Triaxial normal and shear force sensor

Abstract

A triaxial force sensor using a hemispherical target supported by a compliant element such as a spring or an elastomer supported by a rigid support member. The sensor includes 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 elastically deform the compliant element, 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, F.sub.x, F.sub.y, F.sub.z, M.sub.x, M.sub.y, M.sub.z, can be determined from the pulse transit times, the speed-of-sound in the medium or media between the transducers and the target, the deformation response of the compliant element, and the known geometry and spacing of the transducers. 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.

Dependencies are inferred from the claim text.