Method for determining a torque conducted through a transmission, drive system, and robot having a drive system of this type

Abstract

The invention relates to a method for determining a torque conducted through a transmission (15), comprising the steps of: providing a transmission (15), which has a support element (16), an input element (17), an output element (18), and at least one main bearing arrangement (19) for supporting the input element (17) and / or the output element (18) relative to the support element (16) for rotation about an axis of rotation (R) which defines the rotational degree of freedom of the transmission (15) and for fixing the other five degrees of freedom of the three-dimensional cartesian coordinate system, the input element (17) and / or the output element (18) having a first element portion (20.1) which is elastic about the rotational degree of freedom and by means of which the torque is conducted, and having a second element portion (20.2) which is rigid in all six degrees of freedom and by means of which the other five degrees of freedom are supported; simultaneously sensing the rotational angle position of the input element (17) as a first rotational angle value (W1) and the rotational angle position of the output element (18) as a second rotational angle value (W2), while the transmission (15) transmits a torque to be determined; and calculating the transmitted torque by means of a mathematical model of the transmission (15) which takes into account the elastic properties of the first element portion (20.1), on the basis of the sensed first rotational angle value (W1) and the sensed second rotational angle value (W2). The invention also relates to an associated drive system (27) and to a robot (1) having a drive system (27) of this type.

Description

[0001] Method for determining a torque transmitted through a gearbox, drive system and robot with such a drive system

[0002] The invention relates to a method for determining a torque transmitted through a gearbox. The invention also relates to an associated drive system and a robot with such a drive system.

[0003] DE 10 2012 202 181 A1 describes a method for determining a torque acting on a link of a robot arm, wherein the robot arm has several links arranged one behind the other, a first link of which is rotatably mounted relative to a second link of the links with respect to an axis of rotation and is rotatable with respect to the axis of rotation by means of a motor fixed in position relative to the second link and a gearbox downstream of the motor, comprising the method steps of determining the drive-side angle of rotation facing the motor and the output-side angle of rotation facing away from the motor of the gearbox, and of determining the torque acting on the first link based on the determined drive-side and output-side angles of rotation of the gearbox and based on a mathematical model of the gearbox which in particular takes into account elastic properties of the gearbox.

[0004] The object of the invention is to simplify and / or improve the determination of a torque transmitted through a transmission by means of a mathematical model that uses the angular position of the drive element and the driven element to calculate the transmitted torque. This object is achieved by a method for determining a torque transmitted through a transmission, comprising the steps of:

[0005] - Providing a transmission with a support member, a drive member, a driven member and at least one main bearing arrangement for rotatably mounting the drive member and / or the driven member relative to the support member about an axis of rotation which determines the rotational degree of freedom of the transmission, and for defining the remaining five degrees of freedom of the spatial Cartesian coordinate system, wherein the drive member and / or the driven member has a first member section elastic about the rotational degree of freedom, through which the torque is transmitted, and a second member section rigid in all six degrees of freedom, through which the remaining five degrees of freedom are supported,

[0006] - simultaneous detection of the rotational angle position of the drive element as a first rotational angle value and the rotational angle position of the output element as a second rotational angle value, during the transmission of a determined torque through the gearbox,

[0007] - Calculating the transmitted torque using a mathematical model of the transmission, which takes into account the elastic properties of the first link section, based on the measured first and second rotation angle values. In known drive systems, particularly in robotics, it is common practice to measure the torque transmitted through the drive system using special torque sensors. The torque sensors generally used for this purpose include strain gauges attached to special measuring bodies. The strain gauges detect the deformation, in particular a rotation and / or compression, of a surface area of ​​the measuring body to which the strain gauge is attached, in particular glued. The strain gauges thus detect a deformation occurring due to the torque transmitted through the measuring body, in particular a bending of a web section of the measuring body.Within the strain gauge, conductive traces are arranged that convert deformation, particularly elongation, of the traces into a change in electrical resistance. The electrical resistance measured by the strain gauge is then a measure of the transmitted torque. A disadvantage of this method is that the drive systems must be equipped with measuring elements specifically designed to match the strain gauges. The strain gauges themselves also contribute to increased manufacturing costs for the drive system. Furthermore, it cannot be ruled out that the strain gauges may fail due to a defect, making torque measurement impossible and rendering the operation of the drive system or the machine incorporating the drive system inoperable.

