A soft robot imitating bobbit worm

Abstract

The application discloses a soft robot imitating Bobbit worm. The pneumatic bistable driving module of the soft robot is installed on the base through a wire-driven mechanical arm, the root of the four-claw execution module is installed on the pneumatic bistable driving module, and the perception sensor is attached to the four-claw execution module and the pneumatic bistable driving module. The perception sensor is electrically connected with an external acquisition controller, the pneumatic bistable driving module is communicated with an external air pump, and the external acquisition controller is electrically connected with the external air pump. The application can perceive the approaching object in advance and expand the perception range of the soft robot. The energy stored in the bistable diaphragm can be triggered by driving the silicone film capsule, and then the fast closing of the four-claw execution module can be realized, and the response speed of the four-claw execution mechanism is improved. The self-adaptive capture grab can automatically adjust its shape according to the size of the object to implement better grabbing, and the perception sensor on the capture grab increases the friction force when the object is grabbed, so that the purpose of auxiliary grabbing is achieved.

Description

Technical Field

[0001] This invention relates to a soft robot, specifically a soft robot that resembles a Bobbit worm. Background Technology

[0002] As the application of robots continues to deepen, the shortcomings of traditional robots are becoming more and more prominent. Traditional robots have complex structural designs and poor flexibility, so they cannot pass through narrow spaces or adapt to complex-shaped passages. Their poor environmental adaptability limits their application in some fields.

[0003] Due to the limitations of traditional robots, soft robots have become a focus of research. The design inspiration for soft robots largely comes from soft-bodied organisms in nature. These animals can achieve efficient movement by changing their body shape in their natural environment. Based on the movement and physiological structure of soft-bodied organisms, researchers have designed and fabricated various soft robots using soft materials. These robots are characterized by their light weight, small size, high flexibility, and strong environmental adaptability. They can crawl, twist, traverse confined spaces, and perform grasping operations, showing broad application prospects in complex environments.

[0004] The Bobbit worm, which lives in the Pacific Ocean, senses fish movement in real time using five unique sensory tentacles. It then uses its muscles to drive its feeding organs to quickly capture prey. Due to its incredible speed and powerful attack, the Bobbit worm can tear a fish in half instantly. This invention, based on the study of the Bobbit worm's hunting movements, aims to create a soft robot that mimics the Bobbit worm. Summary of the Invention

[0005] To address the problems existing in the background art, the present invention provides a soft robot that mimics the Bobbit worm, thereby improving the robot's flexibility and rapid response.

[0006] The technical solution adopted in this invention is:

[0007] I. A soft robot inspired by the Bobbit worm:

[0008] The soft robot includes a sensing sensor, a four-claw actuator module, a pneumatic bistable drive module, a wire-driven robotic arm, and a base. The pneumatic bistable drive module is mounted on the base via the wire-driven robotic arm. The root of the four-claw actuator module is mounted on the pneumatic bistable drive module. The sensing sensor is attached to the four-claw actuator module and the pneumatic bistable drive module. The sensing sensor and the base are electrically connected to an external data acquisition controller. The pneumatic bistable drive module is connected to an external air pump. The external data acquisition controller is electrically connected to the external air pump.

[0009] The sensing sensor includes five triboelectric non-contact proximity sensing units. Each triboelectric non-contact proximity sensing unit has a tentacle array structure on one side. The other side of four triboelectric non-contact proximity sensing units is attached to the four-jaw actuator module, and the other side of the third triboelectric non-contact proximity sensing unit is attached to the pneumatic bistable drive module. All five triboelectric non-contact proximity sensing units are electrically connected to an external acquisition controller.

