Piezoelectric tactile sensor
First Claim
1. Force magnitude and force pattern responsive tactile sensing apparatus comprising the combination of:
- a two-dimensional array of electrode elements disposed in electrical and physical isolation across a planar surface area portion of a semiconductor substrate member;
a force responsive physically deformable film of piezoelectric effect material disposed over said array of electrode elements and said substrate member surface area portions, in electrical capacitance coupling with said electrode element array;
an electrically conductive common electrode member disposed over a second distal surface portion of said film of piezoelectric effect material and connected with a common return electrical node of said sensing apparatus;
electronic amplifier means, including a plurality of high input impedance electronic amplifier circuits physically disposed adjacent to said array of electrode elements with each said amplifier circuit having respective input nodes connected with one of said electrode elements and with said common return electrical node for amplifying a piezoelectric effect electrical charge signal received on said electrode element during sensed tactile force physical deformations of said film of piezoelectric effect material;
low voltage electrical charge generating means temporarily connected with each said electrode element of said array for pre-conditioning said piezoelectric effect material to a substantially uniform signal generation state prior to each said tactile force physical deformation.
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Abstract
A two-dimensional, electrically-multiplexed robotic tactile sensor realized by capacitively coupling a piezoelectric film such as a polyvinylidene fluoride (PVDF) polymer film to a monolithic silicon integrated circuit. The disclosed integrated circuit incorporates 64 identical sensor electrodes arranged in a symmetrical 8×8 matrix and physically adjacent electronic amplification for each sensor electrode signal. The response of a typical tactile sensor is linear for loads spanning the range of 0.8 to 135 grams of force and provides a response bandwidth of 20-25 Hz. Stability and response reproducibility limitations often associated with piezoelectric-based tactile sensors are resolved by a pre-charge voltage bias sequence for the PVDF film which initializes the pre-and post-load sensor responses. Recognition of sharp-edge, square, trapezoid, isosceles triangle, circle, toroid, slotted screw, and cross-slotted screw shapes using the sensor is also disclosed.
165 Citations
20 Claims
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1. Force magnitude and force pattern responsive tactile sensing apparatus comprising the combination of:
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a two-dimensional array of electrode elements disposed in electrical and physical isolation across a planar surface area portion of a semiconductor substrate member; a force responsive physically deformable film of piezoelectric effect material disposed over said array of electrode elements and said substrate member surface area portions, in electrical capacitance coupling with said electrode element array; an electrically conductive common electrode member disposed over a second distal surface portion of said film of piezoelectric effect material and connected with a common return electrical node of said sensing apparatus; electronic amplifier means, including a plurality of high input impedance electronic amplifier circuits physically disposed adjacent to said array of electrode elements with each said amplifier circuit having respective input nodes connected with one of said electrode elements and with said common return electrical node for amplifying a piezoelectric effect electrical charge signal received on said electrode element during sensed tactile force physical deformations of said film of piezoelectric effect material; low voltage electrical charge generating means temporarily connected with each said electrode element of said array for pre-conditioning said piezoelectric effect material to a substantially uniform signal generation state prior to each said tactile force physical deformation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. The method of tactile force sensing comprising the steps of:
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generating a spatial map related array of discrete electrical signals each representing a force magnitude at a predetermined planar location within an applied force field; said signal generating step including capacitively sensing local quantums of electrical charge displaced to surface adjacent portions of a piezoelectric film by physical deformation of said film from said applied force field; each said signal generating step being preceded by a temporary low voltage electrical signal induced output signal range limiting physical preconditioning of said piezoelectric film; and amplifying each said discrete electrical signal of said array in an amplifying each said discrete electrical signal of said array in an amplifying location disposed adjacent said spatial map signal location.
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Specification