Displacement sensing device and artificial muscle system

Abstract

The invention discloses a displacement sensing device and an artificial muscle system.The displacement sensing device is provided with a fixing frame, a rotation angle measuring rotating part, a rope body, a rotation angle measuring assembly and a turn number measuring module, the rotation angle measuring rotating part is rotationally connected to the fixing frame, one end of the rope body is wound around the rotation angle measuring rotating part, and the other end of the rope body is wound around the turn number measuring module; the other end of the rope body can be connected with pneumatic muscles, when the pneumatic muscles act, the pneumatic muscles can drive the rotation angle measurement rotating piece to rotate under the traction of the rope body, in the rotation process of the rotation angle measurement rotating piece, the rotation angle measurement assembly measures the rotation angle of the rotation angle measurement rotating piece relative to the zero point, and the turn number measurement module measures the number of turns of rotation of the rotation angle measurement rotating piece. By combining the number of rotation turns and the rotation angle of the rotation angle measurement rotating piece, the length led out by the rope body can be finally obtained, and therefore accurate measurement of the displacement elongation of the pneumatic muscle is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of displacement measurement, and in particular to a displacement sensing device and an artificial muscle system. Background Art

[0002] Displacement sensors are devices used to measure the position change of an object. They can convert mechanical displacement into electrical signals. They are widely used in many fields such as industrial automation, building structure monitoring, medical health, automotive engineering, etc. In order to achieve precise control of the joints of pneumatic robots, it is necessary to know the length of the pneumatic muscles. For this purpose, it is necessary to use a displacement sensor to measure the length change of the pneumatic muscles.

[0003] Displacement sensors mainly include resistive displacement sensors and rope displacement sensors. Resistive displacement sensors use the change in resistance value generated by metal materials when stretched or compressed to monitor the position change of an object. The sensor is easy to wear and difficult to measure the length of flexible materials; rope displacement sensors are a device used to measure linear motion. It is connected to a moving object through a flexible rope. When the object moves, the rope is pulled, thereby driving the internal reel to rotate. The reel is connected to an encoder to determine the displacement based on the rotation angle, but because the number of rotations cannot be determined, it is difficult to measure displacement over long distances.

[0004] Pneumatic muscles are flexible displacements over longer distances. Due to the limitations of the measurement range of the above-mentioned displacement sensors, it is difficult to apply them to pneumatic muscles to accurately measure the elongation of pneumatic muscles, which causes inconvenience to the joint control of pneumatic robots. Summary of the invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies and to provide a displacement sensing device to solve the technical problem that the displacement sensors in the prior art are difficult to accurately measure the elongation of pneumatic muscles.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a displacement sensing device, comprising: Fixed frame; An angle measuring rotating member, rotatably connected to the fixed frame; A rope body, one end of which is wound around the angle measuring rotating member; An angle measuring component, connected to the fixing frame, for measuring the angle of the angle measuring rotating member; A revolution measurement module, wherein the revolution measurement module comprises a revolution measurement rotating member and a revolution measurement unit, wherein the revolution measurement rotating member is rotationally connected to the fixed frame and is transmission-connected to the rotation angle measurement rotating member, and the angular velocity of the revolution measurement rotating member is less than the angular velocity of the rotation angle measurement rotating member, and the revolution measurement unit is connected to the fixed frame and is used to measure the number of revolutions of the rotation angle measurement rotating member.

[0007] In some embodiments, the turn measurement module includes a turn measurement rotating member and a turn measurement unit. The turn measurement rotating member is rotatably connected to the fixed frame and connected to the angle measurement rotating member, and rotates synchronously through the drive of the angle measurement rotating member. The angle of the turn measurement rotating member is smaller than the angle of the angle measurement rotating member. The turn measurement unit is used to measure the angle of the turn measurement rotating member.

[0008] In some embodiments, the rotation number measuring rotating member includes a first rotating shaft and a first gear, the first rotating shaft is rotatably connected to the fixed frame, and the first gear is fixedly sleeved on the first rotating shaft. The rotation angle measuring rotating member includes a second rotating shaft and a second gear, the second rotating shaft is rotatably connected to the fixed frame, the second gear is fixedly sleeved on the second rotating shaft and meshes with the first gear, and the tooth diameter of the second gear is smaller than the tooth diameter of the first gear.

