Multi-joint decoupling device of rope-driven dexterous hand

Abstract

The present application relates to the field of robot technology, and more particularly to a kind of multi-joint decoupling device of rope-driven dexterous hand.The technical scheme of the application is applied to tendon-driven multi-joint chain with multiple gear rolling joints, and the technical scheme of the application includes tendon guiding structure for guiding tendon to keep tangential contact with pitch circle of the gear rolling joint;The radius of the pitch circle of the multiple gear rolling joints satisfies geometric compensation relationship, so that when proximal joint angle changes, the length change of tendon caused by proximal pitch circle change is algebraically offset by the length change caused by distal pitch circle change.The present application realizes joint precise decoupling of motion and tension without increasing any special decoupling mechanism, significantly reduces position coupling degree;Through cartridge packaging and redundant sensing design, the practicality of the decoupling device can be quickly changed, monitored and prewarned, and the decoupling device also has chemical environment compatibility and multi-joint chain expansion capability.

Description

Technical Field

[0001] This invention relates to the field of robotics, and in particular to a multi-joint decoupling device for a rope-driven dexterous hand. Background Technology

[0002] Cable-driven multi-joint systems are widely used in dexterous manipulators, humanoid robots, and medical assistive devices. A typical structure involves multiple rotational joints (such as MCP, PIP, and DIP joints) driven by chords (steel wire or polymer fiber cords). The driving chords for distal joints must pass near or around the rotational axis of the proximal joint. When the proximal joint undergoes flexion and extension, the path length of the chords changes—for example, proximal joint flexion causes the chords to wrap around the joint surface for a distance, thus shortening the effective length of the chords from the actuator to the distal joint. This geometric effect leads to a fundamental problem: the actual length change of the chords, originally intended only to drive the distal joint, is affected by the movement of the proximal joint, resulting in undesirable passive movement of the distal joint, known as "path coupling." Simultaneously, because the chords are typically under high tension in the system to eliminate backlash, path coupling also causes tension disturbances between the chords: proximal joint movement increases the tension of one chord, while the tension of other chords crossing the same joint may decrease, forming "tension coupling." The two coupling effects mentioned above are intertwined, resulting in a strongly nonlinear and noncommutative mapping relationship between joint motion and tendon displacement.

[0003] The existence of path coupling and tension coupling poses a significant challenge to the control performance of tethered multi-joint systems. At the position control level, because the motion of the distal joint cannot be independent of the proximal joint, the system's kinematic model is no longer a simple diagonal matrix, but must incorporate complex coupling compensation terms. If the compensation is inaccurate, the position closed-loop accuracy will decrease significantly, with typical position coupling reaching 5% to 15%. At the force control and grasping stability level, tension coupling causes the actual driving torque acting on the distal joint to fluctuate with the proximal joint's pose, making it difficult to maintain the grasping force precisely. Especially in situations requiring delicate manipulation (such as grasping small objects, performing precise chemical experiments, or surgical suturing), the coupling effect can easily cause the object to slip or be damaged. To suppress the aforementioned coupling, existing technologies have proposed several solutions: differential pulley systems achieve displacement ratio cancellation through pulleys and beams with a 2:1 diameter ratio, but the beams occupy valuable space and are sensitive to assembly tolerances; parallel four-bar linkages force empirical coupling through four-bar linkages, but sacrifice independently controllable degrees of freedom; independent tension wheel schemes (such as the Shadow Hand) can partially alleviate tension disturbances, but introduce a large number of tensioning components, increasing the overall size of the device; and the N+1 method based on the pseudo-antisymmetric matrix allocation of tension space is highly dependent on the accuracy of friction modeling and lacks robustness under real working conditions. More importantly, most of the above solutions are permanently fixed structures. Once the tendon ligament breaks or the sensor fails, the entire hand is almost impossible to repair and can only be scrapped or returned to the factory for disassembly. Therefore, how to achieve joint decoupling of motion and tension using the joint's own geometry without adding a dedicated decoupling mechanism or sacrificing degrees of freedom, and to give the decoupling structure maintainability, has become a core technical problem that urgently needs to be solved in this field. Therefore, this application proposes a rope-driven dexterous hand multi-joint decoupling device. Summary of the Invention

[0004] The purpose of this invention is to address the problems existing in the background art by proposing a rope-driven dexterous hand multi-joint decoupling device.

