Accuracy improvement of large area flexible piezoresistive digital tactile array sensing system

Piezoresistive tactile array represent an important tool for pressure distribution analysis. Each site of the matrix acts as variable resistance whose value varies with normal force. A 16 times 16 array of fixed resistances has been realized to simulate the static response of 3.7 times 3.7 cm2 size FSR tactile sensors to strain. Scanning the different sites was performed by a microcontroller-based circuitry. To eliminate leak current paths when selecting a site, this latter must be isolated from the resistance grid. In this study three different conditioning circuits have been tested in order to assess the measurement accuracy. Results have shown that accuracy is enhanced in the region of low R when using the isolating circuit in which the output voltage from a selected row is fed back to all columns except the one selected. On the other hand, the accuracy decreases as analog multiplexer Ron increases. At last, transient effects have been observed when scanning the array is conducted at high rate.