The gravity on the ISS is one millionth of the gravity on Earth, which is almost zero-gravity. This is a state where there is almost no gravity acting on substances. On the ISS, many experiments are conducted using this zero-gravity state. So any vibration which might upset zero-gravity must be suppressed. Zero-gravity must not be disturbed.

The excitation experiment aims to test that the vibration caused by KIROBO would not affect the zero-gravity of the ISS. When KIROBO is not floating it is connected to a fixed arm or cable. If the movements of KIROBO are conveyed through these arms or cables with vibration over the limit, the test fails.

The experiment results proved that KIROBO’s movements do not affect the zero-gravity of the ISS, and was permitted to operate onboard the ISS.