Single-sided contact tendon tension sensor, measurement method and robot

Abstract

The present application relates to a single-side contact tendon tension sensor, a measuring method and a robot, and belongs to the technical field of robot sensors. Three micro rollers are configured to allow the measured tendon to contact in sequence from the same side. When the tendon becomes thin, all contact points sink in the same direction and with the same amplitude, so that the effective deflection distance and the wrap angle remain constant. The influence of tendon aging on tension measurement accuracy is eliminated by using the geometric self-compensation principle. In addition, the single-side contact configuration and the preset offset are used to make the tendon only deflect in one direction when passing through the force roller, thereby generating the required force wrap angle. This completely avoids the harmful reverse bending of the tendon, effectively reduces the internal wear of the tendon in the limited micro space, and prolongs the service life of the tendon.

Description

Technical Field

[0001] This invention relates to a single-sided contact tendon chord tension sensor, a measurement method, and a robot, belonging to the field of robot sensor technology. Background Technology

[0002] Tendon-driven robots are the core actuators for achieving dexterous grasping and precise manipulation, especially in humanoid dexterous hands. Each finger joint typically transmits tension from a remote motor via flexible tendon cords. To achieve precise force control of the robot's joints, tension sensors need to be integrated into the tendon cord path to measure the tension of the tendon cord in real time.

[0003] Currently, most mainstream chord tension sensors employ an S-shaped winding structure, where the chord being measured alternately wraps around multiple rollers on opposite sides in an S-shaped path. (See [reference]). Figure 12 Regarding the accompanying drawings of the prior art, the tension of the tendon ligament is calculated by detecting the normal pressure generated on the intermediate roller. However, this existing S-shaped winding tension sensor has the following drawbacks in practical miniaturization applications: Firstly, in the S-shaped winding structure, the tendon cord contacts different rollers from different sides, i.e., opposite-side contact. When the tendon cord wears down and thins due to long-term cyclic bending, the contact points between the tendon cord and the two side rollers and the middle force-measuring roller will experience opposite displacements, i.e., anti-parallel displacements. This reverse displacement leads to a reduction in the effective deflection distance of the tendon cord, which in turn changes the wrap angle of the tendon cord on the roller, ultimately resulting in a significant change in the measured normal force. This structure has an error amplification effect; even a slight reduction in the diameter of the tendon cord can introduce measurement errors far exceeding the lower limit of robot force control accuracy. This causes the sensor to be unable to maintain stable measurement accuracy throughout the entire lifespan of the tendon cord, and the measurement accuracy is highly susceptible to the wear and aging of the tendon cord, resulting in severe measurement drift.

[0004] Secondly, the available space inside the robot's finger joint is extremely limited. In order to complete bidirectional reverse bending in a very small space, the S-shaped winding structure has to use a small bending radius. This reverse bending in a limited space will significantly aggravate the mutual wear and heat accumulation between the fibers inside the tendon cord, causing damage to the tendon cord inside that has no obvious damage to the outer layer, and shortening the service life of the tendon cord.

[0005] Furthermore, in traditional mechanical transmission designs (such as cranes or elevators), to prevent fatigue fracture of steel wire ropes or flexible tendon ropes, the ratio of roller diameter to tendon rope diameter (D / d ratio) is typically required to be strictly greater than 8:1. However, in micro-tendon-driven robots (such as humanoid dexterous hands), the extremely limited joint space often forces designers to use micro-bearings with extremely small diameters (resulting in a D / d ratio generally lower than 8:1, even as low as 2:1). According to traditional theory, this violation of the D / d limit would cause the tendon rope to rapidly heat up and wear under the intense stretching of the outer fibers and the compression of the inner fibers. Existing micro-tension sensors have failed to adequately address this localized fatigue problem caused by microscopic size constraints at the macroscopic level of geometric topology, leading to significant hysteresis and breakage risks during long-term dynamic operation.

[0006] Therefore, finding a suitable tendon tension sensor is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] To address the shortcomings of the prior art, the present invention aims to provide a single-sided contact tendon chord tension sensor, a measurement method, and a robot.

[0008] According to an embodiment of the present invention, the first embodiment is provided as follows: a single-sided contact tendon tension sensor, comprising a sensor body, an elastic element, a strain measuring element, and at least three miniature rollers; The sensor body includes a rigid region, and the elastic element is supported in the rigid region and has the degree of freedom to deform under force. The at least three miniature rollers are mounted on the sensor body and the elastic element, and the at least three miniature rollers include two limiting guide rollers on both sides and one force measuring roller in the middle; The limiting guide roller is rotatably connected to the rigid area of ​​the sensor body, and the force measuring roller is rotatably connected to the elastic element; The tendon contact surface of the force measuring roller has a preset offset relative to the common tangent of the tendon contact surfaces of the two limiting guide rollers. The at least three miniature rollers are configured to allow the tendon to be tested to contact and pass through sequentially from the same side, and the preset offset causes the tendon to generate a wrap angle on the force measuring roller. When the tendon cord is subjected to tendon cord tension, the wrap angle causes the tendon cord to generate a positive pressure on the force measuring roller, and the slight deformation of the elastic element caused by the positive pressure is detected by the strain measuring element.

[0009] Furthermore, the at least three miniature rollers also include two additional limiting rollers, which are respectively disposed on the side of the two limiting guide rollers away from the force measuring roller, and each additional limiting roller and the adjacent limiting guide roller together form an in-line guide group. The inlet and outlet guide group is configured to forcibly constrain the tangential angle of the tendon cord entering and exiting the single-sided contact tendon cord tension sensor, so that when the tendon cord swings spatially or changes its stretching direction outside the single-sided contact tendon cord tension sensor, the tendon cord still maintains contact on the same side on the at least three micro rollers inside, and the wrap angle and the direction of the positive pressure generated by the tendon cord on the force measuring roller remain constant.

[0010] Furthermore, a connection root is provided between the elastic element and the rigid region of the sensor body, and the strain measuring element is arranged at the connection root; The connection root is configured such that when the force-measuring roller transmits the positive pressure to the elastic element, the connection root generates a local maximum strain. The elastic element is an independent component and is fixedly connected to the rigid region to form the connection root; Alternatively, the elastic element and the sensor body are integrally formed monolithic structures, and the elastic element is a cantilever structure formed by opening a U-shaped groove in the monolithic structure. The connection root is a strain concentration area where the cantilever structure is connected to the rigid area.

[0011] Furthermore, each of the at least three miniature rollers has a miniature bearing embedded inside; The limiting guide roller and the force measuring roller are rotatably connected to the rigid region and the elastic element respectively through the miniature bearing, so as to convert the sliding friction generated when the tested tendon rope moves into rolling friction.

[0012] Furthermore, each of the at least three miniature rollers has an annular anti-detachment guide groove on its tendon contact surface to accommodate the tendon being tested; The preset offset is the vertical distance between the bottom surface of the annular anti-detachment guide groove of the force measuring roller and the common tangent line between the bottom surfaces of the annular anti-detachment guide grooves of the two limiting guide rollers.