[0008] Therefore, technical solutions have already been developed that do not require special measuring elements and strain gauges. For example, it is known from the aforementioned DE 10 2012 202 181 Al to determine a transmitted torque based on the determined input-side and output-side rotation angles of a gearbox and based on a mathematical model of the gearbox, which in particular takes into account the elastic properties of the gearbox. This allows transmitted torques to be determined without the need for special torque sensors.

[0009] Measuring the input and output angles of rotation in a gearbox is not straightforward with conventional gearboxes. Generally, gearboxes are designed for high stiffness. However, this high stiffness means that when torque is applied, the output angle differs only very slightly from the input angle. Therefore, accurately measuring the input and output angles requires very high resolution from the angle sensors. This problem is exacerbated when the gearbox has a very high gear ratio, so that, for example, a relatively large change in the angle of rotation at an input link of the gearbox corresponds to only a very small change in the angle of rotation at the output link.Since it is also common practice to use the position sensors of the drive motors as rotary angle sensors, for example, the resolution of the rotary angle sensors cannot be chosen arbitrarily if the resolution of the position sensors is predetermined by the type of drive motor.

[0010] To simplify and / or improve the determination of the input and output angles of rotation of a gearbox, a method and a drive system are proposed in which the input and / or output member of the gearbox has a first member section that is elastic with respect to one degree of rotational freedom, through which the torque is transmitted, and a second member section that is rigid in all six degrees of freedom, through which the remaining five degrees of freedom are supported. The transmitted torque is calculated using a mathematical model of the gearbox that takes into account the elastic properties, especially of the elastic first member section. The elasticity of the first member section should therefore be several times greater than the elasticity of the other rigid gearbox members.

[0011] Therefore, a predetermined torsional elasticity is introduced into the gear's rotational degree of freedom by means of the first link section. In all other five degrees of freedom of the spatial Cartesian coordinate system, however, the inherently high stiffness of the gear is maintained.

[0012] The measurement accuracy can thus be significantly improved if, in addition to the inherent torsional elasticity (high stiffness) of the gearbox, a further predetermined torsional elasticity (lower stiffness) is introduced into the power flow between the measuring points of the drive element and the driven element, where the rotational angles are recorded. This results in higher measurement accuracy for torque measurement. This is due, among other things, to reduced influences from individual measurement deviations when recording the drive-side and driven-side rotational angles.If the difference between the measured input-side rotation angle and the measured output-side rotation angle is greater, then individual measurement errors in the measurement of the input-side or output-side rotation angle do not have a significant impact on the rotation angle difference between the input-side and output-side rotation angles. However, only the rotation angle difference provides the starting value for determining or calculating the torque transmitted through the gearbox.

[0013] The measurement accuracy can also be improved by ensuring that changes in the gear stiffness characteristic over the service life have less influence on the determination of the angle difference.

[0014] Furthermore, only reduced requirements are placed on the resolution of the rotary angle sensors when detecting the drive-side rotary angle and the output-side rotary angle.

[0015] However, the reduction of the transmission stiffness according to the invention, achieved through the elastic first link section in the transmission as a whole, conflicts with the requirements for positioning accuracy. Specifically, when the method according to the invention is applied in drive systems intended for use in robots, the reduction in transmission stiffness affects the robot's movement behavior.

[0016] The effects of such torsional elasticities, which are undesirable with regard to positioning accuracy, can, however, be limited by appropriate control algorithms that take these torsional elasticities into account in their mathematical models. A more significant requirement for the design of the gearbox, however, is that the gearbox's stiffness is maintained with respect to tilting moments and forces that differ from the torque to be transmitted. In view of the existing possibilities of mathematical modeling and the consideration of the requirements for the gearbox's design, the invention proposes an elastic first link section, which is arranged, in particular, parallel to the main bearing of the gearbox and in series within the gearbox's drive train.A component featuring an elastic first link section can be manufactured cost-effectively and, through appropriate material selection and dimensioning, used to precisely control the gear torsional stiffness. The compliance of the elastic first link section of the component with respect to tilting moments and forces is irrelevant here, as these loads are directly supported via the main bearing through the rigid second link section of the component.

[0017] As mentioned previously, determining the torque requires measuring the output-side angular position while taking into account the additional compliance due to the elastic first link section. This can be achieved, for example, by connecting a sensor for measuring the output-side angular position parallel to the component, which has the elastic first link section and the rigid second link section, via an additional component. This additional component is then neither in the force flow of the torque nor in the force flow of the tilting moments and forces, and is therefore practically unaffected by any external load. Accordingly, it can be designed to be very compact and cost-effective. Such an additional component can be connected to a measuring shaft, described in more detail below, via which the output-side angular position can be measured.Overall, the solution according to the invention results in a very compact and cost-effective gearbox design, in which the torsional elasticity of the gearbox is specifically designed without any negative effects on the stiffness of the gearbox against tilting moments and forces.

