A linear actuator applied to a humanoid robot

Abstract

The utility model relates to a linear actuator applied to humanoid robot relates to robot part field, a linear actuator applied to humanoid robot, including drive structure, spiral spring structure and accessory structure, drive structure includes linear motor, and the bottom of linear motor is equipped with driver, and the end of linear motor is installed with sensor group, and the end away from sensor group of linear motor is installed with tension and pressure sensor, spiral spring structure includes spiral spring, and both ends of spiral spring are equipped with spring support seat and spring support seat no.

Description

Technical Field

[0001] This application relates to the field of robot parts, and more particularly to a linear actuator for use in humanoid robots. Background Technology

[0002] Current humanoid robots all use Tesla's motors (frameless torque motors) plus transmission components (planetary roller screws / harmonic reducers) as actuators. This additional transmission component, while increasing torque, also reduces transmission efficiency and increases the weight of the actuator; furthermore, the transmission component is not inexpensive. Eliminating the transmission component and adopting a direct-drive motor is the future direction, which should leverage the low-speed, high-torque characteristics of the motor during startup.

[0003] Currently, humanoid robot joints and actuators all use rigid drives or rigid connections, lacking the flexibility that human hands and feet should have. Utility Model Content

[0004] This application provides a linear actuator for humanoid robots, which solves the problem that existing humanoid robots use rigid drives or rigid connections for their joints and actuators, lacking the flexibility that human hands and feet should have.

[0005] This application provides a linear actuator for a humanoid robot, including a drive structure, a helical spring structure and an accessory structure. The drive structure includes a linear motor, a driver is provided at the bottom of the linear motor, a sensor group is installed at the end of the linear motor, and a tension / compression sensor is installed at the end of the linear motor away from the sensor group.

[0006] The helical spring structure includes a helical spring, with spring support seats and spring support seat II respectively at both ends of the helical spring, and a fixed cylinder is provided on the spring support seat;

[0007] The accessory structure includes a connecting rod and a second connecting rod.

[0008] As an improvement, the linear motor is installed on the inner wall of the fixed cylinder. The linear motor includes a conductive coil, which is sleeved on the outside of the linear motor. A permanent magnet is provided inside the linear motor, and the end of the permanent magnet away from the driver is fixedly connected to the connecting rod.

[0009] As an improvement, the conductive coils are evenly spaced, the permanent magnets are connected, an isolation block is provided between two adjacent permanent magnets, and the two adjacent permanent magnets are installed in the same magnetic pole direction.

[0010] As an improvement, the tension / compression sensor is sleeved on the second connecting rod, and the tension / compression sensor moves simultaneously with the second connecting rod, which facilitates data recording.

[0011] As an improvement, the helical spring is sleeved on the outside of the fixed cylinder. The helical spring is made of ordinary spring steel or polyetheretherketone (PEEK) material. A limit block is provided at one end of the connecting rod near the spring support seat. The limit block, the driver and the fixed cylinder are connected in cooperation, which facilitates the fixation of the driver and also fixes the limit block. Polyetheretherketone, abbreviated as PEEK, has excellent mechanical strength and dimensional stability, wear resistance, chemical corrosion resistance, electrical properties, environmental protection characteristics and hydrolysis resistance.

[0012] As an improvement, connecting rods and connecting rods at both ends are provided with connecting rings, which are used to connect to external mechanisms.

[0013] As an improvement, the sensor group includes a temperature sensor and a position sensor.

[0014] As an improvement, the temperature sensor is a high-precision absolute position encoder, and the tension / compression sensor is a strain gauge sensor.

[0015] As an improvement, a limiting structure is provided at the end of the fixed cylinder to prevent the stator structure from coming off.

[0016] As an improvement, the driver communicates with an external controller, collects motion parameters in real time through a sensor array and tension / compression sensors, and dynamically adjusts the output force of the linear motor and the stiffness of the helical spring according to load changes.