[0005] The technical solution of the present invention: A rope-driven dexterous hand multi-joint decoupling device, applied in a tendon-wire transmission multi-joint chain with multiple gear rolling joints, the decoupling device comprising:

[0006] A tendon ligament guiding structure is used to guide the tendon ligament to maintain tangential contact with the pitch circle of the gear rolling joint;

[0007] The pitch circle radii of the multiple gear rolling joints satisfy a geometric compensation relationship, such that when the proximal joint angle changes, the length change of the tendon chord caused by the change of the proximal pitch circle is algebraically canceled out by the length change caused by the change of the distal pitch circle.

[0008] A detachable cartridge housing for accommodating the tendon ligament guiding structure, the cartridge housing being connected to the body via a detachable connection structure;

[0009] A redundant sensor group integrated within the cartridge housing, comprising at least one chord tension sensor and one angular displacement sensor, is used to monitor the tension of the chord and the joint angle in real time.

[0010] Optionally, the tendon guide structure is a tendon walkway extending along the pitch circle tangent of the gear rolling joint.

[0011] Optionally, the geometric compensation relationship is that the pitch circle radius of the proximal gear is equal to the pitch circle radius of the distal gear, i.e. .

[0012] Optionally, the geometric compensation relationship is: the ratio of the pitch circle radius of the proximal gear to the pitch circle radius of the distal gear is equal to their tooth ratio.

[0013] Optionally, the detachable connection structure includes an alignment pin and a torque limiting locking component. The assembly and disassembly torque of the cartridge housing is limited to ≤2 Nm, and the number of assembly and disassembly cycles is ≥1000. The diameter of the alignment pin is 1.5 mm, and the fit tolerance is ±0.05 mm.

[0014] Optionally, the cartridge housing has a chemically inert coating on its interior or surface, the coating being PTFE or DLC, which is resistant to organic solvents, acids and alkalis, and localized heat sources up to 80°C.

[0015] Optionally, the cartridge housing also integrates a miniature tensioning cam to automatically eliminate slack in the tendon ligaments after assembly.

[0016] Optionally, when the decoupling residual measured by the redundant sensor group exceeds a preset threshold, the decoupling device outputs an alarm signal to the control cerebellum, wherein the threshold does not exceed 5%.

[0017] Optionally, the tendon ligament guiding structure is integrally formed by SLA or SLM 3D printing with a machining tolerance of ±0.05 mm.

[0018] Optionally, the cartridge housing is covered with a PFA perfluoroalkoxyethylene film and is provided with a set of activated carbon vents.

[0019] Compared with the prior art, this application includes at least one of the following beneficial technical effects:

[0020] This invention utilizes the pure rolling geometry of the pitch circle of a gear rolling joint, and achieves joint decoupling of motion and tension through the routing of the tendon along the tangent of the pitch circle and the conjugate relationship of the pitch circle radius. It eliminates the need for additional differential pulleys, parallel four-bar linkages, or independent tensioning pulleys, thus saving space and not sacrificing joint degrees of freedom.

[0021] This invention ensures that the off-diagonal elements of the tendon-joint transfer matrix are always zero, theoretically resulting in zero coupling. Considering machining and assembly tolerances, the measured positional coupling can be controlled within 1%, which is significantly better than traditional solutions and greatly improves the positional closed-loop accuracy and grasping stability of multi-joint chains.

[0022] The decoupling device is encapsulated in a detachable cartridge housing, and quick assembly and disassembly are achieved through alignment pins and torque limiting locking components. It boasts a repeatability accuracy of ±0.05 mm and can withstand ≥1000 reassembly / disassembly cycles. In case of failure, disassembly is unnecessary, and the overall replacement time is ≤5 minutes, significantly reducing maintenance costs.

[0023] The cartridge integrates a chord tension sensor and an angular displacement sensor. The local microcontroller calculates the decoupling residual in real time, and automatically sends an alarm to the control cerebellum when the residual continuously exceeds a 5% threshold. This makes the decoupling state observable and diagnosable, supporting closed-loop compensation and fault early warning.

