Driving rope with force sensing capability and manipulator system

Abstract

The invention provides a driving rope with force sensing capacity and a mechanical arm system, and belongs to the technical field of bionic mechanical arms, the driving rope 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 the front section of the tensile strain sensor is bonded into a whole through glue with the flexible characteristic to be arranged in a mechanical arm; the tensile strain sensor and the driving rope are separated at the rear section, the separated driving rope is used for being connected with a motor, and the tensile strain sensor is used for being connected to a control system, so that the tensile strain of the driving rope can be measured in real time while power is transmitted, and then the gripping force of the mechanical finger is obtained; and a sensing and driving integrated mode of the bionic tendon is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of bionic dexterous hand driving and sensing. Background Art

[0002] Human hands, with their dexterity, enable us to easily perform a variety of complex manipulations in daily life. Inspired by the human hand, a growing number of bionic dexterous hands have been developed. Currently, bionic dexterous hands are generally composed of structures such as "finger joints," "palm structure," "finger-palm connection," and "bionic tendons." Joints are connected through joint connections, primarily through hinges and flexible connections, allowing the joints to flex freely. The actuation of the fingers of bionic dexterous hands often mimics biological tendon actuation, using high-strength fiber cables acting as tendons. One end of the cable connects to different joints, and the other end connects to a motor. The motor's rotation is controlled to actuate the bionic fingers. For robotic hands to perform complex, human-like manipulations, real-time force feedback sensing is crucial. It can be used to detect the magnitude and distribution of force at the contact interface, identify the physical properties of the manipulated object, and assist in sensing the external environment. To this end, some advanced bionic dexterous hands integrate tactile sensors at the fingertips to provide force feedback. This is a common approach to integrating actuation and perception in robotic hands, significantly improving their intelligence and dexterity. Summary of the Invention

[0003] To improve the intelligence and dexterity of the manipulator, the present invention proposes a new force sensing method that differs from conventional approaches, namely, a force-sensing drive rope and a fingertip force sensing method. The force-sensing drive rope is integrated with a stress sensor, which can sense the strain inside the rope in real time while driving the finger, and calculate the fingertip pressure based on the strain inside the rope. This achieves integrated sensing and driving. Compared with the traditional method of using tactile sensors, the present invention has the advantages of simple structure and low cost. The technical solutions adopted by the present invention are as follows: A force-sensing driving rope comprises a tensile strain sensor 100 and a driving rope 101. The tensile strain sensor 100 comprises an outer packaging layer 102 and an inner base layer 103 and a conductive layer 104. The base 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 a material selected from polyurethane sponge, silicone, or epoxy resin, and the encapsulation layer encapsulates the base layer 103 and the conductive layer 104; The tensile strain sensor 100 is arranged on the surface of the driving rope 101, and the front section is bonded together with glue with flexible properties for arrangement in the manipulator 01. The tensile strain sensor 100 and the driving rope 101 are separated at the rear section. The separated driving rope 101 is used to connect to the motor 03, and the tensile strain sensor 100 is used to connect to the control system 04.

[0004] Preferably, the drive rope 101 is made of a material with high strength.

[0005] The method for preparing the driving rope with force sensing capability comprises the following steps: 1. Preparation of tensile strain sensor 100: 1) Using a laser cutting process to cut out the packaging layer 102 with a groove in the middle; 2) Placing a base layer 103 on one surface of the encapsulation layer 102; then dissolving a conductive material in a dispersant and stirring evenly to obtain a viscous conductive material ink; using a 3D printing method, the viscous conductive material ink is directly embedded into the base layer 103 through a deposition nozzle; and after drying, a conductive layer 104 is formed on the surface of the base layer 103; 3) placing the encapsulation layer 102 on the other side; heating and curing the encapsulation layer 102 to remove gaps on both sides of the encapsulation layer 102; Second, the tensile strain sensor 100 is arranged on the surface of the driving rope 101, and the front section is bonded together with a flexible glue to obtain the driving rope with force sensing capability.

[0006] The present invention also provides a manipulator system with force sensing capability, which includes a manipulator 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; Among them, the manipulator 01 serves as the main actuator, used to clamp or hold objects; the drive-sensing integrated rope 02 is arranged on the pre-set finger surface and groove of the manipulator 01, and the drive-sensing integrated rope 02 is separated outside the manipulator 01. The separated drive rope 101 is connected to the output end of the motor 03, which is used to transmit the power of the motor 03 to the joint of the manipulator 01 to drive the manipulator 01 to move; the tensile strain sensor 100 is connected to the control system 04, measures 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 manipulator finger.

