Abstract
This paper discusses on guidance and control law for an unmanned lunar landing module. The guidance law is required to avoid obstacles on a lunar surface automatically during vertical descending. The main thruster of landing module is used not only for deceleration of descending rate but also for avoidance maneuver. Thus the avoidance guidance law is required to complete the maneuver during main thruster firing. The main purpose of this paper is to show the relation between thruster delay and the landing accuracy through numerical simulation. The results show that the delay time of main thruster affects the accuracy of vertical landing rate. The requirement of landing accuracy, however, is satisfied for the main thruster with common performance.
