Method for detecting a faulty measurement channel in a strain wave gearing mechanism

Abstract

The invention relates to a method for detecting a faulty measurement channel on an elastic transmission element in a strain wave gearing mechanism, wherein a wave generator acts on the elastic transmission element, and the elastic transmission element has a first strain gauge assembly with a first measurement channel. A first measurement signal of the first measurement channel of the first strain gauge assembly is proportional to the torque and is not based on the angular position of the wave generator or is only based on the angular position of the wave generator to a small extent, and the elastic transmission element has a second strain gauge assembly with multiple second measurement channels, second measurement signals of the individual second measurement channels of the second strain gauge assembly being based on the rotational position of the wave generator. The invention is characterized in that: - for each measurement channel of the second measurement channels, a plausibility check is carried out using the first measurement signal and one or more of the second measurement signals.

Description

[0001] Method for detecting a faulty measuring channel in a stress wave transmission

[0002] The invention relates to a method for detecting a faulty measuring channel on an elastic transmission element in a stress wave transmission. Furthermore, the invention relates to a drive module with a stress wave transmission.

[0003] Strain wave gears (also known as strain wave gears, sliding wedge gears, or harmonic drives) enable virtually backlash-free power transmission with a high gear ratio and are therefore particularly suitable for applications requiring precise movements and a small footprint. Because the high gear ratio allows high torques to be generated with relatively small motors, strain wave gears can be used to create very compact drive mechanisms, which are used in robotics, for example.

[0004] A stress wave transmission consists of a wave generator, a rigid outer ring (circular spline) with internal gearing, and an elastic transmission element (flexspline) with external gearing arranged between them. In contrast to rigid transmissions, the transmission of torque between the wave generator and the outer ring is based on elastic deformation, in which the transmission ring is deformed into an oval by the wave generator such that it engages with the outer ring on two opposite sides of its circumference. As the wave generator rotates, the transmission ring rolls on the outer ring, so that torque is transmitted between the transmission ring and the outer ring via the intermeshing gears. The transmission ratio of the transmission is determined by the difference in the number of teeth on the transmission ring and the outer ring.

[0005] During operation, excessive torque, for example when the gearbox is operating against high resistance, can cause so-called meshing disturbances. A meshing disturbance is a loss of at least some of the mesh between the transmission ring and the outer ring, causing the teeth of the transmission ring to skip over the teeth of the outer ring (“ratcheting”). While the rotation of the transmission ring and that of the outer ring are strictly coupled during normal operation, such a meshing disturbance temporarily leads to an uncontrolled relative rotation between the two rings. This creates an unknown angular offset on the output side compared to the input side, making precise control of the angular position impossible.

[0006] Torque sensors in the stress wave transmission can provide information about the condition of the stress wave transmission during operation and serve to monitor its operation. The torque sensors are designed as strain gauges and arranged on the elastic transmission element to measure the mechanical stress on the transmission element. The torque acting on the elastic transmission element is then determined from the mechanical stress. Typically, strain gauge arrangements with multiple strain gauges are used, arranged, for example, in a bridge circuit. If a strain gauge arrangement only covers a limited angular range of the transmission element, the measurement signal depends on the angular position of the wave generator.However, if the strain gauge arrangement extends over the entire or almost the entire circumference of the transmission element, a measurement signal can be obtained which does not depend, or only depends to a small extent, on the angular position of the wave generator.

[0007] To detect faulty strain gauges in a strain gauge array, WO 2021 / 148068 A1 discloses a method for checking an array of strain gauges, which allows for the detection of a single defect in one of several strain gauges. The method uses a predictive model determined by finite element analysis or machine learning and therefore requires considerable computing power.

[0008] Against this background, the task is to provide a method and a system that increases functional safety by detecting a failure or faulty function of a measuring channel of a strain gauge arrangement, while reducing the computing power required to detect such a defect.

