Abstract: Abstract：When mass and force uncertainties are taken into account, it will be difficult for lunar landers to hover on the designed height. To address this problem, we propose a new method for hovering and avoidance which is based on adaption.The core idea is to employ the position as the input of the observer for estimating and compensating the uncertainties. Compared with conventional PID methods, the proposed control strategy enjoys the properties of fast speed and small fluctuation, and it is able to realize high performance for hovering and avoidance. Numerical simulations demonstrate the effectiveness of the proposed approach.  

Key words: Keywords：lunar landing, hovering and avoidance, uncertainties of mass and thrust force, immersion and invariance.