[0018] The support element can be a gearbox housing. Alternatively, the support element can form a flange by means of which the gearbox is installed in a machine component, such as a section of a robot arm. For this purpose, the flange forming the support element can be attached to the machine component, in particular to the section of the robot arm.

[0019] The transmission can be a single-stage design. In this case, the drive element can be a drive shaft connected to a motor. The drive shaft can simultaneously serve as the motor shaft. Alternatively, the transmission's drive shaft can be connected to the motor shaft of the motor.

[0020] The output element can be an output shaft. Alternatively, the output element can form an output flange, by means of which the output element is connected to a driven machine component, such as a section of a robot arm.

[0021] Optionally, the input and / or output members can be formed by transmission elements arranged within the transmission, thus forming transmission components that are positioned upstream or downstream of an associated transmission stage in the torque flow of that stage. The transmission can optionally also be a multi-stage transmission. In this case, the elastic first member section may be implemented only in a single transmission stage of the multi-stage transmission.

[0022] The input and output elements can therefore also be formed by components of this gear stage. In this respect, the input and output elements can also be gear elements, particularly in the case of gear drives, the gears of the relevant gear stage that has the elastic first element section.

[0023] In a specific embodiment, the drive element and the driven element can also be gear elements, particularly in the case of gear drives, the gears of the relevant gear stage, which has an elastic first element section. The angular position of the drive element and / or the angular position of the driven element are not directly detected at these elements, but only indirectly at other gear components that are coupled to the drive element or the driven element via predetermined, upstream or downstream gear stages. Such upstream or downstream gear stages can then preferably be designed without an elastic first element section.These upstream or downstream gear stages can be designed with a particularly high degree of rigidity, so that any differences in rotational angle that may occur when indirectly measuring the angular position of the drive element and / or the driven element are negligible compared to a "soft" gear stage with an elastic first element section. The angular position of the drive element and / or the driven element can be measured either inside or outside the gearbox. Separate angle sensors can be used to measure the angular position of the drive element and / or the driven element.

[0024] Alternatively, other sensors already present in other components of the drive system can be used to detect the angular position of the drive element and / or the angular position of the driven element. For example, to detect the drive-side angular positions, angle sensors already present as sensor components on a motor driving the gearbox can be used. To detect the driven-side angular positions, for example, in the case of a robot arm, angle sensors already present on a joint of the robot arm, particularly for other purposes, can be used. These could be, for example, dual encoders that can measure two positions, one at the drive and one at the driven element, at a common location.To enable this, feedback of the output position towards the motor on which the dual encoder is located can be achieved via an additional component, such as a shaft. For example, the measurement of the output position can be combined with the measurement of the input position via a measuring shaft or a measuring shaft section; that is, a dual encoder can acquire both measured values ​​of the output position and the input position at a single location. Due to the "flexibility" of the gearbox in its degree of freedom achieved by the elastic first link section inserted into the gearbox, these existing rotary angle sensors, which are used for other purposes, do not need to have a particularly high resolution. For torque determination, the resolution sufficient for acquiring the angular positions of a joint in a robot arm or a motor is adequate.

[0025] The calculation of the transmitted torque can be done using a mathematical model of the transmission, which takes into account the elastic properties of the first link section as the essential criterion or the only criterion for determining the transmitted torque.

[0026] If the transmission is designed to be very stiff in its other components compared to the elastic first link section, the elasticities inherent in these stiff components can be disregarded, since they have only a negligible or no effect on the calculation of the torque, i.e., they can be neglected within a permissible tolerance for the measured torque.

[0027] The angular position of the drive element and / or the angular position of the driven element can be detected outside the gearbox.

[0028] If the angular position of the drive element and / or the angular position of the driven element are detected outside the gearbox, then no angle sensors need to be integrated into the gearbox. This has the advantage that the gearbox can be manufactured more cost-effectively and / or designed more compactly. Especially in robot arms for human-robot collaboration, also known as lightweight robots, robot arms are used that are no larger than a human arm, so the gearboxes installed at the joints of such robot arms should be as small and light as possible.

[0029] To detect the angular position of the drive element and / or the angular position of the output element outside the gearbox, the angular position sensors of the drive components different from the gearbox, such as motors, can be used in particular, as already described.

