Robot having shoulder joint assemblies

Abstract

The invention relates to a robot (1) comprising a torso (19) having a first shoulder joint assembly (2) and a second shoulder joint assembly (3), each shoulder joint assembly (2, 3) comprising the following elements: - a housing (20) in which a globoid worm gearing (7) having a worm shaft (8) and a worm gear (9) is arranged, - a drive unit (10), and - a belt drive (11) which operatively connects the globoid worm gearing (7) to the drive unit (10) via a belt (12), wherein the elements of the two shoulder joint assemblies (2, 3) are substantially identical, and wherein the worm gears (9) of the two shoulder joint assemblies (2, 3) are arranged in the associated housing (20) in mutually opposite orientations.

Description

[0001] Robots with shoulder joint configurations

[0002] The invention relates to a robot with two shoulder joint assemblies arranged on a torso or trunk.

[0003] The development of humanoid robots places particular demands on the design of joint drives. These must be compact, cost-effective, and functional, while also meeting specific requirements such as high transmission accuracy, EMC resistance, and ease of adaptation. Known drive variants for humanoid robot joints rely on various concepts, such as planetary gears or wave gears, to convert drive power. However, these gear types are not self-locking, so they require additional brakes. They often have a high weight and a center of gravity that is unfavorable for the overall robot structure.

[0004] CN 2016 / 20948169 U describes a robot joint with a worm drive that provides torque-amplifying transmission. The worm drive is directly coupled to a drive shaft.

[0005] The term "shoulder joint assembly," in the context of a humanoid robot, refers to a mechanical and kinematic structure that mimics the movement of the human shoulder joint. It connects the robot arm to the robot's torso and enables complex movements in multiple degrees of freedom, such as abduction, adduction, rotation, flexion, and extension. Shoulder joint assemblies ensure high precision, load-bearing capacity, and energy efficiency for tasks such as grasping, lifting, and other complex manipulation operations.

[0006] The object of the invention is to provide a robot that has as many identical parts as possible between its shoulder joint assemblies and is easy to assemble. This object is achieved by the subject matter of claim 1. Preferred embodiments can be found in the dependent claims, the description, and the figures.A robot according to the invention has a torso with a first shoulder joint assembly and a second shoulder joint assembly, each shoulder joint assembly comprising a housing in which a globoidal worm gear with a worm shaft and a worm wheel is arranged, a drive unit, and a belt drive that effectively connects the globoidal worm gear to the drive unit via a belt, wherein the elements of the two shoulder joint assemblies are each substantially identical, and wherein the worm wheels of the two shoulder joint assemblies are arranged in reverse orientation in the respective housings. In other words, the housings of the two shoulder joint assemblies, the globoidal worm gears of the two shoulder joint assemblies, the drive units of the two shoulder joint assemblies, and the belt drives of the two shoulder joint assemblies are each substantially identical.The robot can therefore be equipped with identical components for both shoulder joints, thus reducing manufacturing and assembly costs and simplifying robot assembly. Furthermore, the specifically designed shoulder joint arrangements allow for a compact design, particularly in the robot's shoulder area, and optimize weight distribution within the robot. The robot is preferably a humanoid robot.

[0007] The respective belt drive allows the associated globoid worm gear and the drive unit to be arranged at a distance from each other.

[0008] This allows for a more compact design of the robot's shoulder, saving weight and / or optimizing its distribution. It also creates additional installation space for further actuators. The belt drive allows the associated drive unit to be positioned advantageously on the robot, particularly lower in the torso area with respect to the robot's shoulder, for example, as close as possible to the robot's center of gravity or its central axis. Positioning the drive unit lower in the torso can improve the overall center of gravity of the humanoid robot.

[0009] The advantage of each globoidal worm gear lies in its self-locking effect, which eliminates the need for a separate brake in the drive train. By foregoing a brake control, the number of interfaces on the robot's control unit can be reduced. Consequently, the control unit can be designed more simply, with fewer functions.

[0010] Preferably, the respective globoidal worm gear is designed such that several tooth flanks of the worm shaft and the worm wheel are in tooth mesh simultaneously, thereby achieving an increased power density and load-bearing capacity.

[0011] This type of shoulder joint arrangement also allows a component that is at least indirectly connected to the worm gear to rotate 360°. Therefore, if an arm segment is attached to the worm gear, this arm segment can be rotated 360° around the worm gear's axis of rotation, for example, a horizontal axis.

[0012] The worm shaft is a rotationally symmetrical gear element of the globoidal worm gear, which engages with the worm wheel. Its geometry allows for a compact design and a self-locking effect, resulting in high precision and stability. The worm shaft preferably serves as the drive for the respective globoidal worm gear.