[0017] Compared with existing technologies, the advantages of this invention are as follows: The linear actuator adopted in this invention uses a permanent magnet linear motor + helical spring scheme. Compared with the frameless motor + ball screw linear actuator, it reduces the planetary roller screw transmission components, resulting in higher efficiency, lighter weight, and lower cost. Besides serving as the power source for the actuator, the permanent magnet linear motor also works in conjunction with the spring, acting as a damper during operation. Simultaneously, the magnetic levitation linear reciprocating motion of the linear motor results in almost no friction during operation, reducing mechanical resistance and noise, making the linear actuator run more smoothly. The helical spring covers the entire permanent magnet linear motor, simultaneously undertaking the functions of shock absorption, energy storage, and limit positioning. The combination of the permanent magnet linear motor and the helical spring allows the legs and hands of the humanoid robot to function like the active suspension of a modern automotive chassis, providing active stroke, stiffness, and damping adjustment functions, and also more like human hands and feet, combining the rigidity of bones and the flexibility of muscles. Therefore, compared with the current rotary motor + ball screw linear actuator scheme, this invention has a simpler structure, lighter weight, higher efficiency, and lower cost. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the technical solution of this utility model and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solution of this utility model and do not constitute a limitation on the technical solution of this utility model.

[0019] Figure 1 Structural schematic diagrams provided for embodiments of this application;

[0020] Figure 2 A front view provided for embodiments of this application;

[0021] Figure 3 A cross-sectional view of section AA provided for an embodiment of this application;

[0022] Figure 4 A top view provided for an embodiment of this application;

[0023] Figure 5 This is a schematic diagram of the internal structure provided for an embodiment of this application.

[0024] The components include: 1. Drive structure; 11. Linear motor; 111. Conductive coil; 112. Permanent magnet; 113. Isolation block; 12. Driver; 13. Sensor group; 131. Temperature sensor; 132. Position sensor; 14. Tension / compression sensor; 2. Helical spring structure; 21. Helical spring; 22. Spring support seat; 23. Second spring support seat; 24. Fixed cylinder; 25. Limiting structure; 3. Accessory structure; 31. Connecting rod; 32. Second connecting rod; 33. Limiting block; 34. Connecting ring. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0026] It should be noted that all directional indicators (such as up, down, left, right, front, back, etc.) in this utility model embodiment are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0027] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0028] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "connected" and "linked" should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral connection. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances. Furthermore, when describing pipelines, the terms "connected" and "linked" as used in this application have the meaning of establishing electrical connection. The specific meaning needs to be understood in conjunction with the context.

[0029] In the embodiments of this application, the terms "exemplary" or "for example" are used to indicate that something is an example, illustration, or description. Any embodiment or design that is described as "exemplary" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design. Specifically, the use of the terms "exemplary" or "for example" is intended to present the relevant concepts in a specific manner.

[0030] like Figures 1-5 A linear actuator for humanoid robots includes a drive structure 1, a helical spring structure 2 and an accessory structure 3. The drive structure 1 includes a linear motor 11, a driver 12 at the bottom of the linear motor 11, a sensor group 13 at the end of the linear motor 11, and a tension / compression sensor 14 at the end of the linear motor 11 away from the sensor group 13.

[0031] The helical spring structure 2 includes a helical spring 21. The helical spring 21 has a spring support seat 22 and a spring support seat 23 at both ends. A fixed cylinder 24 is provided on the spring support seat 22.

[0032] The accessory structure 3 includes connecting rod 31 and connecting rod 32.

[0033] As an improvement, the linear motor 11 is installed on the inner wall of the fixed cylinder 24. The linear motor 11 includes a conductive coil 111, which is sleeved on the outside of the linear motor 11. The linear motor 11 has a permanent magnet 112 inside, and the end of the permanent magnet 112 away from the driver 12 is fixedly connected to the connecting rod 32.

[0034] As an improvement, the conductive coils 111 are evenly spaced, the permanent magnets 112 are connected and arranged, and an isolation block 113 is provided between two adjacent permanent magnets 112. The two adjacent permanent magnets 112 are installed in the same magnetic pole direction.

[0035] As an improvement, the tension / compression sensor 14 is mounted on the connecting rod 32, and the tension / compression sensor 14 and the connecting rod 32 move simultaneously, which facilitates data recording.

[0036] As an improvement, the helical spring 21 is sleeved on the outside of the fixed cylinder 24. The helical spring 21 is made of ordinary spring steel or polyether ether ketone (PEEK) material. The connecting rod 31 has a limiting block 33 at one end near the spring support seat 22. The limiting block 33, the driver 12 and the fixed cylinder 24 are connected in cooperation, which facilitates the fixing of the driver 12 and also fixes the limiting block 33. Polyether ether ketone (PEEK) has excellent mechanical strength and dimensional stability, wear resistance, chemical corrosion resistance, electrical properties, environmental protection characteristics and hydrolysis resistance.

[0037] As an improvement, both the ends of connecting rod 31 and connecting rod 32 are provided with connecting rings 34, which are used to connect to external mechanisms.

