Bionically flexible joint constraint body for sensing robot joint configuration and motion state

Abstract

The application discloses a bionic flexible joint constraint body capable of sensing robot joint position and motion state, and belongs to the field of bionic robots. The bionic flexible joint constraint body comprises an elastic base body and three intelligent flexible body sensing fibers embedded in the elastic base body. The middle part of the elastic base body is provided with a wrinkle area, an arc area and a reinforcing rib. The wrinkle area and the arc area are arranged on the first side and the second side of the joint respectively. Through the differential wall thickness and modulus design of the two areas, asymmetric flexible motion constraint is realized in the joint flexion and extension motion. The three intelligent flexible body sensing fibers are respectively embedded in the corresponding elastic base body walls of the wrinkle area, the arc area and the reinforcing rib. Each sensing fiber independently outputs a resistance change signal, and the three-dimensional space posture of the joint is solved cooperatively. Without external sensors, real-time sensing of the joint space position and motion state can be realized.

Description

Technical Field

[0001] This invention relates to the field of biomimetic robots, and in particular to a biomimetic flexible joint constraint that can sense the joint configuration and motion state of a robot. Background Technology

[0002] Humanoid robots, due to their resemblance to humans in form, strong mobility on complex terrains, and good environmental adaptability, are well-suited for collaborative work with humans and have broad application prospects in fields such as national defense, aerospace, healthcare, and domestic services. They have become a cutting-edge and hot topic in the international robotics field. The joint performance of a humanoid robot directly determines the stability, flexibility, and compliance of its movement. Currently, most existing robot joint connection schemes use rigid hinges or universal joints. These connections only have one or two definite rotational degrees of freedom, making it difficult to reproduce the multi-degree-of-freedom flexible movement of humanoid joints, and they also lack compliance. While flexible joint structures, such as soft hands, improve compliance to some extent, their load-bearing capacity is weak, making it difficult to meet high-load requirements. Therefore, the industry has proposed rigid-flexible coupling design schemes such as biomimetic tension-compression bodies, where joints use artificial ligaments for connection, maintaining joint stability to a certain extent. Currently, these joint structures have significant advantages in exhibiting human-like multi-degree-of-freedom movement characteristics, but research shows that these joint structures do not yet possess the ability to self-sensitize joint spatial configuration and motion state. Furthermore, to achieve precise force and position control of robot joints, it is necessary to acquire the motion state of the joints in real time. However, the current solutions that mainly rely on external sensors such as inertial measurement units and encoders increase the size of robot joints and the complexity of wiring structures to a certain extent. Therefore, there is an urgent need to develop a new generation of robot joint systems that can sense the spatial configuration and motion state of the joints and are integrated into the robot joint structure itself.

[0003] Biomechanical studies have shown that human joints, in addition to ligaments, also contain joint capsules and other complex soft tissues. These tissues work together to provide asymmetric flexible motion constraints during static load-bearing and movement. Specifically, taking the human knee joint as an example, its anterior and posterior cruciate ligaments exhibit drastically different tension-relaxation characteristics during flexion and extension. Similarly, taking the proximal interphalangeal joint of the finger as another example, the elastic modulus of the dorsal and palmar soft tissues differs by nearly two times, indicating a significant asymmetry in motion constraints between the palmar and dorsal soft tissues during flexion and extension. Furthermore, the joint capsule surface is covered with numerous mechanoreceptors, and existing research indicates that these receptors within biomimetic joint capsules can independently perceive joint status. Therefore, while providing flexible motion constraints, the joint capsule, ligaments, and surrounding soft tissues also possess proprioceptive functions, providing a natural blueprint for the integration of joint motion constraints and self-perception of motion status in biomimetic robots.

[0004] In summary, there is an urgent need for a joint connection solution that integrates biomimetic flexible motion constraint and sensing capabilities, so that the joint system itself has motion constraint characteristics and proprioceptive functions similar to natural joint soft tissue, thereby providing underlying technical support for the motion stability, flexibility and compliance of humanoid robot joints. Summary of the Invention

[0005] The purpose of this invention is to solve the problem that existing joint connection devices have limited functions and cannot achieve body perception while providing motion constraints, and to provide a biomimetic flexible joint constraint that can perceive the robot's joint configuration and motion state.

