Optimization-Based Feedforward Path Following for Model Reference Adaptive Control of an Unmanned Helicopter

Abstract

This paper presents an optimization-based approach to let an unmanned helicopter follow a geometrically defined path. In particular, this approach extends reference model following concepts. Instead of using a model of the vehicle dynamics, the optimization is based on the reference model of the controller. By this means, we can calculate the time- wise progress on the path by means of dynamic optimization without exact knowledge of the real helicopter dynamics. The progression on the path, is defined as a dynamic system subject to an additional virtual control input. The inputs of the reference model and that of the timing law are the decision variables used in the dynamic optimization which is so far performed offline. It will be shown that hereby, an accurate following of the path is possible although the actually identified flight mechanical model is limited to a linear hover model. Furthermore, the approach allows to take constraints on inputs and states into account. Simulation results as well as flight tests conducted with the artis testbed underline that good performance and constraints satisfaction can be achieved.