CONTROLLER FOR ELECTROMECHANICAL CONVERSION ELEMENT WITH NONLINEAR DISPLACEMENT CHARACTERISTICS

PURPOSE: To automatically reduce a nonlinear displacement characteristics since a displacement error for a desired value is large when the nonlinear displacement characteristics exists in an electromechanical conversion element. CONSTITUTION: A nonlinear correction coefficient generation means 103 samples the periodical desired value of a saw-tooth-wave shape generated by a desired value generation means 102 and displacement information obtained from a displacement detection means 108 at least once or more in one period, and sets a nonlinear correction coefficient so that a difference between the desired value and the displacement information becomes within a prescribed range. A switch means 106 selects a manipulated variable obtained from the nonlinear correction coefficient generation means 103 until the nonlinear correction coefficient is set, and selects the manipulated variable obtained from a nonlinear correction means 105 after the nonlinear correction means is set.