[0013] Furthermore, the ratio of the groove bottom diameter of the at least three micro rollers to the initial nominal diameter of the tested tendon cord is configured to be between 2:1 and 8:1; The tested tendon cord defines a geometric circumcircle at the midpoint of the three contact arcs on at least three miniature rollers. The geometric circumcircle has a circumcircle diameter that is larger than the groove bottom diameter of the force measuring roller.

[0014] Furthermore, there is a proportional coordination configuration between the outer circle diameter and the groove bottom diameter of the force measuring roller, and the ratio of the outer circle diameter to the groove bottom diameter of the force measuring roller is configured to be greater than 10.

[0015] Furthermore, the ratio of the circumscribed circle diameter to the groove bottom diameter of the force-measuring roller is configured as follows: When the diameter of the groove bottom is small due to the limited micro-space, the actual wrap angle of the tested tendon rope on the force measuring roller is compressed by increasing the diameter of the outer circle, thereby reducing the accumulation of micro-local bending stress and internal fiber friction caused by macro-normal pressure and achieving mechanical self-compensation.

[0016] Furthermore, the force centerline of the tested tendon rope forms an effective vertical distance between the force measuring roller and the limiting guide roller, and the preset offset is configured such that the effective vertical distance is less than or equal to the initial nominal diameter of the tested tendon rope.

[0017] Furthermore, it also includes an integrated data processing module, which is electrically connected to the strain measurement element and is used to condition and digitize the minute deformation signal output by the strain measurement element to output the final tension measurement signal.

[0018] According to an embodiment of the present invention, utilizing the single-sided contact chord tension sensor in the first embodiment, a second embodiment is provided: a chord tension measurement method, comprising the steps of: A single-sided contact chordae tension sensor is provided. The single-sided contact chordae tension sensor includes at least three miniature rollers, an elastic element, and a strain measuring element. The at least three miniature rollers include two limiting guide rollers and one force measuring roller. The chordae contact surface of the force measuring roller has a preset offset relative to the common tangent of the chordae contact surfaces of the two limiting guide rollers. The tendon rope being tested is made to pass over the at least three miniature rollers in sequence from the same side. The preset offset is used to make the tendon rope wrap around the force measuring rollers and form an effective vertical distance between the force center lines of the tendon rope. When the tendon cord is subjected to tendon cord tension, the constraint of the wrap angle causes the tendon cord to generate a positive pressure on the force measuring roller. The elastic element undergoes a slight deformation due to the positive pressure, and the strain measuring element detects the slight deformation and outputs a tension measurement signal. When the tendon cord becomes thinner due to cyclic wear, the tendon cord is kept in contact with the force measuring roller and the two adjacent limiting guide rollers on the same side. This causes the center line of the tendon cord to sink radially in the same direction and with equal amplitude. This radial sinking keeps the wrap angle and the effective vertical distance constant, thereby offsetting the tension measurement signal error introduced by the thinning of the diameter.

[0019] Furthermore, the number of the at least three miniature rollers is five, and it also includes two additional limiting rollers disposed on the outer side; During the passage of the tested tendon cord through the single-sided contact tendon cord tension sensor, the entry and exit guide group, consisting of two additional limiting rollers and adjacent limiting guide rollers, forcibly constrains the tangential angle of the tendon cord entering and exiting the single-sided contact tendon cord tension sensor. This ensures that when the tendon cord experiences spatial oscillation or changes in its stretching direction outside the single-sided contact tendon cord tension sensor, the tendon cord remains in contact on the same side of the at least three micro rollers inside, and the wrap angle and the direction of the positive pressure generated by the tendon cord on the force measuring roller remain constant.

[0020] Furthermore, the method also includes the following steps: when the tested tendon rope is under a known tension value, record the measurement signal output by the strain measurement element and establish a tension-signal calibration curve. The single-sided contact tendon rope tension sensor also includes an integrated data processing module, and the tension-signal calibration curve serves as the reference for the integrated data processing module to perform signal conversion.

[0021] According to an embodiment of the present invention, utilizing the unilateral contact tendon chord tension sensor in the first embodiment of the present invention, a third embodiment is provided: a tendon-driven robot, including a robot hand, at least one tendon chord, and a unilateral contact tendon chord tension sensor as described in any one of the first embodiments, wherein the unilateral contact tendon chord tension sensor is installed on the tendon chord path of the robot hand for measuring the tendon chord tension.

[0022] Compared with the prior art, the beneficial effects of the independent claims of the technical solution provided in this application are as follows: By configuring three miniature rollers for the tested tendon cord to sequentially contact and pass through from the same side, as the tendon cord becomes thinner, all contact points experience parallel settlement in the same direction and with equal amplitude, thereby keeping the effective deflection distance and wrap angle constant. The geometric self-compensation principle eliminates the influence of tendon cord aging on the accuracy of tension measurement. Furthermore, by utilizing a unilateral contact configuration and a preset offset, the tendon cord only undergoes unidirectional deflection when passing through the force-measuring rollers to generate the required force wrap angle, completely avoiding reverse bending, which is extremely detrimental to the tendon cord's lifespan. This effectively reduces internal wear of the tendon cord within a confined miniature space, extending its service life. Attached Figure Description

[0023] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] in: Figure 1 This is a front cross-sectional view of the three-roller single-sided contact tendon tension sensor in an embodiment of the present invention; Figure 2 This is a front view of the three-roller single-sided contact tendon tension sensor in an embodiment of the present invention; Figure 3 This is a perspective view of a three-roller single-sided contact tendon tension sensor with an integrated data processing module in an embodiment of the present invention. Figure 4 This is a front cross-sectional view of the five-roller single-sided contact tendon tension sensor in an embodiment of the present invention. Figure 5 This is a front view of the five-roller single-sided contact tendon tension sensor in an embodiment of the present invention; Figure 6 This is a perspective view of a five-roller single-sided contact tendon tension sensor with an integrated data processing module in an embodiment of the present invention. Figure 7 This is a schematic diagram illustrating the principle of the tendon rope generating a wrap angle θ of less than 180 degrees after passing through the force measuring roller in an embodiment of the present invention; Figure 8 This is a geometric diagram illustrating the preset offset H of the three miniature roller tendon rope contact surfaces in an embodiment of the present invention. Figure 9 In this embodiment of the invention, the vertical distance H between the center of the force-measuring roller shaft and the center of the limiting guide roller shaft is... center Geometric schematic diagram; Figure 10 The force centerline and effective vertical distance H of the tendon cord in this embodiment of the invention are shown. eff Geometric schematic diagram; Figure 11 This is a schematic diagram illustrating the principle of the bottom of the anti-detachment guide groove and the geometric circumcircle in an embodiment of the present invention; Figure 12 A schematic diagram illustrating the wear state and wrap angle variation of tendon chords in existing bidirectional contact structures. Figure 13 This is a schematic flowchart of the tendon ligament tension measurement method in an embodiment of the present invention.

