Space manipulators are flexible structures. Vibration problem will be unavoidable due to motion or external disturbance excitation. Model based control methods will not maintain the required accuracy because of the existence of nonlinear factors and parameter uncertainties. To solve these problems, fuzzy logic control laws with different membership function groups are adopted to suppress vibrations of a flexible smart manipulator using collocated piezoelectric sensor/actuator pair. Also, dual-mode controllers combining fuzzy logic and proportional integral control are designed, for suppressing the lower amplitude vibration near the equilibrium point significantly. Experimental comparison research is conducted, using fuzzy control algorithms and the dual-mode controllers with different membership functions. The experimental results show that the adopted fuzzy control algorithms can substantially suppress the larger amplitude vibration; and the dual-mode controllers can also damp out the lower amplitude vibration significantly. The experimental results demonstrate that the proposed fuzzy controllers and dual-mode controllers can suppress vibration effectively, and the optimal placement is feasible.

AbstractüSome flexible appendages of spacecraft are cantilever plate structures, such as sun plate, piezoelectric smart structure is used to suppress the multi-modal vibrations of the cantilever plate due to the parameter uncertainties and environmental disturbances.Optimal placement of piezoelectric actuators/sensors in active vibration suppression of flexible plate is conducted to control the vibrations of bending modes and torsional modes. The experimental facility of piezoelectric smart plate for active vibration control was designed and built up. A kind of gain select sliding mode variable structure control method is adopted. And experimental studies of identification and vibration control are conducted. The experimental results demonstrate that the adopted method can suppress the vibration significantly, and the strategy is feasible.