Shen J.-C.Jywe W.-Y.Liu C.-H.Jian Y.-T.Yang J.Wen-Yuh Jywe2022-05-242022-05-242008https://www.scopus.com/inward/record.uri?eid=2-s2.0-56149087183&doi=10.1002%2fasjc.33&partnerID=40&md5=155871715c0cf6d68b05b471b35d2c7fhttps://scholars.lib.ntu.edu.tw/handle/123456789/611957This paper presents the sliding-mode control of a three-degrees-of-freedom nanopositioner (Z, Dx, Oy). This nanopositioner is actuated by piezoelectric actuators. Capacitive gap sensors are used for position feedback. In order to design the feedback controller, the open-loop characteristics of this nanopositioner are investigated. Based on the results of the investigation, each pair of piezoelectric actuators and corresponding gap sensors is treated as an independent system and modeled as a first-order linear model coupled with hysteresis. When the model is identified and the hysteresis nonlinearity is linearized, a linear system model with uncertainty is used to design the controller. When designing the controller, the sliding-mode disturbance (uncertainty) estimation and compensation scheme is used. The structure of the proposed controller is similar to that of a proportional integral derivative controller. Thus, it can be easily implemented. Experimental results show that 3-nm tracking resolution can be obtained.Capacitive sensorsControllersDegrees of freedom (mechanics)HysteresisLinear systemsPiezoelectric actuatorsPiezoelectricityProportional control systemsSliding mode controlTwo term control systemsEstimation and compensationHysteresis non linearitiesLinear system modelNano-positionerOpen loop characteristicPrecision, nonlinearProportional integral derivative controllersThree degrees of freedomFeedbackjournal article10.1002/asjc.332-s2.0-56149087183