[0025] Figure label: 1. Sensor body; 2. Limiting guide roller; 3. Force measuring roller; 4. Tendon rope; 5. Elastic element; 6. Strain measuring element; 7. U-groove; 8. Additional limiting roller; 9. Integrated data processing module; X, rigid region; Y, elastic region; Q, bottom of annular anti-detachment guide groove. Detailed Implementation

[0026] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the 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.

[0027] To more clearly illustrate the geometric relationships, force model, and geometric self-compensation mechanism for eliminating tendon aging measurement drift in the single-sided contact configuration of this invention, standard terminology and mathematical symbols used herein are introduced before detailed descriptions of specific embodiments. Table 1 below uniformly specifies the symbols, standard terms, and their corresponding physical meanings and notes involved in the subsequent derivation of principles and explanations of structures in the embodiments.

[0028]

[0029] Table 1 Example 1 In the existing S-shaped winding structure, see Figure 12 Regarding the wear state and wrap angle change principle of the tendon cord in the existing bidirectional contact structure, the tendon cord alternately wraps around the rollers from different sides. When the tendon cord wears thinner due to long-term cyclic work, its contact points on the two side rollers and the middle roller will undergo opposite displacements, resulting in changes in the effective deflection distance and wrap angle, thus leading to measurement errors. Furthermore, the existing S-shaped winding structure causes the tendon cord to bend in opposite directions within a very small sensor space, accelerating the mutual wear and heat accumulation between the fibers inside the tendon cord. When the tendon cord wears thinner, d1 wears into d2, where d1 > d2.

[0030] See Figure 1 , Figure 2 and Figure 3 As shown, this embodiment provides a single-sided contact tendon chord tension sensor, including a sensor body 1, an elastic element 5, a strain measuring element 6, and at least three miniature rollers; The sensor body 1 includes a rigid region X, and the elastic element 5 is supported on the rigid region X and has the degree of freedom to deform under force. The at least three miniature rollers are mounted on the sensor body 1 and the elastic element 5. The at least three miniature rollers include two limiting guide rollers 2 located on both sides and a force measuring roller 3 located in the middle. The limiting guide roller 2 is rotatably connected to the rigid region X of the sensor body 1, and the force measuring roller 3 is rotatably connected to the elastic element 5; The tendon contact surface of the force measuring roller 3 has a preset offset relative to the common tangent of the tendon contact surfaces of the two limiting guide rollers 2. The at least three micro rollers are configured to allow the tendon 4 to be tested to contact and pass through from the same side in sequence, and the preset offset causes the tendon 4 to generate a wrap angle on the force measuring roller 3. When the tendon cord 4 is subjected to tendon cord tension, the wrap angle causes the tendon cord 4 to generate a positive pressure on the force measuring roller 3, and the slight deformation of the elastic element 5 caused by the positive pressure is detected by the strain measuring element 6.

[0031] It should be noted that the single-sided contact tendon cord in this embodiment is mainly based on geometric deflection force measurement and micro-strain detection. The tendon cord 4 under test enters from one side of the sensor and contacts the outer surfaces of the two end limiting guide rollers 2 and the middle force measuring roller 3 in sequence. Since the middle force measuring roller 3 has a preset offset H relative to the two end limiting guide rollers 2, the tendon cord 4 is forced to produce a unidirectional inverted V-shaped deflection in this area. According to the force composition, the axial tension inside the tendon cord 4 will be converted into an inward positive pressure on the force measuring roller 3 through the inverted V-shaped deflection. This positive pressure is transmitted to the elastic element 5 that supports the force measuring roller 3, forcing the elastic element 5 to undergo a very small deformation. This small deformation is sensed by the strain measuring element 6 attached to or integrated on the elastic element 5. For example, the strain measuring element 6 can be a strain gauge or a piezoresistive sensor, and it is converted into an electrical signal. Finally, the real-time tension value of the tendon cord 4 is calculated through the calibration relationship.

[0032] It should be noted that in all embodiments shown in the accompanying drawings of this application, the tendon cord 4 being tested passes over the same upper side of the three miniature rollers, with the middle force-measuring roller 3 protruding upwards, and the tendon cord 4 exhibiting an inverted V-shape (i.e., ∧-shaped) unidirectional deflection. It should also be noted that the unilateral contact in this application does not limit the tendon cord 4 to being located above or below the rollers. When the assembly orientation is reversed, the shape of the tendon cord 4 may be V-shaped, but its unidirectional deflection geometry remains unchanged.

[0033] Specifically, the sensor body 1 uses a rigid material as its mounting and support base. A limiting guide roller 2 is located in the rigid region X of the sensor body 1. An elastic region Y is located in the middle of the sensor body 1, constituting the elastic element 5. The elastic element 5 has the freedom of deformation under force and proportionally converts the force on the force-measuring roller 3 into strain. The strain measuring element 6 is responsible for converting the physical deformation into a processable electrical signal. Three miniature rollers are provided: two limiting guide rollers 2 and one force-measuring roller 3. The tendon cord 4 passes through the same side of the three miniature rollers. Using a miniature roller structure instead of a fixed contact pin ensures that the tendon cord 4 maintains rolling friction with an extremely low equivalent coefficient of friction between it and the sensor, extending the service life of the tendon cord 4. Furthermore, the tendon cord 4's contact from the same side means that it only undergoes unidirectional deflection within a limited space, avoiding the reverse bending that occurs in traditional S-shaped winding structures where the tendon cord 4 needs to pass from one side to the other. This embodiment adopts a single-sided structure. When the tendon rope 4 wears and thins due to long-term cyclic bending work, since the tendon rope 4 always contacts the three rollers from the same side, its contact points on the three rollers will undergo parallel displacements with the same direction and equal amplitude. The effective vertical distance H between the middle force-measuring roller 3 and the two side limiting guide rollers 2... eff By keeping the diameter constant, the parameter changes caused by the reduction in the diameter of the tendon cord are offset, so that under the assumption of ideal rigidity, the tension measurement error introduced by the change in the diameter of the tendon cord is geometrically canceled out and thus negligible in engineering.

[0034] According to the single-sided contact chord tension sensor provided in this embodiment, three miniature rollers are configured for the chord 4 to be measured to sequentially contact and pass through from the same side. As the chord 4 becomes thinner, all contact points experience parallel settlement in the same direction and with equal amplitude, thereby keeping the effective deflection distance and wrap angle constant. The geometric self-compensation principle is used to eliminate the influence of chord 4 aging on the tension measurement accuracy. In addition, this embodiment utilizes the single-sided contact configuration and a preset offset H to ensure that the chord 4 only undergoes unidirectional deflection when passing through the force-measuring roller 3 to generate the required force wrap angle, completely avoiding reverse bending, which is extremely detrimental to the lifespan of the chord 4. This effectively reduces the internal wear of the chord 4 within the confined miniature space and extends the service life of the chord 4.