[0030] The second link section can be connected to a measuring shaft rotatably mounted around the axis of rotation of the degree of freedom of the gearbox, which has a measuring shaft section leading out of the gearbox, at which the angular position of the measuring shaft is detected.

[0031] The use of an additional measuring shaft can be advantageous, for example, when the drive and driven components are located on opposite sides of the gearbox and the angular position of the drive and driven components is to be measured on the same side of the gearbox. In this way, the measuring shaft can transmit the angular position of the driven component back to the side of the drive component, or it can transmit the angular position of the drive component forward to the side of the driven component.

[0032] The measuring shaft can be very delicate, since the torque transmitted through the gearbox does not pass over the measuring shaft. The measuring shaft is coupled to the rigid second link section and transmits the rotational position, for example of the connected output link, back to the input link side without passing over the elastic first link section again.

[0033] A tension wave gear can be provided as a transmission, comprising a rigid outer ring with internal teeth connected to the support member, a flexible output bushing with external teeth connected to the output member, and a shaft generator rotatably mounted in the transmission and rolling on the flexible output bushing, which is connected to the drive member, wherein the external teeth of the flexible output bushing are in meshing engagement with the internal teeth of the rigid outer ring depending on a rotational movement of the shaft generator, and wherein the output member is connected to the flexible output bushing via the elastic first member section.

[0034] The tension wave transmission can have a main bearing arrangement by which the output member is rotatably mounted relative to the support member about the axis of rotation. The main bearing arrangement supports all five remaining degrees of freedom, which are different from the rotational degree of freedom of the transmission. The main bearing arrangement can include at least one rolling bearing.

[0035] The output member, the elastic first member section, and the flexible output bushing can each be manufactured as separate components and connected to each other via fasteners. Alternatively, the elastic first member section can be formed integrally with the output member. Alternatively or additionally, the elastic first member section can be formed integrally with the flexible output bushing. The elastic first member section and / or the flexible output bushing can be rotatably mounted on a shaft seat about the axis of rotation of the gearbox.

[0036] The elastic first link section can be made from a rigid body, particularly a metallic body, where the desired elasticity is achieved by introducing material weaknesses, such as recesses in a homogeneous rigid body, to create corresponding thin-walled, elastic regions. For example, the elastic first link section can have spoke-like thin web sections connecting a rigid hub section to a rigid circumferential ring section. The rigid circumferential ring section can form the rigid second link section. The spoke-like thin web sections form the elastic first link section. To achieve increased elasticity compared to the homogeneous rigid body, the web sections can, for example, have significantly thinner cross-sections in the circumferential direction than perpendicular to the circumferential direction.The cross-section of the web sections can be, for example, oval or rectangular.

[0037] In a specific embodiment, the flexible output bushing can have a hollow cylindrical first section, on the outer wall of which the external teeth are formed. An annular bottom wall can be attached to the hollow cylindrical first section of the flexible output bushing as a second section. The hollow cylindrical first section can be formed as a single unit with the annular bottom wall as the second section. The annular bottom wall of the flexible output bushing can be connected to the rigid hub section of the elastic first link section, optionally via fasteners or as a single piece. The elastic web sections then extend from the rigid hub section as the first link section and project radially outwards to the rigid circumferential ring section.The rigid hub section, the elastic web sections, and the rigid circumferential ring section can preferably be manufactured from a single, rigid body. The rigid circumferential ring section can also form the rigid second link section, which can be connected to the driven link.

[0038] The problem is also solved by a drive system comprising a transmission with a support member, a drive member, a driven member, and at least one main bearing arrangement for rotatably mounting the drive member and / or the driven member relative to the support member about an axis of rotation which determines the rotational degree of freedom of the transmission, and for defining the remaining five degrees of freedom of the spatial Cartesian coordinate system, wherein the drive member and / or the driven member has a first member section elastic about the rotational degree of freedom, through which the torque is transmitted, and a second member section rigid in all six degrees of freedom, through which the remaining five degrees of freedom are supported, as well as a control device which is designed and configured.to simultaneously detect the angular position of the drive member as a first angular value and the angular position of the driven member as a second angular value during the transmission of a determined torque through the gearbox, wherein a mathematical model of the gearbox, taking into account the elastic properties of the first member section, is stored on the control device, which uses the detected first angular value and the detected second angular value to calculate the torque transmitted by the gearbox.

[0039] The control device may store a mathematical model of the transmission that takes into account the elastic properties of the first link section as the essential criterion or the only criterion for calculating the transmitted torque.

