An externally driven robot force control joint module and robot

Abstract

An externally driven force-controlled joint module for robots and a robot thereof. The module includes an axially connected harmonic reducer, a torque sensor, a brake, a torque motor, and a dual magnetic ring encoder assembly. The torque sensor is mounted at the output end of the reducer; the brake stator is mounted on the reducer housing; the motor rotor is connected to the reducer input shaft via a rotor shaft; the dual magnetic ring encoder includes a first component for measuring the motor shaft and a second component for measuring the output end. Crucially, the driver for the drive motor is an external driver independent of the module body, connected via a wiring harness. This invention externalizes the driver, significantly reducing the axial dimension and weight of the module body, improving heat dissipation, and facilitating maintenance; one driver can control multiple modules, reducing cost and complexity; combined with output torque sensing and dual encoder feedback, it provides the hardware foundation for high-precision force control, suitable for humanoid robots and other fields with stringent requirements for joint performance, size, and weight.

Description

Technical Field

[0001] This utility model belongs to the field of robot joint drive technology, and relates to a joint module for robots, especially humanoid robots, and more particularly to a compact joint module with force control function and external actuator. Background Technology

[0002] With the rapid development of robotics technology, especially the increasing demands on the flexibility and environmental interaction capabilities of humanoid robots, the joint module, as the core driving unit of a robot, directly determines the robot's load capacity, motion accuracy, response speed, and overall size. Traditional robot joint modules typically adopt a highly integrated design approach, integrating motors, reducers, brakes, encoders, and drivers all into a single enclosed housing, forming an independent power unit.

[0003] For example, patent document CN217777024U discloses a typical integrated joint module. This module includes a harmonic reducer assembly, an external rotor motor assembly, a hollow wiring assembly, and a drive and sensor component integrating a drive circuit and encoder. Although this design aims for miniaturization, its driver (drive circuit board assembly 21) is still built into the rear of the module, occupying the same axial space as the motor, encoder, and other components. This integrated structure results in a relatively long axial length of the module, making further reduction in size and weight difficult. Furthermore, in the event of driver failure, the entire module needs to be disassembled for repair, which is inconvenient and costly. In addition, the driver integrated inside the module has limited heat dissipation, and prolonged high-load operation may cause thermal problems.

[0004] Another patent document, CN121157093A, focuses on the connection method between the wave generator and the motor shaft of a reducer (such as a harmonic reducer). It optimizes the axial and radial connection area and fastening method to meet the needs of modules of different sizes. However, the module described in this document also adopts the design concept of integrating the driver with the main body, which does not solve the fundamental contradiction between size and heat dissipation caused by the built-in driver.

[0005] For humanoid robots or lightweight collaborative robotic arms that require multiple joints to work collaboratively and have stringent requirements for joint size and weight, the size and weight of traditional integrated joint modules have become a bottleneck. Meanwhile, with the development of force control technology, torque sensors need to be integrated into the joint output end to achieve precise force / position hybrid control, which further increases the structural complexity and dimensional control difficulty of the module. Therefore, there is an urgent need for a new joint module structure that can retain high-precision force control functionality while significantly reducing the size and weight of the joint module itself, and improving maintainability and heat dissipation performance. Summary of the Invention

[0006] The purpose of this invention is to provide an externally driven force-controlled joint module and robot, to solve the technical problems of large axial dimensions, heavy weight, and difficult heat dissipation and maintenance of the driver in existing integrated joint modules. To achieve the above objective, this invention adopts the following technical solution.

[0007] An externally driven robot force-controlled joint module includes a harmonic reducer, a torque sensor, a brake, a torque motor, and a dual magnetic ring encoder assembly. The torque sensor is mounted on the steel wheel of the harmonic reducer. The brake includes a brake stator and a brake rotor, with the brake stator mounted on the housing of the harmonic reducer. The torque motor includes a motor stator and a motor rotor, with the motor rotor connected to the input shaft of the harmonic reducer via a motor rotor shaft. The dual magnetic ring encoder assembly includes a first encoder assembly for measuring the rotational speed and position of the motor rotor shaft, and a second encoder assembly for measuring the rotational speed and position of the module's output end. It also includes an external driver electrically connected to the stator of the torque motor and the dual magnetic ring encoder assembly via a wiring harness, the external driver being independent of the module's mechanical body.

