Development of an Optical System for High Precision Multi-Axis Force Measurements

Abstract

Accurate and precise force measurements are critical in machining operations for maximizing production, detecting tool failure, and monitoring. Currently, the most accurate force sensors are piezoelectric sensors. The accuracy of these sensors is very high, yet they are expensive, are limited in their measurement bandwidth and are only suited for dynamic measurements. To overcome the challenges of existing sensors an alternative incorporates optical components to measure very small displacements. The sensor uses photo detector technologies which can measure positional changes from a laser on the order of nanometres. To improve sensitivity a mechanical amplification system based on levers is introduced, along with algorithms to extract the effects of multiple sources and a single detector. To extract more accurate information, an analysis of the photodiode and laser beam characteristics is performed. For implementation, a prototype sensor is fabricated. The sensor is benchmarked against a commercial dynamometer to characterize performance.