DRIVE DEVICE FOR A MANIPULATOR

Description

[0001] The present invention relates to a drive device for a joint between two axle members of a manipulator of a robot system.

[0002] Drive units used in manipulators of robot systems or robot arms are used to position one axis of the usually multi-axis robot arm in a movable, preferably rotatable, manner relative to an adjacent axis. The resulting mobility between two adjacent axis leads to the corresponding degrees of freedom of the robot system via the number of axis of the manipulator.

[0003] Industrial robots use drive units that allow rotation of an axis member around an axis running perpendicular to its longitudinal extension. Additional drive devices are designed to allow rotation around the longitudinal axis of the axis member. For this purpose, appropriately dimensioned electric motors are typically used, which may interact with a suitable reduction gear.

[0004] In lightweight robots, the drive devices are built into the self-contained housing of the axle links, since the housings of the manipulators of such types of robots are basically designed like an exoskeleton.

[0005] In the drive devices known from the prior art, at least one sensor device is generally provided on the output side to detect the position, torque, and / or speed of an output element that causes one axle member to rotate relative to the other axle member. A further sensor device is also provided on the motor side or drive side to detect the drive speed, drive torque, and / or position of a drive shaft driven by a motor.

[0006] CA 2 940 490 A1 and CN 207 256 275 U each show examples of drive devices for robots with corresponding sensor devices.

[0007] In order to enable a particularly compact design, a drive device, particularly for use in lightweight robots, has been proposed in German Patent No. 10 2016 004 810, in which both sensor devices are arranged on a single circuit board.

[0008] This drive device for a joint arranged between two axial members of a manipulator of a robot system for the rotational drive of one axial member relative to the other axial member has a motor which drives a drive shaft and an output element which is connected to the one axial member and is rotated directly or indirectly by the drive shaft, wherein a printed circuit board or printed circuit board (PCB) is provided on which a sensor device for the drive provided by the drive shaft and a sensor device for the output provided by the output element are arranged, wherein the sensor device for the drive and the sensor device for the output are arranged on opposite sides of the printed circuit board.

[0009] Furthermore, a sensor shaft is provided, to which the output element is connected in a rotationally fixed manner. The sensor shaft extends through an opening in the circuit board to the side of the circuit board opposite the motor. A positioning or sensor ring is provided in the region of the front axial end of the sensor shaft above the circuit board, which interacts with the sensor device for the output. The sensor ring is rotatably mounted in a bearing seat and is connected in a rotationally fixed manner to the sensor shaft.

[0010] In such a design of the drive device from the prior art, as shown by way of example in the Fig. 1 As shown, several components are provided between the motor output, usually the output shaft, and the output-side sensor device in relation to the sensor ring rotatably mounted above the circuit board, such as a gearbox, various output and bearing elements, the sensor shaft, etc. These components form a tolerance chain into which their individual tolerances ultimately flow, so that the individual tolerance errors naturally add up when the output is detected via the feedback by means of the sensor shaft at a location opposite the actual output side, namely on the circuit board. The gap between the output-side sensor ring and a position sensor assigned to it can therefore possibly become too large compared to the gap between the drive-side sensor ring and the position sensor assigned to it.Furthermore, the surfaces of the position sensor and the sensor ring may not be completely parallel to each other, but may be slightly inclined. Both of these can subsequently lead to significant measurement errors.

[0011] However, this is detrimental to high-precision control, which is essential for a compliance-controlled robot, in particular. The gap between the output-side sensor ring and the corresponding position sensor should therefore be subject to tight tolerances.

[0012] Based on this, it is an object of the present invention to provide a drive device for a drive element between two axle members of a manipulator of a robot system, in particular, but not exclusively, of lightweight construction, which eliminates the above-mentioned disadvantages known from the prior art, in particular enables closely tolerated sensor devices and thereby increases the reliability with regard to the detection of the drive and output-side parameters.

[0013] This object is achieved with a drive device according to claim 1 and with a robot according to claim 9.