[0009] The object is achieved by a method for detecting a faulty measuring channel on an elastic transmission element in a stress wave transmission, wherein a wave generator acts on the elastic transmission element, wherein the elastic transmission element has a first strain gauge arrangement with a first measuring channel, wherein a first measuring signal of the first measuring channel of the first strain gauge arrangement is proportional to the torque and does not depend, or depends only to a small extent, on an angular position of the wave generator, and wherein the elastic transmission element has a second strain gauge arrangement with a plurality of second measuring channels, wherein second measuring signals of the individual second measuring channels of the second strain gauge arrangement are dependent on the rotational position of the wave generator,wherein for each of the second measurement channels a plausibility check is carried out using the first measurement signal and one or more second measurement signals.

[0010] The method according to the invention makes use of an elastic transmission element comprising two strain gauge arrangements. The second strain gauge arrangement has a plurality of second measuring channels, each providing second measuring signals that depend on the rotational position of the wave generator. By linking these second measuring signals, an output signal can be obtained that does not exhibit this dependency and is proportional to the torque. This output signal can be highly accurate and can be used to measure the torque during operation of the transmission element. The first strain gauge arrangement, in contrast, comprises only a first measuring channel, the first measuring signal of which, however, is not dependent, or only slightly dependent, on the angular position of the wave generator.The method according to the invention makes it possible to detect faulty second measuring channels by carrying out a plausibility check for each of the second measuring channels based on the first measuring signal and one or more second measuring signals.

[0011] A measuring channel of a strain gauge arrangement can have one or more strain gauges. The strain gauges measure the mechanical stress in the elastic transmission element, with the mechanical stress being proportional to the applied torque. A faulty measuring channel can occur, in particular, if a strain gauge is damaged. Preferably, each first and each second measuring channel comprises several strain gauges connected in a bridge circuit, in particular a Wheatstone bridge.

[0012] The first strain gauge arrangement has a first measuring channel, the first measurement signal of which depends only slightly or not at all on the angular position of the wave generator. The first strain gauge arrangement can extend around the entire or almost the entire circumference of the elastic transmission element. The first strain gauge arrangement can be arranged on a lateral surface (parallel to the rotational axis of the transmission element) or an end face (perpendicular to the rotational axis of the transmission element) of the elastic transmission element.

[0013] The second strain gauge arrangement can be arranged on a lateral surface (parallel to the rotational axis of the transmission element) or an end face (perpendicular to the rotational axis of the transmission element) of the elastic transmission element. Preferably, the first and second strain gauge arrangements are arranged together on the lateral surface or together on the end face. The strain gauges of the plurality of second measuring channels of the second strain gauge arrangement are preferably arranged such that two second measuring signals each provide a nearly identical value. The redundancy of the measuring signals can further increase the integrity of the stress wave transmission. The torque is determined from the measuring signals and the measured mechanical stresses, whereby the torque determined by the second measuring channels depends on the angular position of the wave generator.The second strain gauge arrangement can, for example, have two, four or eight measuring channels, wherein the second strain gauge arrangement particularly preferably has four measuring channels.

[0014] According to a preferred embodiment, for the plausibility check, a difference is formed between a first term dependent on the first measurement signal and a second term dependent on several second measurement signals. Thus, it is possible to determine whether a measurement channel is faulty by comparing the first and second terms. This simple calculation has a particularly advantageous effect on the required computing power.

[0015] The first and / or second term preferably comprises one or more proportionality factors and / or one or more constants, which are preferably determined empirically. These proportionality factors and constants can be determined from experimental data or from simulation data or by calibration. For plausibility checks, the absolute value of the difference can be calculated and compared with a tolerance value. This tolerance value can be determined empirically or by simulation, whereby the tolerance value can be selected to be identical for all measuring channels or can be determined individually for each measuring channel. Furthermore, the tolerance value can have a fixed value or can be adjusted over the course of the operating period.

[0016] According to a preferred embodiment, a plausibility check of the first measurement channel is performed in a validation step preceding the plausibility check of the second measurement channels. The plausibility check of the first measurement channel can increase the integrity of the plausibility check of the second measurement channels.

