Scalable Retrofit Angular Position Sensor System

Abstract

This article presents an angular position measurement system, designed to match the needs of the ever growing field of robotics and automation. Often existing systems should be equipped with sensors to enable autonomous acting. The presented sensor front-end is comprised of a single transmitter and two receiver coils. The mutual inductance between transmitter and receiver coils is spatially modulated using conductive objects. The resulting measurements are the basis for the absolute angle estimation. Here, the entire geometry requires 270° which makes it retrofittable to existing systems. The coil design is based on Finite Element Method simulation. The simulation framework allows for robust design with respect to detrimental effects such as tilt between the coils and modulating objects. Additionally, the sensor front-end is scalable in size to match different devices in automation. The underlying physical principle guarantees for robustness with respect to many detrimental effects such as moisture, bad illumination or oil contamination. Access to the data is provided using CAN bus as well as Bluetooth wireless connection. The applicability of the sensor system is showcased on the example of an industrial log-grasping crane.