Triaxial normal and shear force sensor
First Claim
1. A sensor for use in determining shear and normal components of a force applied thereto, comprising:
- a target for reflecting ultrasonic waves;
at least two ultrasonic transducers aimed at said target, each of said transducers adapted to emit and detect ultrasonic signals, and each of said transducers being laterally and vertically offset from said target;
a substantially acoustically-transparent, substantially acoustically-nonrefractive medium disposed between each of said transducers and said target; and
compliant means supporting said target.
1 Assignment
0 Petitions
Accused Products
Abstract
A triaxial force sensor using a hemispherical target embedded in a compliant layer such as an elastomer and having a plurality of ultrasonic transducers disposed in a plane at equal intervals about the target and vertically and laterally offset from the target. The transducers are oriented at an oblique angle to the plane, and aimed at the target in its rest position. The target is displaced by sufficient force applied to the surface of the compliant layer, which displacement alters the transit times of ultrasonic signals from the transducers which are reflected from the target. If at least three sensor units are employed non-colinearly, the six force-torque components, Fx, Fy, Fz, Mx, My, Mz, can be determined from the pulse transit times, the speed-of-sound in the compliant layer, the compressibility of the compliant layer, and the known geometry and spacing of the sensor units. Pairs of transducers may be rotationally offset from each other to determine different force-torque components. A plurality of sensors as described may be employed together in a multi-sensor array. An alternative embodiment employing both the amplitude and the transit time of an ultrasonic pulse is also disclosed.
61 Citations
31 Claims
-
1. A sensor for use in determining shear and normal components of a force applied thereto, comprising:
-
a target for reflecting ultrasonic waves; at least two ultrasonic transducers aimed at said target, each of said transducers adapted to emit and detect ultrasonic signals, and each of said transducers being laterally and vertically offset from said target; a substantially acoustically-transparent, substantially acoustically-nonrefractive medium disposed between each of said transducers and said target; and compliant means supporting said target. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
-
-
15. A multi-sensor army for use in determining shear and normal components of a force applied thereto, comprising:
-
a plurality of targets for reflecting ultrasonic waves, said targets being laterally separated and located at predetermined intervals; each of said targets having associated therewith at least two ultrasonic transducers adapted to emit and receive ultrasonic signals, said at least two transducers each being aimed at said target with which each of said transducers is associated and horizontally and vertically offset therefrom; and a substantially acoustically-transparent, substantially acoustically-nonrefractive medium disposed between each of said transducers and said targets; and compliant means supporting said targets. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 30, 31)
-
-
29. A method of determining shear and normal force components of a force, comprising:
-
arranging an acoustically-reflective target; providing at least two ultrasonic transducers horizontally and vertically offset from said target in a common plane, and aiming said transducers at said target from a common distance; compliantly supporting said target with a structure having known compliancy characteristics in a substantially acoustically-transparent, substantially acoustically-nonrefractive medium extending between each of said transducers and said target, said medium having known speed-of-sound; applying said force to said target; emitting an ultrasonic signal from each transducer toward said target, and timing the transit time between emission of each said signal and the emitted signal'"'"'s return to the transducer from which the signal was emitted; and calculating shear and normal force components of said force from said transit times and said known speed-of-sound and compliancy characteristics.
-
Specification