阅读说明：本技术 用于测量扭矩的装置及包括这样的装置的应变波齿轮机构 (Device for measuring torque and strain wave gear mechanism comprising such a device ) 是由 于尔根·吉尔 菲利普·霍宁 罗米娜·贝克施泰特 约亨·达美劳 延斯·海姆 理查德·恩里克· 于 2020-04-29 设计创作，主要内容包括：本发明涉及用于测量应变波齿轮机构的扭矩的装置。该装置包括：被施加扭矩的部件(01,02)；布置在部件(01,02)上的电绝缘的绝缘层(06)；以及布置在绝缘层(06)上的变形敏感测量层(04)。本发明还涉及具有这样的用于测量扭矩的装置的用于机器人手臂的应变波齿轮机构。(The present invention relates to a device for measuring torque of a strain wave gear mechanism. The device includes: a member (01, 02) to which torque is applied; an electrically insulating layer (06) arranged on the component (01, 02); and a deformation-sensitive measurement layer (04) arranged on the insulating layer (06). The invention also relates to a strain wave gear mechanism for a robot arm with such a device for measuring torque.)

1. An apparatus for measuring torque of a strain wave gear mechanism, the apparatus comprising: a flex spline (01, 02) on which the torque acts; an electrically insulating insulation layer (06) arranged on the flexible spline (01, 02); and a deformation-sensitive measurement layer (04) arranged on the insulating layer (06).

2. Device according to claim 1, characterized in that the flexible spline (01, 02) is part of a robot system, in particular a robot arm or a robot arm joint.

3. The device according to claim 1 or 2, characterized in that a protective layer (07) is applied to the measurement layer (04).

4. A device according to claim 3, characterized in that the protective layer (07) is organic or inorganic.

5. A device according to claim 3 or 4, characterised in that the total thickness of the sequence of layers consisting of the measurement layer (04), the insulation layer (06) and the protective layer (07) applied to the flexible spline (01, 02) is less than 200 μm.

6. Device according to one of claims 1 to 5, characterized in that the insulating layer consists of one or more oxides, in particular of an oxide layer and/or a carbon coating.

7. The device according to one of claims 1 to 6, characterized in that the total thickness of the sequence of layers consisting of the measurement layer (04) and the insulation layer (06) applied to the flexible spline (01, 02) is less than 20 μm.

8. Device according to one of claims 1 to 7, characterized in that a further component is arranged on the flexible spline (01, 02).

9. A strain wave gear mechanism for a robot arm, the strain wave gear mechanism comprising a device for measuring torque according to any of claims 1-8, the strain wave gear mechanism further comprising a drive shaft, a wave generator with an inner ring and an outer ring, an internally toothed ring gear and externally toothed flexible splines (01, 02), wherein the externally toothed flexible splines (01, 02) and the internally toothed ring gear are arranged coaxially to each other such that the teeth mesh, and wherein the inner ring is positioned on the drive shaft such that the drive shaft drives and deforms the externally toothed flexible splines (01, 02).

Technical Field

The present invention relates to a device for measuring torque occurring in a strain wave gear mechanism of a robot. In particular, the device is used for a robot joint. The invention also relates to a strain wave gear mechanism.

Background

From DE102010029186a1, a measuring device for determining the torque acting on a shaft is known, wherein the measuring device comprises a first device and a second device. The devices are each designed to generate an analog electrical signal associated with torque. Two independent torques are determined by means of a downstream analog-to-digital converter and a downstream digital evaluation device. The device consists of a strain gauge applied to a mechanical measuring body.

DE102014210379B4 describes a torque sensor and a method for measuring the torque occurring at or in the joints of an articulated arm robot. The sensor comprises a plurality of measuring spokes which are designed such that they deform under the effect of a torque. The sensor further comprises a strain gauge arranged on the measuring spoke.

DE102012208492a1 describes a method for creating a strain gauge structure on the surface of a machine element. A deformation-sensitive measuring layer with a covering protective layer is applied to the surface. The protective layer is locally removed by laser treatment and the exposed measurement layer is electrically contacted. Furthermore, it is known from this disclosure that an insulating layer can be arranged between the surface of the machine element and the measurement layer.

DE102014219737a1 describes a device for measuring the torque applied to a rotatably mounted component. The carrier member is arranged on a rotatable mounting member on which the deformation sensitive material is applied as a coating. The deformation sensitive material forms a torque measuring structure.

From DE10317304a1, a method and a device for determining the output torque of an electric motor are known. A gear with a ring gear is arranged downstream of the electric motor. The dynamic motor torque is measured by means of a torque sensor which is supported in a fixed position on the ring gear.