[0017] According to a preferred embodiment, the plausibility check of the first measuring channel is performed based on predetermined parameters of the stress wave transmission and an input torque value transmitted by a motor control unit of an electric motor connected to the stress wave transmission. The predetermined parameter of the stress wave transmission is preferably determined from the transmission ratio and the transmission efficiency.

[0018] The plausibility is advantageously calculated from the absolute value of the difference between the first term and a third term, the third term being determined from the specified parameter of the stress wave transmission and the input torque value transmitted by a motor control unit of an electric motor connected to the stress wave transmission. The absolute value of the difference can be compared with a tolerance value.

[0019] According to a preferred embodiment, the input torque value is determined based on a measured electrical current and / or based on control signals from the motor control unit. The measured electrical current can be used to determine the existing input torque without the use of an additional strain gauge. Additionally or alternatively, the existing input torque can also be determined from the available control signals for controlling an electric motor. By eliminating the need for an additional strain gauge, a potential source of error is eliminated.

[0020] According to an alternative, preferred embodiment, the plausibility check of the first measuring channel is performed based on predetermined parameters of the stress wave transmission and a sensor torque value transmitted by another torque sensor. The another torque sensor can be arranged on the input or output side of the stress wave transmission.

[0021] A further subject of the invention is a method for determining a torque acting on an elastic transmission element of a stress wave transmission, wherein a wave generator acts on the elastic transmission element, wherein the elastic transmission element has a first strain gauge arrangement with a first measuring channel, wherein a first measuring signal of the first measuring channel of the first strain gauge arrangement is proportional to the torque and does not depend, or only depends to a small extent, on an angular position of the wave generator, and wherein the elastic transmission element has a second strain gauge arrangement with a plurality of second measuring channels, wherein second measuring signals of the individual second measuring channels of the second strain gauge arrangement are dependent on the rotational position of the wave generator,wherein a faulty second measuring channel is detected according to a method according to an embodiment of the present invention, the faulty second measuring channel is corrected based on the first measuring signal and one or more second measuring signals, and wherein the torque acting on the transmission ring is determined based on the corrected second measuring channel and the remaining second measuring channels.

[0022] The inventive detection of a faulty second measurement channel makes it possible to correct the second measurement channel identified as faulty. To correct the faulty second measurement channel, a substitute signal can be determined that depends on the first measurement signal and one or more of the other second measurement signals. Furthermore, the corrected second measurement channel can be included in the determination of the torque acting on the transmission ring. The advantage is that a faulty channel can be corrected or replaced, so that this channel further increases the integrity of the measured torque on the stress wave transmission.

[0023] Preferably, only the first measurement signal and exactly one second measurement signal are required to correct the measurement channel identified as faulty. This eliminates the need for computationally intensive prediction models. Preferably, the first measurement signal and a second measurement signal are each multiplied by a proportionality factor and / or a constant is added to it.

[0024] A further subject of the invention is a drive module with a stress wave transmission, which has an elastic transmission element and a wave generator acting on the elastic transmission element, wherein the elastic transmission element has a first strain gauge arrangement with a first measuring channel, wherein a first measuring signal of the first measuring channel of the first strain gauge arrangement is proportional to the torque and does not depend, or depends only to a small extent, on an angular position of the wave generator, and wherein the elastic transmission element has a second strain gauge arrangement with a plurality of second measuring channels, wherein second measuring signals of the individual second measuring channels of the second strain gauge arrangement are dependent on the rotational position of the wave generator, and with an evaluation unit which is configured toto detect a faulty second measuring channel according to a method according to an embodiment of the present invention, to correct the faulty second measuring channel based on the first measuring signal and one or more second measuring signals, and to determine the torque acting on the transmission ring based on the corrected second measuring channel and the remaining second measuring channels.

[0025] The drive module can achieve the same advantages and effects that have already been described in connection with the method according to the invention for detecting a faulty measuring channel.