[0035] To further clarify the physical and geometric mechanism by which this embodiment overcomes the bottleneck of the prior art from a theoretical perspective, the following mathematical arguments demonstrate the measurement error inevitably introduced by the existing S-shaped unbalanced winding structure due to the thinning of the tendon cord 4, and the mathematical principle of the single-sided same-side contact configuration of this application to achieve accurate self-compensation of error.

[0036] Regarding the basic principles, for ease of mathematical derivation, the following parameter variables are preset: the horizontal distance between the centers of the two limit guide rollers 2 is... The horizontal spacing on one side is The vertical distance between the center axis of the middle force-measuring roller 3 and the two side limiting guide rollers 2 is The radius of the three miniature rollers is 1. The real-time diameter of the tendon 4 is For the sake of brevity, this section uses the example of three miniature rollers with the same radius R; however, it should be noted that the geometric self-compensation principle of this application does not depend on whether the radii of the three miniature rollers are equal, as detailed in the generalized derivation in the "About this application" section below.

[0037] Normal force on force measuring roller 3 With tendon tension The basic mechanical conversion relationships between them are as follows:

[0038] in, The effective vertical distance between the tendon rope 4 and the contact point between the limiting guide roller 2 and the force measuring roller 3 is defined as follows:

[0039] In the above formula, L is the horizontal distance between the axes of the limiting guide roller 2 and the force measuring roller 3. Strictly speaking, the horizontal distance between the contact point between the tendon rope 4 and the roller will be slightly smaller than L due to the existence of the roller radius R, but in H... center In the engineering implementation of L (i.e., the deflection angle α is small), this difference is a second-order small quantity and has little impact. This derivation uses L as a first-order approximation of the horizontal distance between contact points. The conclusions obtained below (especially ΔH) eff The geometric self-compensation relation of ≡0 still holds under strict geometry, because the conclusion depends only on Y. side With Y center The synchronous settlement is independent of the specific value of the horizontal distance.

[0040] Among them, the small angle approximation sinα≈tanα is in the case of α<15° (corresponding to H). eff The relative error introduced within the miniaturized geometric range of / L<0.27) is less than 1%, which is acceptable in engineering. If α exceeds this range, F=2T·sinα should be used directly for accurate conversion.

[0041] Regarding existing technology In a traditional S-shaped winding structure, the tendon cord alternately passes over the rollers at both ends and under the roller in the middle, i.e., making contact on opposite sides. When the tendon cord wears down due to hundreds of thousands of high-frequency cycles, its effective diameter decreases uniformly. When the diameter of the tendon ligament decreases, the contact points on both rollers move downwards. The contact point on the intermediate force-measuring roller 3 moves upward. This antiparallel displacement caused by opposite-sided contact results in the reduction of the effective vertical spacing being directly superimposed:

[0042] At this point, the relative measurement error of the positive pressure is:

[0043] Absolute value analysis error amplification factor :

[0044] Conclusion: In the extremely small sensor space of a robot's dexterous hand, in order to reduce sensor thickness, the effective vertical spacing... They are often compressed to the extreme, and their value is usually less than or close to the diameter of the tendon itself. At this point, the error amplification factor... Under miniaturization constraints, the S-shaped winding structure has an inherent first-order error amplification effect. For every 1% reduction in the diameter of the tendon cord, at least 1% of force measurement error will inevitably be introduced, resulting in serious measurement drift.

[0045] Regarding this application See Figure 7 , Figure 8 , Figure 9 and Figure 10 As shown, Figure 7 This diagram only illustrates the geometric relationship between the local wrap angle θ and deflection angle α of the tendon rope 4 on the force measuring roller 3. For the constraint effect of the two side limiting guide rollers 2, please refer to [the diagram / reference needed]. Figures 8 to 10 In the single-sided contact configuration of this embodiment, the tendon cords all pass through the same side of the three miniature rollers. At this time, with the horizontal line where the miniature roller axis is located as a reference, the absolute positions of each contact point in the vertical direction are as follows: Height of the contact point at both ends of the guide rollers:

[0046] Contact point height at point 3 of the intermediate force-measuring roller:

[0047] in, As the reference height, To limit the height of the contact point, This is for measuring the height of the force contact point.

[0048] At this point, the effective vertical distance between the two contact points and the middle contact point of the tendon ligament force centerline is:

[0049] When the ligament 4 becomes thinner due to long-term wear and tear At that time, because the tendon 4 always maintains contact with the three rollers on the same side, the contact points on the three rollers all move downwards with the same amplitude. Parallel displacement.

[0050] Therefore, the minute change in the effective vertical spacing after wear is:

[0051] Therefore, the relative measurement error of the normal force is:

[0052] Conclusion: The above mathematical deduction proves that, in the unilateral configuration of this application, the diameter of the tendon cord is... This dynamic variable geometric compensation offsets the effective deflection height. It depends only on the physical and mechanical dimensions fixed by the high-rigidity sensor body 1. Therefore, even if the diameter of the tendon cord 4 is significantly reduced due to wear, as long as it does not detach from the guide groove, the deflection angle of the tendon cord 4 will not change. Under the assumption of ideal rigidity, the tension measurement error introduced by the change in the diameter of the tendon cord is geometrically canceled out, and thus can be ignored in engineering. This embodiment achieves geometric self-compensation, avoiding the aging drift problem of miniature tension sensors.

[0053] The above derivation assumes that the radii of the three miniature rollers are all R. In a more general case, let the radii of the two limiting guide rollers 2 be R and R', respectively. s1 and R s2 The radius of the intermediate force-measuring roller 3 is R. c Furthermore, the three may not be equal.

[0054] Taking the axis of any one of the two limiting guide rollers 2 as a reference, the radial positions of the force center lines of the tendon rope 4 at the three rollers relative to the axis of their respective rollers are as follows: At the two limit guide rollers on both sides: r side1 =R s1 +d / 2, r side2 =R s2 +d / 2 At the middle force-measuring roller 3: r center =R c +d / 2 When the tendon 4 wears down, its diameter decreases from d to d. When Δd is reached, the radial position of each contact point relative to its respective roller axis decreases synchronously by Δd / 2: Δr side1 =Δr side2 =Δr center = Δd / 2 Since the axial positions of the three rollers are fixed and unchanged by the rigid area of ​​the sensor body 1, and the tendon cord 4 always contacts the three rollers from the same side, the radial displacement Δd / 2 occurs synchronously in the same direction. This is equivalent to the entire force centerline of the tendon cord 4 being translated parallel to the same direction as a geometric whole by Δd / 2. This parallel translation does not change the relative geometric relationship between any two points on the path of the tendon cord 4, i.e., the deflection angle α and the effective vertical distance H. eff All remain unchanged.

[0055] Therefore, the geometric self-compensation principle of this application is independent of whether the radii of the three miniature rollers are equal. Any configuration in which all three miniature rollers maintain contact with the tested tendon rope 4 on the same side falls within the protection scope of this application.

[0056] Example 2 This embodiment provides a further technical solution based on Embodiment 1.

