Abstract
The present paper validates the effectiveness of the characteristic switching as a locking function for a vertical motion multilayer thin electrostatic actuator supported by only lubricating oil. In the electrostatic actuator, the friction forces often deteriorate the response and positioning accuracy of a control system, especially when the lightweight electrode layers are supported by only lubricating oil. However, the contact condition between the electrode layers can be changed by the attractive forces resulting from the driving signal waveforms, which consequently influences the frictional effect. The large frictional effect that is generated is useful as a locking function which is needed to precisely maintain the stage position especially in vertical motion stages. In this paper, suitable driving signal waveforms for switching between two frictional conditions (i.e., low friction for the wide and fast motion and high friction for the fine motion with a large holding force) are examined and clarified for the vertical motion stage. First, the working principles and experimental setup of the electrostatic actuator in the vertical motion stage are discussed. Then, the open-loop characteristics under the vertical motion stage are discussed based on the frictional effect. Lastly, the resultant effects of the driving signals on the vertical motion characteristics were evaluated, which concluded with the discussion in the signal selection on demand as the locking function.