[0024] In summary, this invention achieves precise decoupling of motion and tension by utilizing the inherent geometric characteristics of gear rolling joints without the need for any additional dedicated decoupling mechanisms, significantly reducing positional coupling. Through cartridge-style packaging and redundant sensing design, the practicality of the decoupling device is improved, enabling quick replacement, monitoring, and early warning. It also possesses chemical environment compatibility and multi-joint chain expansion capabilities. Attached Figure Description

[0025] Figure 1 This is an overall appearance view of the decoupling device cartridge module;

[0026] Figure 2 This is a cross-sectional view of the cartridge module, labeled with the tendon chord walkway, tension cam, and redundant sensor.

[0027] Figure 3 A schematic diagram illustrating the principle of geometrically precise decoupling of the conjugate curve tendon cord of the pitch circle;

[0028] Figure 4 A comparison diagram of the tendon-chord-joint transmission matrix before and after decoupling;

[0029] Figure 5 Flowchart for "plug and play" maintenance of the cartridge module;

[0030] Figure 6 This is a schematic diagram of the interface between the decoupling device and the main body;

[0031] Figure 7 This is a block diagram of the redundant sensor circuit connection.

[0032] Figure label:

[0033] 1. Cartridge housing; 1a. Top cover; 1b. Base; 1c. Main body cavity;

[0034] 2. Alignment pin;

[0035] 3. Torque limiting locking component;

[0036] 10. Strains;

[0037] 11. MCP gears;

[0038] 12. PIP gears;

[0039] 13. Near the knuckle;

[0040] 14. The tendon ligament runs along the tangent of the joint circle;

[0041] 20. Miniature tensioning cam;

[0042] 30. Tendon chord tension sensor;

[0043] 40. Angular displacement sensor;

[0044] 50. Preprocessing circuit;

[0045] 60. Local microcontroller unit;

[0046] 70. Output interface;

[0047] 80. Control the cerebellum. Detailed Implementation

[0048] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0049] I. Overview of Overall Structure and Working Principle

[0050] This invention provides a rope-driven dexterous hand multi-joint decoupling device, applicable to a tendon-wire transmission multi-joint chain with multiple gear rolling joints. For example... Figure 1 As shown, the decoupling device is in the shape of a cartridge. The cartridge housing 1 is made of PEEK engineering plastic and is formed in one piece by SLA 3D printing. The overall size is 30 mm × 25 mm × 10 mm and the weight does not exceed 8 g. Figure 2 This is a cross-sectional view of the cartridge module, clearly showing the layout of the internal passageways, sensors, and tensioning mechanism. The core working principle of this invention can be divided into six sequential stages, with physical quantity transfer and state closed-loop feedback relationships between the preceding and following stages. These will be explained one by one below with reference to the accompanying drawings.

[0051] Step 1: Quick-change assembly process. For example... Figure 6 As shown, the cartridge housing 1 is repeatedly positioned by engaging with corresponding pin holes on the robot body using two 1.5 mm diameter alignment pins 2. The alignment pins 2 and pin holes adopt an H7 / g6 fit system with a tolerance of ±0.05 mm, ensuring consistent position after each installation. Then, an M2 torque limiting locking element 3 secures the cartridge housing 1 to the body. The tightening torque of this torque limiting locking element 3 is limited to below 2 Nm; in this embodiment, it is actually set to 1.5 Nm. This structure allows for at least 1000 repeated assembly and disassembly cycles without failure. When internal components of the cartridge malfunction or the tendon rope needs replacement, the operator does not need to disassemble the entire dexterous hand; simply loosen the torque limiting locking element 3, remove the old cartridge, insert the new cartridge, and re-lock it. The entire replacement process takes no more than 5 minutes, achieving "plug-and-play" maintenance.

