New Open Loop Control Improves Linearity of Piezoelectric Actuators

The piezoelectric material is subject to hysteresis and creep resulting in a nonlinear relationship between the applied voltage and the output mechanical displacement. An approach for compensation of both the hysteresis and creep characteristics of a piezoelectric stack actuator is proposed by utilizing a switched capacitor charge pump. The new charge pump transfers the same amount of charges to the piezoelectric actuator quantitatively, and the actuator will be excited to change its length with constant step. Compared with voltage driving mode, experiments show that both creep and hysteresis of the piezoelectric stack driven by the charge pump are effectively reduced. A hysteresis reduction of 86.10% at 0.01Hz and 94.36% at 5Hz is achieved. At the maximum driving voltage, a creep reduction of 77% is obtained.