Feedback control for yaw angle with input nonlinearity via input-state linearization

This paper discusses the yaw control of small-size unmanned helicopter. The yaw dynamics of helicopter involve input nonlinearity, time-varying parameters and the couplings between main and tail rotor. With respect to such a complicated dynamics, the normal PID control is difficult to realize good tracking performance while maintaining stability and robustness simultaneously. In this paper, a valid control is proposed by applying the derivative of the nonlinear function, the original system is to be extended a new system with a pseudostate variable. This approach makes it possible to avoid using the inverse of the nonlinear function and reduces the calculation load. The simulation results further demonstrate the improvements of the proposed algorithm.