Shoulder joint assembly for a robot

Abstract

The invention relates to a shoulder joint assembly (2) for a robot (1), comprising: a globoid worm gearing (7) having a worm shaft (8) and a worm gear (9); a drive unit (10); and a belt drive (11) which operatively connects the globoid worm gearing (7) to the drive unit (10). The invention also relates to a robot (1) having a shoulder joint assembly (2) of this type.

Description

[0001] Shoulder joint arrangement for a robot

[0002] The invention relates to a shoulder joint arrangement for a robot and to a robot with at least one such shoulder joint arrangement.

[0003] Humanoid robots typically use drive units with wave gears or planetary gears to convert power. However, these types of gears are not self-locking, so they require additional brakes. The coaxial arrangement of the gearbox, electric motor, encoder, and brake results in high weight and an unfavorable center of gravity. This design is limited in terms of complexity and available space.

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

[0005] DE 102023 120475 A1 describes a drive device for a robot with a worm drive. A worm gear engages with the worm shaft. The worm shaft is supported by a bearing element that transmits at least one axial force and is axially supported, at least indirectly, by an axial force measuring device that detects an axial force when a torque is transmitted to the worm shaft via the worm gear.

[0006] 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.

[0007] The object of the invention is to reduce the weight and complexity of a shoulder joint assembly while maintaining performance comparable to wave or planetary gears, to increase performance in the shoulder area by increasing load capacity in the same installation space, and to improve overload capacity.

[0008] The problem is solved by a shoulder joint arrangement according to claim 1 and by a robot comprising such a shoulder joint arrangement according to claim 8. Preferred embodiments can be found in the dependent claims, the description and the figures.

[0009] A shoulder joint arrangement according to the invention for a robot comprises a globoidal worm gear with a worm shaft and a worm wheel, a drive unit, and a belt drive that effectively connects the globoidal worm gear to the drive unit. An advantage of this arrangement is that the respective shoulder joint can be designed compactly and the weight distribution in the robot can be optimized.

[0010] The belt drive allows the globoidal worm gear and the drive unit to be positioned at a distance from each other. This enables a more compact design for the robot's shoulder, reducing or optimizing weight distribution. It also creates additional installation space for further actuators. The belt drive allows the drive unit to be positioned advantageously on the robot, particularly in relation to the robot's shoulder, deeper in the torso area, for example, as close as possible to the center of gravity or to a central axis. The overall center of gravity of the humanoid robot can be improved by positioning the drive unit as desired.

[0011] The advantage of the 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. Furthermore, the overall design of the shoulder joint assembly results in a reduction in weight and complexity compared to conventional joint architectures with planetary or wave gears.

[0012] 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.

[0013] The modular combination of globoid worm gear and belt drive also allows for a high degree of variability in the overall transmission ratio.

[0014] Preferably, the globoidal worm gear is designed such that several tooth flanks of the worm shaft and the worm wheel are in simultaneous tooth meshing, thereby achieving increased power density and load-bearing capacity.

[0015] The worm shaft is a rotationally symmetrical gear element of the globoidal worm gear, which meshes 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 globoidal worm gear.

[0016] The worm gear can be non-rotatably connected to an output component, in particular an output flange, which is intended for connection to an actuator or for receiving an arm segment or other component of the robot to be driven.

[0017] The drive unit and the globoidal worm gear together enable power transmission and control of movement at the 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 globoidal worm gear mechanically converts the drive power from the drive unit. It serves to adapt torque and speed to the requirements of the joint.

[0018] Preferably, the belt drive comprises a first pulley that can be rotated by the drive unit and a second pulley that is rotationally connected to the worm shaft, with one belt of the belt drive transmitting drive power between the pulleys. Thus, 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 with its teeth serves as the output component of the globoidal worm gear. The use of a belt drive allows for flexible center distances and simple gear ratio adjustments.