[0052] Step Two: Threading and Threading the Tendon Cord. (For example...) Figure 3 As shown, each tendon cord 10, after being led out from the actuator, enters the cartridge housing 1 and runs along the tangential direction of the pitch circle of the MCP gear 11 and the PIP gear 12. A dedicated tendon cord channel is provided inside the cartridge, which is integrally machined by SLA or SLM 3D printing with a machining tolerance of ±0.05 mm. This channel precisely constrains the geometric position of the tendon cord 10, ensuring it maintains tangential contact with the gear pitch circle at all times. The inlet and outlet of the tendon cord 10 are marked with black dots for easy orientation identification during assembly.

[0053] Step 3: The principle of geometrically precise decoupling. For example... Figure 3 As shown, the pitch circle radius of the MCP gear 11 is denoted as... The pitch circle radius of PIP gear 12 is denoted as When the proximal joint, i.e., the MCP joint, flexes or extends at a small angle... At this time, the path length of the tendon ligament 10 along the tangent direction of the MCP joint circle will shorten due to the wrapping, and the amount of shortening is exactly equal to Multiply Meanwhile, due to the transmission characteristics of the rolling gear joint, the proximal interphalangeal joint 13 will drive the PIP gear 12 to produce a relative rotation. When the MCP joint rotates... At that time, the rotation angle of PIP gear 12 relative to the proximal phalanx 13 is also... (In the case of equal-diameter gears). Therefore, the path length of the tendon cord 10 along the tangent direction of the PIP pitch circle will extend by an amount equal to... Multiply This invention requires that the pitch circle radii of multiple gear rolling joints satisfy a geometric compensation relationship, that is, the ratio of the proximal pitch circle radius to the distal pitch circle radius is equal to their tooth ratio. In the case of equal-diameter gears, Therefore, the algebraic sum of the shortening and elongation is zero. This can be expressed as: This indicates that the total effective length of the tendon 10 does not change with the movement of the MCP joint, thus preventing undesirable passive movement of the distal joint (PIP joint). Figure 4 The changes in the tendon-joint transfer matrix before and after adopting this invention were compared: In the traditional scheme, the transfer matrix has a large number of off-diagonal elements, and the joint movements are coupled; while with the conjugate routing of the joint circle of this invention, the transfer matrix becomes a diagonal matrix, and the off-diagonal elements are always zero, and the joint movements are completely decoupled. Under the influence of actual machining and assembly tolerances, the positional coupling degree can be controlled within 1%, and theoretically it can approach zero.

[0054] Step Four: Sensing Monitoring and Decoupling Residual Feedback. To achieve real-time observability of the decoupling state, this invention integrates a redundant sensor array within the cartridge. For example... Figure 2 As shown, the sensor group includes a chord tension sensor 30 and an angular displacement sensor 40. The chord tension sensor 30 uses a strain gauge structure with an accuracy of 0.1% of full scale. The angular displacement sensor 40 uses a magnetic encoder with a 12-bit resolution and an accuracy of ±0.1°. The output signals of both types of sensors are first sent to the preprocessing circuit 50, such as... Figure 7 As shown. The preprocessing circuit 50 includes an instrumentation amplifier for amplifying weak signals, an anti-aliasing filter for eliminating high-frequency noise, and an analog-to-digital converter for digitizing the analog signal. The preprocessed signal is transmitted to the local microcontroller unit 60, which calculates the decoupling residual in real time. The definition of decoupling residual is: ,in To measure the change in the length of the tendon ligament, This is the initial length of the tendon ligament. When... When the threshold value continuously exceeds 5%, the local microcontroller unit 60 sends an alarm signal to the control cerebellum 80 via the output interface 70. The output interface 70 uses a 4-core shielded cable and a chemically sealed connector to ensure reliable signal transmission. Upon receiving the alarm, the control cerebellum 80 can pause fine-tuning operations and prompt for cartridge replacement.

[0055] Step 5: Chemical Protection. To withstand corrosive environments such as chemical experiments, this invention coats the inner walkway surface of the cartridge with a chemically inert coating. The coating material can be polytetrafluoroethylene (PTFE) or diamond-like carbon (DLC). The DLC coating has a thickness of 1 to 2 μm, a hardness of not less than 20 Gpa, and superior corrosion resistance compared to the PTFE coating. Simultaneously, the outer surface of the cartridge housing 1 is also covered with a PFA perfluoroalkoxyethylene film, which is resistant to almost all common organic solvents and acids / alkalis. Furthermore, as... Figure 2As shown, the cartridge housing 1 is equipped with a set of activated carbon vents, which can actively discharge any chemical vapors that may be generated during operation. These protective measures enable the device to operate stably for extended periods in an 80°C localized heat source environment.