[0014] The invention accordingly relates to a drive device for a joint arranged between two axle members of a manipulator of a robot system for the rotational drive of one axle member relative to the other axle member, comprising a motor that drives a drive shaft, an output element that is connected to one axle member and is directly or indirectly rotated by the drive shaft, a printed circuit board on which a sensor device for the drive provided by the drive shaft and a sensor device for the output provided by the output element are arranged, wherein the sensor device for the drive and the sensor device for the output are arranged on opposite sides of the printed circuit board, and a sensor shaft to which the output element is connected in a rotationally fixed manner, wherein the sensor shaft extends through an opening in the printed circuit board to the side of the printed circuit board,which is opposite the motor and wherein in the region of the front axial end of the sensor shaft above the circuit board a sensor ring is arranged which cooperates with the sensor device for the output, wherein the sensor ring is rotatably mounted in a bearing seat and is connected to the sensor shaft in a rotationally fixed manner, wherein according to the invention at least one means is provided which is arranged and designed such that it interrupts or dissolves the tolerance chain from the motor to the output-side sensor ring.

[0015] According to the invention, such a means can be realized as at least one ball bearing, preferably a radial bearing, by means of which the sensor ring is rotatably mounted in the bearing seat.

[0016] In an advantageous embodiment of the drive device, the sensor ring is connected to a bearing sleeve that can be connected to the sensor shaft in a rotationally fixed manner. The sensor shaft can, for example, be pressed into the bearing sleeve in such a way that a frictional connection is formed between them. Appropriate means, such as tolerance rings or press rings, can be used for this purpose.

[0017] The bearing sleeve itself is then rotatably mounted in the bearing seat via the ball bearing.

[0018] According to a further embodiment of the drive device, the bearing seat can be firmly connected, for example, screwed, directly to the circuit board. The bearing seat is thus arranged on the side of the circuit board opposite the motor and the other components of the drive device.

[0019] In an advantageous embodiment of the drive device, the bearing seat can be firmly connected to a housing section of the motor housing, wherein the housing section passes through the circuit board.

[0020] In order to enable the drive-side and output-side parameters to be detected by sensor devices arranged on a single circuit board, it is provided according to the invention that the drive shaft driven by the motor is designed as a hollow shaft through which the sensor shaft passes at a radial distance, the drive shaft extending as far as the circuit board.

[0021] Preferably, the sensor devices for both the output and the drive are sensors of the same type, which further simplifies the evaluation electronics.

[0022] In a preferred embodiment according to the invention, it is therefore further provided that the sensor ring for the drive and the sensor ring for the output are congruently located opposite each other on both sides of the circuit board.

[0023] For an exact planar guidance of the sensor ring for the drive, it is provided according to the invention that preferably a radial bearing, which guides the drive shaft in the housing of the motor, axially opposite the output, is arranged constructively and structurally as close as possible to this sensor ring.

[0024] By providing both a radial bearing for the sensor ring for the output and a radial bearing for the drive shaft with appropriate positioning, it is possible to arrange and guide both sensor rings as parallel and concentrically as possible to the sensor chips assigned to them, whereby axial and angular tolerance deviations can be kept extremely low and measurement errors hardly occur.

[0025] The arrangement of the output sensor and the input sensor on a single circuit board is inherently less prone to failure and errors, which also significantly simplifies the programming of the evaluation algorithm. The further decoupling of the output-side tolerance chain by means of a rotary bearing for the sensor ring of the sensor shaft, for example, using at least one radial bearing in a bearing seat, can further reduce the susceptibility to errors in such an arrangement.

[0026] Due to the fact that the presence of the means according to the invention allows the tolerance chain from the motor to the output-side sensor device to be interrupted, manufacturing-related tolerance errors of the individual components within this tolerance chain can be completely ignored during output detection and the corresponding evaluation. This even allows some of the components to be manufactured with larger tolerances and thus more cost-effectively.

[0027] In this context, the invention therefore also relates to a robot with a manipulator comprising a plurality of axle members having a drive device according to the embodiments described above in at least one joint arranged between axle members of the manipulator.

