Spiral self-sensing soft robot and control method and preparation method thereof

Abstract

The invention discloses a spiral self-sensing soft robot, and belongs to the technical field of soft robot sensing, the spiral self-sensing soft robot comprises a main body made of an elastomer material, the main body is provided with a tubular cavity and a tube wall, and an outer spiral line is formed on the tube wall; the metal spring is embedded in the outer spiral line, and the spiral parameter is matched with the spiral parameter of the outer spiral line; when the main body generates axial telescopic deformation under the action of pressure change of the inner cavity, the metal spring deforms synchronously along with the main body, and the inductance value of the metal spring corresponds to the axial length of the main body and serves as a feedback signal of closed-loop control. The sensor provided by the invention provides a sensing hardware basis for closed-loop control, has the characteristics of high repeatability, low hysteresis quality and large elongation under the condition of external load, and provides potential for sensor integration of a sectional continuum robot.

Description

Technical Field

[0001] This invention relates to the field of soft robot sensing technology, and in particular to a spiral self-sensing soft robot and its control and fabrication methods. Background Technology

[0002] In existing technologies, soft robots, due to their high flexibility and super-redundant degrees of freedom, have broad application prospects in fields such as pipeline inspection, disaster search and rescue, and minimally invasive surgery. However, soft robots undergo significant multi-degree-of-freedom deformation during movement, making it difficult to directly integrate traditional rigid sensors into soft structures. Existing flexible sensing solutions have the following limitations: Fiber optic sensors have limited axial elongation capacity, making them difficult to withstand large deformations, and multi-channel sensors are expensive. Resistive sensors: sensitive to temperature, exhibit severe nonlinearity under large deformations, and are difficult to calibrate; Capacitive sensors: susceptible to electromagnetic interference, require a double-electrode structure, and have complex packaging.

[0003] Therefore, there is an urgent need for an integrated solution that can deform in tandem with soft structures and simultaneously perform structural reinforcement and displacement detection functions. Summary of the Invention

[0004] The purpose of this invention is to provide an integrated structure that can deform in tandem with soft structures and simultaneously perform structural reinforcement and displacement detection functions.

[0005] To achieve the above objectives, the present invention has designed the following technical solution: A spiral-shaped self-sensing soft robot, comprising: The main body is made of an elastomeric material and has a tubular cavity and a tube wall, the tube wall being formed with an outer spiral. A metal spring is fitted into the outer helix, and the helix parameters of the metal spring are matched with the helix parameters of the outer helix. When the main body undergoes axial expansion and contraction deformation under the action of internal cavity pressure, the metal spring deforms synchronously. The inductance value of the metal spring is related to the axial length of the main body and can be used as a feedback signal for closed-loop control.

[0006] Preferably, the helical parameters include pitch and helical diameter, the pitch of the metal spring is equal to the pitch of the outer helix, and the outer diameter of the metal spring is adapted to the groove width of the outer helix.

[0007] Preferably, the metal spring is completely covered by the elastomer material, and the two ends of the metal spring are provided with electrode leads that extend through the tube wall.

[0008] Preferably, the elastomer material is a liquid silicone curing molding material, and the metal spring and the main body are integrally molded.

[0009] Preferably, the pipe wall is further formed with an inner helix, which has the same helical parameters as the outer helix but is in opposite phase, forming an alternating concave-convex structure of the bellows.

[0010] Preferably, the cavity is provided with a fluid interface for connecting hydraulic lines and an exhaust port located at the highest point of the main body.

[0011] A control method for a helical self-sensing soft robot includes the following device: Real-time simulator, communication interface, power interface, signal conditioning module, control unit and servo injection pump; The control method is as follows: the real-time simulator runs the control algorithm of the soft robot and communicates bidirectionally with the control unit through the communication interface. The output flow command is sent to the servo injection pump, which delivers the hydraulic medium to the cavity of the main body through the hydraulic pipeline. The metal spring extends synchronously with the main body, and the inductance value of the metal spring increases. The equivalent displacement feedback signal is calculated based on the model. The equivalent displacement feedback signal is sent back to the control unit through the signal conditioning module, forming a closed loop with the inductance sensing principle feedback of the metal spring. The power interface is used to supply power to the servo motor driver in the power stage hardware-in-loop mode.