[0010] The pneumatic bistable drive module includes a silicone bladder, a bistable diaphragm, and an inner support frame. The inner support frame is installed at one end of the linearly driven robotic arm. The silicone bladder is installed on the inner support frame on the side away from the linearly driven robotic arm. The silicone bladder is fitted onto the threaded boss of the inner support frame and fixed with steel wire and silicone adhesive to ensure its airtightness. One side of the bistable diaphragm is attached to the convex surface of the silicone bladder on the side away from the inner support frame. The bistable diaphragm has an annular hollow structure. Several triangular structures extend evenly from the inner periphery of the annular hollow structure toward the center of the bistable diaphragm. The triangular structures do not contact each other, so that the center of the silicone bladder is exposed above the center of the bistable diaphragm. A four-jaw actuator module is fitted onto the outer periphery of the inner support frame and is in close contact with the other side of the bistable diaphragm. The center of the bistable diaphragm serves as the claw center of the four-jaw actuator module. Another triboelectric non-contact proximity sensing unit is attached to the silicone bladder at the center of the bistable diaphragm. The silicone bladder is connected to an external air pump.

[0011] The four-claw execution module includes an outer support frame and four adaptive capture claws. The outer support frame is fitted onto the outer circumferential surface of the inner support frame. The root ends of the four adaptive capture claws are evenly spaced circumferentially connected to the end face of the outer support frame away from the line-driven robotic arm, with the center of the bistable diaphragm as the center. The bottoms of the four adaptive capture claws are in close contact with the circumferential surface of the bistable diaphragm. Four of the sensing sensors are attached to the ventral surface of one of the adaptive capture claws.

[0012] Each adaptive capture claw includes a root link, a fingertip link, a first back-finger link, a second back-finger link, a low link, a first index finger link, and a second index finger link. One end of the root link is connected to the outer support frame, and the other end of the root link is hinged to one side of one end of the low link. The other side of one end of the low link is hinged to one end of the second back-finger link, and the other end of the low link is hinged to one end of the second index finger link. The other end of the second back-finger link is hinged to one end of the first back-finger link, and the other end of the second index finger link is hinged to one end of the first index finger link. The fingertip link is a triangular rod, and the other ends of the first back-finger link and the first index finger link are respectively hinged to two ends of the fingertip link. The other end of the fingertip link serves as the fingertip of the adaptive capture claw. Both the first back-finger link and the second back-finger link are located away from the four-claw actuator. At the center of the block, the low lever, the first indexing lever, and the second indexing lever are all close to the center of the four-claw actuator module. The side of the fingertip lever, the first back-of-the-finger lever, and the second back-of-the-finger lever away from the center of the four-claw actuator module serves as the back side of the claws. The back sides of the claws of the fingertip lever and the first back-of-the-finger lever are connected by a first small spring. The back side of the claw of the second back-of-the-finger lever is connected to one end of the low lever by a second small spring. The side of the fingertip lever, the first indexing lever, and the second indexing lever closer to the center of the four-claw actuator module serves as the front side of the claws. The front sides of the claws of the first indexing lever and the second indexing lever are connected by a third small spring. A triboelectric non-contact proximity sensing unit is attached to the front side of the claw of the fingertip lever. The low lever is tightly attached to the steady-state diaphragm, causing the four adaptive capture claws of the four-claw actuator module to be in an open position. The small springs can absorb some of the energy released from the pneumatic bistable drive module, thereby protecting the object to be captured from damage after capture. The small springs can also allow the four-claw actuator module to adjust its shape according to the shape of the object to be captured to achieve a more stable grasp.

[0013] The described wire-driven robotic arm includes several single-joint connecting plates, several universal joints, and several large springs. The centers of every two adjacent single-joint connecting plates are connected by a universal joint. Four large springs are also connected between every two adjacent single-joint connecting plates, evenly spaced around the universal joints. Each large spring connects to the opposite surfaces of two adjacent single-joint connecting plates at its ends. Each pair of single-joint connecting plates connected to a large spring has a connecting plate through-hole. One single-joint connecting plate at one end of the wire-driven robotic arm is connected to the inner support frame without a connecting plate through-hole, while the other single-joint connecting plate at the other end is connected to the base. In a specific implementation, twenty-eight large springs, six single-joint connecting plates, and seven universal joints can be used.