[0028] Further advantages and features will become apparent from the description of the embodiment illustrated in the accompanying drawings. They show: Fig. 1 shows an axial longitudinal section through a drive device according to the prior art; Fig. 2 shows an axial longitudinal section through a drive device according to the invention; Fig. 3 shows a partial enlarged view of the bearing of the output-side sensor device; and Fig. 4 shows the mechanism according to the invention consisting of a bearing seat, bearing sleeve, and radial bearing.

[0029] In the Fig. 1 For the purpose of understanding, a drive device from the prior art is shown as an example in a cross-sectional view along the axis of rotation, ie the longitudinal extent of the drive device, as is known, for example, from German Patent No. 10 2016 004 810.

[0030] As can be seen, the drive device is essentially constructed from rotationally symmetrical components and parts, implementing a modular design in which several modules interact and interlock in an axial alignment. The modules are individually interchangeable and can be connected to one another using appropriately designed and configured connection technologies.

[0031] The Fig. 1 The drive device shown essentially consists of four functionally different drive modules.

[0032] A first drive module M1 contains a gear unit 1, for example a harmonic drive, which is accommodated in a housing 2. The output element of the gear unit 1 is connected in a rotationally fixed manner, i.e., torque-transmitting, to a housing 4 of a second drive module M2 via an output shaft 3. The second drive module M2 serves the output and, for this purpose, is rotationally fixedly connected to an axle member (not shown) of a manipulator or robot arm, while the housing 2 of the first drive module M1 is connected to a further axle member (not shown) of this manipulator. The housing 4 of the second drive module M2 is rotatably mounted relative to the housing 2 of the first drive module M1 by means of a radial bearing 5.

[0033] Axially opposite the second drive module M2, a third drive module M3 is attached to the first drive module M1, which has a housing 6 in which a motor 7 is arranged, which drives a motor or drive shaft 8.

[0034] The drive shaft 8 is rotatable by a first radial bearing 9 near the gearbox 1 and by a second radial bearing 10 in a cover 11 for the housing 6 and is thus centrally mounted in the drive device.

[0035] A fourth drive module M4 is fastened to the housing 6 of the third drive module M3 or to the cover 11 associated therewith via connecting or spacer holders 12, which fourth drive module M4 has a printed circuit board 13 or PCB for sensor and control electronics.

[0036] The drive shaft 8 of the motor 7, which is designed as a hollow shaft, extends through the cover 11 to the side of the circuit board 13 that faces the cover 11.

[0037] The housing 4 of the second drive module M2 is screwed on the front side via a flange 14 to a flange 15 of a sensor shaft 16 in a rotationally fixed manner.

[0038] As in the Fig. 1 As can be seen, the sensor shaft 16 passes through the output shaft 3 and the drive shaft 8 of the motor 7 at a radial distance and extends through an opening in the circuit board 13 to the side of the circuit board 13 which is opposite the third drive module M3.

[0039] The front axial end of the drive shaft 8 facing the circuit board 13 has a sensor ring 17, while a sensor chip 18 corresponding to this sensor ring 17 is arranged on the circuit board 13. The sensor ring 17 is mounted on a retaining ring 19, so that the sensor ring 17 rotates with the drive shaft 8.

[0040] The sensor shaft 16 also has a sensor ring 20 at its front axial end, which is also fastened in a corresponding retaining ring 21 and thus rotates on the circuit board 13 via a sensor chip 22 assigned to this sensor ring 20.

[0041] In order to guide the sensor ring 20 of the sensor shaft 16 exactly concentrically and parallel to the sensor chip 22, in this prior art a radial sliding guide 23 is arranged on the circuit board 13, which is screwed to the spacers 12.

[0042] In order to guide the sensor ring 17 of the drive shaft 8 exactly concentric and parallel to the sensor chip 18, the second radial bearing 10 of the third drive module M3 is arranged as close as possible to the circuit board 13.

