Heading controller for helicopters based on modified active disturbance rejection control

In order to improve the transient characteristic and working condition adaptability of miniature unmanned helicopters, a heading hold controller is presented based on modified active disturbance rejection control (ADRC). An online forgetting factor recursive least square algorithm is adopted to identify the output gain of the target helicopter. The identification result is condensed into a function of main rotor speed, adapting to various working conditions. This function is contained in the proposed ADRC controller as replenishment to the standard scheme. Experiments are conducted on a 550-class electric helicopter. A reduction of about 40% in transient time (comparing with an off-the-shelf PID controller) is achieved in the experiment. The comparison result shows that the proposed ADRC scheme outperforms the classic PID controller and standard ADRC controller in transient character and condition adaptability.