Research On Cooperative Control Of Multiple Rigid Systems

Cooperative control of multiple rigid systems has received considerable a lot of attention in recent years with the rapid development of computer science and control theory. A difficult task which can be completed by one complex rigid system can also be accomplished by multiple rigid systems. Compared with single system, multiple rigid systems bring us much convenience and benefits such as robustness, strong adaptability and flexible scalability.Cooperative control problem of multiple rigid systems in different dimensions has been considered in this thesis. Tools such as graph theory, nonautonomous cascaded systems theory and stability theory of nonlinear systems have been introduced to solve the cooperative problem in this thesis. The main contents are listed as followings.Firstly, consensus problem of nonholonomic mobile robots is considered. This complex problem is simplified into consensus problems of two subsystems thanks to the theory of nonautonomous cascaded systems. Consensus has been realized using the linear distributed controllers proposed in this thesis no matter whether the group reference signal is persistent excitation or not. In addition, all states of the system are consensused to desired values.Secondly, formation control problem of nonholonomic mobile robots is considered. Cascaded structure is incorporated in the design of formation controllers. Some external perturbing signals are injected into the controllers to overcome the uncontrollability of the system when their reference target converges to zero. Formation control of the system has been realized using the controllers proposed in this thesis and the rigid robots can move according to the specified trajectory.Thirdly, consensus problem of vertical take-off and landing(VTOL) vehicles is considered. The complex model of VTOL vehicle is transformed into some integrator models, which is further simplified into two integrator parts using the theory of nonautonomous cascaded systems. Consensus of this system has been realized using the hierarchical controllers proposed in this paper.Lastly, attitude synchronization problem of ertical take-off and landing vehicles is considered. Distributed controller based on virtual structure has been proposed for the attitude synchronization problem under delay of communicaion.