[0007] Preferably, the manipulator 01 is composed of multiple finger motion mechanisms and palm mechanisms, each finger motion mechanism is composed of a head joint 301, an intermediate joint 302, a terminal joint 303 and a joint and palm connecting member 7; the joint and palm connecting member 7 is composed of two connecting cylindrical holes and an outer palm connecting portion; The head joint 301 is provided with a first cylindrical through hole 3011 at the lower part, and the first cylindrical through hole 3011 is used to be hinged with the second cylindrical through hole 3020 at the upper part of the middle joint 302, so as to ensure that the head joint 301 and the middle joint 302 have the freedom of rotation at adjacent positions; the lower part of the middle joint 302 is provided with a third cylindrical through hole 3021 connected to the fourth cylindrical through hole 3030 at the upper part of the end joint 303, and the fifth cylindrical through hole 3031 at the lower part of the end joint 303 is connected to the connecting cylindrical hole of the joint and the palm connecting piece 7; the connection on the inner side of each joint is provided with an oblique cutting surface to prevent interference between the fingers of the manipulator when bending.

[0008] Preferably, the head end joint 301 is provided with a top groove 3010 at the upper part, and the drive sensing integrated rope 02 is evenly and continuously arranged on the top groove 3010 and the plane on the inner side of the finger, and the top groove 3010 is used to limit the drive sensing integrated rope 02; the head end joint 301 is provided with a first groove 3012 at the center, the middle joint 302 is provided with a second groove 3022 at the center, and the end joint 303 is provided with a third groove 3032 at the center, and the first groove 3012, the second groove 3022 and the third groove 3032 are used to limit and transition the drive sensing integrated rope 02.

[0009] Preferably, the depths of the first groove 3012 , the second groove 3022 and the third groove 3032 are greater than the thickness of the driving sensing integrated rope 02 .

[0010] Preferably, the first end joint 301 , the middle joint 302 and the terminal joint 303 are elliptical cylinders, and the curvature of the inner curved surface is smaller than that of the outer curved surface.

[0011] Beneficial effects of the present invention: 1. The integrated drive-sensing rope in this invention differs from traditional flexible drive ropes in that it integrates a drive rope with a force sensor. When the drive rope stretches, the stretch 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 in the drive rope based on the tensile strain. The integrated drive-sensing rope then transmits the tension to the manipulator's fingers, which then transmit the force to the object. Therefore, the tensile strain can be used to sense the pressure at the interface between the fingers and the outside world. This data can be used to determine the force required by the manipulator's fingers, and the motor's output torque can be adjusted to precisely control the manipulator, achieving a "sensing-drive integration" approach similar to that of bionic tendons. Furthermore, the integrated drive-sensing rope has minimal impact on the overall system, eliminating the need for additional redundant structures.

[0012] 2. The finger structure in the present invention is in the shape of an elliptical cylinder. The inner surface of the finger structure is slightly flat and has a small curvature, which is intended to increase the contact area of ​​the mechanical finger after gripping an object, thereby increasing the gripping force. There is an oblique cutting surface at the connection on the inner side of each joint, the purpose of which is to ensure that when the mechanical finger is bent, the angle between the adjacent finger joint structures becomes smaller, the connection is avoided, and no interference occurs, thereby ensuring that the mechanical finger can bend normally. A groove is provided at the center of the finger surface, and the groove is connected to the driving rope with integrated driving sensing. The groove can limit the position of the rope movement, and the driving sensing rope can only slide inside the groove, ensuring that the position of the driving sensing rope is always in the center, thereby ensuring control accuracy. A cylindrical through hole is provided at the end of the finger joint structure, the purpose of which is to be connected to the end of the next joint in a hinged manner, thereby ensuring that the finger can bend accurately. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Assembly drawing of the robotic system.

[0014] Figure 2 Cross-sectional view of the drive-sensing integrated rope.

[0015] Figure 3 Cross-sectional view of the tensile strain sensor.

[0016] Figure 4 This is the inside of the exploded diagram of a single finger system structure.

[0017] Figure 5 This is the outside of the exploded diagram of a single finger system structure. DETAILED DESCRIPTION

[0018] The technical solution of the present invention will be further explained and illustrated in the following in the form of specific embodiments with reference to the accompanying drawings.

[0019] like Figure 1As shown, this embodiment provides a manipulator system with force sensing capability, which mainly includes a manipulator 01, a drive-sensing integrated rope 02, a motor 03 and a control system 04.

[0020] The robot hand 01 is the main actuator, used to grip or hold objects. The drive-sensing integrated rope 02 is used to transmit the power of the motor to the joint and also measures the tensile strain of the drive rope to reflect the gripping force of the robot finger.