[0006] A biomimetic flexible joint constraint body capable of sensing the joint configuration and motion state of a robot includes an elastic matrix and three sets of intelligent flexible body sensing fibers; the intelligent flexible body sensing fibers are embedded inside the elastic matrix. The elastic matrix includes two axially fixed regions, two adaptive wrapping regions, and a motion constraint region. The two axially fixed regions are respectively located at both ends of the elastic matrix, and the inner sides of the two axially fixed regions are respectively provided with a first and a second buckle that protrude radially inward. In the installed state, the elastic matrix is ​​axially stretched, and a continuous axial preload is applied to the joint contact surface through the first and second buckles. The adaptive wrapping region extends between the axially fixed regions and is constructed to fit tightly against the joint surface with elastic preload, and can stretch and deform with joint movement.

[0007] The motion constraint zone is positioned between two adaptive wrapping zones, covering the flexion, extension, and lateral swing motion areas of the joint. The motion constraint zone includes a pleated region, an arc-shaped region, and several reinforcing ribs. The pleated region is located on one side of the joint and has at least one circumferentially distributed wave-shaped pleat. The arc-shaped region is located on the other side and has a smooth, wrinkle-free surface. The wall thickness of the arc-shaped region is less than that of the pleated region. When the joint bends to one side, the pleated region is compressed, and its wave-shaped pleat structure accommodates the compressive displacement through axial contraction, without generating a compressive reaction force. Simultaneously, the arc-shaped region has a thinner wall and a lower elastic modulus, resulting in a tensile stiffness less than the compressive stiffness of the pleated region. The joint's synergy allows for a greater bending angle to one side; when the joint bends to the other side, the arc-shaped region is compressed, and its smooth, thin-walled surface accommodates the compressive displacement through local buckling deformation without generating compressive reaction force; the folded region is under tension, and because its wall thickness is greater than that of the arc-shaped region and its elastic modulus is higher, it can generate tensile resistance greater than the compressive stiffness of the arc-shaped region, thus limiting the maximum bending angle and bending stiffness of the joint to the other side, thereby simulating the asymmetric motion constraint characteristics of a natural joint; several reinforcing ribs are located on both sides of the folded and arc-shaped regions, and the range of motion constraint in the lateral and flexion-extension directions can be adjusted by adjusting the diameter and modulus of the reinforcing ribs.

[0008] The three intelligent flexible body sensing fibers are the first sensing fiber, the second sensing fiber, and the third sensing fiber: The first sensing fiber is embedded in the elastic matrix wall corresponding to the wrinkled area, and the area where it is located constitutes the first sensing area to sense the tensile and compressive deformation of the wrinkled area. The second sensing fiber is embedded in the elastic matrix wall corresponding to the arc-shaped region, and the area where it is located constitutes the second sensing area to sense the tensile and compressive deformation of the arc-shaped region. The third sensing fiber is embedded in the elastic matrix wall corresponding to the reinforcing rib, and the area where it is located constitutes the third sensing zone to sense the tensile and compressive deformation of the reinforcing rib. The first, second, and third sensing fibers sense the tensile and compressive deformation of their respective regions and work together to acquire the spatial configuration information of the biomimetic flexible joint constraint. This spatial configuration information is used to calculate the spatial posture and motion state of the joint, thereby achieving self-sensing of the joint state.

[0009] The intelligent flexible body sensing fiber is integrally molded and embedded inside the elastic matrix.

[0010] The elastic matrix has a configuration that wraps around the joint and elastically connects adjacent limb segments; the resistance value of the intelligent flexible body sensing fiber changes with its own deformation.

[0011] The first and second buckles are configured to engage with the fixing structures on the corresponding limb segments.

[0012] The elastic modulus and wall thickness of the arc-shaped region are lower than those of the folded region, so that the axial tensile stiffness of the arc-shaped region is less than the axial compressive stiffness of the folded region, and the axial tensile stiffness of the folded region is greater than the axial compressive stiffness of the arc-shaped region, thereby achieving asymmetric motion constraints in the joint flexion and extension directions.