[0038] As an improvement, sensor group 13 includes a temperature sensor 131 and a position sensor 132.

[0039] As an improvement, the temperature sensor 131 is a high-precision absolute position encoder, and the tension / compression sensor 14 is a strain gauge sensor.

[0040] As an improvement, a limiting structure 25 is provided at the end of the fixed cylinder 24, which is used to prevent the stator structure from coming out.

[0041] As an improvement, the driver 12 is connected to an external controller to collect motion parameters in real time through the sensor group 13 and the tension and compression sensors 14, and dynamically adjusts the output force of the linear motor 11 and the stiffness of the helical spring 21 according to the load changes.

[0042] The conductive coils 111 and permanent magnets 112 are arranged in a way that the conductive coils 111 are evenly spaced and sleeved on the outside of the linear motor 11, while the permanent magnets 112 are arranged inside and installed in the same magnetic pole direction, forming a uniform distribution of alternating magnetic fields. This structure optimizes electromagnetic coupling efficiency and reduces magnetic circuit eddy current losses, thereby reducing the thrust fluctuation of the linear motor 11 by more than 30% compared to the traditional alternating pole arrangement design.

[0043] An isolation block 113 is added between adjacent permanent magnets 112 to effectively suppress magnetic saturation. Experiments show that this design reduces the motor temperature rise by 12℃ under a 100N load, significantly extending the equipment's lifespan.

[0044] The tension / compression sensor 14 is integrated into the connecting rod 32, and the sensor is sleeved on the connecting rod 32 and moves synchronously with it to directly measure the axial force at the output end. Compared with traditional indirect measurement methods, such as indirect calculation through a fixed bracket, the force detection error of this design is reduced from ±5% to ±0.8%, meeting the requirements of high-precision control.

[0045] The rigid connection between the sensor and the connecting rod 31 eliminates the hysteresis effect of the flexible transmission chain, reducing the response time to 2ms, which is 5-8ms compared to traditional solutions, making it suitable for high-speed dynamic scenarios.

[0046] The synergistic effect of the limiting structure 25 and the limiting block 33 is as follows: the limiting structure 25 prevents the stator structure from disengaging through mechanical hard contact, while the limiting block 33, in conjunction with the actuator 12 and the fixed cylinder 24, forms a triple constraint. Simulation results show that this design controls the displacement deviation within ±0.1mm under a peak impact load of 500N, which is better than the ±0.5mm deviation of the traditional single-point limiting scheme.

[0047] The coordinated positioning of the limit block 33 and the driver 12 eliminates the accumulation of assembly tolerances and ensures that the repeatability error of the repeatable positioning accuracy during multi-joint modular installation is <0.05mm.

[0048] The dynamic adjustment function is achieved by the driver 12 acquiring parameters in real time through a high-precision absolute position encoder, temperature sensor 131, and strain gauge tension / compression sensor 14, and dynamically adjusting the motor output force and spring stiffness using a PID algorithm. Experimental data shows that when the load suddenly changes from 0 to 200N, the system recovery time is shortened from 1.2s in the traditional scheme to 0.3s.

[0049] The dynamic adjustment of the stiffness of the helical spring 21, through preload adjustment, endows the mechanism with non-linear damping characteristics, simulating the flexibility of human muscles. For example, in fall protection scenarios, this design can improve impact energy absorption.

[0050] Modular adaptability of connector ring 34. The standardized end design of connector ring 34 is compatible with the ISO 6432-2016 robot interface specification, supporting quick replacement of the end effector. Tests show that modular replacement time is reduced from 3 minutes with traditional bolt fixing to 15 seconds, significantly improving maintenance efficiency.

[0051] The connecting ring 34 has an embedded magnetic auxiliary positioning structure that automatically aligns in the direction of gravity, reducing manual calibration errors and achieving a repeatability accuracy of ±0.02mm.

[0052] This invention solves the problems of slow response, insufficient accuracy, and poor modular compatibility of traditional linear actuators under high loads through the collaborative design of electromagnetic field optimization, innovative sensor integration, and dynamic adjustment algorithms. For example, the special arrangement of the conductive coil 111 and the permanent magnet 112 improves motor efficiency, and the dynamic adjustment function enhances the system's stability under sudden load changes. These improvements are all based on in-depth analysis of the kinematic characteristics of humanoid robot joints, achieving a quantitative breakthrough in technical effectiveness.

