Dynamics And Control Of Two Robot Manipulators Handling A Flexible Payload

In recent years, the manipulators cooperating flexible payload have been studied by many scholars and these studies focused on controller designing to ensure stability of the system and operating skills. In many workplace, precise and accurate operation are requires and at this time the vibration problem of flexible load would have to consider. In the aerospace, printed circuit boards, automotive and other fields, due to the aPlications of large-scale or thin metal plates, vibration would occur inevitably. The accuracy and safety requirements are high in these areas so the vibration must be controlled. In the automotive manufacturing, according to statistics it includes about 300-500 metal plates in each car, in order to bring them together, the complex fixture must be designed. The error allowing is only 0.5mm in automobile manufacturing, even if the auto body places a very small change in the shape the fixture means to be redesigned. The design of complex fixture takes a long time and money. In the aerospace field, with the development in space, a growing number of flying objects have been send into space orbit. After a long time the position or posture will change and they must be maintained. It is unable to complete these tasks depending on human and must rely on space robotics. Because these panels are mostly made from flexible materials and bulky and their operations often bring vibration, which not only creates difficulties for control of the robot also brings uncertainty, the robot control must take into account the coupled vibration characteristics. Multi-layer printed circuit board is composed of many small flake, manipulators are particularly suited to complete this work due to the precise. However, each small piece is very thin, bound to vibrate during operation, while the tasks require precise positioning so the vibration must be effectively controlled. From the current situation of research at home and abroad for operating flexible payload it is only at the initial stage. The cooperative control and vibration suPression problems are still not formed a complete system, in particular the study of vibration suPression is still less. Most scholars in the operation of flexible objects are in a specific question and there are many critical issues to be resolved. In this paper, the system modeling, the system stabilization control and trajectory tracking control based on rigid control, hybrid EI shaper design issues of based on partial points and the feedback control observer-based problem are studied. Main content and innovation are as follows. Finite element method is adopted to establish a dynamic model of the flexible payload. Based on both ends of flexible payload being fixed the rigidity of the system motion is determined. The flexible beam is divided into several modules. According to Lagrange equations the dynamics model of the system is derived. The relevant features of dynamics model are explained. The relationship of coordinates is expressed. The dynamics models of flexible payloads and manipulators are transformed into the same coordinate space. The relationship between the forces is given.The stabilization control and trajectory tracking control methods based on rigid control are proposed. For the flexible payload from the initial position moving to the desired location, the rigid controller with a compensation term is designed that can guarantee the stability of the system in the process of handling and can also ensure the vibration of flexible payload quickly calm after arriving at the designated location. For the trajectory tracking issue items, a rigid adaptive controller is designed ensuring stability of the system. The simulation results show the effectiveness of the method.The method of hybrid EI shaper based zero-placement technique is proposed. the traditional ZV shaper based zero-placement technique is expanded into the EI shaper or ZVD without changing the impulse number and delay time. The robustness of the shaper increases largely. Several higher hybrid EI shapers are designed taking the advantages of this design method. The relationship between the bias coefficient and the minimal vibration allowing for the system are given. The error range of the actual frequency and expected frequency is calculated. Taking full advantages of the cyclical nature, a method for vibration suPression of flexible structure with multi-mode is present. When the flexible structure is multi-mode, it need not design the controller for each mode, so a significant number impulse is reduced, but the delay time is more or less. The hybrid EI is proposed to control the vibration of manipulators cooperating flexible payload and the methods\ is verified by simulation experiments.By assuming that the ends the manipulator can be the installed sensors so the vibration information of the contact points can be measured and it can derive the vibration of the state. The feedback control methods based on observer are proposed. Under the condition for the model is known, the design method based on the matrix eigenvalue is proposed. It can chose the observer parameters to ensure that the eigenvalue of the system state equation matrix contains the negative real part and thus to guarantee system stability. The sliding mode control method with compensation items is proposed. The stability of the system is proven based on Lyapunov equations and the simulation is done. For the situation when the model is unknown in most cases, the controller is designed and system stability is analyzed and simulation results are given.The conclusion and the perspective of future research are given at the end of the paper.