[0013] The first, second, and third sensing fibers are each equipped with independent electrodes and leads for connecting to external measurement circuits and calculation units, and can independently output their respective resistance change signals.

[0014] The reinforcing ribs consist of two ribs; the third sensing fiber consists of one rib, which is embedded in the elastic matrix wall corresponding to either of the two reinforcing ribs.

[0015] The biomimetic flexible joint constraint body of the present invention, capable of sensing the joint position and motion state of a robot, is prepared by the following steps: three intelligent flexible body sensing fibers are pre-placed in a mold, and the positioning of the intelligent flexible body sensing fibers corresponds to the first sensing area, the second sensing area, and the third sensing area. The shape of the mold cavity corresponds to the configuration of the wrinkled area, the arc area, the reinforcing rib, and the first and second snap fasteners. Liquid elastomer material is poured into the mold cavity. The mold is placed at 60°C for 1 hour to cure. After the elastomer material has cured, the mold is demolded to obtain the biomimetic flexible joint constraint body of the present invention.

[0016] The beneficial effects of this invention are: Inspired by the integrated characteristics of asymmetric motion constraint and proprioception of human joints, this invention provides a systematic solution for humanoid robot joints that integrates flexible motion constraint and self-sensing through the integrated design of elastic matrix and sensing fiber.

[0017] In terms of motion constraints, the asymmetric flexible motion constraints in the joint flexion and extension directions are achieved by designing differentiated wall thickness and modulus between the folded and arc-shaped regions in the motion constraint area. This allows for large-angle motion during flexion and generates tensile resistance to limit excessive extension during extension. Meanwhile, the lateral reinforcement area can independently control the lateral swing stiffness by adjusting the diameter and modulus of the reinforcing ribs, and it also has a certain adjustment effect in the flexion and extension directions, but its influence is much smaller than that in the lateral swing direction. By reasonably configuring the structural parameters of each region, the independent customization of the constraint characteristics in the three motion directions can still be achieved.

[0018] In terms of sensing, this invention integrates three sensing fibers into an elastic matrix, which deform in tandem with the matrix and independently output resistance change signals. After calculation, the three-dimensional spatial posture of the joint can be obtained in real time without the need for external sensors, effectively reducing the joint volume and wiring complexity.

[0019] In addition, the one-piece molding process enables seamless integration of the sensing network and the constraint structure, which is simple, low-cost, and the mold can be customized to adapt to different joint shapes. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the structure of the elastic matrix according to an embodiment of the present invention.

[0022] Figure 3 This is a three-dimensional exploded view of an embodiment of the present invention.

[0023] Figure 4 This is a schematic diagram of the motion constraint region according to an embodiment of the present invention.

[0024] Figure 5 This is an enlarged schematic diagram of the structure of the intelligent flexible body sensing fiber according to an embodiment of the present invention.

[0025] Figure 6 A diagram showing the modulus relationship between the dorsal and palmar soft tissues of the proximal interphalangeal joints of the human hand.

[0026] Figure 7 Figure (a) shows the curve of the thrust required for 90 degrees of joint flexion according to an embodiment of the present invention, and the curve of the relationship between the wall thickness of different arc-shaped regions and the required maximum thrust. Figure (b) shows the curve of the thrust required for 90 degrees of joint flexion, and the curve of the relationship between the wall thickness of different arc-shaped regions and the required maximum thrust when the joint is flexed at 90 degrees.

[0027] Figure 8 Figure (a) shows the curve of the thrust required for 90-degree joint extension and the curve of the relationship between the wall thickness of different arc-shaped regions and the required maximum thrust in an embodiment of the present invention. Figure (b) shows the curve of the thrust required for 90-degree joint extension and the curve of the relationship between the wall thickness of different arc-shaped regions and the required maximum thrust when the joint is extended by 90 degrees.