[0026] According to a preferred embodiment, it is provided that the drive module has an electric motor and a motor control unit, wherein the evaluation unit is further configured to carry out a plausibility check of the first measuring channel in a validation step preceding the plausibility check of the second measuring channels, wherein the plausibility check of the first measuring channel is carried out on the basis of predetermined parameters of the stress wave transmission and an input torque value transmitted by a motor control unit of an electric motor connected to the stress wave transmission.

[0027] Alternatively or additionally, the advantageous embodiments and features described in connection with the method according to the invention for detecting a faulty measuring channel can also be applied to the drive module, alone or in combination.

[0028] A further subject matter of the invention is a robot arm with at least one drivable arm segment, wherein the arm segment can be driven via the drive module according to one of the preceding embodiments of the invention.

[0029] The robot arm can achieve the same advantages and effects as those already described in connection with the inventive method for detecting a faulty measuring channel. The advantageous embodiments and features described in connection with the inventive method for detecting a faulty measuring channel can also be applied to the robot arm, alone or in combination. Further details and advantages of the invention will be explained below with reference to the exemplary embodiment illustrated in the drawings. Herein:

[0030] Fig. 1 shows an embodiment of an elastic transmission element with a first and a second strain gauge arrangement;

[0031] Fig. 2 is a schematic representation of a preferred connection of strain gauges of a measuring channel;

[0032] Fig. 3 several measurement signals from different second measurement channels;

[0033] Fig. 4 is a schematic flow diagram of an embodiment of the method according to the invention;

[0034] Fig. 5 shows an embodiment of a robot in a schematic representation.

[0035] Fig. 1 shows an elastic transmission element 1, wherein the elastic transmission element 1 comprises a first strain gauge arrangement 10 and a second strain gauge arrangement 20. The elastic transmission element 1 can be used as part of a stress wave transmission. The stress wave transmission can comprise a wave generator, a rigid outer ring with internal gearing, and the elastic transmission element 1 arranged therebetween.

[0036] In the exemplary embodiment, the two strain gauge arrangements are arranged on an end face of the transmission element 1, which is arranged perpendicular to a rotational axis of the transmission element 1. The first strain gauge arrangement 10 extends completely over the circumference of the transmission element, i.e., it completely covers the winding area around the rotational axis. The second strain gauge arrangement 20 comprises a plurality of, here four, second measuring channels 22, 23, 24, 25. In the exemplary embodiment, the second strain gauge arrangement 20 is arranged radially outside the first strain gauge arrangement 10. According to a modification of this exemplary embodiment, the strain gauge arrangement 20 can be arranged radially inside the first strain gauge arrangement 10.

[0037] The first measuring channel and the second measuring channels 22, 23, 24, 25 each have a plurality of strain gauges. As a result of mechanical stress, the strain gauges are deformed, and their electrical resistance changes. This change in resistance can be detected, and the mechanical stress in the elastic transmission element 1 and the torque acting on the transmission element 1 can be derived from it. Fig. 2 shows an exemplary schematic representation of a preferred circuit 30 of the strain gauges of a measuring channel as a Wheatstone bridge. This circuit is preferably used for the first measuring channel and the second measuring channels 22, 23, 24, 25.

[0038] The bridge circuit shown in Fig. 2 comprises four strain gauges 31, 32, 33, 34. Two of these strain gauges 31, 32, 33, 34 are each connected in series to form a branch of the bridge circuit. The bridge circuit comprises two branches connected in parallel. A supply voltage is applied to the branches between a supply voltage terminal 35 and a ground terminal 36. Between the two strain gauges of each branch, a tap 37, 38 is provided, via which the measurement signal of the respective measurement channel can be taken.

