  This paper addresses the problem of distance- and orientation-based formation
control of a class of second-order nonlinear multi-agent systems in 3D space,
under static and undirected communication topologies. More specifically, we
design a decentralized model-free control protocol in the sense that each agent
uses only local information from its neighbors to calculate its own control
signal, without incorporating any knowledge of the model nonlinearities and
exogenous disturbances. Moreover, the transient and steady state response is
solely determined by certain designer-specified performance functions and is
fully decoupled by the agents' dynamic model, the control gain selection, the
underlying graph topology as well as the initial conditions. Additionally, by
introducing certain inter-agent distance constraints, we guarantee collision
avoidance and connectivity maintenance between neighboring agents. Finally,
simulation results verify the performance of the proposed controllers.