[0012] A method for fabricating a spiral-shaped self-sensing soft robot includes the following steps: S1: Position the metal spring in the spiral groove of the mold, so that it is coaxially aligned with the spiral contour of the mold cavity; S2: Inject liquid elastomer material into the mold cavity so that the metal spring is completely covered; S3: After curing and molding, demold to obtain the main body with the metal spring embedded in it; S4: Obtain the mapping relationship between the displacement and inductance of the soft robot.

[0013] Preferably, the liquid elastomer material described in S2 is subjected to vacuum defoaming treatment before injection, and the defoaming conditions are maintained at -0.08 to -0.095 MPa for 10 to 20 minutes.

[0014] Preferably, S4 specifically involves: placing the formed soft robot on a linear calibration stage, applying different axial displacements and simultaneously acquiring the corresponding inductance values, and establishing a mapping relationship between displacement and inductance through polynomial fitting.

[0015] The soft robot provided by this invention adopts an integrated design of drive and perception, avoiding the complex and easily damaged sensor wiring and assembly difficulties of traditional soft robots while enhancing the mechanical strength of the soft robot. Utilizing the principle of variable inductance, highly sensitive detection of the expansion and contraction state of the helical bellows is achieved. A nonlinear mapping relationship is accurately established through a linear calibration stage, achieving a displacement detection accuracy better than 0.1 mm. Employing a hydraulic drive, it features higher output force, better linear response, and stronger load-bearing capacity, making it suitable for high-precision trajectory control and dynamic tasks. Using liquid silicone injection molding, a metal spring is integrally encapsulated within the bellows structure. The process is simple and controllable, and the resulting product exhibits excellent sealing, pressure resistance, and repeatability, making it suitable for mass production.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 This is an overall schematic diagram of a spiral self-sensing soft robot according to the present invention; Figure 2 This is a side view of a spiral self-sensing soft robot according to the present invention; Figure 3 This is a side sectional view of a spiral self-sensing soft robot according to the present invention; Figure 4 This is a top view of a spiral self-sensing soft robot according to the present invention; Figure 5 This is an isometric view of the servo injection pump in this invention; Figure 6 This is a schematic diagram of the servo injection pump driving principle in this invention; Figure 7 This is an isometric view of the linear calibration stage in this invention; Figure 8 This is a schematic diagram of the inductance-displacement calibration principle in this invention; Figure 9 This is the inductance-displacement fitting curve in this invention; Figure 10 This is a schematic diagram of the hardware-in-the-loop control system of the present invention; Figure 11 This is a schematic diagram of the outer mold and insulating support assembly in this invention; Figure 12 This is a schematic diagram of the inner mold core in this invention; Figure 13 This is a schematic diagram of the inner mold assembly in this invention; Figure 14 This is a schematic diagram of the end cap in this invention.

[0018] Figure Labels 1. Helical bellows; 2. Metal spring; 3. Cavity; 4. Vent; 501. Servo motor; 502. Coupling; 503. Lead screw; 504. Servo actuator; 505. Piston; 506. Injection chamber; 507. Sensing unit; 601. Fixed end base; 602. Moving end base; 603. Precision linear guide mechanism; 604. Micro-displacement drive stepper motor; 605. Stepper motor coupling; 606. Stepper lead screw; 607. Lead screw nut base; 608. Micro-displacement measurement unit; 609. Environmental monitoring unit; 610. Electromagnetic shielding and grounding assembly; 701. Outer mold; 702. Insulating support assembly; 703. Inner mold core; 704. Inner mold assembly; 705. End cap. Detailed Implementation

[0019] To enable those skilled in the art to better understand the present application, the technical solutions in specific embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Unless otherwise defined, the technical or scientific terms used in this invention should have the ordinary meaning understood by those skilled in the art. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are only used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections. If a part has a central axis or a hollow cavity, then the "inner side" of the part refers to the side of the part closer to the central axis of the part or disposed inside the hollow cavity; the "outer side" of the part refers to the side of the part away from the central axis of the part.