DE102013204924a1 describes a structure for determining the torque acting on a shaft. In particular, the structure is part of a steering column of a vehicle. The structure includes a first steering shaft portion on a side of a steering wheel, a second steering shaft portion on a side of a steering gear, and a torsion portion connecting the steering shaft portions. Furthermore, the structure comprises a direct coating for torque measurement, the direct coating having a strain gauge.

The prior art shows that for measuring the torque acting on the shaft, measuring arrangements are used in which strain gauges are applied on the outside of the shaft or on the shaft.

For robotic gear mechanisms, it is very important to accurately determine the torque transmitted by the strain wave gear mechanism. For example, in medical technology and other applications, robotic arms are used as prostheses for humans, wherein the robotic arms must perform precise mechanical movements and overall mechanical movements at different speeds and under different loads during operation. The same applies to industrial robots.

In other applications, strain wave gear mechanisms are used as wheel axle drives in robots, in motor vehicles, in machine tools and in printing presses. Torque transmitting strain wave gear mechanisms are also known as harmonic drives or harmonic gear mechanisms. The strain wave gear mechanism typically includes an input shaft, an elliptical disk, a flexible spline, an outer ring, an input shaft, and a housing. The flexible spline is externally toothed and the outer ring is internally toothed, wherein the two parts are arranged coaxially to each other such that the teeth mesh with each other.

Devices for torque measurement in a robot arm are known, which are mounted outside the gear housing of the robot arm. For example, the deformable body on which the strain gauges are arranged is arranged in the region of the robot arm, in particular in the region of the robot joint. Using a strain gauge, shear strain is recorded to determine the torque applied at the robot joint.

Disclosure of Invention

Based on the prior art it was an object of the present invention to provide an improved torque measuring device which is designed to save space while providing a high level of accuracy and robustness.

Said object is achieved by a device for measuring torque according to the appended claim 1. Furthermore, the object is achieved by a strain wave gear mechanism according to claim 9.

The device according to the invention is used for measuring the torque of a strain wave gear mechanism. The torque measuring device comprises a component and a plurality of layers which are arranged one above the other on the component and are part of a direct coating of the strain gauge. An electrically insulating layer is disposed directly on the component. The deformation-sensitive measurement layer is arranged directly on the insulating layer.

The component is part of a robotic system, specifically a strain wave gear mechanism. The member supporting the plurality of layers is a flex spline.

One advantage of the device according to the invention is that it is designed to be space-saving, since no further deformation bodies are required, which are used only for measuring the torque. Another advantage of the device is that it is capable of achieving high accuracy and precision during operation and is very robust.

The component is preferably made of metal. Alternatively, the component is made of a semiconductor material. The flex spline has teeth on its outer radius. For example, the component may be a cylindrical steel sleeve that is flexible within desired limits.

In a preferred embodiment, a protective layer is applied to the deformation-sensitive measuring layer, which protective layer protects the layers located below the protective layer from environmental influences. The protective layer is preferably made of an organic material. Alternatively, the protective layer is preferably made of an inorganic material.

The measurement layer is used to measure the strain or shear of the component, wherein the torque is measured.

The measuring layer preferably consists of a metal or an alloy, in particular a nickel alloy. The nickel alloy is preferably nickel chromium (NiCr).

The measurement layer preferably has a configuration. Particularly preferably, the measurement layer has a spatial configuration forming a stripe pattern. Different embodiments may, for example, have striations in an angular range between 35 ° and 55 ° relative to the longitudinal axis of the part. The structuring is preferably created by means of a laser or by etching, wherein the structuring is only created after the measuring layer has been applied to the component.

The insulating layer is preferably composed of one or more different oxides. Alternatively, the insulating layer is composed of diamond-like carbon (DLC). Alternatively, the insulating layer may be composed of one or more oxides and DLC. The insulating layer is particularly preferably made of Al₂O₃(aluminum oxide) and/or SiO₂(wollastonite).

For example, the insulating layer may be produced by a physical vapor deposition Process (PVD) or a chemically assisted physical vapor deposition Process (PACVD). In one embodiment, the insulating layer is produced by a combination of a PVD process and a PACVD process.

Preferably, the sequence of layers consisting of the measurement layer, the insulating layer and the protective layer applied to the component has a total thickness of less than 200 μm. Particularly preferably, the sequence of layers comprising the measurement layer and the insulating layer has a total thickness of less than 20 μm

Preferably, further elements may be arranged on the component. In one embodiment, electronic components for signal preamplification and/or for signal evaluation and/or for signal transmission are arranged on the component.

In one embodiment, an at least partially contacting conductive contact layer is formed between the stripe portions.