[0009] In some embodiments, the number of turns measuring unit includes a first magnet and a first encoder, the first magnet is fixed to the end of the first rotating shaft, and the first encoder is located on one side of the first magnet and is used to measure the rotation angle of the first magnet.

[0010] In some embodiments, the rotation angle measurement component includes a second magnet and a second encoder, the second magnet is fixed to the end of the second shaft, and the second encoder is located on one side of the second magnet for measuring the rotation angle of the second magnet.

[0011] In some embodiments, the rotation angle measuring rotating member further includes a winding portion, the winding portion is fixedly sleeved on the second rotating shaft, and the rope body is wound around the winding portion.

[0012] In some embodiments, a radius of the winding portion is greater than a radius of the second gear and smaller than a radius of the first gear.

[0013] In some embodiments, the displacement sensing device further includes a coil spring, which is mounted on the fixing frame and connected to the rotation angle measuring rotating member.

[0014] In a second aspect, the present invention further provides an artificial muscle system, comprising the displacement sensor device and a pneumatic muscle, wherein the pneumatic muscle is connected to the rope body.

[0015] In some embodiments, the pneumatic muscle includes a control valve, an artificial muscle, a tendon rope and a fixed seat. The control valve is connected to the artificial muscle and is used to extend and retract the artificial muscle by controlling the internal air pressure of the artificial muscle. One end of the tendon rope is connected to the artificial muscle, and the other end of the tendon rope is used to connect to the joint. The fixed seat is connected to the artificial muscle, and the end of the rope body away from the angle measurement rotating part is connected to the fixed seat.

[0016] In some embodiments, the artificial muscle, the cable body and the tendon cable are arranged in parallel.

[0017] Compared with the prior art, the displacement sensing device provided by the present invention is provided with a fixed frame, an angle measuring rotating member, a rope body, an angle measuring assembly, a number of turns measuring rotating member and a number of turns measuring unit. The angle measuring rotating member is rotatably connected to the fixed frame, one end of the rope body is wound around the angle measuring rotating member, and the other end of the rope body can be connected to the pneumatic muscle. When the pneumatic muscle is in action, the angle measuring rotating member can be driven to rotate under the traction of the rope body. The angle measuring assembly and the number of turns measuring module are both connected to the fixed frame. During the rotation of the angle measuring rotating member, the angle measuring assembly measures the angle of rotation of the angle measuring rotating member relative to the zero point. During the rotation of the angle measuring rotating member, the number of turns measuring rotating member is driven to rotate. The number of turns measuring unit measures the angle of rotation of the number of turns measuring rotating member, thereby obtaining the number of turns rotated by the angle measuring rotating member. By combining the number of turns and the rotation angle of the angle measuring rotating member, the length drawn by the rope body can be finally obtained. The length is the elongation of the pneumatic muscle, thereby realizing accurate measurement of the displacement elongation of the pneumatic muscle. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a schematic structural diagram of a displacement sensing device provided by an embodiment of the present invention; Figure 2 is a front view of an artificial muscle system provided by an embodiment of the present invention; Figure 3 is along Figure 2 A cutaway view of the artificial muscle system.

[0019] Reference numerals in the figures: 10—fixed frame 11—bearing 20—rotation angle measuring rotating part 21 - second rotating shaft 22 - second gear 23 - winding part 24—Second pressing ring 30—Rope body 40—Angle measuring assembly 41 - second encoder 42 - second magnetic steel 50 - turn measurement module 51 - Turns measuring rotating part 52 - Turns measuring unit 60 - Coil spring 70 - Pneumatic muscle 71 - Control valve 72 - Artificial muscle 73 - tendon rope 74 - fixed seat 80 - displacement sensor device 511—first rotating shaft 512—first gear 513—first pressing ring 521 - first encoder 522 - first magnetic steel. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0021] In order to solve the technical problem that the displacement sensor in the prior art is difficult to accurately measure the elongation of the pneumatic muscle, an embodiment of the present invention provides a displacement sensing device that can achieve accurate measurement of the elongation of the pneumatic muscle.

[0022] It should be noted that the displacement sensing device described in the present invention is used for but not limited to the measurement of the elongation of pneumatic muscles, and can also be applied to the measurement of the displacement distance of any displacement component that performs horizontal displacement. For the sake of convenience, in the present invention, only the application of the displacement sensing device to the measurement of the elongation of pneumatic muscles is used as an example for explanation, and the principle of applying the displacement sensing device to other types of equipment is essentially the same as the principle of applying it to the measurement of the elongation of pneumatic muscles, which will not be elaborated here.