[0020] Example 1 The present invention first provides a spiral-shaped self-sensing soft robot, comprising the following core components: The main body is made of an elastomer material, preferably cured and molded from liquid silicone. The overall configuration is a spiral corrugated pipe 1, which has a tubular cavity 3 and a pipe wall. The pipe wall is formed with an inner spiral and an outer spiral, which have the same spiral parameters and opposite phases, forming an alternating concave and convex corrugated structure. This structure gives the corrugated pipe good axial expansion and contraction performance.

[0021] Metal spring 2 is embedded in the outer helix of the spiral bellows 1. Its helical parameters, including pitch and helical diameter, are matched with the helical parameters of the outer helix. That is, the pitch of metal spring 2 is equal to the pitch of the outer helix, and the outer diameter of metal spring 2 is matched with the groove width of the outer helix. Metal spring 2 is arranged coaxially with the outer helix to form an integrally encapsulated structure. Electrode leads protruding from the pipe wall are provided at both ends. This matching design can ensure that when the spiral bellows 1 undergoes axial expansion and contraction deformation under the action of internal pressure, metal spring 2 can deform synchronously with it without causing additional radial compression or axial obstruction to the bellows. The two achieve harmonious co-deformation.

[0022] In addition, a fluid interface is provided at one end of the cavity 3 for connecting the hydraulic pipeline, and an exhaust port 4 is provided at the high point of the corrugations on the spiral bellows 1 to remove residual gas in the cavity 3 and ensure that the hydraulic medium fills the cavity 3.

[0023] The metal spring 2, acting as a variable inductor, exhibits a positive correlation between its inductance and geometric parameters. When the helical bellows 1 extends axially, the metal spring 2 embedded within it extends synchronously, increasing the axial length l and the turn spacing, thus altering the inductance value L. By measuring the change in inductance, the axial displacement of the helical bellows 1 can be deduced, enabling the soft robot's self-sensing function.

[0024] Specifically, the electrode leads of the metal spring 2 are connected to the inductance measurement circuit via a double-core shielded wire. The inductance measurement circuit uses the LC oscillation principle, accurately measuring the inductance value by detecting changes in the oscillation frequency. Preferably, the LDC1614 chip is used as the inductance digital converter, which can directly output digital inductance measurement results.

[0025] The core invention of the spiral self-sensing soft robot provided in this embodiment is that the metal spring 2 serves as both a structural reinforcement to improve the pressure-bearing and rebound capabilities of the bellows and a variable inductance sensor to realize displacement detection. The correspondence between its inductance value and axial length provides a sensing basis for realizing closed-loop position control without the need for additional sensor installation. Furthermore, the inductive sensor is less affected by temperature and electromagnetic interference and has good repeatability.

[0026] Example 2 The embodiment provides a control method for a helical self-sensing soft robot, which adopts a closed-loop control architecture combining hydraulic drive and inductive feedback. The system mainly includes: a servo injection pump, hydraulic lines, an inductive measurement module, a control unit, and the soft robot body.

[0027] First, the drive unit: the servo injection pump is the power source of the soft robot of this invention, responsible for providing precise and controllable hydraulic drive. Its main components include a transmission unit and an injection unit.

[0028] The transmission system includes a servo motor, a coupling, a ball screw drive mechanism, and a servo actuator. The servo motor is connected to the ball screw drive mechanism via the coupling. The forward and reverse rotation of the servo motor drives the ball screw nut in the ball screw drive mechanism to reciprocate axially. The servo actuator is fixedly connected to the ball screw nut and moves together with it, and is used to drive the injection section.