[0013] The drive unit and the associated globoid worm gear of the respective shoulder joint assembly together enable power transmission and control of movement at the respective shoulder joint. The drive unit, preferably designed as an electric motor, provides the mechanical energy. The drive unit converts electrical energy into rotary motion. The globoid worm gear mechanically converts the drive power of the associated drive unit. It serves to adapt torque and speed to the requirements of the joint.

[0014] The electric motor is preferably arranged parallel to the axis of rotation of the worm shaft. In other words, a rotor, a rotor shaft, or a rotational axis of the rotor shaft is arranged parallel to the rotational axis of the worm shaft. This arrangement minimizes the installation space at the shoulder joint and optimizes the load distribution. The electric motor is preferably an external rotor, in particular a BLDC external rotor. A BLDC external rotor (brushless DC motor) is a brushless DC motor in which the rotor is located radially outside and the stator radially inside. This design enables a higher torque density because the larger diameter of the rotor generates more leverage. The electric motor is selected so that its performance characteristics match the gearbox concept of the respective shoulder joint arrangement.An external rotor has the advantage that it is particularly easy to adjust the tension of the belt drive via a central screw and an additional anti-rotation device in a slotted hole in the torso.

[0015] Each worm gear preferably has means at one axial end for a rotationally fixed connection to an output component. The worm gear can be rotationally fixed to an output component, in particular an output flange, which is intended for connection to an actuator or for receiving an arm segment or another component of the robot to be driven.

[0016] In this sense, the respective output component is preferably designed as an output flange, which is detachably connected to the associated worm gear. The detachable connection of the output flange allows for easy maintenance and adjustment of the respective shoulder joint assembly. Furthermore, this enables the assembly of identical shoulder joint assemblies with reversed worm gear orientations. For this purpose, the housing preferably has two coaxial openings, wherein, depending on the orientation of the worm gear in the respective housing, an axial section of the worm gear is connected to the output component through one of the two openings. The other opening is then used only for radial support and rotatable mounting of the worm gear.

[0017] Preferably, the respective worm gear is connected to the associated output flange in a rotationally fixed manner via a spur gear. The spur gear provides the means for the rotationally fixed connection between the worm gear and the associated output component. The spur gear offers a robust and precise power transmission. An axial section of the worm gear can, for example, have claws and teeth that protrude from the respective openings of the associated housing and engage with complementary claws or teeth of the output flange, thus creating a positive locking connection that prevents rotation.

[0018] Preferably, the housing is designed in multiple parts, with cover elements of each housing providing axial preload adjustment for the bearing elements supporting the worm shaft and the worm wheel. The worm shaft and worm wheel are each rotatably mounted on their respective housings via two bearing elements. Separate preload elements for the bearings are therefore unnecessary, as the preload can be achieved via the cover elements and their bolted connection. The bearings can be designed as tapered roller bearings or single-row angular contact ball bearings. This allows for fine adjustment to optimize functionality.

[0019] Preferably, a rotary encoder is arranged on each worm shaft. The rotary encoder is positioned at a distance from the output shaft and any cable routing on the output shaft. Positioning the rotary encoder away from the electronics and cable routing minimizes EMC interference and enables a compact design. It also simplifies the control system. The rotary encoder is also integrated into the associated housing.

[0020] In one embodiment, the belt drive comprises a first pulley that can be rotated by the drive unit and a second pulley that is fixedly connected to the worm shaft, with the belt transmitting drive power between the pulleys. The worm shaft, which can also be understood as a worm and has helical teeth, serves as the drive component of the globoidal worm gear, and the worm wheel, which has teeth meshing with the worm shaft, serves as the output component of the globoidal worm gear. The use of a belt drive allows for flexible center distances and easy adjustments to the gear ratio.

[0021] In one embodiment, the first pulley is / are connected to a drive shaft of the associated drive unit and / or the second pulley is connected to the worm shaft of the associated globoidal worm gear by means of a knurled press fit, preventing rotation. The rotationally fixed connection can also be implemented in any other known form that permits the assembly sequence and power transmission. For example, the respective pulley can be shrunk-fitted or glued on, a splined connection with a locking element can be provided, or a central screw can be used.

[0022] The compact design of each shoulder joint assembly allows for the integration of additional actuators to achieve further degrees of freedom for the arm movement of an arm segment located on the output component. In this sense, one embodiment of the shoulder joint assembly provides that the globoidal worm gear is operatively connected to an actuator via the output component. An output flange can be rotationally fixed to the output component, preferably the worm gear, and act on the actuator.