[0023] The displacement sensing device provided by the embodiment of the present invention is as follows: Figure 1 and 3 As shown, it includes a fixed frame 10, an angle measuring rotating member 20, a rope body 30, an angle measuring assembly 40 and a number of turns measuring module 50. The angle measuring rotating member 20 is rotatably connected to the fixed frame 10; one end of the rope body 30 is wound around the angle measuring rotating member 20, and the other end of the rope body 30 is used for connection to a displacement part; the angle measuring assembly 40 is connected to the fixed frame 10, and is used to measure the angle of the angle measuring rotating member 20; the number of turns measuring module 50 is connected to the fixed frame 10, and is used to measure the number of rotations of the angle measuring rotating member 20.

[0024] In this embodiment, Figure 1 and 3 As shown, the revolution measurement module 50 includes a revolution measurement rotating member 51 and a revolution measurement unit 52. The revolution measurement rotating member 51 is rotatably connected to the fixed frame 10 and is transmission-connected to the angle measurement rotating member 20. It can be synchronously rotated by the angle measurement rotating member 20, and the angular velocity of the revolution measurement rotating member is smaller than the angular velocity of the angle measurement rotating member. The revolution measurement unit 52 is used to measure the angle of the revolution measurement rotating member 51.

[0025] Specifically, the displacement sensing device is provided with a fixed frame 10, an angle measuring rotating member 20, a rope body 30, an angle measuring assembly 40 and a number of turns measuring module 50. The angle measuring rotating member 20 is rotatably connected to the fixed frame 10. One end of the rope body 30 is wound around the angle measuring rotating member 20. The other end of the rope body 30 can be connected to the pneumatic muscle 70. When the pneumatic muscle 70 is actuated, the angle measuring rotating member 20 can be driven to rotate under the traction of the rope body 30. The angle measuring assembly 40 and the number of turns measuring module 50 are both connected to the fixed frame 10. During the rotation process of the angle measuring rotating member 20, In the figure, the angle measuring component 40 measures the angle of rotation of the angle measuring rotating member 20 relative to the zero point, and the number of circles measuring module 50 measures the number of circles rotated by the angle measuring rotating member 20. By combining the number of circles and the rotation angle of the angle measuring rotating member 20, the rotation amount of the angle measuring rotating member 20 during the action of the pneumatic muscle 70 can be obtained. When the radius of the winding portion 23 of the rope body 30 is known, the length drawn out by the rope body 30 can be obtained, and this length is the elongation of the pneumatic muscle 70, thereby realizing accurate measurement of the displacement elongation of the pneumatic muscle 70.

[0026] In this embodiment, when the angle measuring rotating member 20 rotates, the number of turns measuring rotating member 51 is driven to rotate. Since the angular velocity of the number of turns measuring rotating member 51 is smaller than the angular velocity of the angle measuring rotating member 20, the angle of the number of turns measuring rotating member 51 is smaller than the angle of the angle measuring rotating member 20. By designing the transmission ratio, within the measuring range, no matter how much the angle measuring rotating member 20 rotates, the number of turns of the number of turns measuring rotating member 51 will not exceed one circle. The number of turns measuring unit 52 obtains the angle of the number of turns measuring rotating member 51, and when the transmission ratio of the number of turns measuring rotating member 51 and the angle measuring rotating member 20 is known, the number of turns of the angle measuring rotating member 20 can be obtained, and then the extension or contraction of the pneumatic muscle 70 can be measured.

[0027] In this embodiment, the fixing frame 10 is a shell structure, and a mounting cavity is provided inside the shell. The structures such as the angle measurement rotating member 20, the angle measurement assembly 40 and the number of turns measurement module 50 are all arranged in the mounting cavity.

[0028] It can be understood that the number of turns measuring rotating member 51 and the angle measuring rotating member 20 can be connected by a belt, so that during the rotation of the angle measuring rotating member 20, the number of turns measuring rotating member 51 can be driven to rotate synchronously through the transmission of the belt; the number of turns measuring rotating member 51 can also be set as two wheels that rub against each other, and the angle measuring rotating member 20 drives the number of turns measuring rotating member 51 to rotate synchronously through friction.

