Satellite formation control using continuous sliding modes

Satellite formation position control is studied in this work. Three different methods of controlling satellite formations using continuous robust Sliding Mode Control (SMC) are derived and compared. These controllers produce a continuous control signal that is not an approximation but an exact solution which mitigates the chattering problem that can arise with discontinuous SMC. The tracking results are compared to those that use a discontinuous sliding mode controller with a dead zone approximation model of the thruster dynamics. The controllers are designed and compared using trajectories generated via the linearized equations of relative motion under two body dynamics. For the continuous sliding mode control methods, a pulse-width modulation technique is applied to the control signal to control the duty cycle of the simulated satellite thrusters. Results indicate that the continuous sliding mode controllers are effective at reducing the trajectory errors to zero in the face of unknown but bounded disturbances.