[0023] Alternatively, the output flange of the globoidal worm gear can be connected directly or indirectly to a robot arm, in particular to an arm segment of the robot arm. In this sense, the globoidal worm gear, especially the worm wheel, is designed to be directly connected to an arm segment of the robot. This is advantageous when only rotation of the arm segment about the axis of rotation of the worm wheel is required.

[0024] In another embodiment, the belt drive is designed as a toothed belt drive. Standardized toothed belt profiles such as AT3 or AT5 can be used, which can be flexibly selected depending on the application and desired gear ratio. For increased backlash requirements, the pulleys can be designed with SE gaps or zero gaps.

[0025] By choosing a belt drive as the upstream gearbox, the center distance between the respective worm shaft and the associated drive unit can be freely selected and adjusted according to available belt lengths. Furthermore, the overall gear ratio can be easily adjusted by changing the belt drive's ratio without modifying the globoidal worm gear. The drive units are preferably positioned closer to the robot's center of gravity than the globoidal worm gears, resulting in improved weight distribution.

[0026] Further measures improving the invention are described in more detail below, together with a description of a preferred embodiment of the invention, with reference to the figures, wherein identical or similar components are provided with the same reference numeral. The figures show...

[0027] Figure 1 is a highly schematic representation of a robot according to the invention – only partially shown – with two shoulder joint arrangements.

[0028] Figure 2 is a schematic perspective view of an exemplary shoulder joint arrangement of the robot according to the invention as shown in Figure 1.

[0029] Figure 3 shows a first sectional view of the shoulder joint arrangement according to Figure 2.

[0030] Figure 4 shows a second sectional view of the shoulder joint arrangement according to Figure 2 and Figure 3 and

[0031] Figure 5 shows a third sectional view of the shoulder joint arrangement according to Figures 2 to 4.

[0032] Figure 1, in conjunction with Figure 2, shows a robot 1, depicted here only partially and in a highly simplified manner. The robot 1 is designed in the form of a humanoid robot and has a torso 19 to which a head 18 and two shoulder joint assemblies 2, 3 are attached. A corresponding arm segment 15 is pivotably mounted on each shoulder joint assembly 2, 3 within a pivoting range. The structure and function of the shoulder joint assemblies 2, 3 are described in more detail below.

[0033] The shoulder joint assemblies 2 and 3 are mirror-symmetrical about a vertical central axis 4 of the robot 1. Only the left first shoulder joint assembly 2 will be described in detail below. Everything stated here applies equally to the right second shoulder joint assembly 3, which has the same elements. The central axis 4 serves as the axis of symmetry.

[0034] According to Figures 2 to 4, the shoulder joint assembly 2 comprises a multi-part housing 20 in which a self-locking globoidal worm gear 7 with a worm shaft 8 and a worm wheel 9 is arranged. The housing 20 is rigidly connected to a basic structure of the torso 19 (not shown here), in particular by screws. Furthermore, a separate drive unit 10 in the form of an electric motor is provided, which is spatially separated from the globoidal worm gear 7 and is operatively connected to the globoidal worm gear 7 via a belt 12 of a belt drive 11. The belt drive 11 is designed as a toothed belt drive and, according to Figure 5, has a first pulley 13 that can be rotated by the drive unit 10, and according to Figure 3, a second pulley 25 that is non-rotatably connected to the worm shaft 8.The belt drive 11 is arranged in the power flow between the globoidal worm gear 7 and the drive unit 10, with the belt 12 transmitting drive power between the pulleys 13 and 25. In this example, the worm shaft 8 forms the drive element of the globoidal worm gear 7 and is arranged parallel to the axis of the first pulley 13.

[0035] Figure 1 shows that the drive units 10 of both shoulder joint assemblies 2, 3 are arranged closer to a center of gravity 6 of the robot 1 than the two globoidal worm gears 7. This allows the shoulder area of ​​the robot 1 to be designed more slender and with a lower weight. Furthermore, the overall center of gravity of the robot 1 can be improved.

[0036] In the arrangement shown here, the globoid worm gear 7 enables a 360° rotational movement of the attached arm segment 15 around the horizontal position.

