From ETS-VII to HTV:Study of Japanese Rendezvous and Docking/Berthing Technologies

Abstract

The Japanese Engineering Test Satellite VII(ETS-Ⅶ) was launched in November 1997 to conduct the rendezvous docking(RVD) and space robot(RBT) technology experiments.Three RVD experiments(FP-1,FP-2 for V-bar approach,and FP-6 for R-bar approach) were carried out by ETS-Ⅶ,using Global Positioning System(GPS),rendezvous radar(RVR),and proximity sensor(PXS).The RBT experiments with a 2 meter-long,6 DOF manipulator arm aim at developing the technology for the space robot on an unmanned spacecraft which can be teleoperated from a ground station.The RBT experiments include capture and berthing of a target satellite as well as teleoperation,robotic servicing tasks,and coordinated control of satellite attitude and robot arm.The technologies developed through the ETS-Ⅶ project have been applied to the H-ⅡTransfer Vehicle(HTV).HTV-1 and HTV-2 were launched in September 2009 and in January 2011,respectively.HTV is an automated unmanned cargo transport system to the International Space Station(ISS),performing R-bar approach and capture-berthing with the ISS robotics arm(SSRMS).RBT technology also makes HTV have the ability to carry unpressurized cargo in addition to the pressurized cargo.As a visiting vehicle to manned ISS,HTV can meet the requirements of the one-fail operable(1FO) and two-fail safe(2FS),using redundancy technology and safety management functions such as fault detection,isolation and recovery(FDIR) and mission abort control.