[0008] Furthermore, the torque sensor is located on the side of the harmonic reducer away from the torque motor and is directly fixed to the steel wheel end face of the harmonic reducer.

[0009] Furthermore, the dual magnetic ring encoder assembly also includes an encoder stator, a motor encoder rotor mount, an outer encoder rotor, and an inner encoder rotor; the motor encoder rotor mount is fixed on the motor rotor shaft, and the outer encoder rotor is mounted on the motor encoder rotor mount, forming the first encoder assembly; the inner encoder rotor is mounted on a guide shaft, and the guide shaft is connected to and concentrically positioned with the steel wheel of the harmonic reducer, forming the second encoder assembly; the encoder stator is fixed on the rear cover, and the rear cover is mounted on the motor housing, and the encoder stator is provided with sensing parts respectively corresponding to the outer encoder rotor and the inner encoder rotor.

[0010] Furthermore, the cable guide is a hollow structure, and the cable passes through the central hole of the cable guide out of the module.

[0011] Furthermore, it also includes a second bearing, which is disposed between the motor rotor shaft and the guide shaft to provide support for the end of the motor rotor shaft.

[0012] Furthermore, the brake rotor is fixed to the motor rotor shaft by screws.

[0013] Furthermore, the torque motor is an internal rotor torque motor, the motor stator is glued and fixed inside the motor housing, and the motor housing is fixed to the housing of the harmonic reducer by screws.

[0014] Furthermore, the wave generator end of the harmonic reducer is connected to the bobbin via a bearing, and the outer ring of the bearing is mounted on the wave generator end.

[0015] Furthermore, one of the external drivers is electrically connected to at least two of the robot force control joint modules via a wiring harness to independently or collaboratively control the at least two joint modules.

[0016] This utility model also provides a robot, including at least one externally driven robot force control joint module as described above.

[0017] The beneficial technical effects of this utility model include: Significantly reduced module size and weight: By removing the actuators from the joint module body (externalizing them), the axial dimensions and weight of the module body are directly reduced. This allows robot joints, especially those of humanoid robots requiring multiple densely arranged joints, to be designed to be more compact and lightweight, improving the robot's load-to-weight ratio and motion flexibility.

[0018] Improved heat dissipation and reliability: External drivers can be installed in locations with better ventilation and heat dissipation, such as the robot body, avoiding the accumulation of heat in the enclosed joint space of high-power electronic components. This improves the heat dissipation efficiency and operational reliability of the driver and extends its service life.

[0019] Easy maintenance and upgrades: When the drive fails, there is no need to disassemble the complex mechanical parts of the joint module; simply replace the external drive. This greatly simplifies the maintenance process and reduces maintenance costs and downtime. Furthermore, upgrading the drive becomes much easier.

[0020] Enhanced system integration flexibility and reduced costs: A high-performance external driver can control multiple joint modules simultaneously, enabling resource sharing, reducing the number of drivers, and helping to reduce the overall cost, complexity, and wiring difficulty of multi-joint robot systems.

[0021] Achieving high-precision force / position dual closed-loop control: By integrating a torque sensor at the output end (steel wheel) of the harmonic reducer, direct and accurate measurement of the end load torque is achieved. Combined with dual position / speed feedback from the motor input and reducer output provided by the dual magnetic ring encoder, a complete three-loop control system of position, speed, and torque is formed, significantly improving the force control accuracy and dynamic response performance of the joint.

[0022] Compact and rigid structure: Utilizing a layout with axially direct connections for components such as the harmonic reducer, torque motor, brake, and dual encoders, the structure is compact with a short transmission chain. The torque sensor is located at the reducer output end, ensuring a direct measurement path and high rigidity. The use of a spool and hollow wiring design optimizes internal wiring. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall structure of the externally driven force-controlled joint module for robots provided by this utility model.

[0024] Figure 2 This is a schematic diagram of the axial cross-sectional structure of the externally driven robot force control joint module provided by this utility model.

