Identification and validation of a fractional order dynamic model for a piezoelectric tactile sensor

This paper presents the identification of a piezoelectric tactile sensor which aims to give the sense of touch to humanoid robots. The sensor has been characterized in frequency domain and the low frequency behavior reveals a non-integer behavior. A simple model based on the a priori knowledge of the sensor and the observation of the frequency response has been hypothesized and a least squares method has been applied to identify the device. The impulse response has been calculated using the Mittag-Leffler function and validation in time domain has been performed. Simulation and experimental results are in good agreement showing that the identified model, despite its simplicity, is able to represent properly the tactile sensor.