A driving rope and robot system with force sensing capability

Abstract

The application provides a driving rope and mechanical hand system with force sensing capability, and belongs to the technical field of bionic mechanical hands. The system is composed of a tensile strain sensor and a driving rope. The tensile strain sensor is arranged on the surface of the driving rope and is bonded with the front section by using a flexible adhesive to be arranged in a mechanical hand. The tensile strain sensor and the driving rope are separated at the rear section. The separated driving rope is used for connecting a motor, and the tensile strain sensor is used for connecting a control system. In this way, the tensile strain of the driving rope can be measured in real time while power is transmitted, and the gripping force of a mechanical finger is obtained, so that the "sensing and driving integration" mode of a bionic tendon is realized.

Description

Technical Field

[0001] This invention belongs to the field of bionic dexterous hand driving and sensing technology. Background Technology

[0002] Human hands, with their dexterity, can easily perform various complex operations in daily life. Inspired by the human hand, an increasing number of bionic dexterous hands are being developed. Currently, bionic dexterous hands are generally composed of structures such as "finger joint structures," "palm structures," "finger-palm connection structures," and "bionic tendons." The joints are connected by joint connection devices, primarily hinge connections and flexible connections, allowing the joints to have the freedom of bending movement. The actuation of the fingers in bionic dexterous hands typically mimics the actuation of biological tendons, using high-strength fiber ropes as tendons. One end of the rope is connected to different joints, and the other end is connected to a motor. Controlling the motor's rotation drives the bionic finger. For robotic hands to perform complex human-like operations, real-time force feedback sensing information is crucial. This information can be used to sense the magnitude and distribution of force at the contact interface, identify the physical characteristics of the manipulated target, and assist in perceiving the external environment. Therefore, some advanced bionic dexterous hands integrate tactile sensors in the fingertips to provide force feedback. This is a common approach to achieving integrated actuation and sensing in robotic hands, significantly improving their intelligence and dexterity. Summary of the Invention

[0003] To improve the intelligence and dexterity of robotic arms, this invention proposes a novel force sensing method, differing from conventional approaches. Specifically, it proposes a force-sensing drive rope and a fingertip force sensing method. This force-sensing drive rope integrates a stress sensor, enabling real-time sensing of strain within the rope while simultaneously actuating the finger. The fingertip pressure is then calculated based on this strain. This achieves integrated sensing and actuation. Compared to traditional methods using tactile sensors, this invention offers advantages such as a simpler structure and lower cost. The specific technical solution adopted in this invention is as follows:

[0004] A force-sensing drive rope is provided, comprising a tensile strain sensor 100 and a drive rope 101. The tensile strain sensor 100 is composed of an outer encapsulation layer 102 and an inner substrate layer 103 and a conductive layer 104.

[0005] The substrate layer 103 is made of a material with good flexibility and resilience; the conductive layer 104 is made of a conductive material, which is selected from graphite, carbon nanotubes, graphene, copper nanowires or silver nanowires; the encapsulation layer 102 is made of polyurethane foam, silicone or epoxy resin, and the encapsulation layer wraps the substrate layer 103 and the conductive layer 104 inside.

[0006] Tensile strain sensor 100 is arranged on the surface of drive rope 101 and the front section is bonded together with a flexible adhesive for placement in robot arm 01. Tensile strain sensor 100 and drive rope 101 are separated at the rear section. The separated drive rope 101 is used to connect to motor 03, and tensile strain sensor 100 is used to connect to control system 04.

[0007] Preferably, the drive rope 101 is made of a high-strength material.

[0008] The method for preparing the force-sensing drive rope comprises the following steps:

[0009] I. Fabrication of a tensile strain sensor 100:

[0010] 1) A packaging layer 102 with a groove in the middle is cut out using laser cutting technology;

[0011] 2) Place the substrate layer 103 on one side of the encapsulation layer 102; then dissolve the conductive material in the dispersant, stir evenly to obtain a viscous conductive material ink, and use 3D printing to directly embed the viscous conductive material ink into the substrate layer 103 through the deposition nozzle. After drying, a conductive layer 104 is formed on the surface of the substrate layer 103.

