Research on High Linearity Drive Technology for Point-Ahead Angle Mechanisms in Space Gravitational Wave Detection Systems

The point-ahead angle mechanism (PAAM) is a critical component for achieving ultralong-distance and nanoradian (nrad) pointing accuracy in space-based gravitational wave detection telescopes. Piezoelectric actuators, which are the essential elements of the PAAM, precisely control displacement via external voltage or charge inputs, thereby enabling accurate pointing in spaceborne telescopes. Therefore, the displacement response of the piezoelectric actuator directly affects the pointing accuracy of the PAAM. However, due to the hysteresis and creep effects inherent in piezoelectric actuators, the resulting nonlinear displacement response poses significant challenges to the ultrahigh-precision pointing of the PAAM. This article investigates ultrahigh-precision pointing and testing techniques for the PAAM to improve its positioning accuracy in spaceborne gravitational wave detection telescopes. First, an nrad-level piezoelectric tilting mirror specifically designed for space-based gravitational wave detection is proposed. A highly linear charge-driven circuit for piezoelectric actuators was designed and implemented. Then, a test platform was established to evaluate the performance of both the newly developed drive circuit and the piezoelectric tilting mirror. The test results show that when the piezoelectric actuator is driven by a sinusoidal signal in the range of 5–0.005 Hz, the displacement linearity is maintained within 2% and the nonlinearity is reduced by 30%–90% compared to conventional charge driving methods. When the piezoelectric tilting mirrors are driven with the same signal, the angular displacement linearity is maintained within 3%, reducing nonlinearity by 80%–90% compared to conventional voltage-drive methods and by 30%–80% compared to conventional charge-drive methods. These improvements significantly improve the displacement linearity of piezoelectric actuators and provide feasible analysis methods and implementation strategies for high-precision pointing control of the PAAM in spaceborne gravitational wave detection telescopes.