[0057] See Figure 4 and Figure 5 As shown, in this embodiment, the at least three miniature rollers further include two additional limiting rollers 8. The two additional limiting rollers 8 are respectively disposed on the side of the two limiting guide rollers 2 away from the force measuring roller 3, and each additional limiting roller 8 together with the adjacent limiting guide roller 2 constitutes the inlet and outlet guide group. The inlet and outlet guide group is configured to forcibly constrain the tangential angle of the tendon cord 4 entering and exiting the single-sided contact tendon cord tension sensor, so that when the tendon cord 4 undergoes spatial swing or changes in stretching direction outside the single-sided contact tendon cord tension sensor, the tendon cord 4 still maintains contact on the same side on the at least three micro rollers inside, and the wrap angle and the direction of the positive force generated by the tendon cord 4 on the force measuring roller 3 remain constant.

[0058] It should be noted that this embodiment expands upon the three-roller single-sided contact configuration, forming a five-roller single-sided tension sensor arrangement with two pairs of limiting rollers and one force-measuring roller 3. Multi-point constraints are used to isolate the internal force environment. Specifically, an additional limiting roller 8 is added to the outer side of each of the two end limiting guide rollers 2. The outer additional limiting rollers 8 are paired with the adjacent inner limiting guide rollers 2, forming an in-line / out-line guide group. When the tendon cord 4 passes through this in-line / out-line guide group sequentially, its tangent angles entering and exiting the sensor's force-measuring area are locked, creating a geometrically constrained force isolation zone inside the sensor. For example, when the robot's finger joints perform complex actions such as grasping or bending, the tendon cord 4 may swing vertically or horizontally outside the sensor, or its stretching direction may change. Due to the constraint of the in-line / out-line guide group, these external path disturbances are completely blocked outside the additional limiting rollers 8. The incident angle and travel path of the tendon rope 4 after entering the sensor are still restricted to a fixed geometric tangent, thus ensuring that its interaction with the intermediate force measuring roller 3 is not affected by the external environment.

[0059] It should be noted that the core geometric self-compensation drift-reduction mechanism of this invention relies solely on the three core rollers (i.e., one force-measuring roller 3 and two limiting guide rollers 2) within the measurement area maintaining unilateral contact with the tendon ligament 4 being measured. The two additional limiting rollers 8 added on the outer side serve purely as guides and limiters, used to establish stable boundary conditions and lock the geometric tangent of the tendon ligament 4 into the measurement area.

[0060] In practical engineering applications, the tendon cord 4 can even pass through the opposite side of the measurement area when passing the additional limiting roller 8 (i.e., forming a local physical clamp at the inlet and outlet guide group). Such structural changes, size adjustments, or roller spacing adjustments outside the measurement area will not negatively affect the force measurement accuracy as long as the incident and exit tangents are firmly locked and the tendon cord 4 maintains contact on the same side on the three core force measuring rollers inside. Even if the outer rollers wear out or the tendon cord 4 becomes thinner, the wrap angle of the middle force measuring roller 3 remains constant because the three contact points in the main measurement area still experience parallel settlement in the same direction and with equal amplitude. Therefore, the five-roller configuration of this embodiment cleverly isolates external resistance to spatial disturbances from internal high-precision self-compensating measurement mechanically.

[0061] Specifically, the overall dimensions of the three-roller solution are approximately 11mm × 4mm × 5mm, while the overall dimensions of the five-roller solution are approximately 15mm × 4mm × 5mm.

[0062] In this embodiment, the elastic element 5 and the rigid region X of the sensor body 1 have a connection root, and the strain measuring element 6 is arranged at the connection root; The connection root is configured such that when the force measuring roller 3 transmits the positive pressure to the elastic element 5, the connection root generates a local maximum strain. The elastic element 5 is an independent component and is fixedly connected to the rigid region X to form the connection root; Alternatively, the elastic element 5 and the sensor body 1 are integrally formed monolithic structures, and the elastic element 5 is a cantilever structure formed by opening a U-shaped groove 7 on the monolithic structure. The connection root is a strain concentration area where the cantilever structure is connected to the rigid region X.

[0063] It should be noted that the strain concentration effect is used to amplify and sense minute normal pressure. When the tendon 4 generates normal pressure on the force-measuring roller 3, this force is transmitted along the axis of the force-measuring roller 3 to the elastic element 5 below. Since one end of the elastic element 5 is suspended under force, and the other end is connected to the rigid region X of the sensor body 1 to form a connection root, this constitutes a typical bending cantilever beam structure. In this force model, the root, as the supporting end of the moment, will undergo the most severe material deformation under the bending moment caused by the normal pressure, thus generating the maximum local strain (i.e., the strain concentration area). By precisely arranging strain measuring elements 6, such as strain gauges or piezoresistive sensors, at this connection root, the mechanical deformation signal with the largest amplitude can be directly captured and converted into an electrical signal output.

[0064] In terms of configuration, firstly, the sensor body 1 adopts an assembly type, with the elastic element 5 being an independent component, fixed to the rigid body by mechanical fastening or welding, and the mating surface is the connection root. Secondly, the sensor body 1 adopts an integral molding structure, with a U-shaped groove 7 cut out inside the whole piece of high-rigidity material. The existence of the U-shaped groove 7 naturally isolates an elastic region Y of the cantilever structure. The elastic element 5 is set on the elastic region Y. The thin-walled transition area connecting this cantilever structure with the ungrooved rigid body constitutes the connection root that generates local strain.

[0065] In this embodiment, each of the at least three miniature rollers has a miniature bearing embedded inside; The limiting guide roller 2 and the force measuring roller 3 are respectively rotatably connected to the rigid region X and the elastic element 5 through the miniature bearing, so as to convert the sliding friction generated when the tested tendon 4 moves into rolling friction.

[0066] It should be noted that this embodiment, by embedding miniature bearings inside the rollers, transforms sliding contact into rolling friction with an equivalent friction coefficient of extremely low (typically 0.001–0.005). This ensures that the total cumulative friction loss of the tendon cord 4 as it passes through the three miniature rollers is strictly controlled to within 1%, thereby guaranteeing that the tension from the remote motor can be efficiently and without damage transmitted to the robot's distal finger joints without affecting transmission efficiency. By converting the contact method to rolling friction, the miniature rollers can rotate synchronously with the axial movement of the tendon cord 4, eliminating surface cutting and scratching caused by relative sliding. This protects the outer structure of the miniature synthetic fiber tendon cord 4 and significantly extends its overall service life under complex dynamic conditions.

[0067] In this embodiment, an annular anti-detachment guide groove is provided on the tendon contact surface of the at least three miniature rollers to accommodate the tendon 4 being tested; The preset offset H is the vertical distance between the bottom surface of the annular anti-detachment guide groove of the force measuring roller 3 and the common tangent line between the bottom surfaces of the annular anti-detachment guide grooves of the two limiting guide rollers 2.