[0012] 3) Place the other side of the encapsulation layer 102; heat and cure the encapsulation layer 102 to remove the gaps on both sides of the encapsulation layer 102;

[0013] 2. The tensile strain sensor 100 is arranged on the surface of the drive rope 101, and the front end is bonded together with a flexible adhesive to obtain the drive rope with force sensing capability.

[0014] The present invention also provides a robotic arm system with force sensing capability, the system comprising a robotic arm 01, a drive sensing integrated rope 02, a motor 03 and a control system 04; wherein the drive sensing integrated rope 02 is the drive rope with force sensing capability.

[0015] The robotic arm 01 serves as the main actuator, used to grip or hold objects. The integrated drive and sensing rope 02 is arranged on the pre-set finger surface and groove of the robotic arm 01. The integrated drive and sensing rope 02 separates outside the robotic arm 01, and the separated drive rope 101 is connected to the output end of the motor 03 to transmit the power of the motor 03 to the joints of the robotic arm 01 to drive the robotic arm 01 to move. The tensile strain sensor 100 is connected to the control system 04 to measure the tensile strain of the drive rope 101 and transmits the measured signal to the control system 04 to obtain the gripping force of the robotic fingers.

[0016] Preferably, the robotic arm 01 consists of multiple finger movement mechanisms and a palm mechanism. Each finger movement mechanism consists of a proximal joint 301, an intermediate joint 302, a distal joint 303, and a joint-palm connector 7. The joint-palm connector 7 consists of two connecting cylindrical holes and an outer palm connection part.

[0017] The first end joint 301 has a first cylindrical through hole 3011 at its lower part. The first cylindrical through hole 3011 is used to hinge with the second cylindrical through hole 3020 at the upper part of the intermediate joint 302, so as to ensure that the first end joint 301 and the intermediate joint 302 have rotational freedom at adjacent locations. The lower part of the intermediate joint 302 has a third cylindrical through hole 3021 that connects to the fourth cylindrical through hole 3030 at the upper part of the end joint 303. The fifth cylindrical through hole 3031 at the lower part of the end joint 303 connects to the connecting cylindrical hole of the joint and palm connector 7. The connection points on the inner side of each joint have oblique cut surfaces to prevent interference when the robotic hand fingers are bent.

[0018] Preferably, the first joint 301 has a top groove 3010 on its upper part, and the driving sensing integrated rope 02 is evenly and continuously arranged on the plane of the top groove 3010 and the inner side of the finger. The top groove 3010 is used to limit the driving sensing integrated rope 02. The first joint 301 has a first groove 3012 at its center, the middle joint 302 has a second groove 3022 at its center, and the end joint 303 has a third groove 3032 at its center. The first groove 3012, the second groove 3022, and the third groove 3032 are used to limit and transition the driving sensing integrated rope 02.

[0019] Preferably, the depths of the first groove 3012, the second groove 3022, and the third groove 3032 are greater than the thickness of the integrated driving and sensing rope 02.

[0020] Preferably, the first joint 301, the middle joint 302, and the last joint 303 are elliptical cylinders, and the curvature of the inner surface is less than that of the outer surface.

[0021] The beneficial effects of this invention are:

[0022] 1. The integrated drive-sensing rope in this invention differs from traditional flexible drive ropes. It integrates the drive rope with a force sensor. When the drive rope is stretched, the tension sensor stretches along with the drive rope and transmits the tensile strain to the control system in the form of an electrical signal. The control system calculates the tension of the drive rope based on the tensile strain. The integrated drive-sensing rope transmits the tension to the fingers of the robotic hand, and the force on the fingers is then transmitted to the object. Therefore, the pressure at the interface between the finger and the external environment can be sensed by the tensile strain. The data is used to determine the required force for the robotic finger, and then the output torque of the motor is adjusted to precisely control the robotic finger, achieving an integrated sensing and drive mechanism for bionic tendons. Furthermore, the integrated drive-sensing rope has minimal impact on the overall system and does not require additional redundant structures.

