Sensor systems integrated with footwear
Sensors and sensor systems incorporating piezoresistive materials for integration with footwear are described.
1. A sensor system, comprising:
a flexible piezoresistive fabric substrate having a shape of a portion of an article of footwear, the piezoresistive substrate having top and bottom surfaces;
an array of sensors, each sensor including two conductive traces, both of the two conductive traces for each sensor being printed, screened, or deposited directly on a same one of the surfaces of the piezoresistive substrate, each sensor being positioned on the substrate to align with a region of the exterior of a human foot; and
sensor circuitry configured to energize the sensors to generate sensor signals, and to receive the sensor signals from the array of sensors, each sensor signal representing a force associated with a corresponding one of the sensors, the sensor circuitry being further configured to determine a force value for each sensor signal using calibrated sensor data representing a response of the corresponding sensor.
2. The sensor system of claim 1 , further comprising a flexible dielectric substrate having the shape of the portion of an article of footwear, the flexible dielectric substrate being aligned with the flexible piezoresistive substrate and in contact with the array of sensors, the flexible dielectric substrate being secured to the flexible piezoresistive substrate only at locations on the flexible piezoresistive substrate where there are no sensors.
3. The sensor system of claim 2 , wherein the flexible dielectric substrate is secured to the flexible piezoresistive substrate at the locations with patches of adhesive.
4. The sensor system of claim 2 , wherein the flexible piezoresistive substrate and the flexible dielectric substrate are included among a plurality of layers, the plurality of layers further including, a stiffener, and top and bottom layers that combine to enclose and provide environmental protection to the flexible piezoresistive substrate, the flexible dielectric substrate, and the stiffener.
5. The sensor system of claim 1 , wherein the sensor circuitry is disposed on a printed circuit board positioned in an aperture in the flexible piezoresistive substrate.
6. The sensor system of claim 1 , wherein the sensor circuitry is configured to determine the force value for each sensor signal by mapping an analog-to-digital converter (ADC) value for each sensor signal to the force value stored in memory associated with the sensor circuitry.
7. The sensor system of claim 1 , wherein the sensor circuitry is configured to determine the force value for each sensor signal corresponding to a sensor of interest by generating a first value with the sensor of interest activated, generating a second value with remaining sensors of the array activated, and processing the first and second values to account for parasitic resistances of the sensor array.
8. The sensor system of claim 1 , wherein the sensor circuitry is further configured to process the sensor signals corresponding to multiple sensors to determine a speed and a direction of one or more of the corresponding forces.
9. The sensor system of claim 1 , wherein the shape of the portion of an article of footwear is a shape of an insole, and wherein a first set of the sensors is positioned on the flexible piezoresistive substrate to align with undersides of toes of the human foot, a second set of the sensors is positioned on the flexible piezoresistive substrate to align with a ball of the human foot, and a third set of the sensors is positioned on the flexible piezoresistive substrate to align with a heel of the human foot.
10. The sensor system of claim 9 , wherein a fourth set of the sensors is positioned on the flexible piezoresistive substrate to align with an outside edge of the human foot.
11. The sensor system of claim 1 , wherein the shape of the portion of an article of footwear is a shape of an upper.
12. A sensor system, comprising:
piezoresistive fabric;
a flexible dielectric substrate having a shape of a portion of an article of footwear, the flexible dielectric fabric, the flexible dielectric substrate having top and bottom surfaces being aligned with the piezoresistive fabric, the flexible dielectric substrate having top and bottom surfaces;
an array of sensors, each sensor including two conductive traces, both of the two conductive traces for each sensor being printed, screened, or deposited directly on a same one of the surfaces of the flexible dielectric substrate, the conductive traces being in contact with the piezoresistive fabric, each sensor being positioned on the flexible dielectric substrate to align with a region of the exterior of a human foot; and
sensor circuitry configured to energize the sensors to generate sensor signals, and to receive the sensor signals from the array of sensors, each sensor signal representing a force associated with a corresponding one of the sensors, the sensor circuitry being further configured to determine a force value for each sensor signal using calibrated sensor data representing a response of the corresponding sensor.
13. The sensor system of claim 12 , wherein the flexible dielectric substrate is secured to the piezoresistive fabric only at locations on the flexible dielectric substrate where there are no sensors.
14. The sensor system of claim 13 , wherein the flexible dielectric substrate is secured to the piezoresistive fabric at the locations with patches of adhesive.
15. The sensor system of claim 13 , wherein the piezoresistive fabric and the flexible dielectric substrate are included among a plurality of layers, the plurality of layers further including, a stiffener, and top and bottom layers that combine to enclose and provide environmental protection to the piezoresistive fabric, the flexible dielectric substrate, and the stiffener.
16. The sensor system of claim 12 , wherein the sensor circuitry is disposed on a printed circuit board positioned in an aperture in the flexible dielectric substrate.
17. The sensor system of claim 12 , wherein the sensor circuitry is configured to determine the force value for each sensor signal by mapping an analog-to-digital converter (ADC) value for each sensor signal to the force value stored in memory associated with the sensor circuitry.
18. The sensor system of claim 12 , wherein the sensor circuitry is configured to determine the force value for each sensor signal corresponding to a sensor of interest by generating a first value with the sensor of interest activated, generating a second value with remaining sensors of the array activated, and processing the first and second values to account for parasitic resistances of the sensor array.
19. The sensor system of claim 12 , wherein the sensor circuitry is further configured to process the sensor signals corresponding to multiple sensors to determine a speed and a direction of one or more of the corresponding forces.
20. The sensor system of claim 12 , wherein the shape of the portion of an article of footwear is a shape of an insole, and wherein a first set of the sensors is positioned on the flexible dielectric substrate to align with undersides of toes of the human foot, a second set of the sensors is positioned on the flexible dielectric substrate to align with a ball of the human foot, and a third set of the sensors is positioned on the flexible dielectric substrate to align with a heel of the human foot.
21. The sensor system of claim 20 , wherein a fourth set of the sensors is positioned on the flexible dielectric substrate to align with an outside edge of the human foot.
22. The sensor system of claim 12 , wherein the shape of the portion of an article of footwear is a shape of an upper.