[0043] The present invention relates in the broadest sense to an alternative embodiment of the module M4 and is therefore fundamentally independent of the actual design of the other modules M1 to M3 and their components. However, the structure of these modules M1 to M3 can, in principle, be implemented analogously to the prior art, as can be seen from the Fig. 2 can be seen.

[0044] In this Fig. 2 , which schematically shows a similar axial cross-sectional view through a drive device, identical components are provided with the same reference numerals for the sake of simplicity.

[0045] As in the prior art, the sensor ring 20 for the output is rotatably mounted relative to the position sensor or sensor chip 22, but not by means of a sliding guide 23.

[0046] Rather, according to the invention, the sensor ring 20 is connected in a rotationally fixed manner to a bearing sleeve 24. The bearing sleeve 24 is designed and constructed such that it can be connected in a rotationally fixed manner to the sensor shaft 16. The sensor shaft 16 is pressed into the bearing sleeve 24 in such a way that a frictional connection is preferably formed between them with the interposition of tolerance compensation rings or similar means 25. In principle, however, a force and / or form fit would also be conceivable.

[0047] The bearing sleeve 24 is rotatably mounted in a housing of a bearing seat 27 via a radial bearing 26. The bearing seat 27 is firmly screwed to a housing section 29 of the housing 11 of the motor 7 by means of screws 28, wherein the housing section 29 at least partially extends through an opening 30 in the circuit board 13.

Claims

1. Drive device for a joint arranged between two axis members of a manipulator of a robot system for rotatably driving one of the axis members relative to the other axis member, with a motor (7) which drives a drive shaft (8), with an output element (3, 4) which is in connection with the one axis member and is set in rotation indirectly or directly by the drive shaft (8), with a circuit board (13) on which a sensor device (18) for the drive provided by the drive shaft (8) and a sensor device (22) for the output provided by the output element (3, 4) are arranged, wherein the sensor device (18) for the drive and the sensor device (22) for the output being arranged on opposite sides of the circuit board (13), and with a sensor shaft (16) to which the output element (3, 4) is connected in a rotationally fixed manner, wherein the sensor shaft (16) extends through an opening in the circuit board (13) to the side of the circuit board (13) that is located opposite the motor (7), and wherein a sensor ring (20) which cooperates with the sensor device (22) for the output is arranged in a region of the axial end of the sensor shaft (16) that is located on the side of the circuit board (13) that is located opposite of the motor (7),, wherein the sensor ring (20) is rotatably mounted in a bearing seat (27) and is connected to the sensor shaft (16) in a rotationally fixed manner, characterized in that the sensor ring (20) is rotatably mounted in the bearing seat (27) by means of at least one ball bearing (26).

2. Drive device according to claim 1, in which the sensor ring (20) is connected to a bearing sleeve (24) which can be connected to the sensor shaft (16) in a rotationally fixed manner.

3. Drive device according to claim 2, in which the bearing sleeve (24) is connected to the sensor shaft (16) by means of a frictional bond.

4. Drive device according to claim 2 or 3, in which the bearing sleeve (24) is rotatably mounted in the bearing seat (27), which is fixedly connected to the circuit board (13).

5. Drive device according to claim 2 or 3, in which the bearing seat (27) is firmly connected to a housing section (29) of the motor housing (11), wherein the housing section (29) engages at least partially through the circuit board (13).

6. Drive device according to one of the preceding claims, in which the drive shaft (8) is formed as a hollow shaft and the sensor shaft (16) passes through the drive shaft (8) at a radial distance and extends to the circuit board (13).

7. Drive device according to claim 6, in which the sensor shaft (16) is formed as a hollow shaft for receiving line components.

8. Drive device according to claim 7, in which a sensor ring (17) is arranged at the axial end of the drive shaft (8) facing the circuit board (13), which cooperates with the sensor device (18) for the drive, and in which the sensor ring (17) for the drive and the sensor ring (20) for the output are located opposite to one another congruently on both sides of the circuit board (13).

9. Robot with a manipulator comprising a plurality of axis member and having a drive device according to claims 1 to 8 in at least one joint arranged between axis members of the manipulator.