Development and kinematic calibration for measurement structure of a micro parallel mechanism platform

This paper presents a micro-positioning platform based on a unique parallel mechanism developed by the authors. The platform has a meso-scale rectangular shape whose size is 20 x 23 mm. The stroke is 5 mm for both the xand yaxes and 100 degrees for the α-axis. The platform is actuated by three sets of dual stage linear actuators: a linear motor for rough positioning and a piezo actuator for fine positioning. The developed micro-positioning platform has a measurement system that consists of three linear sensors. The position and orientation values of the movable platform can be measured directly and used in a feedback control system. Selecting 18 kinematic error parameters of a measurement system (feedback control system), a two-stage kinematic calibration method is proposed. Constant error parameters are found in the first stage and variable error parameters are found in the second stage of kinematic calibration. After kinematic calibration the position error is reduced to within 0.5 μm and error reduction rate is over 90%.