Design and Implementation of a Simple and Low-Cost Optoelectronic Force Sensor for Robotic Applications

This paper presents the design and implementation of a force sensor based on optoelectronic components. The sensor is designed for a twisted string actuation module that can be used for a large set of robotic applications where tendon driven mechanisms are required. The proposed sensor measures the force applied by the twisted string actuation system by detecting the deformation of a properly designed compliant structure integrated into the actuation module. The main advantages of the proposed sensor consist in the use of a very compact commercial light fork as a sensing element. This solution is characterized by a very simple assembly procedure and allows a good sensor response in terms of sensitivity, linearity and noise rejection to be achieved using an extremely simple electronics, thereby obtaining in this way a reliable and very cheap sensor that can be easily integrated in actuation modules for robots and can easily adapted to a wide application set. The paper presents the basic working principle and the design of the force sensor. The sensor compliant frame has been verified both by finite element analysis and by experimental measures, and the results have been compared. Moreover, the sensor calibration and the experimental validation have been performed both in static and dynamic conditions.