[0056] Step Six: Multi-Joint Chain Extension. The decoupling principle of this invention is not only applicable to two-joint chains, but can also be extended to three- or more-level joint chains. For example, for a three-level MCP-PIP-DIP chain, as long as the ratio of the radii of each joint circle satisfies... ,in For the corresponding number of teeth on a gear, the coupling degree of the entire kinematic chain is always zero, regardless of the number of joints. This characteristic allows the same cartridge module design to be reused for dexterous hands with different degrees of freedom, including the 5-DOF chain of the thumb. Specific Implementation

[0057] Example 1: Basic Geometric Decoupling (Equal Diameter Gears)

[0058] This embodiment corresponds to Figures 1 to 4 , Figure 6 The structure is shown. The cartridge housing 1 is made of PEEK engineering plastic and is formed in one piece by SLA 3D printing. The overall dimensions are 30 mm × 25 mm × 10 mm, and the weight does not exceed 8 g. Figure 3 As shown, the pitch circle radius of MCP gear 11 The pitch circle radius of PIP gear 12 is 8 mm. Also 8 mm, the two are equal. The tendon 10 runs along line 14 in the direction of the pitch circle tangent of the two gears. When the MCP joint is flexed at an angle... At that time, the shortening of the tendon 10 at the MCP gear 11 was Simultaneously, due to the counter-rotation of the proximal phalanx 13 relative to the PIP gear 12, the extension of the tendon chord 10 at the PIP gear 12 is also... The two cancel each other out, and the PIP joint position remains unchanged.

[0059] like Figure 2 As shown, a miniature tensioning cam 20 is also integrated inside the cartridge housing 1. This miniature tensioning cam 20 rotates automatically after the cartridge is assembled, eliminating the slack in the tendon chord 10 caused by long-term use, without the need for manual calibration. A tendon chord tension sensor 30 is attached to the path of the tendon chord 10 to monitor the tension value in real time; an angular displacement sensor 40 is installed at the shaft of the PIP gear 12 to monitor the distal joint angle in real time. Figure 6 As shown, the cartridge housing 1 is positioned against the main body by two 1.5 mm diameter alignment pins 2, and then secured by an M2 torque-limiting locking element 3, with a torque limit of 1.5 Nm. When the cartridge needs to be replaced, as... Figure 5As shown, the operator performs the following steps in sequence: First, the decoupling residual is detected to exceed the threshold; second, the old cartridge is removed; third, a new cartridge is inserted; fourth, the system automatically calibrates; fifth, operation resumes. The entire process takes no more than 5 minutes.

[0060] Example 2: Conjugate Relationship under Non-Equal Diameter Gear Combinations

[0061] The main difference between this embodiment and Embodiment 1 is that the pitch circle radii of MCP gear 11 and PIP gear 12 are not equal. Specifically, let the pitch circle radius of MCP gear 11 be... The pitch circle radius of PIP gear 12 is 10 mm. A pitch circle radius of 6 mm corresponds to a gear ratio of 10:6, or 5:3. In this case, the geometric compensation relationship requires the ratio of pitch circle radii to the gear ratio. When the MCP joint rotates... At that time, the shortening of the tendon ligament 10 at the proximal end was Since the gear ratio is 5:3, the rotation angle of the PIP joint is... The extension of chord 10 distally along the PIP joint circle tangent is equal to... Multiply by the rotation angle of the PIP joint, i.e. The shortening and elongation remain equal, canceling each other out algebraically. Therefore, even with non-equal diameter gear combinations, as long as the above proportional relationship is satisfied, the decoupling effect is exactly the same as in Example 1. This embodiment is applicable to scenarios where different sized gears must be used due to structural space constraints.