[0014] The base includes a base plate, two motors, motor mounts, two synchronous pulleys, and four flexible steel cables. The motor mounts are connected to a single-joint connecting plate at the other end of the linearly driven robotic arm via the base plate. Base through holes are provided at positions directly opposite the four connecting plate through holes on the base plate and the single-joint connecting plate. The two motors are mounted on the motor mounts, with their output shafts parallel to the single-joint connecting plate connected to the base. The output shafts of the two motors are perpendicular to each other and arranged opposite each other. The output shafts of the two motors are synchronously connected to a synchronous pulley. Two flexible steel cables are wound around one end of each synchronous pulley. The other end of each flexible steel cable passes through the base through hole and then sequentially passes through a connecting plate through hole of each single-joint connecting plate along the arm length direction of the linearly driven robotic arm, finally connecting to the surface of a single-joint connecting plate at one end of the linearly driven robotic arm mounted on the inner support frame. The two motors are electrically connected to an external data acquisition controller. The four flexible steel cables serve as drive lines, running through the interior of a large spring and ultimately driven by the synchronous pulleys, thereby controlling the bending degree and direction of the linearly driven robotic arm.

[0015] II. A method for fabricating a triboelectric non-contact proximity sensing unit for a soft robot:

[0016] The method includes the following steps:

[0017] Step 1) Template preparation: First, a 3D printing mold of the triboelectric non-contact proximity sensing unit (1) is prepared by 3D printing. Then, the 3D printing template is subjected to surface activity treatment. After the treatment is completed, the sensing unit mold is obtained. The treatment can facilitate the demolding of the substrate in the later stage.

[0018] Step 2) Preparation of PDMS flexible substrate: After uniformly mixing the PDMS precursor liquid and curing agent, degassing is performed, and then the mixture is poured into the sensing unit mold. After vacuum degassing and constant temperature drying and curing, a PDMS flexible substrate with a tendril array structure is obtained and removed from the sensing unit mold.

[0019] Step 3) Fabrication of sensing electrodes: The sensing electrodes are obtained by sputtering one side of the PDMS flexible substrate with the tendril array structure, and then connected to an external acquisition controller through external leads.

[0020] Step 4) Preparation of triboelectric non-contact proximity sensing unit: BTO nanoparticles are added to PDMS precursor solution and stirred evenly, then ultrasonically dispersed to obtain a mixed solution. PDMS curing agent is added and stirred evenly and degassed under vacuum to obtain particle-doped mixed stock solution. The particle-doped mixed stock solution is evenly spin-coated onto one side of the PDMS flexible substrate with a tendril array structure, and then cured at a constant temperature to obtain the triboelectric non-contact proximity sensing unit.

[0021] In step 1), the surface activity treatment specifically involves uniformly spraying RD-518 fluorine release agent onto the surface of the 3D printed mold, then placing it in an oven at 50°C and heating it for 5 minutes. After repeating the above spraying and heating operations 3 times, a sensing unit mold that is easy to demold is obtained.

[0022] In step 2), the PDMS precursor liquid and curing agent are mixed uniformly at a mass ratio of 10:1 and degassed. Then, the mixture is poured into the sensing unit mold, vacuum degassed for 10 minutes, and dried and cured at 70°C for 1 hour to obtain the PDMS flexible substrate.

[0023] In step 3), the sputtering process specifically involves placing the PDMS flexible substrate into a VTC-16-3HD three-target plasma sputtering coating instrument, uniformly sputtering one side with the tentacle array structure for 120 seconds using a sputtering target, with a sputtering vacuum of 7 Pa and a sputtering current below 10 mA. After sputtering, a sensing electrode is obtained. In practice, a gold target can be used as the sputtering target, and after sputtering, a uniform gold electrode can be applied to the surface of the tentacle array.

[0024] In step 4), BTO nanoparticles are added to PDMS precursor solution at a mass fraction of 15wt% and stirred evenly. Then, the solution is placed in an ultrasonic cleaner for ultrasonic dispersion treatment for 30 minutes to obtain a mixed solution. Then, PDMS curing agent with a mass ratio of 10:1 to the mixed solution is added, stirred evenly, and vacuum degassed for 10 minutes to obtain a particle-doped mixed stock solution. The particle-doped mixed stock solution is evenly spin-coated onto one side of the PDMS flexible substrate with a tendril array structure. Then, it is heated and cured at a constant temperature of 70°C in a drying oven for 1 hour to obtain a triboelectric non-contact proximity sensing unit.