[0029] It can be understood that the angle measuring rotating member 20 can be a rotating member such as a rotating shaft or a rotating wheel that can rotate on the fixing frame 10 .

[0030] It can be understood that the rope body 30 can be any flexible rope that can be wound and led out.

[0031] To achieve the measurement of muscle contraction, in one embodiment, Figure 1 and 3 As shown, the displacement sensing device 80 further includes a coil spring 60, which is mounted on the fixing frame 10 and connected to the angle measuring rotating member 20. Specifically, the coil spring 60 can form a driving force acting on the rotation of the angle measuring rotating member 20 by connecting to the angle measuring rotating member 20, and the driving force is balanced with the force of the rope body 30 acting on the angle measuring rotating member 20. Through the action of the driving force, the rope body 30 is always in a taut state. When the muscle contracts, the rope body 30 relaxes instantly. At this time, the coil spring 60 will drive the angle measuring rotating member 20 to rotate, so that the rope body 30 is wound around the angle measuring rotating member 20 until it is in a taut state again. At this time, by obtaining the winding length of the rope body 30 wound around the angle measuring rotating member 20, the contraction amount of the pneumatic muscle 70 can be measured. Therefore, when the winding radius of the rope body 30 and the rotation amount of the angle measuring rotating member 20 are known, the contraction amount of the pneumatic muscle 70 can be measured.

[0032] It can be understood that the number of revolutions measurement module 50 can be an electronic counter, which is used in conjunction with a rotary encoder or a Hall sensor to receive pulse signals and count them, thereby realizing the measurement of the number of revolutions; the number of revolutions measurement module 50 can also be a Hall sensor, which uses the Hall effect to detect changes in the magnetic field, thereby measuring the movement of the angle measurement rotating member 20. By installing a magnetic element on the angle measurement rotating member 20 and installing a Hall sensor at a fixed position, when the magnetic element rotates with the rotating shaft, the Hall sensor will output a pulse signal, and the counter can calculate the number of revolutions according to the number of pulses.

[0033] In one embodiment, if Figure 1 and 3 As shown, the revolution measuring rotating member 51 includes a first rotating shaft 511 and a first gear 512, the first rotating shaft 511 is rotatably connected to the fixed frame 10, and the first gear 512 is fixedly sleeved on the first rotating shaft 511. The rotation angle measuring rotating member 20 includes a second rotating shaft 21 and a second gear 22, the second rotating shaft 21 is rotatably connected to the fixed frame 10, the second gear 22 is fixedly sleeved on the second rotating shaft 21 and meshes with the first gear 512, and the tooth diameter of the second gear 22 is smaller than the tooth diameter of the first gear 512.

[0034] Specifically, the revolution measuring rotating member 51 and the rotation angle measuring rotating member 20 are rotatably connected to the fixed frame 10 through the first rotating shaft 511 and the second rotating shaft 21 respectively, and the transmission is realized by the meshing of the first gear 512 and the second gear 22. The tooth diameter of the second gear 22 is smaller than the tooth diameter of the first gear 512. In the process of the pneumatic muscle 70 driving the second rotating shaft 21 to rotate rapidly through extension and contraction, the first rotating shaft 511 rotates a certain angle under the transmission of the first gear 512 and the second gear 22. When the transmission ratio of the first gear 512 and the second gear 22 and the rotation angle of the first rotating shaft 511 are known, the number of revolutions of the second rotating shaft 21 can be obtained. Finally, combined with the rotation angle of the second rotating shaft 21, the accurate measurement of the extension and contraction amount of the pneumatic muscle 70 can be realized.

[0035] In this embodiment, the transmission ratio of the first gear 512 and the second gear 22 can be adaptively set according to the actual displacement requirements. Usually, in order to achieve long displacement measurement, the transmission ratio of the first gear 512 and the second gear 22 is maintained in a larger threshold range.

[0036] In this embodiment, Figure 1 and 3 As shown, the fixing frame 10 is provided with a bearing 11 , and the first rotating shaft 511 and the second rotating shaft 21 are both rotatably connected to the fixing frame 10 via the bearing 11 .