[0062] Example 3: Enhanced version of chemical experiment scenario

[0063] This embodiment adds specific protective measures against chemically corrosive environments based on Embodiment 1. First, in addition to the original PEEK material, the outer surface of the cartridge housing 1 is further coated with a layer of PFA (perfluoroalkoxyethylene) film. This film is resistant to almost all common chemical reagents, including concentrated sulfuric acid, concentrated nitric acid, hydrofluoric acid, acetone, toluene, etc. Second, the surface of the tendon tether walkway inside the cartridge does not use a conventional PTFE coating, but rather a diamond-like carbon (DLC) coating. This coating has a thickness of 1 to 2 micrometers, a hardness of not less than 20 GPa, and its corrosion resistance and wear resistance are superior to those of PTFE coatings. Third, as... Figure 2 As shown, the cartridge housing 1 is provided with a set of activated carbon vents. The vents are equipped with an activated carbon filter layer, which can actively adsorb and discharge any chemical vapors that may be generated during the operation of the dexterous hand, preventing corrosive gases from accumulating inside the cartridge. The other structures in this embodiment are the same as in Embodiment 1.

[0064] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A rope-driven dexterous hand multi-joint decoupling device, applied in a tendon-wire transmission multi-joint chain with multiple gear rolling joints, characterized in that, The decoupling device includes: A tendon ligament guiding structure is used to guide the tendon ligament (10) to maintain tangential contact with the pitch circle of the gear rolling joint; The pitch circle radii of multiple gear rolling joints satisfy the geometric compensation relationship, so that when the proximal joint angle changes, the length change of the tendon cord (10) caused by the change of the proximal pitch circle is algebraically canceled by the length change caused by the change of the distal pitch circle. A detachable cartridge housing (1) is provided for accommodating the tendon cord guiding structure, and the cartridge housing (1) is connected to the body via a detachable connection structure; A redundant sensor group is integrated within the cartridge housing (1), the redundant sensor group including at least one tendon tension sensor (30) and one angular displacement sensor (40) for real-time monitoring of the tension and joint angle of the tendon (10).

2. The rope-driven dexterous hand multi-joint decoupling device according to claim 1, characterized in that, The tendon ligament guiding structure is a tendon ligament walkway extending along the pitch circle tangent direction of the gear rolling joint.

3. The rope-driven dexterous hand multi-joint decoupling device according to claim 1, characterized in that, The geometric compensation relationship is as follows: the pitch circle radius of the proximal gear is equal to the pitch circle radius of the distal gear, that is... .

4. The rope-driven dexterous hand multi-joint decoupling device according to claim 1, characterized in that, The geometric compensation relationship is as follows: the ratio of the pitch circle radius of the proximal gear to the pitch circle radius of the distal gear is equal to their tooth ratio.

5. The rope-driven dexterous hand multi-joint decoupling device according to claim 1, characterized in that, The detachable connection structure includes a positioning pin (2) and a torque limiting locking element (3). The mounting and dismounting torque of the cartridge housing (1) is limited to ≤2 Nm, and it can be mounted and dismounted ≥1000 times. The diameter of the positioning pin (2) is 1.5 mm, and the fit tolerance is ±0.05 mm.

6. The rope-driven dexterous hand multi-joint decoupling device according to claim 1, characterized in that, The cartridge housing (1) has a chemically inert coating on its interior or surface, the coating being PTFE or DLC.

7. The rope-driven dexterous hand multi-joint decoupling device according to claim 1, characterized in that, The cartridge housing (1) also integrates a micro tensioning cam (20) for automatically eliminating the slack of the tendon cord (10) after assembly.

8. The rope-driven dexterous hand multi-joint decoupling device according to claim 1, characterized in that, When the decoupling residual measured by the redundant sensor group exceeds a preset threshold, the decoupling device outputs an alarm signal to the control cerebellum (80), and the threshold does not exceed 5%.

9. The rope-driven dexterous hand multi-joint decoupling device according to claim 1, characterized in that, The tendon tractor guide structure is integrally formed by SLA or SLM 3D printing with a machining tolerance of ±0.05 mm.

10. The rope-driven dexterous hand multi-joint decoupling device according to claim 1, characterized in that, The cartridge housing (1) is covered with a PFA perfluoroalkoxyethylene film and is provided with a set of activated carbon ventilation and exhaust ports.

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