Modeling And Control Of A Dual-manipulator System Handling A Flexible Payload

Recently, robot manipulator has been used in many fields. There are many scholars who have done much work in manipulating rigid object, while in many fields, such as shipbuilding, car and air craft, flexible material has been used largely. So far, there are few scholars who have done such work. The system composed of robot manipulators and flexible payload has characteristics as following: exceeding nonlinearity, strong coupling and infinite degree of freedom. In the process of handling flexible payload two actions will happen that are rigid motion and vibration. Considering the current conditions domestic and abroad, the study of manipulating flexible payload is underway and the methods of control aren't perfect. There are many questions needed to be solved.In this paper the study of two manipulators handling a flexible payload has been done. The contributions of this paper are the modeling and the controller that is based on the other's work. Firstly, the background and significance are introduced. The system of manipulator manipulating flexible payload is divided into two species single and cooperative and the conditions are introduced singly. The characteristics of current methods are analyzed.In term of this paper, the structures that will appear in cooperative manipulation are analyzed and the structure we need in this paper is chose. Based on this structure the concept of virtual link is present to be the benchmark of flexible body. The object coordinate is located on this benchmark. The FEM is a new analytical method which depends on computer. The FEM can divide a complicated structure into finite elements and the structure is combined by the elements in the node. The displacement of the element is expressed by the interpolation function of node. The FEM has the same procedure from the choice of displacement to the modeling of dynamic equations, so it's suited to be computed by computer. The physical meaning of flexible coordinates is clear because the generalized coordinates are the displacement of node not the mode. Because of these advantages we will use the FEM to model the dynamic equation of the flexible payload. The flexible payload is divided into four elements in the object coordinate. There is a special condition appearing when we define the flexible coordinates both sides of the object coordinate because of the choice of coordinates and the explanation is given. On the last basis the rigid dynamic equation and vibration equation are deduced. In this paper three kinds of coordinates will appear that are joint coordinates, end-effector coordinates and object coordinate. In order to have a uniform expression the relations of three coordinates are listed and the rigid dynamic equation and vibration equation of the system are derived in the object coordinate. The characteristics of the system are introduced.So far, there are few scholars who have studied the whole system and some scholars have only studied certain problem because of the complexity of the system. The control of vibration is very difficult because the state vibration is unmeasurable. The method in this paper based on the'rigid control'that it needs only the measurable coordinates in the controller which was brought out by James. The stability of the system is proved by the theory of stability and the results of the simulation validate the method of modeling and the controller. The hybrid controller is designed using the feedback signal of force. The boundary of the force is analyzed and simulation is done. Some prepared work was done for two manipulators handling a flexible payload. Because it's a very complex system many problems will appear in dealing with the system. This paper mostly solved the problem of model and designed a controller to validate the veracity but there are many works remained that needed to be solved.