[0025] III. A control method for a soft robot:

[0026] The method includes the following steps:

[0027] The external acquisition controller includes an acquisition module, an ADC (Analog-to-Digital Converter) module, and an MCU (Microcontroller Unit). The acquisition module is electrically connected to five triboelectric non-contact proximity sensing units. The output signal of the acquisition module is transmitted to the MCU control unit via the ADC module. The MCU control unit is electrically connected to an external air pump and two motors on the base. Initially, the four adaptive capture claws of the four-claw actuator module are open. As the object to be captured gradually approaches the five triboelectric non-contact proximity sensing units, the five units generate five voltage signals in real time and output them to the acquisition module of the external acquisition control module. The acquisition module then sequentially outputs the five voltage signals to the ADC module and the MCU control unit in real time. The MCU control unit compares the magnitudes of the five received voltage signals with preset voltage thresholds. In a comparison, when the magnitudes of the processed voltage signals all exceed a preset voltage threshold, the MCU control unit controls an external air pump to draw a preset volume of gas from the silicone bladder of the pneumatic bistable drive module. The drawn-in silicone bladder causes the bistable diaphragm to contract, which in turn causes the four adaptive grippers to close, thus grasping the object to be captured. Then, the MCU control unit controls the two motors on the base to rotate, sequentially driving two synchronous pulleys to rotate and, through four flexible steel cables, changing the bending degree and direction of the linear drive robotic arm. This moves the four-jaw actuator module to a preset position. The MCU control unit then controls the external air pump to inflate the silicone bladder. The inflated silicone bladder causes the bistable diaphragm to expand, which in turn causes the four adaptive grippers of the four-jaw actuator module to move from a tightened state to an open state, releasing the object to be captured. This repeated inflation and deflation of the silicone bladder by the air pump allows the four grippers of the four-jaw actuator module to return from a tightened state to an open state, and then back to a tightened state repeatedly. The MCU control unit interacts with the PC via a serial port, and outputs to the lower-level machine, i.e., external actuators such as air pumps and motors, through the IO port.

[0028] The beneficial effects of this invention are:

[0029] 1) By using a triboelectric proximity sensing unit, it is possible to detect approaching objects in advance in a non-contact manner, thus expanding the sensing range of soft robots.

[0030] 2) The pneumatic bistable drive module triggers the energy stored in the bistable membrane by driving the silicone diaphragm, thereby enabling the four-jaw actuator to close quickly and improving the response speed of the four-jaw actuator.

[0031] 3) The adaptive capture gripper with a four-claw execution module equipped with a triboelectric proximity sensing unit can automatically adjust its shape according to the size of the object to perform better grasping. The tentacle array structure of the triboelectric proximity sensing unit increases the friction force when the adaptive capture gripper grasps the object, thus achieving the purpose of assisting grasping. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of the Bobbit worm-inspired soft robot mechanism of the present invention;

[0033] Figure 2 A schematic diagram of the adaptive capture structure;

[0034] Figure 3 This is a schematic diagram of the pneumatic bistable drive module structure;

[0035] Figure 4 This is a schematic diagram of a single joint structure of a robotic arm;

[0036] Figure 5 This is a schematic diagram of the base structure;

[0037] Figure 6 Fabrication diagram of the triboelectric proximity sensing unit;

[0038] Figure 7 This is a schematic diagram of the integrated sensing and actuation control of a soft robot modeled after the Bobbit worm.

[0039] Figure 8 Output voltage diagram of triboelectric proximity sensing unit at different distances;

[0040] In the diagram: 1. Triboelectric non-contact proximity sensing unit; 2. Four-jaw actuator module; 3. Pneumatic bistable drive module; 4. Wire-driven robotic arm; 5. Base; 11. Outer support frame; 12. Adaptive capture claw; 13. Fingertip; 14. Back of first finger; 15. Back of second finger; 16. Low bar; 17. Top of first finger; 18. Top of second finger; 19. Silicone diaphragm; 20. Bistable diaphragm; 21. Inner support frame; 22. Universal joint; 23. Single-joint connecting plate; 24. Base plate; 25. Motor; 26. Motor mount; 27. Synchronous pulley; 28. Large spring. Detailed Implementation

