Complementary Ground Testing Method for Autonomous Flight System of Space Free-Flying Robot

Automation and autonomy of onboard tasks using space robotics technologies have been studied actively in recent years for reducing crew tasks in the International Space Station (ISS). Due to the difficulties of repairing space robots in orbit, prior verification tests on ground are essential to ensure that the robots perform required tasks in space environment without any problems. However, it is difficult to completely reproduce microgravity environment on ground in prior verification tests, and therefore several verification tests in different conditions are needed. An appropriate strategy to select and conduct the tests in suitable approach for each verification items is required to comprehensively evaluate the validity of the all functions. Japan Aerospace Exploration Agency (JAXA) is developing a free-flying robot named Int-Ball2 capable of performing photography tasks instead of crews in the Japanese Experiment Module (JEM). This robot has an ability to maneuver autonomously toward a target position for capturing images and videos. This paper presents a strategy of ground verification tests for the robot, which allows to validate the required functions comprehensively and efficiently. In particular, as a practical example, we introduce actually performed ground tests in Int-Ball2 project. The proposed validation policies are not limited to Int-Ball2, but can be widely applied as a ground verification process for general free-flying space robots.