Decentralized output-feedback formation control of multiple 3-DOF laboratory helicopters

The decentralized formation control problem of multiple 3-degree of freedom laboratory helicopter models is studied on directed communication topologies in this paper. The laboratory helicopter models are subjected to non-linearity, under-actuated, and equipped only with angular position sensors. We present a decentralized formation controller which includes a non-linear uncertainty and disturbance estimation (UDE) term to compensate the model uncertainties and disturbances in each helicopter and from its neighborhood. The UDE consists of a second-order auxiliary system and a discontinuous term, neither the measurement of angular velocity nor its asymptotic estimation is required. Convergence of the formation tracking error is analyzed using invariance-like theorems. It is also proved that the UDE term will converge to the actual uncertainties and disturbances. Simulation results show that, on a one-way communication topology which only contains one spanning tree, a group of four helicopters reaches the desired formation shape while tracking a given reference trajectory using proposed method.