[0029] The injection section includes an injection chamber and a plunger. The injection chamber is a sealed cylindrical cavity. The outlet of the injection chamber is connected to the cavity 3 of the soft robot through a hydraulic pipeline to transmit hydraulic medium. The plunger is connected to a servo actuator and reciprocates in the injection chamber under its drive. When the plunger moves forward, it compresses the hydraulic medium in the cavity to generate positive pressure, and when the plunger moves backward, it generates negative pressure.

[0030] It also includes a sensing unit, which is used to detect the plunger position in real time and provide feedback for the closed-loop flow control of the injection pump.

[0031] The servo motor driver receives an analog signal (±10V bipolar voltage) output from the control unit, which is generated by the DAC module. The DAC module communicates with the control unit via the SPI bus.

[0032] The working principle of hydraulic drive is as follows: During the elongation process, the control unit sends a forward drive command to the servo motor. The servo motor rotates forward, the plunger advances, the injection chamber volume decreases, and the hydraulic medium is forced into the cavity 3 through the pipeline, generating positive pressure. Under the action of positive pressure, the spiral bellows 1 elongates axially, and the embedded metal spring 2 elongates synchronously. When additional air is found in the cavity 3 after the hydraulic medium is injected, the vent hole 4 is opened to release the air. When only hydraulic medium remains in the cavity 3, the vent hole 4 is closed.

[0033] During the shortening process, the control unit sends a reverse drive command to the servo motor, causing the servo motor to reverse, the plunger to retract, the injection chamber volume to increase, and the hydraulic medium to flow back from cavity 3, generating negative pressure. Under the action of negative pressure and its own elastic restoring force, the spiral bellows 1 shortens axially, and the metal spring 2 shortens synchronously.

[0034] Compared with pneumatic drive, hydraulic drive has the following advantages: the incompressibility of liquids ensures more precise position control; high output stiffness and strong load-bearing capacity; fast response speed and good dynamic performance.

[0035] Secondly, regarding the inductance measurement section, the inductance measurement circuit is based on the LC oscillation principle. The metal spring 2, acting as a variable inductor, is connected in parallel with the fixed capacitor to form an LC resonant circuit. The relationship between the resonant frequency and the inductance value is as follows: Where f is the resonant frequency, L is the total inductance (including the metal spring inductor and the series fixed inductor), and C is the parallel capacitor. The LDC1614 inductor-to-digital converter chip is preferred. This chip integrates an LC oscillation circuit and a frequency measurement circuit, and can directly output a digital value corresponding to the inductance value. The chip connects via I... 2 The C-bus communicates with the control unit, and the sampling rate can reach thousands of times per second, meeting the requirements of real-time control.

[0036] Specifically, due to the nonlinear relationship between inductance and displacement, a mapping model needs to be established through precise calibration. Calibration utilizes a dedicated linear calibration stage, the structure of which includes: The rigid base consists of a fixed-end base 601 and a movable-end base 602, which are used to clamp the two ends of the spiral bellows 1, respectively. The fixed-end base 601 is rigidly connected to the frame, and the movable-end base 602 is mounted on the linear displacement module.

[0037] The linear displacement module includes a precision linear guide 603 with precision linear bearings, a stepper motor 604, a stepper coupling 605, a stepper screw 606, and a screw nut base 607. The stepper motor 604 drives the stepper screw 606 through the stepper coupling 605, causing the screw nut base 607 to produce precise and controllable micro-displacement. The moving end base 602 is mounted on the screw nut base 607 and moves synchronously with it.

[0038] The micro-displacement measurement unit 608 uses a high-precision displacement sensor, such as a grating ruler or a laser displacement sensor, to measure the axial displacement of the soft robot in real time as a calibration reference.

[0039] The inductance measurement module uses an LDC1614 chip, which is connected to the electrodes at both ends of the metal spring 2 to synchronously acquire the inductance value.

[0040] The environmental monitoring unit 609 includes a temperature sensor that records the ambient temperature during calibration for temperature compensation.

[0041] The data acquisition and processing unit simultaneously acquires displacement and inductance data, and completes data storage and curve fitting.