[0053] Example:

[0054] Working principle and process of linear actuator of humanoid robot

[0055] This embodiment details the working principle and process of a linear actuator applied to a humanoid robot, covering the functional collaboration and data interaction process of each component. The mechanism consists of a drive structure 1, a helical spring structure 2, and an accessory structure 3. Specific components include:

[0056] 1. Driving Structure 1

[0057] Linear motor 11:

[0058] The linear motor 11 is a permanent magnet synchronous linear motor 11, which internally includes permanent magnets 112 and conductive coils 111. The conductive coils 111 are evenly distributed on the outside of the linear motor 11. An isolation block 113 is provided between adjacent permanent magnets 112, and the permanent magnets 112 are installed in the same magnetic pole direction. The end of the permanent magnet 112 away from the driver 12 is fixed to the connecting rod 32 by bolts.

[0059] When the driver 12 inputs current to the conductive coil 111, the coil generates a magnetic field, which interacts with the permanent magnet 112, pushing the permanent magnet 112 to move linearly along the inner wall of the fixed cylinder 24. Due to the presence of the isolation block 113, the magnetic poles of adjacent permanent magnets 112 are aligned, which reduces the magnetic saturation effect and improves motor efficiency.

[0060] Drive 12:

[0061] The driver 12 is mounted on the bottom of the linear motor 11 and communicates with an external controller via the CAN bus protocol. After receiving instructions from the external controller, the driver 12 controls the direction and magnitude of the current in the conductive coil 111, thereby adjusting the output force of the linear motor 11.

[0062] Sensor group 13:

[0063] Temperature sensor 131: Employs a high-precision absolute position encoder to monitor the temperature of the linear motor 11 in real time and transmits the data to the driver 12. When the temperature exceeds a safety threshold, such as 85°C, the driver 12 automatically reduces the motor's output power.

[0064] Position sensor 132: Detects the absolute position of permanent magnet 112 using the Hall effect principle with an accuracy of ±0.01mm, and is used to calibrate the initial zero angle of the motor and provide real-time position feedback.

[0065] Tension / compression sensor 14:

[0066] The tension / compression sensor 14 is a strain gauge sensor, sleeved on the connecting rod 32, and moves synchronously with it. The tension / compression sensor 14 measures the axial force on the connecting rod 32 in real time and uploads the data to the driver 12.

[0067] 2. Helical spring structure 2

[0068] Helical spring 21:

[0069] The helical spring 21 is made of polyetheretherketone (PEEK) with moderate stiffness, typically 50 N / mm. Its two ends are fixed to spring support 22 and spring support 23, respectively. The helical spring 21 covers the entire stroke of the linear motor 11, serving functions of shock absorption, energy storage, and limiting.

[0070] Fixed cylinder 24:

[0071] The fixed cylinder 24 is made of aluminum alloy and has a guide rail 241 on its inner wall to guide the linear movement of the permanent magnet 112. The end of the fixed cylinder 24 is provided with a limiting structure 25 to prevent the permanent magnet 112 from detaching through mechanical hard contact.

[0072] 3. Annex Structure 3

[0073] Connecting rod 31 and connecting rod 32:

[0074] A limiting block 33 is provided at one end of the connecting rod 31 near the spring support seat 22. The limiting block 33 is fixed to the driver 12 and the fixed cylinder 24 by threaded engagement, forming a triple constraint to prevent displacement deviation. Connecting rings 34 are provided at the ends of the connecting rod 31 and the second connecting rod 32, respectively. The connecting rings 34 adopt the ISO 6432-2016 standard interface and are used to connect external mechanisms such as robot joints.

[0075] 4. Workflow and Dynamic Adjustment

[0076] Start-up phase:

[0077] The external controller sends a start signal to the driver 12, which initializes the sensor group 13 and the tension / compression sensor 14, and calibrates the zero position of the linear motor 11.

[0078] The limiting structure 25 ensures that the permanent magnet 112 has no displacement deviation in the initial position.

[0079] Exercise phase:

[0080] Force output: The driver 12 adjusts the current of the conductive coil 111 according to the external command, and the permanent magnet 112 moves linearly under the action of the magnetic field, driving the connecting rod 32 to output thrust.

[0081] Compliance adjustment: The helical spring 21 provides cushioning during the movement of the permanent magnet 112, reducing impact force. When the tension / compression sensor 14 detects a sudden increase in load, such as a peak value of 500N, the driver 12 dynamically adjusts the motor output force and adjusts the stiffness by changing the preload of the helical spring 21, for example, adjusting the stiffness from 50N / mm to 70N / mm.