[0028] Figure 9 Figure (a) shows the curve of the thrust required for 90-degree joint flexion according to an embodiment of the present invention, and the curve of the relationship between different reinforcing rib diameters and the required maximum thrust. Figure (b) shows the curve of the thrust required for 90-degree joint flexion, and the curve of the relationship between different reinforcing rib diameters and the required maximum thrust when the joint is flexed at 90 degrees.

[0029] Figure 10 Figure (a) shows the curve of the thrust required for 90-degree joint extension and the curve of the relationship between different reinforcing rib diameters and the required maximum thrust in an embodiment of the present invention. Figure (b) shows the curve of the thrust required for 90-degree joint extension and the curve of the relationship between different reinforcing rib diameters and the required maximum thrust when the joint is extended by 90 degrees.

[0030] Figure 11 Figure (a) shows the thrust variation curve required for a 30-degree lateral joint swing according to an embodiment of the present invention, and the relationship curve between different reinforcing rib diameters and the required maximum thrust. Figure (b) shows the relationship curve between different reinforcing rib diameters and the required maximum thrust when the joint swings to 30 degrees.

[0031] Figure 12 This is a graph showing the relationship between the rate of change of resistance and the current joint flexion and extension angle in an embodiment of the present invention.

[0032] Figure 13 This is a graph showing the relationship between the rate of change of resistance and the current lateral swing angle of the joint in an embodiment of the present invention. Detailed Implementation

[0033] Please see Figures 1 to 13 The image shown is an embodiment of the present invention.

[0034] A biomimetic flexible joint constraint that can sense the joint position and motion state of a robot is mainly used to wrap and constrain the interphalangeal joints of the human body, the knee joints, or the rotating joints of a robot.

[0035] Please see Figure 1 As shown, the constraint body includes an elastic matrix 1 made of highly elastic silicone rubber and three sets of intelligent flexible body sensing fibers 2, which are embedded inside the elastic matrix 1. The three sets of intelligent flexible body sensing fibers 2 include a first sensing fiber 21, a second sensing fiber 22, and a third sensing fiber 23. The elastic matrix 1 is integrally formed by a casting process, completely encapsulating the intelligent flexible body sensing fibers 2, ensuring that their deformation is synchronized with the matrix without relative slippage. The intelligent flexible body sensing fibers 2 are composed of conductive nanomaterials and a flexible polymer matrix; their resistance increases with axial stretching and decreases with axial compression.

[0036] Please see Figure 2 and Figure 3 As shown, the elastic matrix 1 is divided into three functional areas in the axial direction: axially fixed area 11, adaptive wrapping area 12, and motion constraint area 13.

[0037] Two axial fixing areas 11 are respectively disposed at both ends of the elastic base. The inner sides of the two axial fixing areas 11 are respectively provided with a first buckle 111 and a second buckle 112 that protrude radially inward. The first buckle 111 and the second buckle 112 are configured to cooperate with the fixing structure on the corresponding limb segment to apply axial preload to the joint contact surface. The principle of generating axial preload is as follows: the axial distance between the first buckle 111 and the second buckle 112 in the natural state is designed to be slightly smaller than the distance between the two positioning structures on the corresponding limb segment. During installation, the elastic base 1 needs to be axially stretched so that the two buckles are respectively engaged in the corresponding positioning structures. After installation, the stretched elastic base 1 has a tendency to retract, thereby applying a continuous and stable axial preload to the joint surface through the first buckle 111 and the second buckle 112 to ensure that the restraint body does not move axially in any posture.

[0038] The two adaptive wrapping zones 12 are two thin-walled cylindrical structures located between the axial fixation zones 11. Their inner diameter is slightly smaller than the outer diameter of the joint in the relaxed state to achieve elastic pre-tightening fit, ensuring close contact with the corresponding bone surface under various movement postures.

[0039] The motion constraint zone 13 is located between the two adaptive wrapping zones 12, corresponding to the joint space and the main deformation area of ​​flexion and extension movements.