[0042] An electromagnetic shielding and grounding assembly 610 is installed on the outside of the above-mentioned structures to achieve electromagnetic shielding.

[0043] The specific calibration process is as follows: The soft robot is mounted on a calibration platform, with its two ends clamped to a fixed end base 601 and a mobile end base 602, respectively, so that the soft robot is in its natural length state. The initial displacement value and inductance value are recorded. The stepper motor 604 drives the mobile end base 602 to generate a small displacement increment, and the displacement value and inductance value are recorded simultaneously. The previous step is repeated until the maximum elongation is reached. Then, the robot moves in the opposite direction, returning from the maximum elongation to its natural length. The return data is collected. Finally, polynomial fitting is performed on the collected data to establish a displacement-inductance mapping relationship.

[0044] The mapping model is fitted using a third-order polynomial: in This represents the fitted displacement, in mm. This indicates the digital inductance value acquired by the LDC1614 inductance measurement module. , , , The fitting constant, along with the ambient temperature during calibration, is stored in the control unit. The actual length of the soft robot can be obtained from this formula.

[0045] To facilitate the development and verification of control algorithms, a hardware-in-the-loop testing system can be constructed. The system includes: A real-time simulator is used to run control algorithms for soft robots and output flow commands.

[0046] The communication interface is used for a bidirectional data channel between the real-time simulator and the control unit.

[0047] The power interface is used to provide power to the servo motor driver.

[0048] The signal conditioning module is used to filter, amplify, and level-convert the inductance measurement signal.

[0049] The specific process involves running the control algorithm of the soft robot in a real-time simulator, communicating bidirectionally with the control unit through a communication interface, and outputting flow commands to the servo injection pump. The servo injection pump transmits the hydraulic medium to the cavity 3 of the spiral bellows 1 through the hydraulic pipeline. The metal spring 2 extends synchronously with the spiral bellows 1, and the inductance value of the metal spring 2 increases. The equivalent displacement feedback signal is calculated based on the model and further sent back to the control unit through the signal conditioning module. Combined with the inductance value feedback of the metal spring 2 detected by the LDC1614 inductance measurement module, a closed loop is formed.

[0050] Hardware-in-the-loop testing connects real soft robots and servo injection pumps as controlled objects to a simulation environment, allowing the effectiveness and robustness of control algorithms to be verified in a protected environment.

[0051] Example 3 This embodiment provides a method for manufacturing a soft robot, specifically using liquid silicone injection molding to integrally encapsulate a metal spring 2 within a spiral bellows 1 structure. The entire manufacturing process includes: mold preparation, spring positioning, mold closing, silicone injection, curing and demolding, post-processing, and calibration.

[0052] The mold system consists of the following components: The outer mold 701 is divided into two identical halves radially, and its inner surface is machined with helical grooves that conform to the outer contour of the helical bellows 1. The helical grooves in one half of the outer mold 701 are used to position and accommodate the metal spring 2. The two halves of the outer mold 701 are aligned by locating pins and locked by bolts.

[0053] An insulating support assembly 702 is placed within the spiral groove of the outer mold 701 to support the metal spring 2 and set its initial pitch and preload. Insulating material prevents the spring from conducting through the mold.

[0054] The inner mold core 703 and the inner mold assembly 704 are provided. The inner mold core 703 is provided with a positioning shoulder to assist in the installation and positioning of the inner mold assembly 704. The inner mold assembly 704 is divided into 8 parts in the radial direction, which are spliced ​​onto the inner mold core 703 in sequence during use.

[0055] End cap 705 includes two parts, upper and lower. The upper end cap is used to close the upper end of the mold and has an injection port for injecting liquid silicone, an exhaust port for venting gas in the mold cavity, and an electrode lead-out sealing seat for leading out the electrode end of the metal spring 2. The lower end cap is used to close the lower end of the mold and is positioned in conjunction with the inner mold core 704.

[0056] The mold housing is used to house all mold components and provide overall rigid support.