[0037] A significant advantage of this invention is that the elements of the two shoulder joint assemblies 2, 3 can each be essentially identical. In other words, many identical parts can be used between the left and right shoulder joints without changing the general installation conditions in the torso 19. This reduces manufacturing and assembly costs as well as assembly effort, since the risk of incorrect assembly is reduced. Furthermore, an identical screw pattern for attaching the housing 20 to the torso 19 and an identical installation position for the respective belt drive 11 can be implemented. Additionally, it is possible to mount an actuator or the arm segment 15 externally on the torso 19. Furthermore, large cable passages can be ensured if the worm gear 9 has a corresponding inner diameter 41 (see Figure 4).The design of the shoulder joint arrangements 2, 3 shown here also enables a simple sensor concept for position control, which is as free as possible from EMC influences (“EMC” stands for electromagnetic compatibility).

[0038] The worm gear 9 has means at one axial end for a rotationally fixed connection to an output component. At this end, the worm gear 9 projects out of the housing 20 – to the left, as shown in Figure 4. In this case, the respective output component is designed as an output flange 16, which is detachably connected to the worm gear 9, here via a face gear 22.

[0039] As shown in Figure 3 in conjunction with Figures 4 and 5, the housing 20 is designed in multiple parts. In addition to a main housing 14, several cover elements 23, 24, 27 are provided to spatially define the interior of the housing 20. While the axial preload of the bearing elements 30, 31 of the worm gear 9 can be adjusted using the cover elements 23, 24, the axial preload of the bearing elements 28, 29 of the worm shaft 8 can be adjusted using the cover element 27. The bearing elements 28, 29, 30, 31 are each designed as tapered roller bearings.

[0040] On the opposite side of the worm shaft 8 from the second pulley 25, a rotary encoder 21 is arranged and covered by a plastic cover 17. The rotary encoder 21 is thus positioned at the end of the worm shaft 8, spaced away from the output. This places it relatively far from the cable bundles (not shown) that run through the hollow shaft of the output. This significantly reduces the EMC sensitivity of the system. Furthermore, this installation position allows for the use of a considerably smaller rotary encoder 21. For position control at the output, only the gear ratio of the globoidal worm gear 7 needs to be considered. The rotary encoder 21 is, for example, an absolute multiturn encoder. Hall sensors can also be used for positioning on the drive unit 10. Alternatively, sensorless control of the electric motor is also conceivable.This depends, among other things, on the control unit used and the type of drive unit 10.

[0041] According to Figure 3, sealing elements 34, here in the form of radial shaft seals, are arranged between the worm shaft 8 and the housing 20 to protect the interior of the housing 20 from external influences. According to Figure 4, sealing elements 35, here also in the form of radial shaft seals, are arranged between the worm gear 9 and the housing 20 to protect the interior of the housing 20 from external influences. This allows for oil or grease lubrication. O-rings can also be arranged on static components, but these are not shown or described in detail here.

[0042] As already mentioned, the shoulder joint assemblies 2, 3 are arranged in a mirror image about the central axis 4, as shown in Figure 1, and have essentially identical components. According to Figure 4, the housing 20 with the cover elements 23, 24 is designed such that the orientation of the worm gear 9 can be easily reversed without having to make any modifications to the design of the housing 20. For this purpose, the cover elements 23, 24 are essentially mirror-symmetrical and, in the assembled state, have coaxial openings 32, 33, wherein an axial section 34 of the worm gear 9, on which the face teeth are formed, passes through one of the two openings 32, 33, depending on the orientation.In Figure 4, the worm gear 9 of the first shoulder joint assembly 2 is oriented to the left, while the worm gear 9 of the second shoulder joint assembly 3 is oriented to the right, so that the output flange 16 is connected on the right side. This ensures the mirror-symmetrical design. Therefore, the worm gears 9 of the two shoulder joint assemblies 2 and 3 are arranged in reverse orientation within the corresponding housing 20. No adjustment or modification of the elements of the shoulder joint assemblies 2 and 3 is required for this.

[0043] According to Figure 5, the first pulley 13 is non-rotatably connected to a drive shaft 26 of the associated drive unit 10 by means of a knurled press fit. According to Figure 3, the second pulley 25 is non-rotatably connected to the worm shaft 8 of the associated globoid worm gear 7 by means of a knurled press fit.

[0044] According to Figure 5, the electric motor is designed as an external rotor, with a rotor 36 arranged radially outside a stator 37 and rotatably mounted via bearing elements 38 in the form of ball bearings. The rotor 36 is rotationally connected to the drive shaft 26. A screw 39 can be provided to fasten the drive unit 10 to the base structure of the torso 19. Furthermore, an anti-rotation device 40 is provided on the stator 37 to hold the drive unit 10 in its position on the torso 19. The position of the drive unit 10 is adjustable relative to the globoidal worm gear 7, so that the belt 12 of the belt drive 11 can be tensioned.

