Abstract: The vibration problem of space robot and flexible appendages of spacecraft will be unavoidable when they are slewing or external disturbance happens. Especially the lower amplitude vibration near the equilibrium point is hard to be suppressed, which will affect the stability and the pointing accuracy of the system. To solve this problem, a kind of acceleration sensor based feedback nonlinear control algorithm is proposed, and the stability and advantages are analyzed theoretically. The control system is non-minimum phase system due to the phase lag caused by non-collocated placement of acceleration sensor and piezoelectric actuator or AC servomotor. Thus phase shifting method for compensating the phase lag is applied. The proposed nonlinear control algorithm is used to damp out the vibration quickly, especially for the low amplitude vibration around the equilibrium point. This process is achieved by combing acceleration signal phase shifting low-pass filter proportional feedback with positive position feedback and nonlinear logic integral damping control. The experimental setup of piezoelectric smart structure is designed and built up. Acceleration sensor, piezoelectric patches and AC servomotor actuator are used to attenuate the vibrations, and several control methods are used to develop the experimental comparison researches. The experimental results demonstrate that the presented methods can suppress the vibration quickly, especially for the lower amplitude vibration near the equilibrium point.

Key words: Acceleration feedback control, Active vibration control, Flexible smart structures, Nonlinear control