Attitude synchronization of multiple 3-DOF helicopters without angular velocity measurements by bounded distributed control

The problem of designing distributed attitude synchronization control protocol is considered for multiple 3-DOF helicopters without angular velocity measurements. To explicitly take into account the actuator saturations constraint, the notion of local neighborhood synchronization error (LNSE) is extended to the nonlinear case using the hyperbolic tangent functions which are prior bounded. It is proved that under a connected communication topology, the convergence of attitude tracking errors can be achieved by forcing the extended LNSEs to zero. An auxiliary nonlinear filter and a continuous bounded distributed controller are designed for each helicopter to achieve attitude synchronization in both elevation and pitch channels, where only angular position signals are used. Numerical simulation results are provided to illustrate the effectiveness of the presented control scheme.