Research On Cooperative Attitude Control Of Multiple Rigid Bodies System

The research on multi-agent system evolved from the study of collective behavior in nature. The researchers have abstracted the model of multi-agent system and summarized its basic control law from various subjects such as biology, mathematics, artificial intelli-gence, communication and computing science. Depending on the advantages of low cost, high efficiency, easy deployment, high flexibility and fault tolerance, multi-agent system has attracted great attention all over the world. Multiple rigid bodies system, which is a special kind of multi-agent system, has all the advantages mentioned above, and it is paid more and more attentions by researchers nowadays due to its broad applicability in many engineering applications such as distributed spacecraft system, swarm robot system, multiple unmanned aircrafts system and distributed camera network system. The cooperative attitude control, which has an important value on many engineering applications such as spacecraft formation flying, robot team formation and distributed video surveillance, is the core field of research on multiple rigid bodies system. The object of cooperative attitude control is to drive the attitudes of all rigid bodies in system to the desired states by designing the distributed co-operative attitude controller. However, the analysis is always a complex problem due to the nonlinear characters of the state equation and the state space of the rigid body attitude control model, and the study on cooperative attitude control is just at the initial stage. The design problem of high-performance controller with the factors such as actuator failures, external disturbances and system parametric uncertainties is seldom considered, and there are still no efficient methods to reduce the communication network pressure in the existing research. Furthermore, the existing cooperative attitude controller for multiple rigid bod-ies system on nonlinear manifold SO(3) can only perform simple tasks, and there is rarely in-depth research on the complex attitude control tasks.Based on a review of the existing research literatures, the limitation of the present study of the cooperative attitude control of multiple rigid bodies system is analyzed, and then the research work for some key problems is carried out in this dissertation. The main contents are outlined as follows: This dissertation studies the robust finitc-time cooperative attitude control. Since the higher accuracy, better disturbance rejection property and faster convergence rate can be ob-tained under finite-time control, we construct the finite-time cooperative attitude controller for multiple rigid bodies system combined with the methods of sliding-mode control and adaptive control. Under the designed controller, the orientations of the follower rigid bod-ies will converge to the convex hull formed by the orientations of the leader rigid bodies in a finite time. Moreover, the issues of actuator failures, external disturbances and system parametric uncertainties are taken into account in the controller design, which makes the controller more valuable in practical applications.Also, this dissertation considers the event-triggered cooperative attitude control. In or-der to implement the controller designed in the past literatures, each rigid body in system needs to broadcast information periodically via wireless network in engineering applica-tions. This conservative information exchange method will increase the pressure of net-work, which may lead to the communication delay, packet dropout and failure of control task. In order to prevent this problem, the event-triggering strategy is introduced in the cooperative attitude controller design. A corresponding event-triggering procedure is con-structed for each rigid body, which makes all of the rigid bodies can discretely broadcast their information only when needed. This novel control strategy can reduce the pressure of communication network and save the energy of system.The cooperative attitude control for multiple rigid bodies system on manifold SO(3) is studies. In order to describe the movement of the rigid body attitude more accurately, the cooperative attitude control of multiple rigid bodies on manifold SO(3) is studied in this dissertation. An auxiliary variable in Lie algebra so(3) is introduced for each rigid body in our controller design method. Based on this auxiliary variable, using the knowledge of nonlinear manifold and the stability theory of asymptotically autonomous system, the consensus-based attitude coordinated controller is designed so that more complex coopera-tive attitude control tasks can be performed.The event-triggered cooperative attitude control for multiple groups rigid bodies sys-tem on manifold SO(3) is investigated. Applying the control method on manifold SO(3) and event-triggered controller design approach, the cooperative attitude control of multiple groups rigid bodies system is studied in this dissertation. Under the designed inter-group attitude anti-consensus controller and intra-group event-triggered attitude synchronization controller, the orientations of all rigid bodies can converge to multiple values which are dif-ferent from each other, and the pressure of intra-group communication network is reduced. The content preliminarily discusses the multi-task control method of multiple rigid bodies system, which is extremely valuable in engineering applications and lack of research until now.Finally, a summary has been done for all discussions in the dissertation and the research works in future study are presented.