Controllable Trade-Off Between Performance and Constrained Input for Vibration Suppression in Flexible Space Structures

Achieving vibration suppression of flexible space structures requires not only considering the vibration settling time, but also avoiding excessive control forces that might damage the structure. In this article, an active control scheme is designed to suppress undesired vibrations in flexible structures by exerting small cable forces. It employs a cable-driven parallel robot (CDPR) as an actuator. The prominent feature of the controller lies in its ability to achieve a controllable trade-off between the effectiveness of vibration suppression and control inputs. Moreover, the controller can effectively suppress vibrations even when cable forces are constrained. The underlying principle is that the vibration energy is consumed through the negative work done by the cable forces until the tip displacement is ultimately reduced to a small range. The stability of the controller is verified by the Lyapunov method. Simulations demonstrate the effectiveness of the proposed control scheme, while experimental validation on a prototype consisting of a six-meter-long flexible structure and a four-cable CDPR further supports these findings.