[0040] Please see Figure 4 As shown, the motion constraint zone 13 is structurally divided into three sub-regions: a wrinkled region 131 located on one side of the joint. This region has one or more circumferentially extending peaks and a relatively thick wall, approximately 130% of the wall thickness of the adaptive wrapping zone 12. An arcuate region 132 located on the other side of the joint has a smooth, wrinkle-free curved surface and a relatively thin wall, approximately 70% of the wall thickness of the adaptive wrapping zone 12. The wall thickness and modulus of the wrinkled region 131 and the arcuate region 132 can be configured according to actual needs to adjust the range of flexion and extension movements. Reinforcing ribs 133 are located on the left and right sides of the above two regions. The diameter and modulus of the reinforcing ribs 133 can adjust the range of motion constraint in the lateral and flexion / extension directions.

[0041] The principle of asymmetric constraint on the constraint body in this embodiment is as follows: When the joint flexes to one side, the folded region 131 is compressed and the crests are squeezed together, resulting in axial contraction. Since the folded region mainly bears compression, its large wall thickness does not hinder the flexion movement. At the same time, the arc-shaped region 132 is stretched. Because its wall is thin, its elastic modulus is low, and its tensile stiffness is small, it can generate a large axial elongation with the flexion movement, thereby allowing the joint to achieve a large angle of flexion.

[0042] When the joint extends backward to the other side, the process is reversed. The arc-shaped region 132 is compressed because its smooth curved surface and thin wall thickness make it easy to undergo local deformation to accommodate the compression displacement, thus providing little resistance to the extension movement. Meanwhile, the folded region 131 is stretched, and the crests are pulled apart. Due to its larger wall thickness, higher elastic modulus, and greater tensile stiffness, it can generate strong tensile resistance, thereby effectively limiting the excessive extension of the joint and playing a key protective role in joint movement. At the same time, it simulates the asymmetric motion constraint characteristics of a natural joint constraint body.

[0043] When the joint swings laterally, the reinforcing ribs 133 on both sides provide customized lateral constraint stiffness through their diameter and modulus, effectively preventing abnormal lateral swing of the joint.

[0044] Please see Figure 5 As shown, to achieve proprioception, three sets of intelligent flexible proprioception fibers 2 are independently arranged, each forming a separate sensing area: The first sensing fiber 21 is distributed along the crests and troughs of the folded region 131, and the area in which it is located constitutes the first sensing zone. Regardless of whether this zone is under compression or tension, the fiber can generate a corresponding change in electrical resistance.

[0045] The second sensing fiber 22 is embedded linearly along the axial direction within the elastic matrix wall corresponding to the arc-shaped region 132, and the region in which it is located constitutes the second sensing area. Since this area is mainly subjected to smooth stretching or compression, the linear arrangement can provide a sensing signal with high linearity.

[0046] The third sensing fiber 23 is embedded inside the reinforcing rib 133, and the area where it is located constitutes the third sensing zone, which is used to sense the tensile and compressive deformation caused by lateral swing.

[0047] Each of the sensing fibers is equipped with an independent electrode and lead wire, which connects to an external measurement circuit and calculation unit, and can independently output its own resistance change signal. After calibration and calculation, the spatial configuration of the constraint body itself can be uniquely determined, and the flexion angle, extension angle and lateral swing angle of the joint can be calculated to realize the self-sensing of the joint state.

[0048] The following is a method for preparing the biomimetic flexible joint restraint described in this embodiment: According to the product design, three pre-prepared intelligent flexible body sensing fibers 2, namely the first sensing fiber 21, the second sensing fiber 22, and the third sensing fiber 23, are positioned and fixed on the core of the mold according to the preset spatial orientation of the wrinkled region 131, the arc-shaped region 132, and the reinforcing rib 133, respectively. The two ends of each of the three sets of sensing fibers are led out from both ends of the mold for subsequent electrical connection. The mold is closed, and the mold cavity precisely contains the geometric configuration corresponding to the crests of the wrinkled region 131, the curved surface of the arc-shaped region 132, the reinforcing rib 133, and the first and second latches 111 and 112 of the axial fixing area 11. Liquid medical-grade addition-curing silicone rubber is slowly injected into the mold under vacuum to ensure complete filling and coating of the fibers. The mold is cured at 60°C for 1 hour. After the elastomer material is completely cured, the mold is opened, and the formed biomimetic flexible joint restraint is removed. After demolding, the constraint body is trimmed to remove burrs, and the final product is obtained.

