Strain wave gear and elastic transmission element therefor, robotic arm and method for arranging a strain gauge

Abstract

An elastic transmission element is used in a strain wave gear. Such strain wave gears are also referred to as Harmonic Drives. The elastic transmission element is also referred to as a flexspline. Outer toothing is formed on the elastic transmission element. Furthermore, at least one strain gauge for measuring a mechanical strain of the elastic transmission element is arranged on the elastic transmission element. The at least one strain gauge is formed as a coating directly on a metallic surface of the elastic transmission element.

Claims

1. An elastic transmission element of a strain wave gear, wherein an outer toothing is formed on the elastic transmission element, and wherein at least one strain gauge for measuring a mechanical strain of the elastic transmission element is arranged on the elastic transmission element, wherein the at least one strain gauge is formed as a coating directly on a metallic surface of the elastic transmission element.

2. The elastic transmission element according to claim 1, wherein the at least one strain gauge has formed a direct integral connection with the metallic surface of the elastic transmission element.

3. The elastic transmission element according to claim 1, wherein the at least one strain gauge forms a component of a torque sensor and is connected to a measurement signal processing unit of the torque sensor via electrical connections.

4. The elastic transmission element according to claim 1, wherein the at least one strain gauge comprises an electrically insulating layer which is formed as a coating directly on the metallic surface of the elastic transmission element.

5. The elastic transmission element according to claim 1, wherein the at least one strain gauge is applied directly to the metallic surface of the elastic transmission element by a sputter deposition.

6. The elastic transmission element according to claim 1, wherein it has a bushing-shaped portion on which the outer toothing is formed and on which the at least one strain gauge is arranged, wherein the at least one strain gauge is formed as a coating directly on the metallic surface of the bushing-shaped portion of the elastic transmission element.

7. The elastic transmission element according to claim 1, wherein a plurality of the strain gauges are each formed as a coating directly on the metallic surface of the elastic transmission element, which are distributed circumferentially around the elastic transmission element.

8. A strain wave gear having a wave generator comprising a non-annular disk, a rigid outer ring having internal toothing and an elastic transmission element according to claim 1.

9. A robotic arm having at least one drivable arm element which is coupled via a strain wave gear according to claim 8.

10. A method for arranging a strain gauge on an elastic transmission element of a strain wave gear, wherein an outer toothing is formed on the elastic transmission element, and wherein the strain gauge is applied as a coating directly to a metallic surface of the elastic transmission element.

11. A transmission element of a strain wave gear, the transmission element comprising: an annular flange portion adapted for fixation to a shaft; an elastic bushing-shaped portion fixed at a first axial end to the flange portion and having external toothing formed at a second axial end opposite the first axial end; and a plurality of strain sensors formed as a coating on the bushing-shaped portion and circumferentially spaced from one another.

12. The transmission element of claim 11, wherein the bushing-shaped portion is metal.

13. The transmission element of claim 11, wherein the plurality of sensors are equally spaced around a perimeter of the bushing-shaped portion.

14. The transmission element of claim 11, wherein the plurality of sensors form a Wheatstone bridge.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Further advantages, details and developments of the elastic transmission element will become apparent from the following description of a preferred embodiment, with reference to the accompanying drawings. The single FIGURE is a pictorial view of an elastic transmission element for use in a strain wave gear.

DETAILED DESCRIPTION

[0037] The single FIGURE shows a preferred embodiment of an elastic transmission element of a strain wave gear. The elastic transmission element, which is also referred to as a flexspline, has a bushing-shaped portion 01, to which an annular portion 02 is connected. The annular portion 02 forms a flange and has a plurality of fastening holes 03 for fastening a shaft (not shown) to which a torque is transmitted by the strain wave gear. On the bushing-shaped portion 01, an external toothing 04 is formed, which engages in an internal toothing (not shown) of an outer ring of the strain wave gear.

[0038] Four strain gauges 06 are also arranged on the bushing-shaped portion 01 of the elastic transmission element. The elastic transmission element consists of a metal, wherein the strain gauges 06 are applied as a coating directly to the metallic surface of the elastic transmission element.

[0039] The four strain gauges 06 are circumferentially evenly distributed on the circumference of the bushing-shaped portion 01 of the elastic transmission element and form a Wheatstone bridge.

LIST OF REFERENCE SIGNS

[0040] 01 Bushing-shaped portion [0041] 02 Annular portion [0042] 03 Fastening holes [0043] 04 Outer toothing [0044] - [0045] 06 Strain gauge