[0037] In one embodiment, if Figure 1 and 3 As shown, the angle measuring rotating member 20 further includes a winding portion 23, which is fixedly sleeved on the second rotating shaft 21, and the rope 30 is wound on the winding portion 23. Specifically, the winding portion 23 can be wound by the rope 30 alone, and the winding portion 23 has the same rotation angle as the second rotating shaft 21. By measuring the rotation angle of the second rotating shaft 21, the rotation angle of the winding portion 23 can be obtained. When the rotation radius of the winding portion 23 is known, the elongation and recovery length of the rope 30 can be measured.

[0038] In this embodiment, the radius of the winding portion 23 is R, and the radius of the second gear 22 is R A , the radius of the first gear 512 is R B , R B >R A , if the second gear 22 rotates one circle, the first gear 512 will rotate R A / R B If the rope elongation is positive, the elongation of the rope body 30 and the recovery length L satisfy the following formula:

[0039] Wherein, θ0 is the set zero angle of the second gear 22, which is stored in the microcontroller, and θ Ais the absolute angle of the second gear 22, θ B is the absolute angle of the first gear 512 .

[0040] In this embodiment, Figure 1 and 3 As shown, the winding portion 23 is provided with a winding groove, and the winding groove can accommodate the wound rope body 30.

[0041] In one embodiment, if Figure 1 and 3 As shown, the radius of the winding portion 23 is greater than the radius of the second gear 22, and smaller than the radius of the first gear 512. Specifically, the radius of the winding portion 23 is greater than the radius of the second gear 22, so that the radius of the winding portion 23 can be increased as much as possible, and the number of turns of the rope body 30 can be reduced. Moreover, the radius of the winding portion 23 is smaller than the radius of the first gear 512, so that the rope body 30 will not contact the first rotating shaft 511.

[0042] In one embodiment, if Figure 1 and 3 As shown, the revolution measurement unit 52 includes a first encoder 521 and a first magnetic steel 522. The first magnetic steel 522 is fixed to the end of the first rotating shaft 511. The first encoder 521 is located on one side of the first magnetic steel 522 and is used to measure the rotation angle of the first magnetic steel 522. Specifically, the first encoder 521 can obtain the rotation angle of the first rotating shaft 511 by measuring the rotation angle of the first magnetic steel 522. In this embodiment, Figure 1 and 3 As shown, the revolution measuring rotating member 51 further includes a first pressing ring 513 , which is fixed to the first rotating shaft 511 by bolts, and the first magnetic steel 522 is fixed to the first pressing ring 513 .

[0043] In one embodiment, the rotation angle measuring assembly 40 includes a second magnetic steel 42 and a second encoder 41 . The second magnetic steel 42 is fixed to the end of the second rotating shaft 21 . The second encoder 41 is located on one side of the second magnetic steel 42 and is used to measure the rotation angle of the second magnetic steel 42 .

[0044] In this embodiment, Figure 1 and 3 As shown, the rotation angle measuring rotating member 20 further includes a second pressing ring 24 , which is fixed to the second rotating shaft 21 by bolts, and the second magnetic steel 42 is fixed to the second pressing ring 24 .

[0045] In this embodiment, the first encoder 521 and the second encoder 41 are absolute displacement encoders. Each position of the absolute value encoder has a unique absolute value. Regardless of whether the power is off or not, as long as the encoder is at a certain position, it can output the value of the position after power is restored. Therefore, the first encoder 521 and the second encoder 41 can record the position information after power is off, and read the displacement change after power is restored.

[0046] The embodiment of the present invention also provides an artificial muscle system, such as Figure 2 and 3 As shown, the displacement sensor device 80 and the pneumatic muscle 70 are included, and the pneumatic muscle 70 is connected to the rope body 30. Specifically, the measurement system can achieve accurate measurement of the elongation and contraction amount of the pneumatic muscle 70 by setting the displacement sensor device 80.

[0047] In one embodiment, if Figure 2 and 3 As shown, the pneumatic muscle 70 includes a control valve 71, an artificial muscle 72, a tendon rope 73 and a fixing seat 74. The control valve 71 is connected to the artificial muscle 72 and is used to control the internal air pressure of the artificial muscle 72 to make the artificial muscle 72 extend and retract. One end of the tendon rope 73 is connected to the artificial muscle 72, and the other end of the tendon rope 73 is used to connect the joint. The fixing seat 74 is connected to the artificial muscle 72, and one end of the rope body 30 away from the angle measurement rotating member 20 is connected to the fixing seat 74. Specifically, the control valve 71 adjusts the internal air pressure of the artificial muscle 72 to the inside of the artificial muscle 72, thereby controlling the length of the artificial muscle 72. When the artificial muscle 72 is extended or contracted, the tendon rope 73 is driven to move, thereby driving the joint to move. At the same time, during the extension or contraction of the artificial muscle 72, the fixing seat 74 will be driven to move, thereby causing the rope body 30 to move, thereby achieving accurate measurement of the extension or contraction of the artificial muscle 72. Furthermore, the absolute displacement reading can be performed through the first encoder 521 and the second encoder 41, so that the displacement distance of the pneumatic muscle 70 during power failure can be identified through the first encoder 521 and the second encoder 41 after the artificial muscle system is restarted.

