The coupling control of orbit and attitude for hazard avoidance based on modified reference model

The coupling control of orbit and attitude for hazard avoidance based on the modified reference model in the environment of small body is presented in this paper. The presented method fires the thrusters at each time step according to the state error information. In particular, in the presence of hidden hazards, the emergency maneuvering trajectory derived from the potential function method may cause transient behaviour. In order to especially improve the position tracking accuracy during hazard avoidance over the existing thrusters' command strategy, the original reference model is modified by feeding back a term proportional to position error. This idea particularly takes into consideration of the position error, and, as the tracking error approaches zero, the modified reference model can also approach its original form. Thus, it can improve any state tracking accuracy easily according to the need. The results of mathematical simulations in the environment of small body show that in the presence of hidden hazards, the transient behaviour of nominal trajectory is very obvious, and the control method based on modified reference model shows good tracking accuracy in both position and attitude, and shows improved performance over the traditional one.