Low-Cost IR Reflective Sensors for Submicrolevel Position Measurement and Control

This paper investigates the feasibility of using commercially available, low-cost IR reflective sensors for micro- to sub- microscale position measurement and control. These sensors are typically used as optical switches; however, their application for detecting fine motion, such as the movement of a piezoactuator, has not been investigated. Five IR sensors were evaluated to determine their range, resolution, linear distortion, noise characteristics, and bandwidth. Experimental results show that the performance of the IR sensors compares well with a commercial inductive sensor that costs significantly more. For example, the measured resolution was within several hundred nanometers over a plusmn200 mum range and the linear distortion was significantly lower than the inductive sensor. A selected IR sensor was used in the design of a state-feedback control system to compensate for hysteresis and creep in an experimental piezopositioner. Compared to the open-loop system, by using the IR sensor in feedback, the output hysteresis was reduced by over 95 %. These results show the potential of such sensors in the design of low-cost microprecision mechatronic positioning systems.