Device for detecting force and torque including multiple piezoelectric force measuring cells mechanically biased in a horizontal plane

Patent metadata

Field	Value
Publication number	US-10254183-B2
Application number	US-201615753496-A
Country	US
Kind code	B2
Filing date	Jul 25, 2016
Priority date	Sep 4, 2015
Publication date	Apr 9, 2019
Grant date	Apr 9, 2019

Abstract

A device for force and torque detection includes piezoelectric force measuring cells that are mechanically biased in a horizontal working plane against end surfaces of a mounting platform and detect power components. At least one first end surface of the mounting platform is disposed obliquely to at least one second end surface.

First claim

The invention claimed is:

1. A device for force and moment measurement, comprising:
a mounting platform having a plurality of end surfaces that include a first end surface and a second end surface disposed perpendicularly with respect to the first end surface;
a first coordinate axis extends in a direction that is normal to the first end surface;
a second coordinate axis extends in a direction that is normal to the second end surface;
a plurality of piezoelectric load cells for detecting force components (F x , F y , F z ) and including a first piezoelectric load cell and a second piezoelectric load cell, each of the plurality of piezoelectric load cells being disposed in a horizontal working plane (XY) and mechanically preloaded against a respective one of the plurality of end surfaces of the mounting platform, wherein the first piezoelectric load cell is preloaded against the first end surface of the mounting platform, and wherein the second piezoelectric load cell is preloaded against the second end surface of the mounting platform;
a first piezoelectric load cell of the plurality thereof is arranged at the first end surface;
a second piezoelectric load cell of the plurality thereof is arranged at the second end surface;
said first piezoelectric load cell is configured to measure a first force component (F x ) by a longitudinal effect and a second force component (F y ) by a shear effect;
wherein said second piezoelectric load cell is configured to measure the first force component (F x ) by the shear effect and the second force component (F y ) by the longitudinal effect; and
wherein each respective piezoelectric load cell is mechanically preloaded by a respective single preloading screw that is screwed in a respective thread defined in the respective end surface.

2. The device according to claim 1 , wherein each of the first force component (F,) and the second force component (Fy) are detected on the one hand by the shear effect and on the other hand by the longitudinal effect whereby the device has isotropic sensitivity in the horizontal working plane.

3. The device according to claim 1 , wherein the first piezoelectric load cell is configured to measure a third force component by the shear effect; and wherein the second piezoelectric load cell is configured to measure the third force component by the shear effect.

4. The device according to claim 1 , wherein the mounting platform is a cuboid comprising a rectangular base area, said base area being arranged in a horizontal working plane; wherein the plurality of end surfaces of said mounting platform comprises four rectangular end surfaces, each of said four rectangular end surfaces extending perpendicularly to the base area; and wherein two of said four rectangular end surfaces are arranged in a first vertical plane and two of said four rectangular end surfaces are arranged in a second vertical plane.

5. The device according to claim 4 , wherein a piezoelectric load cell is arranged at each of the four rectangular end surfaces or wherein a load cell is arranged in the center of each of the four rectangular end surfaces.

6. The device according to claim 5 , wherein the piezoelectric load cells are arranged at an equal distance to each other and/or the piezoelectric load cells are arranged on the working platform in the form of a cross.

7. The device according to claim 5 , wherein a utilization ratio of a sum of areas of hollow cylinder diameters of the piezoelectric load cells to a sum of areas of the end surfaces is greater than/equal to 25%.

8. The device according to claim 5 , wherein each piezoelectric load cell defines a central passage therethrough, and each respective piezoelectric load cell is mechanically preloaded by a respective preloading screw passing through the center of the central passage of the respective piezoelectric load cell.

9. The device according to claim 5 , wherein the piezoelectric load cells are arranged in recesses in the four rectangular end surfaces.

10. The device according to claim 9 , wherein a stiffness along the first coordinate axis is a sum of a compressive strength of the piezoelectric load cells and a shear stiffness of the piezoelectric load cells; the stiffness along the second coordinate axis is a sum of the compressive strength of the piezoelectric load cells and the shear stiffness of the piezoelectric load cells whereby the device has an isotropic stiffness in the horizontal working plane; and in that a natural frequency of the device is isotropic in the horizontal working plane.

11. The device according to claim 9 , further comprising a first signal line, a second signal line and a third signal line; wherein each piezoelectric load cell comprises a plurality of piezoelectric transducers; a force to be detected and/or a moment to be detected acting on surfaces of said piezoelectric transducers generates electric polarization charges on these surfaces; wherein each of the plurality of piezoelectric transducers includes a respective signal electrode electrically connected to the respective surface of the respective piezoelectric transducer, said signal electrodes being configured for picking up the electrical polarization charges; and wherein the first, second and third signal lines transmit the picked up electric polarization charges as signals.

12. The device according to claim 11 , wherein
the signal electrodes electrically connected to first ones of the plurality of piezoelectric transducers are electrically connected with each other in series and configured to transmit, via the first signal line, a signal that is a sum of the electrical polarization charges proportional to the first force component of the force;
the signal electrodes electrically connected to second ones of the plurality of piezoelectric transducers are electrically connected with each other in series and configured to transmit, via the second signal line, a signal that is a sum of the electric polarization charges proportional to the second force component of the force; and
the signal electrodes electrically connected to third ones of the plurality of piezoelectric transducers are electrically connected with each other in series and configured to transmit, via the third signal line, a signal that is a sum of the electric polarization charges proportional to the third force component of the force.

13. The device according to claim 12 , wherein
two first signal electrodes associated with the first piezoelectric transducers are electrically contacted with each other in series and transmit, via a signal line, a signal that is a sum of the electrical polarization charges proportional to the first force component of the force;
two second signal electrodes associated with the second piezoelectric transducers are electrically contacted with each other in series and transmit, via a signal line, a signal that is a sum of the electric polarization charges proportional to the second force component of the force;
two further signal electrodes associated with the first piezoelectric transducers and two further signal electrodes associated with the second piezoelectric transducers are electrically contacted with each other in series and transmit, via a signal line, a signal that is a sum of the electric polarization charges proportional to a third moment component of a moment; and
that the signal electrodes associated with the third piezoelectric transducers are electrically contacted with each other in series and transmit, via a signal line, a signal that is a sum of the electrical polarization charges proportional to the force component of the force.

14. The device accordin

Assignees

• Kistler Holding Ag

Inventors

• Kohler Denis

Classifications

• G01L5/167 Primary

  using piezoelectric means · CPC title