Piezoelectrics in Positioning - PZT & Piezo Actuators: Sub ...

Piezo • Nano • PositioningDynamic Digital Linearization(DDL)DDL is similar in performanceto Input Preshaping, but is simplerto use. In addition, it canoptimize multi-axis motionsuch as a raster scan or tracingan ellipse. This methodrequires no external metrologyor signal processing (see p.2-108). DDL uses the positioninformation from capacitivesensors integrated in the piezomechanics (requires directmetrology) to calculate theoptimum control signal. Aswith preshaping, the result isan improvement in linearityand tracking accuracy of up to 3orders of magnitude.Fig. 37 a. Elliptical scan in a laser micro-drilling application with XYpiezo scanning stage, conventional PID controller. The outer ellipsedescribes the target position, the inner ellipse shows the actualmotion at the stageLinear Actuators & MotorsNanopositioning / PiezoelectricsPiezo Flexure Stages /High-Speed Scanning SystemsLinearVertical & Tip/Tilt2- and 3-Axis6-AxisFast Steering Mirrors /Active OpticsPiezo Drivers /Servo ControllersSingle-ChannelMulti-ChannelModularAccessoriesPiezoelectrics in PositioningNanometrologyMicropositioningIndexFig. 37 b. Same scan as before, with a DDL controller. Targetand actual data can hardly be discerned. The tracking error hasbeen reduced to a few nanometers2-203