The strain wave gear mechanism according to the invention comprises a device for measuring torque according to the above-described device and all its embodiments. Further, the strain wave gear mechanism includes a drive shaft, a wave generator, which may be a rolling bearing having a non-circular (e.g., elliptical) inner ring and a deformable outer ring, a ring gear mechanism, and an elastic sleeve, which is called a flexible spline. The rear part of the device exhibits external teeth and the ring gear mechanism exhibits internal teeth. The flexible spline and the ring gear mechanism are arranged coaxially with each other such that the gear mechanism teeth mesh with each other. The inner ring of the wave generator is positioned on the drive shaft such that the inner ring drives the component.

The strain wave gear mechanism preferably also has a housing in which the aforementioned transmission components are at least partially arranged.

The strain wave gear mechanism according to the invention advantageously saves installation space, since the device and its coating are arranged in the housing and no further deformation body is required. The device and the strain wave gear mechanism are suitable for use in the field of robotics and are particularly advantageous in this field due to the high accuracy that the device provides by accurately measuring torque. In particular, the device and the strain wave gear mechanism are advantageous in terms of preventing collision or adjusting force and rigidity.

Drawings

Further advantages and details of the invention emerge from the following description of a preferred embodiment with reference to the drawings. In the drawings:

fig. 1 shows a side view and a detailed view of a first embodiment of the device according to the invention;

FIG. 2 shows a cross-sectional view and a detailed view of the device shown in FIG. 1;

FIG. 3 shows a plan view of a second embodiment of the device;

FIG. 4 shows a side view of the device shown in FIG. 3;

fig. 5 shows a cross-sectional view and a detailed view of a side view of the device shown in fig. 4.

Detailed Description

Fig. 1 shows a side view and a detailed view of a first embodiment of the device according to the invention. The device presents a flexible spline that can be used in a strain wave gear mechanism, wherein the flexible spline consists of a disc 01 and a cylindrical part 02 axially adjoining the disc. Preferably, the flexible splines are made of steel. A cylindrical member 02 or sleeve is disposed on the inner diameter of the disc 01. The cylindrical part 02 has external teeth 03 on its part facing away from the disk 01. A deformation-sensitive measuring layer 04 in the form of a strain gauge, in particular a Sensotect strain gauge, is arranged on the portion of the cylindrical part 02 facing the outer circumference of the disk 01. An insulating layer 06 is formed between the base material of the cylindrical part 02 and the deformation-sensitive measuring layer 04. The torque of the strain wave gear mechanism is determined by means of the deformation-sensitive measurement layer 04. The measurement layer preferably has a configuration forming a stripe pattern.

Fig. 1 also shows a detailed view of the deformation-sensitive measuring layer 04. In the example shown, the shaped structure of the measurement layer 04 extends in a plurality of curves, the axis of the non-curved part of the structure being inclined to the axis of the cylinder of the part 02.

One of the advantages of the device according to the invention is that the device is designed to save installation space.

Fig. 2 shows a cross-sectional view of the flex spline with disc 01 and cylindrical part 02 shown in fig. 1. In the detailed view of fig. 2, the sequence of layers of the device is shown. An insulating layer 06 is applied to a cylindrical component 02 made of steel, to which a deformation-sensitive measuring layer 04 and a protective layer 07 arranged thereon are applied. The deformation-sensitive measurement layer 04 is a structured NiCr functional layer.

Fig. 3 shows a plan view of an unclaimed embodiment of the device. In contrast to the arrangement shown in fig. 1, the disk 01 has a deformation-sensitive measuring layer 04 here. No deformation-sensitive measurement layer is formed on the outer circumference of the cylindrical member 02. The individual components of the deformation-sensitive measuring layer 04 are distributed circumferentially on the disk 01. The device is designed here as a spindle sleeve.

Fig. 4 shows a side view of the collar sleeve shown in fig. 3. Since the deformation-sensitive measurement layer 04 is formed on the disk 01, the measurement layer on the outer circumference of the cylindrical part 02 is missing. In the region of the cylindrical part 02 facing away from the disk 01, teeth 03 are also formed on the outer circumference.

Fig. 5 shows a cross-sectional view of a side view of the device shown in fig. 4. Fig. 5 furthermore shows a detailed view of the sequence of the layers of the disc 01. Preferably Al₂O₃A constituent insulating layer 06 is disposed on the steel disc 01. A deformation-sensitive measurement layer 04, on which a protective layer 07 is arranged, is arranged on the insulating layer 06. Contact layers 08 for making electrical contact are located between the respective deformation-sensitive measurement layers 04.

List of reference numerals

01 disc 02 cylindrical part 03 external teeth 04 deformation sensitive measurement layer 05-06 insulating layer 07 protective layer 08 contact layer.