reliability of the means applying the neuralnetwork into the area of has been deeply studied and a 4-5-3 structure real-timevaried PID arithmetic has been also carefully designed. Thus the problem ofhigh-quality performance difficult to realize in fixed-parameter control isovercome.A computed torque method with the framework of outer PID control plus innernonlinear feedback has been designed. The following error result from dynamicfactors is compensated through a mass matrix relating the joint acceleration withthe actuator torque. Hence, the high quality control performance has beenachieved.The works accomplished in this thesis are very meaningful for promoting thecontrol strategy research on high-speed and light-weight parallel manipulators andimproving our capacity in the competitive automatic industries.