[0025] Reference numerals in the attached diagram: 1-O-ring seal; 2-Bearing 1; 3-Torque sensor; 4-Silicon guide; 5-Harmonic reducer; 6-Brake stator; 7-Brake rotor; 8-Motor rotor shaft; 9-Motor rotor; 10-Motor stator; 11-Motor housing; 12-Rear cover; 13-Motor encoder rotor mount; 14-Bearing 2; 15-Encoder outer rotor; 16-Encoder stator; 17-Encoder inner rotor; 18-External driver. Detailed Implementation

[0026] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without creative effort are within the protection scope of this utility model.

[0027] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance, quantity, or position.

[0028] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances. Example 1

[0029] An externally driven robot force-controlled joint module, such as Figure 1 and Figure 2 As shown. This module mainly includes, from the output end (left side) to the input end (right side): torque sensor 3, harmonic reducer 5, brake (including stator 6 and rotor 7), torque motor (including stator 10 and rotor 9), and dual magnetic ring encoder assembly. All components are arranged along the same axis, resulting in a compact structure.

[0030] The harmonic reducer 5 is the core speed reduction and torque amplification component of the module, with its steel wheel as the fixed end and the flexible wheel as the output end. The torque sensor 3 is preferably a strain gauge torque sensor, which is directly mounted on the left end face of the steel wheel of the harmonic reducer 5 (i.e., the final output end of the module) using screws. This mounting method allows the torque sensor 3 to directly and without delay measure the load torque on the output shaft after speed reduction and torque amplification by the harmonic reducer 5, resulting in the shortest measurement path, good rigidity, and high accuracy. The signal line of the torque sensor 3 can be led out through the guide shaft 4, which will be described later.

[0031] The brake stator 6 is mounted on the housing of the harmonic reducer 5 using screws. The brake is preferably a power-off brake (normally closed type), which engages when power is off to prevent movement of the joints due to external force or its own weight, ensuring safety. The brake rotor 7 is fixedly mounted on the motor rotor shaft 8 using screws. When the brake stator 6 is energized, the brake rotor 7 is released, allowing the motor to rotate freely; when power is off, the brake stator 6 and brake rotor 7 generate friction, locking the motor rotor shaft 8.

[0032] The torque motor, serving as the power supply component, is an internal rotor torque motor with low-speed, high-torque output characteristics. The motor rotor 9 is bonded to the motor rotor shaft 8 using high-strength adhesive. The motor stator 10 is fixed to the inner wall of the motor housing 11 using high-strength adhesive. The motor housing 11 is then fixed to the housing of the harmonic reducer 5 using screws, thus permanently connecting the entire motor assembly to the reducer assembly. The right end of the motor rotor shaft 8 is directly connected to the input shaft of the wave generator of the harmonic reducer 5 using screws, enabling power input.

[0033] The dual-magnetic-ring encoder assembly provides high-precision position and speed feedback, which is crucial for achieving closed-loop control. Specifically, it includes a first encoder assembly and a second encoder assembly. The first encoder assembly (motor-side encoder) measures the rotational speed and angular position of the motor rotor shaft 8. It includes a motor encoder rotor housing 13 and an outer encoder rotor 15. The motor encoder rotor housing 13 is fixed to the motor rotor shaft 8 with screws. The outer encoder rotor 15 is threaded onto the motor encoder rotor housing 13 and rotates synchronously with the motor rotor shaft 8. The second encoder assembly (output-side encoder) measures the rotational speed and angular position of the module's final output end (i.e., the steel wheel / guide shaft 4 of the harmonic reducer 5). It includes an inner encoder rotor 17 and a guide shaft 4. The guide shaft 4 is concentrically positioned with the steel wheel of the harmonic reducer 5 via bearings and is fixed with screws, thus rotating synchronously with the output end. The inner encoder rotor 17 is threaded onto the right end of the guide shaft 4.