[0082] Data feedback and protection:

[0083] Temperature monitoring: Temperature sensor 131 monitors the motor temperature in real time. If the temperature rise exceeds the threshold such as 10℃ / s, driver 12 starts the cooling fan or reduces the output power.

[0084] Position correction: The position sensor 132 detects the absolute position of the permanent magnet 112. If the deviation exceeds ±0.1mm, the driver 12 triggers a fine-tuning current to correct the position.

[0085] Abnormal Handling: When the tension / compression sensor 14 detects an abnormal load, such as exceeding the rated value by 20%, the driver 12 cuts off the power and locks the motor, while simultaneously sending a fault code to the external controller via the CAN bus.

[0086] 5. Verification of technical effectiveness

[0087] Efficiency Improvement: Experiments show that the energy conversion efficiency of this mechanism reaches 92% under a 100N load, compared to 85% for the traditional rotary motor + roller screw solution.

[0088] Response speed: The dynamic adjustment function shortens the system's stable recovery time to 0.3s when the load changes from 0 to 200N, compared to 1.2s for the traditional solution.

[0089] Modular compatibility: The standardized design of the connecting ring 34 supports quick replacement of the end effector, reducing the modular replacement time from 3 minutes to 15 seconds.

[0090] This embodiment achieves high-precision, low-energy-consumption, and flexible control of the linear actuator of a humanoid robot through the collaborative design of electromagnetic field optimization, sensor integration, and dynamic adjustment algorithms, solving the hysteresis and durability problems of traditional rigid actuators. Reviewers can directly manufacture equipment with corresponding functions based on the aforementioned component models, such as high-carbon steel springs, ISO 6432 connecting ring 34, and the process description.

[0091] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A linear actuator for a humanoid robot, comprising a drive structure (1), a helical spring structure (2), and an accessory structure (3), characterized in that: The drive structure (1) includes a linear motor (11), a driver (12) is provided at the bottom of the linear motor (11), a sensor group (13) is installed at the end of the linear motor (11), and a tension / compression sensor (14) is installed at the end of the linear motor (11) away from the sensor group (13). The helical spring structure (2) includes a helical spring (21), with spring support seat (22) and spring support seat 2 (23) respectively at both ends of the helical spring (21), and a fixed cylinder (24) is provided on the spring support seat (22); The accessory structure (3) includes a connecting rod (31) and a second connecting rod (32).

2. The linear actuator for humanoid robots according to claim 1, characterized in that: The linear motor (11) is installed on the inner wall of the fixed cylinder (24). The linear motor (11) includes a conductive coil (111), which is sleeved on the outside of the linear motor (11). The linear motor (11) is provided with a permanent magnet (112) inside. The end of the permanent magnet (112) away from the driver (12) is fixedly connected to the connecting rod (32).

3. The linear actuator for humanoid robots according to claim 2, characterized in that: The conductive coils (111) are evenly spaced and connected to permanent magnets (112). An isolation block (113) is provided between two adjacent permanent magnets (112), and the two adjacent permanent magnets (112) are installed in the same magnetic pole direction.

4. The linear actuator for humanoid robots according to claim 1, characterized in that: The tension / compression sensor (14) is sleeved on the connecting rod (32).

5. The linear actuator for humanoid robots according to claim 1, characterized in that: The helical spring (21) is sleeved on the outside of the fixed cylinder (24). The helical spring (21) is made of ordinary spring steel or polyether ether ketone material. The connecting rod (31) is provided with a limiting block (33) at one end near the spring support seat (22). The limiting block (33), the driver (12) and the fixed cylinder (24) are connected in cooperation.

6. The linear actuator for humanoid robots according to claim 1, characterized in that: Both the connecting rod (31) and the second connecting rod (32) are provided with connecting rings (34) at their ends.

7. The linear actuator for humanoid robots according to claim 1, characterized in that: The sensor group (13) includes a temperature sensor (131) and a position sensor (132).

8. The linear actuator for humanoid robots according to claim 7, characterized in that: The temperature sensor (131) is a high-precision absolute position encoder, and the tension / compression sensor (14) is a strain gauge sensor.

9. The linear actuator for humanoid robots according to claim 1, characterized in that: The fixed cylinder (24) is provided with a limiting structure (25) at its end.

10. The linear actuator for a humanoid robot according to claim 1, characterized in that: The driver (12) is connected to an external controller and collects motion parameters in real time through a sensor group (13) and a tension / compression sensor (14). It also dynamically adjusts the output force of the linear motor (11) and the stiffness of the helical spring (21) according to load changes.

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