[0040] If the transmission is designed to be very stiff in its other components compared to the elastic first link section, the elasticities inherent in these stiff components can be disregarded, since they have only a negligible or no effect on the calculation of the torque, i.e., they can be neglected within a permissible tolerance for the measured torque.

[0041] The drive system may have a first angle sensor for detecting the angle of rotation of the drive member, which is located outside the gearbox, and / or a second angle sensor for detecting the angle of rotation of the driven member, which is located outside the gearbox.

[0042] If the angular position of the drive element and / or the angular position of the driven element are detected outside the gearbox, then no angle sensors need to be integrated into the gearbox. This has the advantage that the gearbox can be manufactured more cost-effectively and / or designed more compactly. Especially in robot arms for human-robot collaboration, also known as lightweight robots, robot arms are used that are no larger than a human arm, so the gearboxes installed at the joints of such robot arms should be as small and light as possible.

[0043] To detect the angular position of the drive element and / or the angular position of the output element outside the gearbox, the angular position sensors of the drive components different from the gearbox, such as motors, can be used in particular, as already described.

[0044] The drive system can have a measuring shaft connected to the second link section, which is rotatably mounted about the axis of rotation of the rotational degree of freedom of the gearbox, and which has a measuring shaft section leading out of the gearbox, on which the rotational angular position of the measuring shaft is detected.

[0045] The use of an additional measuring shaft can be advantageous, for example, when the drive and driven components are located on opposite sides of the gearbox and the angular position of the drive and driven components is to be measured on the same side of the gearbox. In this way, the measuring shaft can transmit the angular position of the driven component back to the side of the drive component, or it can transmit the angular position of the drive component forward to the side of the driven component.

[0046] The measuring shaft can be very delicate, since the torque transmitted through the gearbox does not pass over the measuring shaft. The measuring shaft is coupled to the rigid second link section and transmits the rotational position, for example of the connected output link, back to the input link side without passing over the elastic first link section again.

[0047] The transmission can be designed as a stress wave transmission comprising a rigid outer ring with internal teeth connected to the support member, a flexible output bushing with external teeth connected to the output member, and a shaft generator rotatably mounted in the transmission and rolling on the flexible output bushing, which is connected to the drive member, wherein the external teeth of the flexible output bushing are in meshing engagement with the internal teeth of the rigid outer ring depending on a rotational movement of the shaft generator, and wherein the output member is connected to the flexible output bushing via the elastic first member section.

[0048] The task is also solved by a robot comprising a robot arm with several links and joints connecting the links that are adjustable to each other, wherein at least one of the joints is equipped with a drive system according to one of the described embodiments.

[0049] Specific embodiments of the invention are explained in more detail in the following description with reference to the accompanying figures. Specific features of these exemplary embodiments can, regardless of the specific context in which they are mentioned, and optionally also individually or in further combinations, represent general features of the invention. The figures show:

[0050] Fig. 1 shows a schematic representation of a first embodiment of a robot, in particular an industrial robot, comprising a robot arm with drive systems and a control device which is designed and configured to carry out a method according to the invention.

[0051] Fig. 2 shows a schematic representation of a second embodiment of a robot, in particular a lightweight robot, designed for human-robot collaboration, comprising a robot arm with drive systems and a control device designed and configured to carry out a method according to the invention.

[0052] Fig. 3 shows a flowchart of the steps in the basic method according to the invention.

[0053] Fig. 4 shows a schematic sectional view of a transmission in the design of a tension wave transmission with an elastic first element section, which connects the output element with a flexible output bushing of the tension wave transmission, and Fig. 5 shows a schematic representation of a drive system according to the invention.

[0054] Figure 1 shows an exemplary robot 1 of the type of industrial robot with a control device 2 and a robot arm 3. The robot arm 3 has a base frame 5 as its first element G1, on which a carousel 7 as its second element G2 is rotatably mounted about a first vertical axis A1 and driven by a first drive motor M1. The axes A1-A6 of the robot arm 3 can also be referred to as joints L1-L6 of the robot arm 3. A rocker arm 8 as its third element G3 is pivotably mounted on the carousel 7 about a second horizontal axis A2 and driven by a second drive motor M2. The rocker arm 8 carries a boom 9, which is pivotably mounted about a third horizontal axis A3 and driven by a third drive motor M3.On the arm extension 9, whose base arm 10 forms a fourth link G4, a fourth axis A4 is provided, which runs in the longitudinal extension of the arm extension 9 and drives a front arm 11 via a fourth drive motor (not shown), which forms a fifth link G5.