[0019] The compact design of the joint allows for the integration of additional actuators to achieve further degrees of freedom in arm movement. In this respect, one embodiment of the shoulder joint arrangement provides that the globoidal worm gear is operatively connected to an actuator on the output side. An output flange can be rotationally fixed to the output component, preferably the worm gear, and act upon the actuator.

[0020] 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.

[0021] If the drive unit includes an electric motor, then this is preferably arranged parallel to the axis 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 axis of rotation of the worm shaft.

[0022] 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.

[0023] 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 ratio of the belt drive, without modifying the globoidal worm gear itself.

[0024] Preferably, the position of the drive unit relative to the globoidal worm gear is adjustable to allow flexible adaptation to different operating conditions. In particular, the pretension of the belt drive can be adjusted.

[0025] According to a second aspect of the invention, a robot comprises a shoulder joint assembly according to the first aspect of the invention. The robot is preferably a humanoid robot. The robot has a torso, wherein the shoulder joint assembly is attached to a base structure of the torso.

[0026] Preferably, the robot comprises two shoulder joint assemblies that are mirror-symmetrical (i.e., reversed) with respect to a central axis of the robot, wherein the globoidal worm gears are spaced apart from each other. This allows for optimal space utilization and flexibility in the design. The closer the gears are to each other, i.e., the smaller the aforementioned distance, the more installation space can be provided for an optional actuator.

[0027] Preferably, the drive units are positioned closer to the robot's center of gravity than the globoid worm gears, resulting in improved weight distribution.

[0028] The above definitions and explanations regarding technical effects, advantages and advantageous embodiments of the shoulder joint arrangement according to the first aspect of the invention also apply analogously to the robot according to the second aspect of the invention, and vice versa.

[0029] 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...

[0030] Figure 1 shows a highly schematic representation of a robot according to the invention with two shoulder joint arrangements according to the invention and

[0031] Figure 2 is a highly schematic representation of a torso of the robot according to Figure 1.

[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 corresponding pivot range 17. The structure and function of the shoulder joint assemblies 2, 3 are described in more detail below.

[0033] Figure 2 shows in more detail the upper region of the torso 19 of the robot 1, on which the shoulder joint assemblies 2 and 3 are provided. The shoulder joint assemblies 2 and 3 are mirror-symmetrical about a vertical central axis 4 of the robot 1 and are arranged on a base structure of the torso 19. The central axis 4 thus serves as the axis of symmetry. Only one shoulder joint assembly, namely the first one 2, will be described in detail below. Everything stated here applies equally to the second shoulder joint assembly 3 on the right, which has the same elements.

[0034] The shoulder joint assembly 2 comprises a self-locking globoid worm gear 7 with a worm shaft 8 and a worm wheel 9, a separate drive unit 10 designed as an electric motor (i.e., spatially separated from the globoid worm gear 7), and a belt drive 11 in the form of a toothed belt drive. The belt drive 11 is arranged in the power flow between the globoid worm gear 7 and the drive unit 10. A belt 12 of the belt drive 11 transmits drive power from the drive unit 10 between a first pulley 13, which is rotatably connected to a rotor of the drive unit 10 (not shown here), and a second pulley 20, which is rotatably connected to the worm shaft 8 of the globoid worm gear 7. In this example, the worm shaft 8 forms the drive element of the globoid worm gear 7 and is arranged axially parallel to the first pulley 13 on the drive unit 10.

[0035] In the arrangement shown, the globoid worm gear 7 enables a 360° rotation of the attached arm segment 15 around its horizontal position. A housing 21 for receiving elements of the shoulder joint assembly 2 is rigidly connected to the basic structure of the torso 19.

[0036] In this case, the drive unit 10 is positioned closer to the center of gravity 6 of the robot 1 than the 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.

