Research On Control Method Of Manipulator Handling A Flexible Payload Based On Distributed Parameter Model

With the improvement of science and technology, robot technology has been widelyused in the fields such as industry、military affairs、manufacturing and medical scienceand service. In aerospace, automobile, shipbuilding and other fields, the accuracy andsafety requirements are very high, and the elastic sheets and flexible slightness beams arealways need to be moved and assembled. For example, in the automotive industry, weneed design the complex fixture since the sheet flexible metal must be held while robotsspot weld them together. When the auto body places a small change in space, the fixtureneed be redesigned. However, the design for fixture always spent a great number oflabour power and material resources. This will require the manipulators instead of fixtureto modify task goals of the program without redesigning the hardware for the shapechange. In space field, it requires space robot to maintain and replace the failing batteriesfor the aircraft. These panels are mostly made from flexible materials and their operationsoften bring vibration, so the robot control must consider the coupled vibrationcharacteristics. Besides, in other industry areas, many parts are made of flexible material,these operations all involve the issue of flexible payload，so efficiency and safety can begreatly improved while the manipulators are used. Thus, the study on manipulatorhandling flexible payload is of great significance in theory and practical value inengineering.Manipulator handling a flexible payload is a nonlinear, rigid-flexible coupled andinfinite dimensional complex dynamic system，which including not only the rigid motionof large range, but also the local elastic deformation. Compared with the researchachievement about rigid payload, the research achievement about flexible payload arerelatively few, which exists many problems to be solved. When manipulator moved andassembled, the position control and the vibration suppression should be considered. Inpractice, the uncertain parameters and external disturbance of the system, and the contactforce between flexible payload and manipulator, all the above problems increase thecomplexity of the system kinetic analysis and control. From the current situation ofresearch at home and abroad for the system with flexible structure, many researches studythe system analysis and control design based on the simplified lumped parameter model,however, the simplified model may bring control/observer overflow problem. Thus, theresearch on manipulator handling a flexible payload based on distributed parameter modelis of importance and significance. In this paper, manipulator handling a flexible payload is researched based ondistributed parameter model, and the finite dimensional approximation model is not used.So the overflow problem of the lumped parameter model is avoided. The position controlproblem and the infinite dimensional observer are researched, the robust control isresolved based on the system with uncertainties and external disturbance, and theforce/position control problem of the two manipulators handling a flexible payload isresearched. The main content and innovation are a follows.The position control for manipulator handling a flexible payload based on distributedparameter model is researched. By using the system total energy, the static feedbackcontroller is constructed by applying the Lyapunov method, and the operator of theclosed-loop system generate aC0semigroup. The asymptotic stability in theneighbor-hood of the desired states of the closed-loop system is proved by LaSalleinvariance principle. The angle can arrived at the desired position, as well as the elasticvibration of flexible payload is suppressed. Considering that it is impractical for flexiblepayload to be equipped with sensors, this paper proposed infinite dimensional nonlinearobserver to estimate the vibration information of flexible payload, and designed theposition controller based on the observer. The asymptotic stability of the closed-loopsystem is analysis, and the effectiveness of the control strategy is supported by somesimulations.The position control of manipulator handling a flexible payload is researched underthe parameter uncertain. Based on the energy dynamic of payload, a sliding modecontroller is proposed by designing a coupled sliding surface, and then extended to anadaptive scheme to cope with the upper bounds of the uncertainties were unknown. Thesliding surface is designed as the joint angle error and angular velocity error with thevibration information of the payload. By using the positive real lemma, the dynamicfeedback control was used in the system of manipulator handling a flexible payload, it canintroduces extra degrees of freedom in designing controllers. The asymptotic stability ofthe closed-loop system is proved by semigroup theory and LaSalle invariance principle.The force/position control for manipulator handling a flexible payload wasresearched. Based on the analysis of static states, the force/position controller wasproposed by using Lyapunov method, the angle and the force can arrived at the desiredstate, as well as the elastic vibration of flexible payload is suppressed. Considering thesystem with uncertainties, the sliding-mode force/position controller was proposed, thesystem was proved to be Lyapunov stable.Based on the research on distributed parameter system, flexible multi-body system and the manipulating system, the conclusion and the perspective of future research aregiven at the end of the paper.