[0055] From the forearm 11, a first leg 12a and a second leg 12b extend forward in a fork-like shape. The two legs 12a, 12b support a bearing for a hand 13, which forms a sixth link G6. The bearing defines a fifth axis A5 of the robot arm 3, about which the hand 13 can be pivoted by means of a fifth drive motor (not shown). Additionally, the hand 13 has a sixth axis A6 to enable a sixth drive motor (not shown) to drive a mounting flange 14, which forms a seventh link G7, in a rotatable manner. Each axis A5 to A6 is associated with a joint LI to L6, which, in the case of the illustrated embodiment, connect the links G6 to G7 in the manner of a serial kinematic system of a kick-arm robot.

[0056] One or more of the joints LI to L6 of the robot arm 3 can have a drive system according to the invention.

[0057] Figure 2 shows a modified design of a robot arm 3 in the form of a lightweight robot 3a with a total of six or seven axes. This lightweight robot 3a is particularly well suited for human-robot collaboration. The lightweight robot 3a can be operated with force / torque control, especially in compliance control mode. This lightweight robot 3a has several links G and joints L that adjust the links G relative to each other, each of which is designed as a rotary joint. In this respect, each joint G connects a first link G of the robot arm 3 to an immediately adjacent second link G2 of the robot arm 3 in a rotatable manner, the corresponding rotary joint G being able to have a drive system according to the invention in one of the described embodiments.

[0058] In Fig. 3 the inventive method for determining a torque transmitted through a gearbox 15 is shown schematically.

[0059] The procedure for determining a torque transmitted through the gearbox 15 comprises the following steps:

[0060] In a first step S 1 of the method, a gearbox 15 is provided with a support member 16, a drive member 17, an output member 18 and at least one main bearing arrangement 19 for rotatably mounting the output member 18, in the case of the present embodiment, relative to the support member 16 about an axis of rotation R, which determines the rotational degree of freedom of the gearbox 15, and for defining the remaining five degrees of freedom of the spatial Cartesian coordinate system, wherein in the case of the present embodiment the output member 18 has a first member section 20.1 that is elastic about the rotational degree of freedom, through which the torque is transmitted, and a second member section 20.2 that is rigid in all six degrees of freedom, through which the remaining five degrees of freedom are supported.

[0061] In a second step S2 of the procedure, the rotational angle position of the drive member 17 is simultaneously recorded as a first rotational angle value and the rotational angle position of the output member 18 as a second rotational angle value, during a transmission of a torque to be determined through the gearbox 15.

[0062] In a third step S3 of the procedure, the transmitted torque is calculated using a mathematical model of the gear unit 15, which takes into account the elastic properties of the first link section 20 . 1, based on the recorded first rotation angle value and the recorded second rotation angle value.

[0063] The transmitted torque can be calculated using a mathematical model of the transmission 15, which considers the elastic properties of the first link section 20 as the essential criterion or the sole criterion for determining the transmitted torque. The angular position of the drive link 17 and / or the angular position of the output link 18 can be determined outside the transmission.

[0064] In Fig. 4 a tension wave gear 15a is shown as an exemplary gear 15 .

[0065] The tension wave gear 15a has a rigid outer ring 21 with internal teeth 22 connected to the support member 16. A flexible output sleeve 23, connected to the output member 18, is provided with external teeth 24. The tension wave gear 15a also has a shaft generator 25 rotatably mounted in the gear 15 and rolling on the flexible output sleeve 23, which is connected to the drive member 17. The external teeth 24 of the flexible output sleeve 23 mesh with the internal teeth 22 of the rigid outer ring 21 as a function of the rotational movement of the shaft generator 25. The output member 18 is connected to the flexible output sleeve 23 via the elastic first member section 20.1.

[0066] The elastic first link section 20 . 1 and the flexible output bushing 23 can be rotatably mounted on a shaft seat 26 about the axis of rotation R of the gearbox 15 as shown.

[0067] The elastic first link section 20.1 can be made from a rigid body, where the desired elasticity is achieved by introducing material weaknesses, such as cutouts in a homogeneous rigid body, to form corresponding thin-walled, elastic regions. For example, the elastic first link section 20.1 can have spoke-like thin web sections that connect a rigid hub section to a rigid circumferential ring section. The rigid circumferential ring section can form the rigid second link section 20.2. The spoke-like thin web sections form the elastic first link section 20.1. To achieve increased elasticity compared to the homogeneous rigid body, the web sections can, for example, have significantly thinner cross-sections in the circumferential direction than perpendicular to the circumferential direction.The cross-section of the web sections can be, for example, oval or rectangular.

