Estimation Algorithm of Relative Position and Attitude during Proximity Rendezvous Using Multiple Ultra-Wide-Band Devices

This research proposes estimation algorithms of relative position and attitude during interplanetary proximity rendezvous and docking by using ultra-wide-band (UWB) devices — which are small, low-power devices to be used for communication between several spacecraft, and are suitable to be mounted on micro- or nano-spacecraft. The device provides high-precision ranging and high-speed communication between two spacecraft during rendezvous and docking, whose information is used for estimating their relative position and attitude. This paper proposes two estimation algorithms using UWB properties. The first one estimates the relative position by using the ranging data of the UWB devices and the relative attitude information, which is shared by the UWB communication and provided by the attitude sensors. In the second algorithm, assuming that the attitude sensor of the chaser cannot be used, the relative attitude is estimated using the multiple ranging data of the UWB devices. This research evaluates the estimation accuracy of the two proposed algorithms using a rendezvous simulator, which reveals the conditions to obtain accurate and stable relative position and attitude estimations. This paper will contribute to autonomous navigation method for the proximity rendezvous and docking phases of micro- and nano-spacecraft, which have strict limitations of size and power for navigation sensors.