[0048] In one embodiment, the artificial muscle 72, the rope 30 and the tendon 73 are arranged in parallel. Specifically, the parallel arrangement of the muscle 72, the rope 30 and the tendon 73 can ensure that the artificial muscle 72, the rope 30 and the tendon 73 move in the same direction, thereby facilitating the accurate measurement of the extension and contraction amount of the artificial muscle 72.

[0049] The specific implementation of the present invention described above does not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A displacement sensing device, characterized in that: include: Fixed frame; An angle measuring rotating member, rotatably connected to the fixed frame; A rope body, one end of which is wound around the angle measuring rotating member; An angle measuring component, connected to the fixing frame, for measuring the angle of the angle measuring rotating member; A revolution measurement module, wherein the revolution measurement module comprises a revolution measurement rotating member and a revolution measurement unit, wherein the revolution measurement rotating member is rotationally connected to the fixed frame and is transmission-connected to the rotation angle measurement rotating member, and the angular velocity of the revolution measurement rotating member is less than the angular velocity of the rotation angle measurement rotating member, and the revolution measurement unit is connected to the fixed frame and is used to measure the number of revolutions of the rotation angle measurement rotating member.

2. The displacement sensor device according to claim 1, characterized in that: The rotation number measuring rotating member includes a first rotating shaft and a first gear, the first rotating shaft is rotatably connected to the fixed frame, and the first gear is fixedly sleeved on the first rotating shaft. The rotation angle measuring rotating member includes a second rotating shaft and a second gear, the second rotating shaft is rotatably connected to the fixed frame, the second gear is fixedly sleeved on the second rotating shaft and meshes with the first gear, and the tooth diameter of the second gear is smaller than the tooth diameter of the first gear.

3. The displacement sensor device according to claim 2, characterized in that: The revolution measurement unit includes a first magnetic steel and a first encoder. The first magnetic steel is fixed to the end of the first rotating shaft. The first encoder is located on one side of the first magnetic steel and is used to measure the rotation angle of the first magnetic steel.

4. The displacement sensor device according to claim 2, characterized in that: The rotation angle measuring assembly includes a second magnetic steel and a second encoder. The second magnetic steel is fixed to the end of the second rotating shaft. The second encoder is located on one side of the second magnetic steel and is used to measure the rotation angle of the second magnetic steel.

5. The displacement sensor device according to claim 2, characterized in that: The rotation angle measuring rotating member further comprises a winding portion, the winding portion is fixedly sleeved on the second rotating shaft, and the rope body is wound around the winding portion.

6. The displacement sensor device according to claim 5, characterized in that: The radius of the winding portion is larger than the radius of the second gear and smaller than the radius of the first gear.

7. The displacement sensing device according to any one of claims 1 to 6, characterized in that: The displacement sensing device also includes a coil spring, which is mounted on the fixing frame and connected to the rotation angle measuring rotating member.

8. An artificial muscle system, characterized in that: It comprises a displacement sensing device as described in any one of claims 1 to 7 and a pneumatic muscle, wherein the pneumatic muscle is connected to the rope body.

9. The artificial muscle system according to claim 8, characterized in that: The pneumatic muscle includes a control valve, an artificial muscle, a tendon rope and a fixed seat. The control valve is connected to the artificial muscle and is used to extend and retract the artificial muscle by controlling the internal air pressure of the artificial muscle. One end of the tendon rope is connected to the artificial muscle, and the other end of the tendon rope is used to connect to the joint. The fixed seat is connected to the artificial muscle, and the end of the rope body away from the angle measurement rotating part is connected to the fixed seat.

10. The artificial muscle system according to claim 9, characterized in that: The artificial muscle, the rope body and the tendon rope are arranged in parallel.

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