[0068] Specifically, in this embodiment, refer to Figure 11 As shown, the bottom Q of the annular anti-detachment guide groove refers to the circumference of the smallest radius point in the annular groove opened on the contact surface of the miniature roller tendon rope. The miniature roller is either the limiting guide roller 2 or the force-measuring roller 3. The groove bottom diameter refers to the diameter of the circumference of the groove bottom, which is twice the distance from the roller's rotation axis to the circumference of the groove bottom. The surface where the groove bottom is located refers to a cylindrical surface with the roller's rotation axis as its axis and half the groove bottom diameter as its radius. When the tendon rope 4 being tested is embedded in the annular anti-detachment guide groove, its force center line extends along the generatrix of the groove bottom circumference, meaning the actual contact point between the tendon rope 4 being tested and the roller is located on the circumference of the groove bottom.

[0069] It should be noted that this embodiment further constrains the spatial state of the tendon 4 inside the sensor. An annular guide groove is formed on the tendon 4 contact surface of the micro roller. When the tendon 4 is embedded in the groove, its degree of freedom along the roller axis is restricted. The tendon 4 can only move along the arc trajectory at the bottom of the groove, and is limited to a preset offset H. For example, in the highly dynamic grasping operation of a robot's dexterous hand, joint movements are often accompanied by violent shaking and transient relaxation of the tendon 4. The annular anti-detachment guide groove can restrict the tendon 4 under these extreme conditions, preventing it from slipping off the side of the roller and derailing, thereby ensuring the extremely high working reliability of the sensor in complex three-dimensional motion environments and preventing the tendon 4 from falling off.

[0070] In this embodiment, the ratio of the groove bottom diameter of the at least three micro rollers to the initial nominal diameter of the tested tendon rope 4 is configured to be between 2:1 and 8:1.

[0071] It should be noted that this embodiment breaks through the conventional understanding that traditional mechanical transmission must rely on large-diameter rollers (i.e., the ratio of groove bottom diameter to tendon diameter D / d > 8:1) to extend tendon life. Addressing the extreme spatial constraints of microrobots (e.g., the use of micro-bearings forcing the D / d ratio to drop to between 2:1 and 8:1), this application creatively introduces a collaborative compensation mechanism between the "macro-geometric circumcircle" and the "micro-local groove bottom diameter".

[0072] Specifically, the tendon rope 4 being tested passes through three actual contact points in sequence: the two side limiting guide rollers 2 and the middle force measuring roller 3. These three points geometrically uniquely define a circumcircle, the diameter of which is defined as D. circum Traditional fatigue wear analysis often focuses only on the local maximum bending strain caused by the microscopic groove bottom diameter D. However, this embodiment reveals that due to the configuration of a very large circumscribed circle diameter D... circum (That is, the overall path presents a shallow V-shape with a large obtuse angle), which greatly compresses the actual contact angle θ of the tested tendon rope 4 on the intermediate force measuring roller 3. This proportionally coordinated configuration of "large circumscribed circle and small groove bottom" (D circum A ratio of / D greater than 10 results in two significant technical effects: First, positive macroeconomic pressure and D circum Inversely proportional, a large circumscribed circle diameter significantly reduces the radial load on the tendon cord clamping micro roller, thereby greatly reducing rolling friction and measurement hysteresis of the system and improving the transparency of force control; Secondly, the tiny actual contact wrap angle results in an extremely short high-stress contact arc length of the tendon chord on the roller. Although the small local D / d ratio leads to high instantaneous bending stress, the minimal normal pressure and weak contact area prevent this stress from being converted into severe internal fiber frictional heat generation within sufficient physical space. In other words, the large macroscopic circumcircle curvature effectively dilutes and compensates for the local strain loss caused by the microscopically small roller. This allows the micro-sensor of this application to obtain sufficient tension deformation signals within a limited volume while simultaneously solving the bottleneck problems of tendon chord wear and lifespan.

[0073] Example 3 This embodiment provides a further technical solution based on Embodiment 1 or Embodiment 2.

[0074] In this embodiment, the force center line of the tested tendon rope 4 forms an effective vertical distance between the force measuring roller 3 and the limiting guide roller 2, and the preset offset is configured such that the effective vertical distance is less than or equal to the initial nominal diameter of the tested tendon rope 4.

[0075] It should be noted that the effective vertical distance Heeff formed between the force measuring roller 3 and the limiting guide roller 2 on the center line of the tendon rope force is configured to be less than or equal to the initial nominal diameter d1 of the tendon rope 4, that is, Heeff≤d1, so that the height / thickness of the sensor body 1 can be made thin and light, which meets the requirements of the internal space envelope of the robot's dexterous finger joint.

[0076] See Figure 6 As shown, in this embodiment, an integrated data processing module 9 is also included. The integrated data processing module 9 is electrically connected to the strain measuring element 6 and is used to condition and digitize the minute deformation signal output by the strain measuring element 6 to output the final tension measurement signal.

[0077] It should be noted that the integrated data processing module 9 includes a digital processing unit capable of digitizing analog voltage signals. This transforms the single-sided contact tension sensor into an independent intelligent module with complete signal acquisition and processing capabilities, directly outputting standardized digital tension signals. This eliminates the need for a dedicated analog sampling circuit in the robot's main controller, reducing the hardware burden on the host computer and the complexity of external wiring.

[0078] Example 4 Based on Embodiment 1, Embodiment 2, or Embodiment 3, this embodiment provides further technical solutions.

[0079] See Figure 13 As shown, this embodiment provides a method for measuring tendon chord tension, including a single-sided contact tendon chord tension sensor as described in any of the embodiments 1, 2, or 3. The measurement method includes the following steps: S1. Provide a single-sided contact chordae tension sensor, the single-sided contact chordae tension sensor includes at least three miniature rollers, an elastic element 5 and a strain measuring element 6, the at least three miniature rollers include two limiting guide rollers 2 and one force measuring roller 3, the chordae contact surface of the force measuring roller 3 has a preset offset relative to the common tangent of the chordae contact surfaces of the two limiting guide rollers 2; Specifically, during assembly, the common tangent reference of the two limiting guide rollers 2 is fixed through the rigid area X of the sensor body 1, while the intermediate force measuring roller 3 is arranged on the elastic element 5. The tendon contact surface of the force measuring roller 3 extends beyond the common tangent, forming a preset offset.

[0080] S2. The tendon rope 4 to be tested passes over the at least three miniature rollers in sequence from the same side. The preset offset is used to make the tendon rope 4 form a wrap angle on the force measuring roller 3 and form an effective vertical distance between the force center lines of the tendon rope 4. Specifically, the tendon cord 4 passes over three rollers sequentially from one side. Using the preset offset of the force measuring roller 3 as a physical barrier, the originally straight tendon cord 4 is forced to undergo a unidirectional inverted V-shaped deflection, thereby naturally fitting against the surface of the middle roller to form a wrap angle, and establishing an effective vertical distance between the force center lines of the tendon cord 4 that corresponds to the mechanical reference of the sensor.