[0045] With such a shoulder joint arrangement 2, 3, a reduction in the weight and complexity of the robot 1's shoulder can be achieved. Furthermore, the joint's performance in the shoulder area can be increased. Consequently, heavier loads can be moved. In addition, the overload capacity can be increased, especially when several tooth flanks of the worm shaft 8 are in mesh with the worm gear 9.

[0046] Furthermore, standard electric motors and belt drives can be combined as desired for the respective shoulder joint arrangement 2, 3, allowing for a high spread between drive speed and output torque.

[0047] The entire housing unit, consisting of main housing 14 and cover elements 23, 24, 27, as well as the worm shaft 8, can always be used identically, with the only difference being the respective installation direction of the worm wheel 8 and thus also of the output flange 16 for the two shoulder joint arrangements 2, 3. (Reference symbol list)

[0048] 1 robot

[0049] 2 Shoulder joint arrangement

[0050] 3 Shoulder joint arrangement

[0051] 4 Central axis

[0052] 5 distance

[0053] 6. Focus

[0054] 7 Globoid worm gears

[0055] 8 worm shaft

[0056] 9 worm gear

[0057] 10 Drive unit

[0058] 11 Belt drive

[0059] 12 belts

[0060] 13 First pulley

[0061] 14 Main case

[0062] 15 arm segment

[0063] 16 Output flange

[0064] 17 plastic lids

[0065] 18 heads

[0066] 19 Torso

[0067] 20 cases

[0068] 21 Rotary Angle Encoders

[0069] 22 Front teeth

[0070] 23 Cover element

[0071] 24 lid element

[0072] 25 Second pulley

[0073] 26 Drive shaft

[0074] 27 lid elements

[0075] 28 Bearing element

[0076] 29 Bearing element

[0077] 30 bearing element

[0078] 31 Bearing element

[0079] 32 Opening 33 Opening

[0080] 34 Sealing element

[0081] 35 Sealing element

[0082] 36 Rotor of the drive unit 37 Stator of the drive unit 38 Bearing element

[0083] 39 screw

[0084] 40 Anti-rotation device

[0085] 41 inner diameter

Claims

Patent claims 1. Robot (1) comprising a torso (19) with a first shoulder joint assembly (2) and a second shoulder joint assembly (3), each shoulder joint assembly (2, 3) comprising the following elements: - a housing (20) in which a globoid worm gear (7) with a worm shaft (8) and a worm wheel (9) is arranged, - a drive unit (10), and - a belt drive (11) that effectively connects the globoid worm gear (7) to the drive unit (10) via a belt (12), wherein the elements of the two shoulder joint arrangements (2, 3) are each essentially identical in design, and wherein the worm gears (9) of the two shoulder joint arrangements (2, 3) are arranged in reverse orientation in the associated housing (20).

2. Robot (1) according to claim 1 , characterized in that the respective worm wheel (9) has means at an axial end for a rotationally fixed connection with an output component.

3. Robot (1) according to claim 2, characterized in that the respective worm gear (9) is connected to an associated output flange (16) via a face gear (22) in a rotationally fixed manner.

4. Robot (1) according to any one of the preceding claims, characterized in that the respective housing (20) is formed in multiple parts, wherein cover elements (23, 24, 27) of the respective housing (20) are provided for adjusting an axial preload of bearing elements (28, 29) for supporting the worm shaft (8) and bearing elements (30, 31) for supporting the worm wheel (9).

5. Robot (1) according to one of the preceding claims, characterized in that a rotary angle encoder (21) is arranged on the respective worm shaft (8).

6. Robot (1) according to any one of the preceding claims, characterized in that the belt drive (11) has a first pulley (13) which can be rotated by the respective drive unit (10) and a second pulley (25) which is rotatably connected to the worm shaft (8), wherein the belt (12) transmits a drive power between the pulleys (13, 25).

7. Robot (1) according to claim 6, characterized in that the first pulley (13) is or are rotatably connected to a drive shaft (26) of the associated drive unit (10) and / or the second pulley (25) is or are connected to the worm shaft (8) of the associated globoid worm gear (7) by means of a knurled press fit.

8. Robot (1) according to any one of the preceding claims, characterized in that the respective drive unit (10) comprises an electric motor which is arranged parallel to the axis and spaced apart from the worm shaft (8).

9. Robot (1) according to claim 8, characterized by the fact that the respective electric motor is designed as an external rotor.

10. Robot (1 ) according to claim 9, characterized in that the drive units (10) are arranged closer to a center of gravity (6) of the robot (1) than the globoid worm gears (7).

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