Identification of a Force Sensing Resistor for Tactile Applications

A force sensing resistor (FSR) is a conductive polymer that changes resistance with the application of pressure at its surface. FSR can be used for tactile applications. In this work, the use of FSR to measure the fingertip force within an electronic Braille reading device is considered. To achieve this goal, an experimental procedure to test the FSR’s response is proposed. In this experiment, the FSR is placed between a linear actuator and a load cell. The linear actuator generates different loading profiles to mimic various tactile forces. Identification process starts by applying static loadings at the FSR’s surface. These loads are used to calibrate the FSR and study its time drift. In the next phase of the process, an up-chirp signal is used to identify the dynamics of the FSR. The resulting data are modeled using system identification techniques to obtain possible dynamic models for the FSR. Both linear and nonlinear models are proposed. The linear model is compared to Hammerstein, Wiener, and Hammerstein-Wiener nonlinear models. The accuracy and robustness of the four models are assessed using various loading profiles. Numerical criteria are developed to compare these models with respect to the experimental results.