[0057] The mold is preferably made of aluminum alloy or steel, and the surface is polished to facilitate demolding. The machining accuracy of the spiral groove should be better than ±0.1mm to ensure the accurate positioning of the metal spring 2 and the geometric accuracy of the spiral bellows 1.

[0058] The detailed preparation steps are as follows: Positioning of S1 metal spring 2: First, clean the outer mold 701 to ensure that the spiral groove is free of impurities. Place the insulating support group 702 in the preset position in the spiral groove and place the metal spring 2 on the insulating support group 702 so that it extends along the spiral groove. Adjust the initial pitch and preload of the metal spring 2 to match the design parameters of the outer spiral and check the coaxiality of the metal spring 2 with the inner mold axis. Then, reserve the electrode lead-out ends at both ends of the metal spring 2 at the mold end.

[0059] Inner mold assembly of S2: First, assemble the lower end cover with the inner mold core 703, and use the positioning shoulder of the inner mold core 703 to ensure accurate axial positioning. Subsequently, install the inner mold components 704 in sequence to form a complete inner mold.

[0060] Mold closing of S3: First, place the inner mold into the first part of the outer mold 701. Subsequently, install the second part of the outer mold 701, align it through the positioning pins, and use bolts to coaxially lock the two parts of the outer mold 701 with the inner mold core 704. Then, install the upper end cover to ensure the correct positions of the pouring port, exhaust port, and electrode lead-out sealing seat. Finally, place all the mold components into the mold shell.

[0061] Silicone perfusion of S4: First, mix the two-component liquid silicone according to the ratio. The liquid silicone includes the base glue and the curing agent. Subsequently, place the mixed liquid silicone in a vacuum environment to defoam. The preferred conditions are -0.08 to -0.095 MPa for 10 to 20 minutes until no obvious bubbles are generated. Finally, slowly inject the defoamed liquid silicone into the mold cavity from the pouring port of the upper end cover. During the perfusion process, keep the pouring port at the lower position of the mold and the exhaust port at the higher position to allow the gas to naturally escape. Observe the exhaust port. When silicone overflows and there are no bubbles, it means the mold cavity is full. At this time, close the pouring port and the exhaust port.

[0062] Curing and demolding of S5: Cure according to the process requirements of the silicone material. Room temperature curing or heat curing can be selected. After curing, remove the mold shell, end cover, outer mold, and inner mold part in sequence. Subsequently, take out the formed spiral bellows 1 to obtain the initial blank of the soft robot coated with the metal spring 2.

[0063] Trimming and end assembly of S6: First, remove the edge defects such as flash, burr, and毛刺 on the surface of the spiral bellows 1. Subsequently, assemble the fluid interface or flange at the inlet end of the cavity 3 for connecting the hydraulic pipeline. Then, assemble the sealing ring to ensure the sealing performance of the fluid interface. Finally, arrange the electrode lead-out end to ensure reliable connection with the inductance measurement circuit.

[0064] Airtight and pressure resistance test of S7: First, connect the soft robot to the test system. When performing the positive pressure holding test, inject the hydraulic medium with 1.1 to 1.5 times the working pressure into the cavity 3 at room temperature and hold the pressure for a certain period of time to observe for leakage. When performing the vacuum collapse test, pump out the hydraulic medium in the cavity 3 to form a negative pressure and check whether the bellows structure collapses or has abnormal deformation. Finally, after checking for no leakage, no bubble residue, and no structural abnormality, it is judged to be qualified.

[0065] Displacement-inductance calibration of S8: Install the qualified finished soft robot on the displacement-inductance linear calibration platform, collect the inductance values at different axial displacements and perform polynomial fitting to obtain the displacement-inductance mapping relationship. Record the environmental temperature during calibration, calculate the temperature coefficient, and write the fitting coefficient and temperature coefficient into the memory of the control unit.

