A Fuzzy Fast Terminal Approach for Tracking a Probe Around an Asteroid

This paper employs the fast terminal sliding mode control with the sign and the saturation function to track the landing trajectory of a probe on an asteroid and to further improve the dynamic tracking performance. Then the controller is enhanced by adding the fuzzy control to both fast terminals. To make fair judgments on the performance of the suggested method, the proportional derivative sliding mode control with both the sign function and the saturation function is simulated as well. The two-point barycentric gravitational model is used to describe the weak gravity around the asteroid. The proposed fuzzy fast terminal method raises the convergence speed, improves the desired trajectory tracking accuracy and ensures that the system modes are placed on the sliding surface in a short, limited time. The absolute errors for the proportional derivative sliding mode controller, fast terminal sliding mode controller and improved fast terminal sliding mode controller are about ۲۴۴, ۱۳۹ and ۱۱۳. The trajectories along all three coordinate axes in the proportional derivative sliding mode controller, fast terminal sliding mode controller and improved fast terminal sliding mode controller were tracked in ۸ seconds, ۵ seconds and ۴ seconds. The results show how the fuzzy-fast terminal sliding mode control with the saturation function is the better choice of controller and how the fuzzy system is able to adapt to the momentary fluctuations and cover them successfully.

Keywords:

FTSMC with the Sign Function , FTSMC with the Saturation Function , Probe Landing , Lyapunov Stability , fuzzy control