[0081] S3. When the tendon cord 4 is subjected to tendon cord tension, the tendon cord 4 generates a positive pressure on the force measuring roller 3 based on the constraint of the wrap angle. The elastic element 5 undergoes a slight deformation due to the positive pressure. The strain measuring element 6 detects the slight deformation and outputs a tension measurement signal. Specifically, when the tendon cord 4 is subjected to tendon cord tension, due to the constraint of the wrap angle, the taut tendon cord 4 will squeeze the force measuring roller 3 inward, generating positive pressure. This positive pressure causes the elastic element 5 connected below to undergo slight physical bending or compression deformation, and the strain measuring element 6 attached to it will then generate resistance or piezoresistive changes, thereby outputting an electrical signal proportional to the true tension value.

[0082] S4. When the tendon cord 4 becomes thinner due to cyclic wear, the tendon cord 4 is kept in contact with the force measuring roller and the two adjacent limiting guide rollers on the same side. This causes the center line of the force on the tendon cord 4 to undergo radial settlement in the same direction and with equal amplitude. This radial settlement keeps the wrap angle and the effective vertical distance constant, thereby offsetting the tension measurement signal error introduced by the thinning of the diameter.

[0083] Specifically, in traditional contralateral contact, the thinning of the tendon cord over long-term use leads to antiparallel displacement between the contact points on both sides and the middle contact point, thereby changing the wrap angle and causing measurement drift. However, in the same-side contact configuration of this embodiment, the spatial settlement of the three contact points due to diameter reduction is parallel. During the calculation of the height difference between the force measuring point and the limiting point, this equal-amplitude settlement is precisely and completely canceled out, ensuring that the wrap angle is mathematically and physically unaffected by the change in tendon cord diameter. In this embodiment, when the device undergoes millions of high-frequency cycles and the tendon cord 4 experiences irreversible wear and thinning (e.g., its diameter shrinks from the initial nominal diameter d1 to d2), the structure that maintains same-side contact between the tendon cord 4 and the micro-rollers ensures that the center lines of the tendon cord force at each roller experience radial settlement in the same direction and with equal amplitude.

[0084] In this embodiment, the number of the at least three micro rollers is five, and it also includes two additional limiting rollers 8 disposed on the outer side; During the passage of the tested tendon cord 4 through the single-sided contact tendon cord tension sensor, the entry and exit guide group formed by the two additional limiting rollers 8 and the adjacent limiting guide roller 2 forcibly constrains the tangential angle of the tendon cord 4 entering and exiting the single-sided contact tendon cord tension sensor. This ensures that when the tendon cord 4 undergoes spatial swing or changes in stretching direction outside the single-sided contact tendon cord tension sensor, the tendon cord 4 still maintains contact on the same side on the at least three micro rollers inside, and the direction of the positive pressure generated by the tendon cord 4 on the force measuring roller 3 remains constant.

[0085] It should be noted that in this embodiment, an additional limiting roller 8 is added to the outer side of each of the two limiting guide rollers 2 at the ends of the basic structure, forming a combination of two pairs of limiting rollers and a force measuring roller 3. During the passage of the tendon ligament 4 through the sensor, the outer additional limiting roller 8 and the adjacent inner limiting guide roller 2 together form an entry and exit guide group. This guide group forcibly constrains the tangential angle of the tendon ligament 4 as it enters and exits the sensor. After the tendon ligament 4 passes through these two pairs of guide groups, its travel path and incident angle to the middle force measuring roller 3 are locked on a fixed geometric tangent, thereby ensuring that the wrap angle generated by the tendon ligament 4 on the force measuring roller 3 and the direction of the inward compressive force are not affected by changes in the external environment.

[0086] In this embodiment, the method further includes the following steps: when the tested tendon 4 is under a known tension value, the measurement signal output by the strain measuring element 6 is recorded, and a tension-signal calibration curve is established. The single-sided contact tendon tension sensor also includes an integrated data processing module 9, and the tension-signal calibration curve serves as the reference for signal conversion by the integrated data processing module 9.

[0087] It should be noted that before the sensor is put into actual operation of the robot, a series of known standard tension values ​​are applied to the tendon rope 4 under test using a standard force measuring device. Simultaneously, the corresponding electrical signals output by the strain measuring element 6 under each standard tension state are collected and recorded. A mapping relationship between the tendon rope tension value and the measured signal is established through data fitting, i.e., a tension-signal calibration curve. Subsequently, the mapping parameters of this calibration curve are stored in the sensor's local integrated data processing module 9, serving as the benchmark for subsequent signal digitization and physical quantity calculation during the module's operation.

[0088] Example 5 This embodiment provides a further technical solution based on Embodiment 1, Embodiment 2, or Embodiment 3.

[0089] This embodiment provides a tendon-driven robot, including a robot hand, at least one tendon chord, and a single-sided contact tendon chord tension sensor as described in any one of Embodiments 1, 2, or 3. The single-sided contact tendon chord tension sensor is installed on the tendon chord path of the robot hand and is used to measure the tendon chord tension.

[0090] It should be noted that in this embodiment, a single-sided contact sensor with geometric self-compensation characteristics is installed on the tendon ligament path, so that the sensor adapts to the wear and thinning of the tendon ligament caused by long-term high-frequency operation. This enables the robot's force control loop to obtain a drift-free, high-fidelity tension measurement signal throughout its life cycle, and maintain highly accurate and stable dexterous hand grasping force control without relying on other software compensation and frequent periodic recalibration.

[0091] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. The above embodiments only illustrate several implementation methods of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of this application's patent. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the concept of this application, and these all fall within the protection scope of this application.

[0092] It should be noted that when an element is referred to as being "fixed to" or "set on" another component, it can be directly or indirectly set on the other component; when a component is referred to as being "connected to" another component, it can be directly or indirectly connected to the other component. It should be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or component 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 application.

[0093] Furthermore, in the description of this application, "multiple" or "several" means two or more, unless otherwise explicitly specified.

[0094] It should be noted that the structures, proportions, sizes, etc., shown in the accompanying drawings are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed in the specification, and are not intended to limit the conditions under which this application can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size should still fall within the scope of the technical content disclosed in this application, provided that they do not affect the effects and purposes that this application can produce.

Claims

1. A single-sided contact chordae tendon tension sensor, characterized in that, It includes a sensor body, an elastic element, a strain measuring element, and at least three miniature rollers; The sensor body includes a rigid region, and the elastic element is supported in the rigid region and has the degree of freedom to deform under force. The at least three miniature rollers are mounted on the sensor body and the elastic element, and the at least three miniature rollers include two limiting guide rollers on both sides and one force measuring roller in the middle; The limiting guide roller is rotatably connected to the rigid area of ​​the sensor body, and the force measuring roller is rotatably connected to the elastic element; The tendon contact surface of the force measuring roller has a preset offset relative to the common tangent of the tendon contact surfaces of the two limiting guide rollers. The at least three miniature rollers are configured to allow the tendon to be tested to contact and pass through sequentially from the same side, and the preset offset causes the tendon to generate a wrap angle on the force measuring roller. When the tendon cord is subjected to tendon cord tension, the wrap angle causes the tendon cord to generate a positive pressure on the force measuring roller, and the slight deformation of the elastic element caused by the positive pressure is detected by the strain measuring element.