[0034] Common stator section: Includes encoder stator 16. Encoder stator 16 is mounted on a rear cover 12 by screws, which in turn is mounted on the right end face of motor housing 11 by screws. Encoder stator 16 maintains a small air gap with the rotating encoder outer rotor 15 and encoder inner rotor 17, forming two independent magnetoelectric encoders. Encoder stator 16 integrates the signal processing circuitry of both encoders.

[0035] To support and ensure motion accuracy, the module contains multiple bearings: Bearing 1 (2) and Bearing 2 (14). Bearing 1 (2): Its outer ring is mounted on the end (right end) of the wave generator in the harmonic reducer 5, and its inner ring mates with the guide shaft 4. It primarily supports the end of the wave generator and determines its relative position to the guide shaft 4. Bearing 2 (14): It is installed between the inner hole at the right end of the motor rotor shaft 8 and the outer side of the left end of the guide shaft 4. It provides an additional support point for the right end of the motor rotor shaft 8, forming a span support together with the bearing at the left end, greatly improving the rotational stiffness and motion accuracy of the motor rotor shaft 8 and reducing vibration and runout during high-speed rotation. Corresponding bearings are also provided for radial support at the connection between the guide shaft 4 and the steel wheel of the harmonic reducer 5, and between the motor rotor shaft 8 and the motor housing (not shown in detail in the figure).

[0036] The cable guide spool 4 is designed as a hollow structure, with its central through-hole serving as a centralized channel for the internal cables of the module (including the signal lines of the torque sensor 3, the motor power lines, the encoder signal lines, etc.). The cables are introduced from the module output end (left side), pass through the central hole of the cable guide spool 4, and exit from the right side of the module, connecting to the external driver 18. An O-ring seal 1 is installed at the interface between the cable guide spool 4 and the external device for dust and water protection.

[0037] The external driver 18 is the key difference between this solution and existing technologies. It is an independent electronic control unit connected to the motor stator 10 and encoder stator 16 terminals on the module body via a wiring harness (typically including a power cable and a communication cable). The external driver 18 receives position / velocity feedback signals from the dual magnetic ring encoder assembly and torque feedback signals from the torque sensor 3. Based on the motion commands from the host computer, it performs complex control algorithm calculations (such as position loop, velocity loop, current loop, and even impedance / admittance force control algorithms) to generate PWM drive signals to control the current in the motor stator 10 windings, thereby precisely driving the joint movement. The external driver 18 can be installed in a space with ample space and good heat dissipation, such as the robot base or torso, and is completely physically separated from the mechanical body of the joint module.

[0038] A high-performance multi-axis external driver 18 can simultaneously control multiple (e.g., 6 or more) such joint modules through multiple line harnesses, realizing centralized control and coordinated movement of multiple joints, which greatly simplifies the complexity of the robot's electrical system.

[0039] The working process of the externally driven robot force control joint module is as follows: After receiving the control command from the host computer, the external driver 18 outputs drive current to the stator 10 of the torque motor. The stator 10 generates a rotating magnetic field, driving the motor rotor 9 to rotate the motor rotor shaft 8. The motor rotor shaft 8 drives the wave generator of the harmonic reducer 5 to rotate. The wave generator causes the flexible wheel to undergo elastic deformation and mesh with the steel wheel to achieve speed reduction and torque increase. The steel wheel of the harmonic reducer 5 drives the torque sensor 3 and the guide shaft 4 to rotate synchronously, outputting torque. The dual magnetic ring encoder detects the operating parameters in real time: the encoder outer rotor 15 rotates with the motor rotor shaft 8 to detect the motor speed and position signals, and the encoder inner rotor 17 rotates with the guide shaft 4 to detect the position and speed signals at the module output end. These signals are transmitted to the external driver 18. The torque sensor 3 detects the torque signal of the end load in real time and transmits it to the external driver 18. The external driver 18... The received detection signals are processed and compared with the control commands from the host computer. The drive current output to the motor stator 10 is adjusted through a PID algorithm to achieve closed-loop control of the module output position, speed, and torque. When the module needs to brake, the external driver 18 cuts off the power supply to the brake, and the friction pads of the brake engage with the brake to achieve braking lock. When the drive components need to be repaired, the wiring harness connection between the external driver 18 and the module body can be directly disconnected, and a new external driver can be replaced. Example 2

[0040] A robot comprising at least one externally driven force-controlled joint module as described in Embodiment 1. The robot can be a humanoid robot, a collaborative robotic arm, an exoskeleton, or other automated device requiring precise force control and compact joints. Due to the use of the aforementioned joint module, the robot's joints are lighter and more compact, exhibiting excellent force control performance, and the overall electrical layout and maintenance convenience are significantly improved.

