Recent advances in precision measurement & pointing control of spacecraft

There exists an increasing need for precision measurement&pointing control and extreme motion stability for current and future space systems,e.g.,Ultra-Performance Spacecraft(UPS).Some notable technologies of realizing Ultra-Pointing(UP)ability have been developed particularly for Ultra-accuracy Ultra-stability Ultra-agility(3 U)spacecraft over recent decades.Usually,Multilevel Compound Pointing Control Techniques(MCPCTs)are deployed in aerospace engineering,especially in astronomical observation satellites and Earth observation satellites.Modern controllers and/or algorithms,which are a key factor of MCPCTs for 3 U spacecraft,especially the jitter phenomena that commonly exist in a UPS Pointing Control System(PCS),have also been effectively used in some UP spacecraft for a number of years.Micro-vibration suppression approaches,however,are often proposed to deal with low-level mechanical vibration or disturbance in the microgravity environment that is common for UPS.This latter approach potentially is one of the most practical UP techniques for 3 U tasks.Some emerging advanced Disturbance-Free Payload(DFP)satellites that exploit the benefits of non-contact actuators have also been reported in the literature.This represents an interesting and highly promising approach for solving some challenging problems in the area.This paper serves as a state-of-the-art review of UP technologies and/or methods which have been developed,mainly over the last decade,specifically for or potentially could be used for 3 U spacecraft pointing control.The problems discussed in this paper are of reference significance to UPS and millisecond optical sensors,which are involved in Gaofeng Project,deep space exploration,manned space flight,and gravitational wave detection.