The Korea Aerospace Research Institute relies on measurement technology from Kistler to perform force-limited vibration tests on satellites. 24 force sensors – aligned in a ring structure and connected to LabAmp charge amplifiers and data acquisition units – provide the basis for integrated acceleration control to prevent damage caused by overtesting.
South Korea is one of the young member nations in the space exploration community. Activities started back in 1989, when the Korea Aerospace Research Institute (KARI) was established. Located in the central city of Daejeon, KARI is part of the Daedeok Innopolis science and research cluster where over 20,000 researchers are at work. After developing its first rockets for space vehicles in the 1990s, KARI currently focuses on developing smart unmanned aerial vehicles (UAVs), satellite programs, and – in collaboration with NASA – lunar exploration.
In an ongoing project launched in June 2018, engineers at KARI have pursued the goal of implementing an infrastructure to perform flexible vibration tests for large payloads. Force-limited vibration testing (FLVT) is a proven procedure for simulating the mechanical stresses caused by vibrations during the launch and in flight. The UUT (unit under test) is placed on a shaker that can trigger defined and controlled excitation of masses. It is important to prevent overtesting, which could possibly lead to severe damage or even destruction of the UUT: to achieve this, acceleration levels are often controlled with additional force sensors. “This method has proven more sensitive, reliable and practical than monitoring acceleration only,” according to Sung-Hyun Woo, Director and Principal Researcher in the Space Environment Test Division at KARI. “Our goal was to create a control that automatically notches the excitation in response to the feedback from the force sensors.” Notching is the technical term for a reduction of acceleration input in narrow frequency bands, and it is usually applied in frequency bands where a test object has resonances.