[0023] 2. The finger structure in this invention is elliptical cylindrical in shape, with a slightly flattened inner curved surface and a small curvature. This design aims to increase the contact area after the mechanical finger grips an object, thereby increasing the gripping force. Each joint has a beveled cut at its inner connection point to ensure that the angle between adjacent finger joints decreases when the mechanical finger bends, preventing interference at the connection points and ensuring normal bending. A groove is provided at the center of the finger surface, through which a drive rope integrating drive and sensing is connected. The groove restricts the rope's movement, allowing it to slide only within the groove, ensuring it remains centered and guaranteeing control precision. A cylindrical through-hole is provided at the end of each finger joint structure for hinged connection to the end of the next joint, ensuring accurate finger bending movement. Attached Figure Description

[0024] Figure 1 This is an assembly drawing of the robotic arm system.

[0025] Figure 2 Cross-sectional view of the driving sensing integrated rope.

[0026] Figure 3 This is a cross-sectional view of a tensile strain sensor.

[0027] Figure 4 The inside of the exploded view of a single-finger system structure.

[0028] Figure 5 The outer side of the exploded view of a single finger system structure. Detailed Implementation

[0029] The technical solution of the present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments.

[0030] like Figure 1As shown, this embodiment provides a robotic arm system with force sensing capability. The system mainly includes a robotic arm 01, a drive and sensing integrated rope 02, a motor 03, and a control system 04.

[0031] The robotic arm 01 serves as the main actuator, used to grip or hold objects. The integrated drive and sensing rope 02 transmits the motor's power to the joints and also measures the tensile strain of the drive rope to reflect the gripping force of the robotic fingers.

[0032] like Figure 2 As shown, the integrated drive and sensing rope 02 comprises two parts: a tensile strain sensor 100 and a drive rope 101. The drive rope 101 is arranged on the surface of a pre-set finger of the robotic arm or in a groove. The tensile strain sensor 100 is arranged on the surface of the drive rope 101, and the tensile strain sensor 100 faces outward of the robotic arm. The tensile strain sensor 100 can be connected to the drive rope 101 using a flexible adhesive or similar material, thereby integrating the tensile strain sensor 100 and the drive rope 101 together to obtain the integrated drive and sensing rope 02.

[0033] The tensile strain sensor 100, which is wrapped around the drive rope 101 on the surface of the integrated drive and sensing rope 02, can sense the tensile strain of the drive rope 101. When the robotic hand's fingers exert force on the outside, the greater the force, the greater the pull of the drive rope 101, and the greater its strain. Since the sensor and rope are integrated, the strain of the sensor also changes, and the electronic arrangement inside the sensor changes. The strain signal is converted into an electrical signal and transmitted to the control system. The control system calculates the force on the finger through the strain signal and changes the torque output of the drive motor, thereby realizing real-time adjustment of the gripping force of the robotic hand.

[0034] like Figure 3 As shown, the tensile strain sensor 100 consists of an outer encapsulation layer 102 and an inner substrate layer 103 and conductive layer 104. The substrate layer 103 should be made of a material with good flexibility and resilience, such as SEBS, PDMS, or rubber, avoiding traditional materials like ceramics and glass. The conductive layer 104 is made of materials such as carbon nanotubes, which are lightweight, have good conductivity, and good mechanical properties. The encapsulation layer 102 is made of materials such as polyurethane foam, silicone, or epoxy resin, encapsulating the substrate layer 103 and conductive layer 104.