[0037] In this case, the worm gear 9 is operatively connected to an optional actuator 14 via a rotationally fixed output flange 16. The actuator 14 is shown here, in a highly simplified manner, as a dashed rectangle. This rectangle illustrates the installation space provided for the respective actuator 14, which depends, among other things, on the distance 5 between the globoidal worm gears 7. This is intended to clarify that by relocating the drive unit 10 from the shoulder closer to the center of gravity 6 of the robot 1, more installation space becomes available in the respective shoulder, which can be used to accommodate the actuator 14. Thus, more space is available to realize the degrees of freedom for the movement of the arm segment 15 and to adapt them to the requirements.

[0038] The position or orientation of the drive unit 10 relative to the globoidal worm gear 7 is adjustable, allowing the belt 12 to be tensioned. Appropriate means may be provided to execute and fix the respective positioning movement.

[0039] The distance 5 between the globoidal worm gears 7 can be variably adjusted to the requirements. If the distance 5 is chosen to be small, additional installation space can be provided for the output and possible actuators 14.

[0040] If the arm segment 15 requires or has to implement fewer degrees of freedom, the worm gear 9 or the output flange 16 can also be directly connected to the corresponding arm segment 15 of the robot 1.

[0041] With such a shoulder joint arrangement 2, 3, a reduction in the weight and complexity of the respective shoulder of the robot 1 can be achieved. Furthermore, the performance of the joint 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.

[0042] For the respective shoulder joint arrangements 2 and 3, standard electric motors and belt drives can be combined as desired, thus enabling a high spread between drive speed and output torque. (See list of symbols.)

[0043] 1 robot

[0044] 2 Shoulder joint arrangement

[0045] 3 Shoulder joint arrangement

[0046] 4 Central axis

[0047] 5 distance

[0048] 6. Focus

[0049] 7 Globoid worm gears

[0050] 8 worm shaft

[0051] 9 worm gear

[0052] 10 Drive unit

[0053] 11 Belt drive

[0054] 12 belts

[0055] 13 First pulley

[0056] 14 Actuator

[0057] 15 arm segment

[0058] 16 Output flange

[0059] 17 Swivel range

[0060] 18 heads

[0061] 19 Torso

[0062] 20 Second pulley

[0063] 21 cases

Claims

Patent claims 1. Shoulder joint arrangement (2) for a robot (1) comprising - a globoid worm gear (7) with a worm shaft (8) and a worm wheel (9), - a drive unit (10), and - a belt drive (11) that effectively connects the globoid worm gear (7) to the drive unit (10).

2. Shoulder joint arrangement (2) according to claim 1 , characterized in that the belt drive (11) has a first pulley (13) rotatably driven by the drive unit (10) and a second pulley (20) rotatably connected to the worm shaft (8), wherein a belt (12) of the belt drive (11) transmits a drive power between the pulleys (13, 20).

3. Shoulder joint arrangement (2) according to claim 1 or claim 2, characterized in that the globoid worm gear (7) is operatively connected to an actuator (14) on the output side.

4. Shoulder joint arrangement (2) according to claim 1 or claim 2, characterized in that the globoid worm gear (7) is designed to be directly connected to an arm segment (15) of the robot (1).

5. Shoulder joint arrangement (2) according to one of the preceding claims, characterized in that the drive unit (10) comprises an electric motor which is arranged parallel to the axis and spaced apart from the worm shaft (8).

6. Shoulder joint arrangement (2) according to one of the preceding claims, characterized in that the belt drive (11) is a toothed belt drive.

7. Shoulder joint arrangement (2) according to one of the preceding claims, characterized in that a position of the drive unit (10) is adjustable in relation to the globoid worm gear (7).

8. Robot (1) comprising at least one shoulder joint arrangement (2) according to one of the preceding claims.

9. Robot (1) according to claim 8, characterized by two shoulder joint arrangements (2, 3) designed in a mirror-symmetrical manner with respect to a central axis (4) of the robot (1), wherein the globoid worm gears (7) are arranged spaced apart from each other by a distance (5).

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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