[0049] Please see Figure 6 To investigate the mechanical properties of the human body's motion restraint zone, elastic modulus measurements were conducted on the dorsal and palmar soft tissues of the natural proximal interphalangeal joints. Shear wave elastography was employed using an Aixplorer ultrasound imager. The measurement areas were the dorsal and palmar skin and subcutaneous soft tissues of the proximal interphalangeal joints. The results showed that the elastic modulus of the dorsal soft tissue of the proximal interphalangeal joints was approximately 49.8 kPa, while that of the palmar soft tissue was approximately 94.4 kPa, representing a nearly two-fold difference. This modulus ratio guided the differentiated configuration of elastic modulus between the folded and curved regions in this embodiment.

[0050] The biomimetic flexible joint constraint body was assembled onto a 3D-printed biomimetic joint to form a joint constraint system. Flexion, extension, and lateral swing motion experiments were conducted on the joint constraint system. The maximum thrust required for 90° flexion, 90° extension, and 30° lateral swing was measured. Furthermore, the adjustment mechanism of the structural dimensions of the motion constraint region 13 on the joint constraint characteristics was explored by changing the wall thickness of the arc-shaped region 132 and the diameter of the reinforcing rib 133. The measuring equipment was an SH-Ⅱ-500N digital push-pull force gauge.

[0051] Please see Figure 7 and Figure 8 Differential regulation of flexion-extension motion by wall thickness in the arc-shaped region: The wall thickness of the arc-shaped region 132 was set to 2mm, 1.5mm, 1mm, and 0.5mm respectively, while keeping other structural parameters constant. The thrust-time variation curves of the biomimetic flexible joint constraint body under the four sizes during joint flexion and extension were measured, as shown in the figures below. Figure 7 and Figure 8 As shown.

[0052] The two graphs present completely different adjustment patterns. Figure 7 As shown in the flexion process, the maximum thrust required increases linearly with the increase of the wall thickness of the arcuate region 132—the thrust required for 90° flexion increases approximately 2.4 times when the wall thickness increases from 0.5 mm to 2 mm. This indicates that the arcuate region 132, acting as the stretching side, provides the main tensile resistance during joint flexion, and its wall thickness is a key design parameter determining the flexibility of flexion movement. Figure 8 During the extension process shown, the maximum thrust required did not differ significantly when the wall thickness of the arcuate region 132 was 1.5 mm, 1 mm, and 0.5 mm; it only increased slightly when the wall thickness was 2 mm. This indicates that during joint extension, the arcuate region 132 becomes the compression side, and its smooth, thin-walled structure easily undergoes local deformation under compression to accommodate compressive displacement, generating almost no compressive reaction force. The above comparison clearly verifies the asymmetric constraint mechanical mechanism of this invention, where "the tension side provides the main resistance, and the compression side has minimal resistance"—the same arcuate region is the main contributor to constraint stiffness during buckling, but generates almost no constraint effect during extension, thus achieving independent customization of the constraint characteristics in the joint's buckling and extension directions.

[0053] Please see Figure 9 , Figure 10 and Figure 11 The effect of stiffener diameter on flexion-extension and lateral swing motion: The diameter of stiffener 133 was set to 0mm (i.e., no stiffener), 0.8mm, 1.2mm, and 1.6mm respectively, while keeping other structural parameters unchanged. The thrust-time variation curves of the biomimetic flexible joint constraint body in four sizes during joint flexion, extension, and lateral swing were measured, as shown in the figures below. Figure 9 , Figure 10 and Figure 11 As shown.