[0068] In a specific embodiment, the flexible output sleeve 23 can have a hollow cylindrical first section 23.1, on the outer surface of which the external teeth 24 are formed. A circular base wall can adjoin the hollow cylindrical first section 23.1 of the flexible output sleeve 23 as a second section 23.2 of the flexible output sleeve 23. The hollow cylindrical first section 23.1 can be formed as a single unit with the circular base wall as the second section 23.2.

[0069] The annular base wall of the flexible output bushing 23 can be connected to the rigid hub section 20.3 of the elastic first link section 20.1, optionally via fasteners or as a single piece. The elastic web sections then extend from the rigid hub section 20.3 as the first link section 20.1 and project radially outwards to the rigid circumferential ring section. The rigid hub section 20.3, the elastic web sections, and the rigid circumferential ring section can preferably be manufactured from a single rigid body. The rigid circumferential ring section can also form the rigid second link section 20.2, which is connected to the output link.

[0070] 18 is connected.

[0071] Fig. 5 schematically shows a drive system 27 comprising the gearbox 15 with the support member 16, the drive member 17, the output member 18, and at least one main bearing arrangement 19 for rotatably mounting the drive member 17 and / or the output member 18 relative to the support member 16 about a respective axis of rotation R, which determines the rotational degree of freedom of the gearbox 15, and for defining the other five degrees of freedom of the spatial Cartesian coordinate system. Depending on the specific design of the gearbox, the two axes of rotation R shown schematically in Fig. 5 can also be coaxial with each other.

[0072] In the case of the illustrated embodiment, the output member 18 has the first member section 20 . 1, which is elastic about the rotational degree of freedom and through which the torque (arrows P) is transmitted, and a second member section 20 . 2, which is rigid in all six degrees of freedom and through which the remaining five degrees of freedom are supported.

[0073] The control device 2 is designed and configured to simultaneously detect the angular position of the drive member 17 as a first angular value W1 and the angular position of the output member 18 as a second angular value W2 during the transmission of a determined torque through the transmission 15. A mathematical model of the transmission 15, taking into account the elastic properties of the first member section 20.1, is stored on the control device 2. This model uses the detected first angular value W1 and the detected second angular value W2 to calculate the torque transmitted by the transmission 15. Alternatively, the control device 2 may store a mathematical model of the transmission 15 that considers the elastic properties of the first member section 20.1 as the essential or sole criterion for calculating the transmitted torque.A motor 30 can be coupled to the drive element 17.

[0074] In the present embodiment, the drive system 27 comprises a first angle sensor 28.1, which detects the angle of rotation of the drive member 17 and is arranged outside the gearbox 15, and a second angle sensor 28.2, which detects the angle of rotation of the driven member and is arranged outside the gearbox 15.

[0075] The drive system 27 can, as shown in Fig. 5, have a measuring shaft 29 connected to the second link section 20.2, which is rotatably mounted about the axis of rotation R of the rotational degree of freedom of the gearbox 15, and which has a measuring shaft section 29a extending from the gearbox 15, at which the rotational angle position of the measuring shaft 29 can be detected by means of a separate rotational angle sensor 28.3. The separate rotational angle sensor 28.3 can be used instead of the second rotational angle sensor 28.2. The separate rotational angle sensor 28.3 can be arranged on the same side of the gearbox as the first rotational angle sensor 28.1.

Claims

Patent claims 1. Method for determining a torque transmitted through a gear (15), comprising the steps: - Providing a transmission (15) with a support member (16), a drive member (17), a driven member (18) and at least one main bearing arrangement (19) for rotatably mounting the drive member (17) and / or the driven member (18) relative to the support member (16) about an axis of rotation (R) which determines the rotational degree of freedom of the transmission (15), and for defining the remaining five degrees of freedom of the spatial Cartesian coordinate system, wherein the drive member (17) and / or the driven member (18) has a first member section (20.1) that is elastic about the rotational degree of freedom, through which the torque is transmitted, and a second member section (20.2) that is rigid in all six degrees of freedom, through which the remaining five degrees of freedom are supported, - simultaneous detection of the rotational angle position of the drive element (17) as a first rotational angle value (Wl) and the rotation angle position of the output member (18) as a second rotation angle value (W2) , during a transmission of a determined torque through the transmission (15) , - Calculating the transmitted torque using a mathematical model of the transmission (15) which incorporates the elastic properties of the first Section (20.1) is taken into account, based on the recorded first rotation angle value (W1) and the recorded second rotation angle value (W2).