[0035] In the fabrication process, the encapsulation layer 102 is first cut out using laser cutting technology, and the substrate layer 102 is placed on one side of the encapsulation layer 102. Then, conductive materials such as carbon nanotubes are dissolved in a dispersant, stirred evenly, and 3D printed to directly embed the viscous nanomaterial ink into the elastic membrane through a deposition nozzle. After drying, a conductive layer 104 is formed on the surface of the substrate layer 103, and then the other side of the encapsulation layer 102 is placed. The encapsulation layer 102 is then heated and cured to remove the gap between the two encapsulation layers 102. The tensile strain sensor fabricated using this process can achieve a tensile rate of up to 400%, sufficient to sense the strain of the driving rope.

[0036] In this invention, the drive rope 101 should be made of a high-strength material to facilitate the mechanical movement of the mechanical finger.

[0037] The robotic hand 01 consists of multiple finger movement mechanisms and a palm mechanism, such as... Figures 4-5 As shown, each finger movement mechanism consists of a proximal joint 301, an intermediate joint 302, a distal joint 303, and a joint-palm connector 7.

[0038] The proximal joint 301, intermediate joint 302, and distal joint 303 are elliptical cylinders, with the curvature of the inner surface being less than that of the outer surface. The inner surface of the finger structure is slightly flat with a smaller curvature, designed to increase the contact area after the mechanical finger grips an object, thereby increasing the gripping force.

[0039] The first end joint 301 has a first cylindrical through hole 3011 at its lower part. The first cylindrical through hole 3011 is used to hinge with the second cylindrical through hole 3020 at the upper part of the intermediate joint 302, thereby ensuring that the first end joint 301 and the intermediate joint 302 have rotational freedom at adjacent locations. Similarly, the lower part of the intermediate joint 302 has a third cylindrical through hole 3021 that connects to the fourth cylindrical through hole 3030 at the upper part of the end joint 303, and the lower part of the end joint 303 has a fifth cylindrical through hole 3031 that connects to the connecting cylindrical hole of the joint and palm connector 7.

[0040] The connection points on the inner side of each joint have oblique cut surfaces. The purpose is to ensure that when the mechanical finger bends, the angle between the adjacent finger joint structures becomes smaller, the connection points are not obstructed, and there is no interference, so that the mechanical finger can bend normally.

[0041] The head joint 301 has a top groove 3010 on its upper part. The integrated driving and sensing rope 02 is evenly and continuously arranged on the plane of the top groove 3010 and the inner side of the finger. The top groove 3010 is used to limit and reverse the transition of the integrated driving and sensing rope 02. A pulley can also be used for the transition at the top, but this embodiment does not limit this.

[0042] The outer part of the finger, such as Figure 5As shown, the first joint 301 has a first groove 3012 at its center, the middle joint 302 has a second groove 3022 at its center, and the end joint 303 has a third groove 3032 at its center. The first groove 3012, the second groove 3022, and the third groove 3032 are used to limit and transition the integrated drive and sensing rope 02. Since the robotic hand fingers do not bend outward, the depth of the first groove 3012, the second groove 3022, and the third groove 3032 on the outside can be greater than the thickness of the rope, ensuring that the rope is inside the groove and thus protecting the rope.

[0043] The outer side of the joint and palm connector 7 is provided with a cylindrical protrusion 7010 for connecting with the groove corresponding to the palm position, which functions similarly to a hinge, giving the finger system as a whole the freedom of left and right movement, increasing the flexibility of the entire finger system. This allows the individual joints of the entire finger to not only bend, but also to move left and right as a whole.