[0054] The responses in the three directions of motion showed significant differences. Figure 11 In the lateral swing motion shown, the maximum required thrust increases significantly with the increase of the diameter of the stiffener 133: when the diameter increases from 0 mm to 1.6 mm, the thrust required for a 30° lateral swing increases by approximately 1.55 times, and the two show an approximately linear relationship. This indicates that the stiffener 133 is the core source of the lateral swing constraint stiffness, and the constraint range of the joint's lateral swing motion can be customized over a wide range by adjusting the diameter of the stiffener 133. Figure 9 The buckling and Figure 10 During the extension motion, the change in the diameter of the stiffener 133 also leads to an increase in the required thrust. This result shows that, on the one hand, the coupling effect of the stiffener 133 on the flexion-extension motion cannot be ignored and needs to be considered in actual design; on the other hand, it also shows that by reasonably configuring the two independent structural parameters of the wall thickness of the arc region 132 and the diameter of the stiffener 133, the flexion-extension constraint and the lateral swing constraint can be decoupled and adjusted separately, thereby achieving independent customization of the constraint stiffness of the flexion-extension motion and the lateral swing motion.

[0055] Based on the above experimental results, the three sub-regions of the motion constraint region 13 exhibit a clear functional division: the wall thickness of the arc-shaped region 132 mainly adjusts the motion constraint in the flexion direction, while having a negligible impact on the extension direction; the pleated region 131 provides the main resistance in the extension direction through its crest structure, working together with the arc-shaped region 132 to achieve asymmetric constraints in both flexion and extension directions; the reinforcing rib 133 mainly provides constraint stiffness in the lateral swing direction, while changes in its diameter and modulus also have a certain regulatory effect on the flexion and extension directions. The three regions work together to achieve the design of the joint's motion constraint characteristics in the flexion, extension, and lateral swing directions, providing ample structural freedom for the customized design of biomimetic flexible joint constraint bodies.

[0056] Please see Figure 12 and Figure 13 This further explains the principles of perception.

[0057] Figure 12 and Figure 13 The curves showing the relationship between the rate of change of resistance and the joint motion angle, measured during the laboratory calibration phase of the embodiments of the present invention, are given respectively.

[0058] Figure 12This is a graph showing the rate of change of resistance in the first and second sensing areas as a function of the joint flexion-extension angle. The horizontal axis represents the joint flexion-extension angle, with the joint in its natural extended position defined as zero degrees. Angles bending towards the first side (flexion direction) are defined as positive angles, and angles bending towards the second side (extension direction) are defined as negative angles. The vertical axis represents the rate of change of resistance, defined as (current resistance value R - initial resistance value R0) / initial resistance value R0 × 100%. Sensor1 represents the response characteristics of the first sensing area, and Sensor 2 represents the response characteristics of the second sensing area. When the joint flexes positively from the zero position to the first side, the area sensed by the first sensing fiber 21 is in a compressed state, and its resistance change rate increases negatively (resistance decreases) as the flexion angle increases; the area sensed by the second sensing fiber 22 is in a stretched state, and its resistance change rate increases positively (resistance increases) as the flexion angle increases. Both curves maintain good monotonicity within the flexion range of 0° to 90°, and the resistance change rate and angle show an approximately linear relationship. When the joint extends negatively from the zero position to the second side, the deformation state of the area sensed by the first sensing fiber 21 causes its resistance change rate to increase positively, while the area sensed by the second sensing fiber 22 is in a compressed state. Its resistance change rate should have increased negatively, but due to the limiting effect of the folded area 131, the extension angle of the joint to the second side is limited to the range of 0° to -30°. Furthermore, the second sensing area is relatively thin, and the second sensing fiber 22 is not significantly compressed within this range, so its resistance change rate shows a positive increasing trend. After calibration, the correspondence between the resistance change rate of the two sensing fibers and the flexion-extension angle can be used to calculate the current flexion-extension angle and direction of motion of the joint in real time.