2. Method according to claim 1, characterized in that the calculation of the transmitted torque is carried out using a mathematical model of the transmission (15) which takes into account the elastic properties of the first link section (20.1) as the essential criterion or the only criterion for determining the transmitted torque.

3. Method according to claim 1 or 2, characterized in that the angular position of the drive element (17) and / or the angle of rotation of the output member (18) outside the gearbox (15).

4. Method according to claim 3, characterized in that the second member section (20.2) is connected to a measuring shaft (29) rotatably mounted about the axis of rotation (R) of the degree of freedom of the transmission (15), which has a measuring shaft section (29a) extending out of the transmission (15) at which the angular position of the measuring shaft (29) is detected.

5. Method according to one of claims 1 to 4, characterized in that a tension wave gear (15a) is provided as the gear (15), which has a rigid outer ring (21) connected to the support member (16) with an internal toothing (22), a flexible output bushing (23) connected to the output member (18) with a external toothing (24) , and one rotatable in the gearbox (15) comprising a mounted shaft generator (25) rolling on the flexible output bushing (23), which is connected to the drive member (17), wherein the external toothing (24) of the flexible output bushing (23) is in meshing engagement with the internal toothing (22) of the rigid outer ring (21) depending on a rotational movement of the shaft generator (25), and wherein the output member (18) is connected to the flexible output bushing (23) via the elastic first member section (20.1).

6. Drive system comprising a transmission (15) with a support member (16), a drive member (17), a driven member (18) and at least one main bearing arrangement (19) for rotatably mounting the drive member (17) and / or the driven member (18) relative to the support member (16) about an axis of rotation (R) which determines the rotational degree of freedom of the transmission (15), and for defining the other five degrees of freedom of the spatial Cartesian coordinate system, wherein the drive member (17) and / or the driven member (18) has a first member section (20.1) that is elastic about the rotational degree of freedom, through which the torque is transmitted, and a second member section (20.1) that is rigid in all six degrees of freedom.2) has, over which the remaining five degrees of freedom are supported, and a control device (2) which is designed and configured to simultaneously detect the angular position of the drive member (17) as a first angular value (W1) and the angular position of the driven member (18) as a second angular value (W2) during a transmission of a determined torque through the transmission (15), wherein the control device (2) has a control device that measures the elastic properties of the first member section. (20.1) a mathematical model of the gearbox (15) is stored, which uses the first recorded rotation angle value (Wl) and the second recorded rotation angle value (W2) to calculate the torque transmitted by the gearbox (15).

7. Drive system according to claim 6, characterized in that a mathematical model of the transmission (15) is stored on the control device (2) which takes into account the elastic properties of the first link section (20.1) as the essential criterion or the only criterion for calculating the transmitted torque.

8. Drive system according to claim 6 or 7, comprising a first angle sensor (28.1) detecting the angle of rotation of the drive member (17), which is arranged outside the gearbox (15) and / or a second angle sensor (28.2) detecting the angle of rotation of the driven member (18), which is arranged outside the gearbox (15).

9. Drive system according to one of claims 6 to 8, comprising a measuring shaft (29) connected to the second member section (20.2), which is rotatably mounted about the axis of rotation (R) of the degree of freedom of the gearbox (15), and which has a measuring shaft section (29a) extending out of the gearbox (15), on which the angular position of the measuring shaft (29) is detected.

10. Drive system according to one of claims 6 to 9, characterized in that the transmission (15) is configured as a The tension wave transmission (15a) comprises a rigid outer ring (21) with internal teeth (22) connected to the support member (16), a flexible output bushing (23) with external teeth (24) connected to the output member (18), and a [missing element] in the transmission. (15) rotatably mounted on the flexible output bushing (23) rolling shaft generator (25) which is connected to the drive member (17), wherein the external toothing (24) of the flexible output bushing (23) is in meshing engagement with the internal toothing (22) of the rigid outer ring (21) depending on a rotational movement of the shaft generator (25), and wherein the output member (18) is connected to the flexible output bushing (23) via the elastic first member section (20.1).

11. Robot comprising a robot arm (3) with several segments (Gl - G7) and joints (LI - L6) connecting the segments (Gl - G7) adjustable relative to each other, wherein at least one of the joints is connected to a drive system (27) is equipped according to one of claims 6 to 10.

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