[0039] Fig. 3 shows second measurement signals ST_0, ST_45, ST_90, ST_135 of the second measurement channels 22, 23, 24, 25. It can be seen that the second measurement signals ST_0, ST_45, ST_90, ST_135 exhibit a sinusoidal waveform depending on the rotational position W of the wave generator. The second measurement channels 22, 23, 24, 25 are arranged such that the second measurement signals ST_0, ST_45, ST_90, ST_135 each exhibit a phase shift of 45° from one another. Two of the second measurement signals are each symmetrical (e.g., measurement signals ST_0 and ST_90, and ST_45 and ST_135), so that their oscillations cancel each other out when added together. The sum of all four measuring signals ST_0, ST_45, ST_90, ST_135 is proportional to the torque on the elastic transmission element 1. The torque can thus be calculated by multiplying the sum of all four measuring signals ST_0, ST_45, ST_90, ST_135 by a predetermined proportionality factor (e2).

[0040] T Ges = e2*(ST_0+ST_45+ST_90+ST_135)

[0041] In a preferred embodiment, each measurement signal ST_0, ST_45, ST_90, ST_135 has a proportionality factor and / or a constant. It is conceivable that the factors and constants are adjusted over the course of the operating time.

[0042] However, a torque present at a second measuring channel can be determined using the measurement signals from two measuring channels offset by 180°. For example, the following torque values ​​T_0, T_45, T90, and T135 result:

[0043] T_0 = a1*ST_0 + a2*ST_90 + b1 T_45 = a3*ST_45 + a4*ST_135 + b2 T_90 = a5*ST_90 + a6*ST_0 + b3

[0044] T_135 = a7*ST_135 + a8*ST_45 + b4

[0045] The first measuring signal ST_circular of the first measuring channel of the first strain gauge arrangement 10, however, is only slightly dependent or not at all on a rotational position W of the wave generator.

[0046] The torque values ​​can alternatively be determined from the symmetrical second measurement signals ST_0, ST_45, ST_90, ST_135 and the first measurement signal ST_circular:

[0047] ST_90_hat = c1*ST_0 + c2*ST_circular + d1

[0048] ST_135_hat = c3*ST_45 + c4*ST_circular + d2 ST_0_hat = c5*ST_90 + c6*ST_circular + d3 ST_45_hat = c7*ST_135 + c8*ST_circular + d4

[0049] Here, a1 to a7, b1 to b4 and c1 to c8 are predefined values ​​that were determined, for example, during calibration.

[0050] If the first measuring channel is functional, torque values ​​can be specified based on the above equations by inserting ST_90_hat for ST_90 etc., which are only dependent on a second measuring channel and the first measuring channel:

[0051] T_0 = a1*ST_0 + a2*( c1*ST_0 + c2*ST_circular + d1) + b1 T_45 = a3*ST_45 + a4*( c3*ST_45 + c4*ST_circular + d2) + b2 T_90 = a5*ST_90 + a6*( c5*ST_90 + c6*ST_circular + d3) + b3 T_135 = a7*ST_135 + a8*( c7*ST_135 + c8*ST_circular + d4) + b4

[0052] Fig. 4 shows a flowchart of an embodiment of a method 400 for detecting and correcting a faulty measuring channel. In a first method step 401, the plausibility of the measurement signal of the first measuring channel is checked in a plausibility check. In this step, it is validated to what extent the determined torque of the first measuring channel differs from the actual torque. For this purpose, the torque present at the elastic transmission element 1 can be determined based on predetermined parameters of the stress wave transmission and an input torque value transmitted by a motor control unit of an electric motor connected to the stress wave transmission. The motor control unit can transmit the input torque value and / or other parameters to an evaluation unit, for example, using the SPI protocol (serial peripheral interface).The input torque value can be determined based on a measured electrical current and / or control signals from the motor control unit. Alternatively, the first measurement channel can be validated using another torque sensor located on the input or output side of the stress wave gearbox.

[0053] In a first comparison step 402, it is determined whether the measured torque value of the first measuring channel lies within a specified tolerance range. If the measured torque value lies outside this tolerance range (arrow 403'), an error state 404 of the first measuring channel is present. In a notification step 405, an error message is generated and transmitted, for example, to the engine control unit.