[0041] Although embodiments of the present invention have been shown and described above, it is understood that these embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and alterations to the above embodiments within the scope of the present invention without departing from its principles and spirit. The scope of protection of the present invention is defined by the claims and their equivalents.

Claims

1. An externally driven robot force-controlled joint module, characterized in that, Includes a harmonic reducer (5), a torque sensor (3), a brake, a torque motor, and a dual magnetic ring encoder assembly; The torque sensor (3) is mounted on the steel wheel of the harmonic reducer (5); The brake includes a brake stator (6) and a brake rotor (7), the brake stator (6) being mounted on the housing of the harmonic reducer (5); The torque motor includes a motor stator (10) and a motor rotor (9), and the motor rotor (9) is connected to the input shaft of the harmonic reducer (5) through a motor rotor shaft (8). The dual magnetic ring encoder assembly includes a first encoder assembly that measures the rotational speed and position of the motor rotor shaft (8), and a second encoder assembly that measures the rotational speed and position of the module output. It also includes an external driver (18) electrically connected to the stator (10) of the torque motor and the dual magnetic ring encoder assembly via a wiring harness, the external driver (18) being independent of the mechanical body of the module.

2. The externally driven robot force-controlled joint module according to claim 1, characterized in that, The torque sensor (3) is located on the side of the harmonic reducer (5) away from the torque motor and is directly fixed to the steel wheel end face of the harmonic reducer (5).

3. The externally driven robot force-controlled joint module according to claim 1, characterized in that, The dual magnetic ring encoder assembly also includes an encoder stator (16), a motor encoder rotor mount (13), an encoder outer rotor (15), and an encoder inner rotor (17). The motor encoder rotor seat (13) is fixed on the motor rotor shaft (8), and the encoder outer rotor (15) is mounted on the motor encoder rotor seat (13), forming the first encoder assembly; The inner rotor (17) of the encoder is mounted on the guide shaft (4), and the guide shaft (4) is connected to the steel wheel of the harmonic reducer (5) and is concentrically positioned to form the second encoder assembly; The encoder stator (16) is fixed on the rear cover (12), which is mounted on the motor housing (11). The encoder stator (16) is provided with sensing parts that correspond to the encoder outer rotor (15) and encoder inner rotor (17), respectively.

4. The externally driven robot force-controlled joint module according to claim 3, characterized in that, The cable guide (4) has a hollow structure, and the cable passes through the central hole of the cable guide (4) to exit the module.

5. The externally driven robot force-controlled joint module according to claim 3 or 4, characterized in that, It also includes a second bearing (14), which is disposed between the motor rotor shaft (8) and the wire guide shaft (4).

6. The externally driven robot force-controlled joint module according to claim 1, characterized in that, The brake rotor (7) is fixed to the motor rotor shaft (8) by screws.

7. The externally driven robot force-controlled joint module according to claim 1, characterized in that, The torque motor is an internal rotor torque motor. The motor stator (10) is fixed inside the motor housing (11), and the motor housing (11) is fixed on the housing of the harmonic reducer (5).

8. The externally driven robot force control joint module according to claim 3, characterized in that, The wave generator end of the harmonic reducer (5) is connected to the guide shaft (4) via a bearing (2), and the outer ring of the bearing (2) is installed at the wave generator end.

9. The externally driven robot force-controlled joint module according to any one of claims 1-8, characterized in that, One of the external drivers (18) is electrically connected to at least two of the robot force control joint modules via a wiring harness to independently or collaboratively control the at least two joint modules.

10. A robot, characterized in that, It includes at least one externally driven robot force-controlled joint module as described in any one of claims 1-9.

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