[0021] like Figure 2 As shown, the drive-sensing integrated rope 02 comprises two parts: a tensile strain sensor 100 and a drive rope 101. The drive rope 101 is placed on the surface or in a groove of a pre-set finger of the manipulator. The tensile strain sensor 100 is arranged on the surface of the drive rope 101, facing the outside of the manipulator. The tensile strain sensor 100 can be connected to the drive rope 101 using a flexible glue or the like, thereby integrating the tensile strain sensor 100 and the drive rope 101 to form the drive-sensing integrated rope 02.

[0022] The tensile strain sensor 100 wrapped around the driving rope 101 on the surface of the driving sensing integrated rope 02 can sense the tensile strain of the driving rope 101; when the manipulator finger exerts a force on the outside world, the greater the force, the greater the amount of pulling the driving rope 101, and its strain also increases accordingly. Since the sensor and the rope are integrated into one, the strain of the sensor also changes accordingly, and the internal electronic arrangement of the sensor changes, and the strain signal is converted into an electrical signal and transmitted to the control system. The control system calculates the force applied to the finger through the strain signal to change the torque output by the driving motor, thereby realizing real-time adjustment of the gripping force of the manipulator.

[0023] like Figure 3 As shown, the tensile strain sensor 100 consists of an outer encapsulation layer 102 and an inner base layer 103 and conductive layer 104. Base layer 103 should be made of a material with good flexibility and resilience, such as SEBS, PDMS, or rubber, rather than traditional ceramics or glass. Conductive layer 104 should be made of materials such as carbon nanotubes, which offer both lightweight and excellent conductivity and superior mechanical properties. Encapsulation layer 102 is made of materials such as polyurethane sponge, silicone, or epoxy resin, encapsulating base layer 103 and conductive layer 104.

[0024] During fabrication, the encapsulation layer 102 is first cut using a laser cutting process, and the base layer 102 is placed on one side of the encapsulation layer 102. A conductive material, such as carbon nanotubes, is then dissolved in a dispersant and stirred evenly. A viscous nanomaterial ink is then deposited directly into the elastic membrane using a 3D printing method through a deposition nozzle. After drying, a conductive layer 104 is formed on the surface of the base layer 103, and the encapsulation layer 102 is then placed on the other side. The encapsulation layer 102 is then heated and cured to remove gaps between the two sides. This tensile strain sensor can achieve a stretch ratio of 400%, sufficient to sense the strain of the actuating cable.

[0025] In the present invention, the driving rope 101 should be made of high-strength material to facilitate supporting the mechanical movement of the robotic finger.

[0026] The manipulator 01 is composed of multiple finger motion mechanisms and palm mechanisms, such as Figure 4~Figure 5 As shown, each finger movement mechanism consists of a head joint 301 , a middle joint 302 , a terminal joint 303 and a joint and palm connecting piece 7 .

[0027] The first joint 301, the middle joint 302, and the terminal joint 303 are elliptical cylinders, with the inner surface having a smaller curvature than the outer surface. The slightly flat inner surface of the finger structure is designed to increase the contact area when the mechanical finger grasps an object, thereby increasing the gripping force.

[0028] The head joint 301 has a first cylindrical through-hole 3011 at its lower portion, which is used to articulate with the second cylindrical through-hole 3020 at the upper portion of the middle joint 302, thereby ensuring that the head joint 301 and the middle joint 302 have rotational freedom when adjacent to each other. Similarly, the middle joint 302 has a third cylindrical through-hole 3021 at its lower portion, which connects to the fourth cylindrical through-hole 3030 at the upper portion of the end joint 303. The fifth cylindrical through-hole 3031 at the lower portion of the end joint 303 connects to the cylindrical hole connecting the joint to the palm connector 7.

[0029] The connection points on the inner side of each joint are provided with oblique cutting surfaces. The purpose is to ensure that when the robotic finger bends, the angle between the adjacent finger joint structures becomes smaller, the connection points are avoided, and no interference occurs, ensuring that the robotic finger can bend normally.

[0030] The head joint 301 has a top groove 3010 at its upper portion. The drive-sensing integrated rope 02 is evenly and continuously arranged on the top groove 3010 and the plane inside the finger. The top groove 3010 is used to limit the position of the drive-sensing integrated rope 02 and to provide reverse transition. A pulley transition can also be used for top transition, but this embodiment does not limit this.

[0031] The outer part of the finger Figure 5As shown, the first end joint 301 is provided with a first groove 3012 at the center, the middle joint 302 is provided with a second groove 3022 at the center, and the end joint 303 is provided with a third groove 3032 at the center. The first groove 3012, the second groove 3022 and the third groove 3032 are used to limit and transition the drive-sensing integrated rope 02. Since the manipulator fingers will 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, which can protect the rope.

[0032] The outer side of the joint-to-palm connection 7 is provided with a cylindrical protrusion 7010 for connecting with a groove corresponding to the palm position, functioning like a hinge, allowing the entire finger system to swing freely in the left and right directions, thereby increasing the flexibility of the entire finger system. This allows the individual joints of the entire finger to not only bend, but also to swing left and right as a whole.