2. The single-sided contact tendon chord tension sensor according to claim 1, characterized in that, It also includes two additional limiting rollers, which are respectively disposed on the side of the two limiting guide rollers away from the force measuring roller, and each additional limiting roller and the adjacent limiting guide roller together form an in-line and out-line guide group. The inlet and outlet guide group is configured to forcibly constrain the tangential angle of the tendon cord entering and exiting the single-sided contact tendon cord tension sensor, so that when the tendon cord swings spatially or changes its stretching direction outside the single-sided contact tendon cord tension sensor, the tendon cord still maintains contact on the same side on the at least three micro rollers inside, and the wrap angle and the direction of the positive pressure generated by the tendon cord on the force measuring roller remain constant.

3. The single-sided contact tendon chord tension sensor according to claim 1, characterized in that, The elastic element has a connection root between itself and the rigid region of the sensor body, and the strain measuring element is arranged at the connection root. The connection root is configured such that when the force-measuring roller transmits the positive pressure to the elastic element, the connection root generates a local maximum strain. The elastic element is an independent component and is fixedly connected to the rigid region to form the connection root; Alternatively, the elastic element and the sensor body are integrally formed monolithic structures, and the elastic element is a cantilever structure formed by opening a U-shaped groove in the monolithic structure. The connection root is a strain concentration area where the cantilever structure is connected to the rigid area.

4. The single-sided contact tendon chord tension sensor according to claim 1, characterized in that, Each of the at least three miniature rollers has a miniature bearing embedded inside; The limiting guide roller and the force measuring roller are rotatably connected to the rigid region and the elastic element respectively through the miniature bearing, so as to convert the sliding friction generated when the tested tendon rope moves into rolling friction.

5. The single-sided contact tendon chord tension sensor according to claim 1, characterized in that, The tendon contact surfaces of the at least three miniature rollers are all provided with annular anti-detachment guide grooves for accommodating the tendon being tested. The preset offset is the vertical distance between the bottom surface of the annular anti-detachment guide groove of the force measuring roller and the common tangent line between the bottom surfaces of the annular anti-detachment guide grooves of the two limiting guide rollers.

6. The single-sided contact tendon chord tension sensor according to claim 5, characterized in that, The ratio of the groove bottom diameter of the at least three miniature rollers to the initial nominal diameter of the tendon rope being tested is configured to be between 2:1 and 8:1; The tested tendon cord defines a geometric circumcircle at the midpoint of the three contact arcs on at least three miniature rollers. The geometric circumcircle has a circumcircle diameter that is larger than the groove bottom diameter of the force measuring roller.

7. The single-sided contact chordae tendon tension sensor according to claim 6, characterized in that, There is a proportional coordination configuration between the outer circle diameter and the groove bottom diameter of the force measuring roller, and the ratio of the outer circle diameter to the groove bottom diameter of the force measuring roller is configured to be greater than 10.

8. The single-sided contact chord tension sensor according to claim 7, characterized in that, The ratio of the circumscribed circle diameter to the groove bottom diameter of the force-measuring roller is configured as follows: When the diameter of the groove bottom is small due to the limited micro-space, the actual wrap angle of the tested tendon rope on the force measuring roller is compressed by increasing the diameter of the outer circle, thereby reducing the accumulation of micro-local bending stress and internal fiber friction caused by macro-normal pressure and achieving mechanical self-compensation.

9. The single-sided contact chordae tendon tension sensor according to claim 1, characterized in that, The force centerline of the tested tendon rope forms an effective vertical distance between the force measuring roller and the limiting guide roller, and the preset offset is configured such that the effective vertical distance is less than or equal to the initial nominal diameter of the tested tendon rope.

10. The single-sided contact tendon chord tension sensor according to claim 1, characterized in that, It also includes an integrated data processing module, which is electrically connected to the strain measurement element and is used to condition and digitize the minute deformation signal output by the strain measurement element to output the final tension measurement signal.

11. A method for measuring tendon ligament tension, characterized in that, The method for using the unilateral contact tendon chord tension sensor according to any one of claims 1 to 10, the method comprising the steps of: A single-sided contact chordae tension sensor is provided. The single-sided contact chordae tension sensor includes at least three miniature rollers, an elastic element, and a strain measuring element. The at least three miniature rollers include two limiting guide rollers and one force measuring roller. The chordae contact surface of the force measuring roller has a preset offset relative to the common tangent of the chordae contact surfaces of the two limiting guide rollers. The tendon rope being tested is made to pass over the at least three miniature rollers in sequence from the same side. The preset offset is used to make the tendon rope wrap around the force measuring rollers and form an effective vertical distance between the force center lines of the tendon rope. When the tendon cord is subjected to tendon cord tension, the constraint of the wrap angle causes the tendon cord to generate a positive pressure on the force measuring roller. The elastic element undergoes a slight deformation due to the positive pressure, and the strain measuring element detects the slight deformation and outputs a tension measurement signal. When the tendon cord becomes thinner due to cyclic wear, the tendon cord is kept in contact with the force measuring roller and the two adjacent limiting guide rollers on the same side. This causes the center line of the tendon cord to sink radially in the same direction and with equal amplitude. This radial sinking keeps the wrap angle and the effective vertical distance constant, thereby offsetting the tension measurement signal error introduced by the thinning of the diameter.

12. The method for measuring tendon and ligament tension according to claim 11, characterized in that, The number of the at least three miniature rollers is five, and it also includes two additional limiting rollers disposed on the outer side; During the passage of the tested tendon cord through the single-sided contact tendon cord tension sensor, the entry and exit guide group, consisting of two additional limiting rollers and adjacent limiting guide rollers, forcibly constrains the tangential angle of the tendon cord entering and exiting the single-sided contact tendon cord tension sensor. This ensures that when the tendon cord experiences spatial oscillation or changes in its stretching direction outside the single-sided contact tendon cord tension sensor, the tendon cord remains in contact on the same side of the at least three micro rollers inside, and the wrap angle and the direction of the positive pressure generated by the tendon cord on the force measuring roller remain constant.

13. The method for measuring tendon ligament tension according to claim 11, characterized in that, The method also includes the following steps: when the tested tendon rope is under known tension, record the measurement signal output by the strain measurement element and establish a tension-signal calibration curve. The single-sided contact tendon rope tension sensor also includes an integrated data processing module, and the tension-signal calibration curve serves as the reference for signal conversion by the integrated data processing module.

14. A tendon-driven robot, characterized in that, The device includes a robot hand, at least one tendon tractor, and a unilateral contact tendon tractor tension sensor as described in any one of claims 1 to 10, wherein the unilateral contact tendon tractor tension sensor is mounted on the tendon tractor path of the robot hand and is used to measure the tendon tractor tension.

Images