[0059] Figure 13 This is a graph showing the rate of change of resistance in the area sensed by the third sensing fiber 23 as a function of the joint's lateral swing angle. The horizontal axis represents the lateral swing angle, with zero degrees defined as the joint being in a neutral position, leftward swing defined as a positive angle, and rightward swing defined as a negative angle; the vertical axis represents the rate of change of resistance. The rate of change of resistance in the area sensed by the third sensing fiber 23 (Sensor 3) increases monotonically with increasing lateral swing angle. Within the lateral swing range of -20° to +20°, the curve exhibits good monotonicity and near-linearity. By adjusting the diameter and modulus of the reinforcing rib 133, the lateral constraint stiffness can be changed, and the slope of the curve also changes accordingly, thus achieving customized adjustment of the lateral swing sensing sensitivity. After calibration, this curve, combined with the outputs of the first sensing fiber 21 and the second sensing fiber 22, can be used to calculate the complete posture of the joint in three-dimensional space.

Claims

1. A biomimetic flexible joint constraint capable of sensing the joint configuration and motion state of a robot, characterized in that: It includes an elastic matrix (1) and three sets of intelligent flexible body sensing fibers (2); the intelligent flexible body sensing fibers (2) are embedded inside the elastic matrix (1); The elastic matrix (1) includes two axially fixed areas (11), two adaptive wrapping areas (12), and a motion constraint area (13); the two axially fixed areas (11) are respectively located at the two ends of the elastic matrix (1), and the inner sides of the two axially fixed areas (11) are respectively provided with a first buckle (111) and a second buckle (112) that protrude radially inward; the adaptive wrapping area (12) is axially located between the two axially fixed areas (11); The motion constraint area (13) is set between two adaptive wrapping areas (12), including a wrinkled area (131), an arc-shaped area (132) and several reinforcing ribs (133); the wrinkled area (131) is set on one side of the joint and has at least one wavy wrinkle distributed in the circumferential direction; the arc-shaped area (132) is set on the other side and has a smooth curved surface without wrinkles; the wall thickness of the arc-shaped area (132) is less than the wall thickness of the wrinkled area (131), and several reinforcing ribs (133) are located on both sides of the wrinkled area (131) and the arc-shaped area (132); The first sensing fiber (21) of the intelligent flexible body sensing fiber (2) is embedded in the wall of the elastic matrix (1) corresponding to the folded area (131), the second sensing fiber (22) is embedded in the wall of the elastic matrix (1) corresponding to the arc area (132), and there are several third sensing fibers (23), which are embedded in the wall of the elastic matrix (1) corresponding to the reinforcing rib (133).

2. The biomimetic flexible joint constraint body capable of sensing the joint configuration and motion state of a robot according to claim 1, characterized in that: The intelligent flexible body sensing fiber (2) is integrally molded and embedded inside the elastic matrix (1).

3. The biomimetic flexible joint constraint body capable of sensing the joint configuration and motion state of a robot according to claim 1, characterized in that: The elastic matrix (1) has a configuration that wraps around the joint and elastically connects adjacent limb segments; the resistance value of the intelligent flexible body sensing fiber (2) changes with its own deformation.

4. The biomimetic flexible joint constraint body capable of sensing robot joint configuration and motion state according to claim 1, characterized in that: The first buckle (111) and the second buckle (112) are configured to cooperate with the fixing structure on the corresponding limb segment.

5. The biomimetic flexible joint constraint body capable of sensing robot joint configuration and motion state according to claim 1, characterized in that: The elastic modulus and wall thickness of the arc-shaped region (132) are lower than those of the folded region (131), so that the axial tensile stiffness of the arc-shaped region (132) is less than the axial compressive stiffness of the folded region (131), and the axial tensile stiffness of the folded region (131) is greater than the axial compressive stiffness of the arc-shaped region (132), thereby achieving asymmetric motion constraint between the joint flexion direction and extension direction.

6. The biomimetic flexible joint constraint body capable of sensing robot joint configuration and motion state according to claim 1, characterized in that: The first sensing fiber (21), the second sensing fiber (22), and the third sensing fiber (23) are each provided with independent electrodes and leads for connecting external measurement circuits and calculation units, and can independently output their respective resistance change signals.

7. The biomimetic flexible joint constraint body capable of sensing the joint configuration and motion state of a robot according to claim 1, characterized in that: The reinforcing ribs (133) consist of two ribs, and the third sensing fiber (23) consists of one rib, which is embedded in the elastic matrix (1) wall corresponding to any one of the two reinforcing ribs (133).

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