Adaptive Sliding Mode Control of Inclination Angle and Tension for a Suspended Anti-Gravity Device

Abstract

In 2020, space probes such as “Perseverance”, “Chan-g’e-5” and “Tianwen-1” have been launched to explore Mars and the moon. It shows that human beings are marching toward deep space, ushering in a new era of rapid development of space technology. As we all know, it is difficult for human beings to reach space, which determines that the development of space technology is particularly dependent on ground experiments [1–3]. Since microgravity is the most important feature of space environment, many important devices have been developed to construct microgravity environment on the ground, including drop tower, air-floating platform, Suspended Anti-gravity Device (SAGD), etc. However, the operation time and internal movable space of the drop tower and air-floating platform are limited. The SAGD offset the gravity of test object through the tension of hanging wire, breaking through the above limitations [4,5]. In the 1990s, Carnegie Mellon University developed an experimental device to verify various algorithms of space manipulator. The device uses counter-weight, pulleys and other mechanical structures to generate constant tension on the steel wire to offset the gravity of space manipulator. Subsequently, SAGD is concerned by many scientific research institutions [6]. Harbin Institute of Technology used single sling to offset five-sixths of the gravity of “YuTu” lunar rover, and measured its wheel pressure in a simulated lunar gravity environment. In 2019, Beijing Institute of Space Electromechanical Research developed a landing test device to verify the performance of probe during the landing phase in extraterrestrial body. It has been successfully applied to the landing test of Mars probe. The height of the device is 140 m, and the diameter of the experimental area is 120 m. By adjusting the tension of 36 steel wires, it can simulate the gravity environment of extraterrestrial body.