[0054] If the measured torque value is within the specified tolerance range (arrow 403), the first measuring channel is in a functional operating state 406. The first measuring channel can therefore be used for the subsequent testing of the plausibility of the second measuring signals ST_0, ST_45, ST_90, ST_135 of the second measuring channels 22, 23, 24, 25 in a test step 407.

[0055] In this test step 407, for each second measurement signal, a difference is formed from the product of the first measurement signal ST_circular with a predetermined proportionality factor e1 and the respective torque value T_0, T_45, T_90, T_135, which depends only on a second measurement signal and the first measurement signal ST_circular.

[0056] If abs(e1*ST_circular - T_0) > tolerance_value_0, the second measuring channel 22 belonging to the second measuring signal ST_0 is faulty. If abs(e1*ST_circular - T_45) > tolerance_value_45, the second measuring channel 23 belonging to the second measuring signal ST_45 is faulty. If abs(e1*ST_circular - T_90) > tolerance_value_90, the second measuring channel 24 belonging to the second measuring signal ST_90 is faulty. If abs(e1*ST_circular - T_135) > tolerance_value_135, the second measuring channel 25 belonging to the second measuring signal ST_135 is faulty.

[0057] The tolerance values ​​0, 45, 90, 135 can be identical or different. This also includes the variant where the tolerance values ​​0, 90 are identical and the tolerance values ​​45, 135 are identical, but the tolerance value 0, 90 and the tolerance value 45, 135 are different. First, in a method step 408, a check is carried out to determine whether all second measuring channels 22, 23, 24, 25 are faulty. If this is the case (arrow 409), a state 414 with four defective second measuring channels 22, 23, 24, 25 exists. In a notification step 415, an error message is generated and, if necessary, transmitted to the engine control unit. Error correction is not possible.

[0058] If not all second measuring channels 22, 23, 24, 25 are defective (arrow 409'), error registers are set for the respective defective measuring channels 22, 23, 24, 25 in step 410. Subsequently, in step 411, it is checked whether only a single second measuring channel

[0059] 22, 23, 24, 25 is defective. If such a single error of a second measuring channel 22,

[0060] 23, 24, 25 is present (arrow 412), the respective faulty second measurement channel 22, 23, 24, 25 is corrected. The respective equation with the index _hat is used for the correction. For example, the measurement signal ST_0 is replaced by ST_0_hat, the measurement signal ST_45 by ST_45_hat, etc. Thus, the correction is performed based on the first measurement signal ST_circular and a second measurement signal.

[0061] Fig. 5 shows a schematic representation of an embodiment of a robot embodied as an industrial robot 200 with multiple arm segments 201, each rotatably connected via drive modules 100, in which the invention is implemented. Even though the industrial robot 200 depicted here has three arm segments 201 and three drive modules 100, configurations of the industrial robot 200 with a different number of arm segments 201 and drive modules 100 are conceivable, for example, four, five, six, or seven. Furthermore, one drive module 100 can be used for any robot joint. Such industrial robots 200 are often used as collaborative robots that work in close cooperation with humans.

Claims

Patent claims 1. Method for detecting a faulty measuring channel on an elastic transmission element (1) in a stress wave transmission, wherein a wave generator acts on the elastic transmission element (1), wherein the elastic transmission element (1) has a first strain gauge arrangement (10) with a first measuring channel, wherein a first measuring signal (ST_circular) of the first measuring channel of the first strain gauge arrangement (10) is proportional to the torque and does not depend, or depends only to a small extent, on an angular position of the wave generator, wherein the elastic transmission element (1) has a second strain gauge arrangement (20) with a plurality of second measuring channels (22, 23, 24, 25), wherein second measuring signals (ST_0, ST_45, ST_90, ST_135) of the individual second measuring channels (22, 23, 24, 25) of the second strain gauge arrangement (20) depend on the rotational position of the wave generator are characterized bythat for each of the second measuring channels (22, 23, 24, 25) a plausibility check is carried out using the first measuring signal (ST_circular) and one or more second measuring signals (ST_0, ST_45, ST_90, ST_135).

