A new coordination scheme for multi-robot systems is proposed.A state space model of the multi robot system is defined and constructed in which the systems initial and goal states are included along with the task definition and the systems internal and external constraints.Task accomplishment is considered a transition of the system state in its state space(SS)under the systems constraints.Therefore,if there exists a connectable path within reachable area of the SS from the initial state to the goal state,the task is realizable.The optimal strategy for the task realization under constraints is investigated and reached by searching for the optimal state transition trajectory of the robot system in the SS.Moreover,if there is no connectable path,which means the task cannot be performed successfully,the task could be transformed to be realizable by making the initial state and the goal state connectable and finding a path connecting them in the systems SS.This might be done via adjusting the systems configuration and/or task constraints.Experiments of multi-robot formation control with obstacles in the environment are conducted and simulation results show the validity of the proposed method.