[0066] It should be noted that, for this invention, the core inventive concept is the use of a metal spring as the skeleton of the helical bellows, while simultaneously utilizing the principle of inductive measurement to achieve self-sensing. The compatibility of the helical parameters of the metal spring and the helical bellows is an important technical feature of this invention, which is described in detail in the specification. Some other conventional mechanical structures and connection methods are briefly or omitted in the specification. In addition, all electrical signal controls mentioned in the specification adopt mature industrial control systems. It should be understood that, in addition to the structures mentioned in the specification, this invention also includes structures necessary for industrial control, as well as other unmentioned but reasonable structures and components that are reasonable in the art or known to those skilled in the art.

[0067] Finally, it should be noted that the described embodiments are merely some, not all, of the embodiments of the present invention. Those skilled in the art will understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the claims and their equivalents; that is, all other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A spiral-shaped self-sensing soft robot, characterized in that, include: A spiral-shaped body made of elastomeric material has a tubular cavity and a tube wall, the tube wall being formed with an outer spiral line; A metal spring is fitted into the outer helix, and the helix parameters of the metal spring are matched with the helix parameters of the outer helix. When the main body undergoes axial expansion and contraction deformation under the action of changes in internal cavity pressure, the metal spring deforms synchronously. The inductance value of the metal spring is related to the axial length of the main body, serving as a feedback signal for closed-loop control.

2. The spiral self-sensing soft robot according to claim 1, characterized in that: The helical parameters include pitch and helical diameter. The pitch of the metal spring is equal to the pitch of the outer helix, and the outer diameter of the metal spring is adapted to the groove width of the outer helix.

3. The spiral self-sensing soft robot according to claim 1, characterized in that: The metal spring is completely covered by the elastomer material, and the two ends of the metal spring are provided with electrode leads that extend through the tube wall.

4. The spiral self-sensing soft robot according to claim 1, characterized in that: The elastomer material is a liquid silicone curing molding material, and the metal spring and the main body are integrally encapsulated and molded.

5. The spiral self-sensing soft robot according to claim 1, characterized in that: The pipe wall also has an inner spiral line, which has the same spiral parameters as the outer spiral line but is opposite in phase, forming an alternating concave-convex structure of the bellows.

6. The spiral self-sensing soft robot according to claim 1, characterized in that: The cavity is provided with a fluid interface for connecting hydraulic lines and an exhaust port located at the highest point of the main body.

7. A control method for a spiral self-sensing soft robot as described in any one of claims 1-6, characterized in that, This can be achieved through the following devices: Real-time simulator, communication interface, power interface, signal conditioning module, control unit and servo injection pump; The control method is as follows: the real-time simulator runs the control algorithm of the soft robot and communicates bidirectionally with the control unit through the communication interface. The output flow command is sent to the servo injection pump, which delivers the hydraulic medium to the cavity of the main body through the hydraulic pipeline. The metal spring extends synchronously with the main body, and the inductance value of the metal spring increases. The equivalent displacement feedback signal is calculated based on the model. The equivalent displacement feedback signal is sent back to the control unit through the signal conditioning module, forming a closed loop with the inductance sensing principle feedback of the metal spring. The power interface is used to supply power to the servo motor driver in the power stage hardware-in-loop mode.

8. A method for fabricating a spiral self-sensing soft robot as described in any one of claims 1-6, characterized in that, Includes the following steps: S1: Position the metal spring in the spiral groove of the mold, so that it is coaxially aligned with the spiral contour of the mold cavity; S2: Inject liquid elastomer material into the mold cavity so that the metal spring is completely covered; S3: After curing and molding, demold to obtain the main body with the metal spring embedded in it; S4: Obtain the mapping relationship between the displacement and inductance of the soft robot.

9. The preparation method according to claim 8, characterized in that: The liquid elastomer material described in S2 is subjected to vacuum defoaming treatment before injection, and the defoaming conditions are maintained at -0.08 to -0.095 MPa for 10 to 20 minutes.

10. The preparation method according to claim 8, characterized in that, S4 specifically involves placing the formed soft robot on a linear calibration stage, applying different axial displacements and simultaneously acquiring the corresponding inductance values, and establishing a mapping relationship between displacement and inductance through polynomial fitting.

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