2. Method according to claim 1, characterized in that for the plausibility check a difference is formed between a first term dependent on the first measurement signal and a second term dependent on a plurality of second measurement signals (ST_0, ST_45, ST_90, ST_135).

3. Method according to one of the preceding claims, characterized in that in a validation step preceding the plausibility check of the second measuring channels (22, 23, 24, 25), a plausibility check of the first measuring channel is carried out.

4. Method according to claim 3, characterized in that the plausibility check of the first measuring channel is carried out on the basis of predetermined parameters of the stress wave transmission and an input torque value transmitted by a motor control unit of an electric motor connected to the stress wave transmission.

5. Method according to claim 4, characterized in that the input torque value is determined based on a measured electrical current and / or based on Control signals from the engine control unit.

6. A method for determining a torque acting on an elastic transmission element (1) of a stress wave transmission, wherein a wave generator acts on the elastic transmission element (1), wherein the elastic transmission element (1) has a first strain gauge arrangement (10) with a first measuring channel, wherein a first measuring signal (ST_circular) of the first measuring channel of the first strain gauge arrangement (10) is proportional to the torque and does not depend, or depends only to a small extent, on an angular position of the wave generator, and wherein the elastic transmission element (1) has a second strain gauge arrangement (20) with a plurality of second measuring channels (22, 23, 24, 25), wherein second measuring signals (ST_0, ST_45, ST_90, ST_135) of the individual second measuring channels (22, 23, 24, 25) of the second strain gauge arrangement (20) are dependent on the rotational position of the wave generator, where a faulty second measuring channel (22, 23, 24,25) is detected according to a method according to one of the preceding claims, the faulty second measuring channel (22, 23, 24, 25) is corrected using the first measuring signal and one or more second measuring signals (ST_0, ST_45, ST_90, ST_135), and the torque acting on the transmission ring (1) is determined using the corrected second measuring channel and the remaining second measuring channels (22, 23, 24, 25).

7. A drive module (100) with a stress wave transmission comprising an elastic transmission element (1) and a wave generator acting on the elastic transmission element (1), wherein the elastic transmission element (1) comprises a first strain gauge arrangement (10) with a first measuring channel, wherein a first measuring signal (ST_circular) of the first measuring channel of the first strain gauge arrangement (10) is proportional to the torque and does not depend, or depends only to a small extent, on an angular position of the wave generator, and wherein the elastic transmission element (1) comprises a second strain gauge arrangement (20) with a plurality of second measuring channels (22, 23, 24, 25), wherein second measuring signals (ST_0, ST_45, ST_90, ST_135) of the individual second measuring channels (22, 23, 24, 25) of the second strain gauge arrangement (20) are dependent on the rotational position of the wave generator, and with an evaluation unit configured to to detect a faulty second measuring channel (22, 23, 24, 25) according to a method according to one of claims 1 to 5, to correct the faulty second measuring channel (22, 23, 24, 25) based on the first measuring signal and one or more second measuring signals (ST_0, ST_45, ST_90, ST_135) and to determine the torque acting on the transmission ring (1) based on the corrected second measuring channel and the remaining second measuring channels (22, 23, 24, 25).

8. Drive module (100) according to claim 7, characterized in that the drive module (100) has an electric motor and a motor control unit, wherein the evaluation unit is further configured to carry out a plausibility check of the first measuring channel in a validation step preceding the plausibility check of the second measuring channels (22, 23, 24, 25), wherein the plausibility check of the first measuring channel is carried out on the basis of predetermined parameters of the stress wave transmission and an input torque value transmitted by a motor control unit of an electric motor connected to the stress wave transmission.

9. Robot arm (200) with at least one drivable arm segment (201), wherein the arm segment (201) is drivable via the drive module (100) according to claim 8.

Images