[0033] It should be noted that the above embodiments are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the contents of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

Claims

1. A driving rope with force sensing capability, characterized in that: A manipulator driving rope with force sensing capability is composed of a tensile strain sensor (100) and a driving rope (101), wherein the tensile strain sensor (100) is composed of an outer packaging layer (102) and an inner base layer (103) and a conductive layer (104); The base 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 packaging layer (102) is made of a material selected from polyurethane sponge, silicone or epoxy resin, and the packaging layer wraps the base layer (103) and the conductive layer (104); The tensile strain sensor (100) is arranged on the surface of the driving rope (101), and the front section is bonded together into one piece using glue having flexible properties for arrangement in the manipulator (01). The tensile strain sensor (100) and the driving rope (101) are separated at the rear section. The separated driving rope (101) is used to connect to the motor (03), and the tensile strain sensor (100) is used to connect to the control system (04).

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

3. The method for preparing a driving rope with force sensing capability according to claim 1, characterized in that: The steps of this method are as follows:

1. Preparation of tensile strain sensor (100): 1) using a laser cutting process to cut out a packaging layer (102) with a groove in the middle; 2) placing a base layer (103) on one side of the encapsulation layer (102); then dissolving a conductive material in a dispersant, stirring evenly to obtain a viscous conductive material ink, and using a 3D printing method to directly embed the viscous conductive material ink into the base layer (103) through a deposition nozzle, and forming a conductive layer (104) on the surface of the base layer (103) after drying; 3) placing the packaging layer (102) on the other side; heating and curing the packaging layer (102) to remove gaps on both sides of the packaging layer (102); Second, the tensile strain sensor (100) is arranged on the surface of the driving rope (101), and the front section is bonded together with a flexible glue to obtain the manipulator driving rope with force sensing capability.

4. A manipulator system with force sensing capability, characterized in that: The system comprises a manipulator (01), a driving and sensing integrated rope (02), a motor (03) and a control system (04); wherein the driving and sensing integrated rope (02) is the driving rope with force sensing capability as described in claim 1; The manipulator (01) serves as a main actuator for gripping or holding an object; the driving sensing integrated rope (02) is arranged on the finger surface and groove of the pre-set manipulator (01); the driving sensing integrated rope (02) is separated outside the manipulator (01); the separated driving rope (101) is connected to the output end of the motor (03) for transmitting the power of the motor (03) to the joint of the manipulator (01) to drive the manipulator (01) to move; the tensile strain sensor (100) is connected to the control system (04) to measure the tensile strain of the driving rope (101), and transmit the measured signal to the control system (04) to obtain the gripping force of the manipulator finger.

5. The manipulator system with force sensing capability according to claim 4, characterized in that: The manipulator (01) is composed of a plurality of finger motion mechanisms and a palm mechanism, each finger motion mechanism being composed of a head end joint (301), an intermediate joint (302), a terminal joint (303), and a joint and palm connecting member (7); the joint and palm connecting member (7) being composed of two connecting cylindrical holes and an outer palm connecting portion; The first end joint (301) is provided with a first cylindrical through hole (3011) at the bottom, and the first cylindrical through hole (3011) is used to be hinged with the second cylindrical through hole (3020) at the top of the middle joint (302), so as to ensure that the first end joint (301) and the middle joint (302) have rotational freedom at adjacent positions; the middle joint (302) is provided with a third cylindrical through hole (3021) at the bottom, which is connected to the fourth cylindrical through hole (3030) at the top of the end joint (303); the fifth cylindrical through hole (3031) at the bottom of the end joint (303) is connected to the connecting cylindrical hole of the joint and palm connecting piece (7); the connection on the inner side of each joint is provided with an oblique cutting surface to prevent interference between the fingers of the manipulator when bending.

6. The manipulator system with force sensing capability according to claim 5, characterized in that: The head end joint (301) is provided with a top groove (3010) at the top, and the driving sensing integrated rope (02) is evenly and continuously arranged on the top groove (3010) and the plane of the inner side of the finger, and the top groove (3010) is used to limit the driving sensing integrated rope (02); the head end joint (301) is provided with a first groove (3012) at the center, the middle joint (302) is provided with a second groove (3022) at the center, and the end joint (303) is provided with a third groove (3032) at the center, and 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).

7. The manipulator system with force sensing capability according to claim 6, 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 driving and sensing integrated rope (02).

8. The manipulator system with force sensing capability according to claim 5, characterized in that: The first end joint (301), the middle joint (302), and the terminal joint (303) are elliptical cylinder-shaped, and the curvature of the inner curved surface is smaller than that of the outer curved surface.

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