[0044] It should be noted that the above embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A robotic arm system with force sensing capability, characterized in that, The system includes a robotic arm (01), a drive and sensing integrated rope (02), a motor (03), and a control system (04). Among them, the integrated driving and sensing rope (02) consists of a tensile strain sensor (100) and a driving rope (101); the tensile strain sensor (100) is arranged on the surface of the driving rope (101) and is bonded together with a flexible adhesive. The tensile strain sensor (100) consists of an outer encapsulation layer (102) and an inner substrate layer (103) and conductive layer (104); the substrate layer (103) is made of a material with good flexibility and resilience; the conductive layer (104) is made of a conductive material selected from graphite, carbon nanotubes, graphene, copper nanowires or silver nanowires; the encapsulation layer (102) is made of polyurethane foam, silicone or epoxy resin, and the encapsulation layer wraps the substrate layer (103) and the conductive layer (104) inside; The robotic hand (01) serves as the main actuator for gripping or holding objects. The integrated drive and sensing rope (02) is arranged on the finger surface and groove of the robotic hand (01) in a pre-set manner. The integrated drive and sensing rope (02) is separated outside the robotic hand (01). The separated drive rope (101) is connected to the output end of the motor (03) to transmit the power of the motor (03) to the joints of the robotic hand (01) to drive the robotic hand (01) to move. The tensile strain sensor (100) is connected to the control system (04) to measure the tensile strain of the drive rope (101) and transmit the measured signal to the control system (04) to obtain the gripping force of the robotic fingers.

2. The robotic arm system with force sensing capability according to claim 1, characterized in that, The drive rope (101) is made of a high-strength material.

3. The robotic arm system with force sensing capability according to claim 1, characterized in that, The preparation steps of the integrated driving and sensing rope (02) are as follows: I. Fabrication of a tensile strain sensor (100): 1) A packaging layer with a groove in the middle is cut out using laser cutting technology (102); 2) Place the substrate layer (103) on one side of the encapsulation layer (102); then dissolve the conductive material in the dispersant, stir evenly to obtain a viscous conductive material ink, and use 3D printing to directly embed the viscous conductive material ink into the substrate layer (103) through the deposition nozzle. After drying, a conductive layer (104) is formed on the surface of the substrate layer (103). 3) Place the other side of the encapsulation layer (102); heat and cure the encapsulation layer (102) to remove the gaps on both sides of the encapsulation layer (102); 2. The tensile strain sensor (100) is placed on the surface of the drive rope (101), and the front end is bonded together with a flexible adhesive to obtain the drive sensing integrated rope (02).

4. The robotic arm system with force sensing capability according to claim 1, characterized in that, The robotic arm (01) consists of multiple finger movement mechanisms and a palm mechanism. Each finger movement mechanism consists of a proximal joint (301), an intermediate joint (302), a distal joint (303), and a joint-palm connector (7). The joint-palm connector (7) consists of two connecting cylindrical holes and an outer palm connection part. The first end joint (301) has a first cylindrical through hole (3011) at its lower part. The first cylindrical through hole (3011) is used to hinge with the second cylindrical through hole (3020) at the upper part of the intermediate joint (302) to ensure that the first end joint (301) and the intermediate joint (302) have a degree of freedom of rotation at adjacent locations. The lower part of the intermediate joint (302) has a third cylindrical through hole (3021) that connects to the fourth cylindrical through hole (3030) at the upper part of the end joint (303). The lower part of the end joint (303) has a fifth cylindrical through hole (3031) that connects to the cylindrical hole connecting the joint and the palm connector (7). The connection points on the inner side of each joint have oblique cut surfaces to prevent interference when the robotic hand fingers are bent.

5. The robotic arm system with force sensing capability according to claim 4, characterized in that, The first joint (301) has a top groove (3010) on its upper part. The driving sensing integrated rope (02) is evenly and continuously arranged on the plane of the top groove (3010) and the inner side of the finger. The top groove (3010) is used to limit the driving sensing integrated rope (02). The first joint (301) has a first groove (3012) at its center, the middle joint (302) has a second groove (3022) at its center, and the end joint (303) has a third groove (3032) at its center. The first groove (3012), the second groove (3022) and the third groove (3032) are used to limit and transition the driving sensing integrated rope (02).

6. The robotic arm system with force sensing capability according to claim 5, characterized in that, The depths of the first groove (3012), the second groove (3022), and the third groove (3032) are greater than the thickness of the integrated driving and sensing rope (02).

7. The robotic arm system with force sensing capability according to claim 4, characterized in that, The first joint (301), the middle joint (302), and the last joint (303) are elliptical cylinders, and the curvature of the inner surface is less than that of the outer surface.

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