An RPT approach to time-critical path following of an unmanned helicopter

In the last decade, small-scale unmanned helicopters have attracted a significant interest due to their unique abilities. Autonomous path following of them is one of the challenging missions, especially a time-critical one. In the paper, a path following control system has been designed to steer unmanned helicopters along a predefined 3D path maintaining a specified flight speed and accounting for constraints of time implicitly. The task is formulated as a robust and perfect tracking problem and accomplished via a cascaded solution framework. The main advantage lies without time lag in steady-state responses. The promising performance has been demonstrated by flight tests.