[0041] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0042] like Figure 1 As shown, a Bobbit worm-like soft robot of the present invention includes a sensing sensor, a four-clawed actuation module 2, a pneumatic bistable drive module 3, a wire-driven robotic arm 4, and a base 5. The pneumatic bistable drive module 3 is mounted on the base 5 via the wire-driven robotic arm 4. The root of the four-clawed actuation module 2 is mounted on the pneumatic bistable drive module 3. The sensing sensor is attached to the four-clawed actuation module 2 and the pneumatic bistable drive module 3. The sensing sensor and the base 5 are electrically connected to an external data acquisition controller. The pneumatic bistable drive module 3 is connected to an external air pump. The external data acquisition controller is electrically connected to the external air pump.

[0043] The sensing sensor includes five triboelectric non-contact proximity sensing units 1. Each triboelectric non-contact proximity sensing unit 1 has a tentacle array structure on one side. The other side of four triboelectric non-contact proximity sensing units 1 is attached to the four-jaw actuator module 2, and the other side of the third triboelectric non-contact proximity sensing unit 1 is attached to the pneumatic bistable drive module 3. All five triboelectric non-contact proximity sensing units 1 are electrically connected to an external acquisition controller.

[0044] like Figure 3 As shown, the pneumatic bistable drive module 3 includes a silicone diaphragm 19, a bistable diaphragm 20, and an inner support frame 21. The inner support frame 21 is mounted on one end of the linearly driven robotic arm 4. The silicone diaphragm 19 is mounted on the inner support frame 21 on the side away from the linearly driven robotic arm 4. The silicone diaphragm 19 is fitted onto the threaded boss of the inner support frame 21 and is fixed with steel wire and silicone adhesive to ensure its airtightness. One side of the bistable diaphragm 20 is attached to the convex surface of the silicone diaphragm 19 on the side away from the inner support frame 21. The bistable diaphragm 20 has an annular perforated structure. Several triangular structures extend from the inner periphery of the plate towards the center of the bistable diaphragm 20 at uniform intervals along the circumferential direction. The triangular structures do not contact each other, so that the center of the silicone diaphragm 19 is exposed to the center of the bistable diaphragm 20. The four-jaw actuator 2 is fitted on the outer periphery of the inner support frame 21 and closely attached to the other side of the bistable diaphragm 20. The center of the bistable diaphragm 20 serves as the claw center surface of the four-jaw actuator 2. Another triboelectric non-contact proximity sensing unit 1 is attached to the silicone diaphragm 19 at the center of the bistable diaphragm 20. The silicone diaphragm 19 is connected to an external air pump.

[0045] like Figure 3 As shown, when the air pump inflates, the silicone bladder 19 expands, causing the bistable diaphragm 20 to open upwards, thus rapidly opening the four-jaw actuator module 2 that is attached to the bistable diaphragm 20. At this time, when the four grasping claws of the four-jaw actuator module 2 are open, the bistable diaphragm is in steady state one. When the air pump inhales, the silicone bladder 19 contracts, causing the bistable diaphragm 20 to contract downwards, thus rapidly closing the four-jaw actuator module 2 that is attached to the bistable diaphragm 20. At this time, the four adaptive grasping claws 12 of the four-jaw actuator module 2 are in a tightened state, and the bistable diaphragm 20 is in steady state two. Due to the energy transition mechanism of the bistable structure, once the bistable device is triggered from one steady state, it will switch to another steady state very quickly due to the rapid energy transition. Therefore, by using this characteristic of the bistable structure to drive the soft robot, the soft robot can complete the grasping operation at a relatively fast speed.

[0046] like Figure 2As shown, the four-jaw execution module 2 includes an outer support frame 11 and four adaptive capture claws 12. The outer support frame 11 is fitted onto the outer peripheral surface of the inner support frame 21. The root ends of the four adaptive capture claws 12 are evenly spaced circumferentially connected to the side end face of the outer support frame 11 away from the line-driven robotic arm 4, with the center of the bistable diaphragm 20 as the center. The bottoms of the four adaptive capture claws 12 are in close contact with the peripheral surface of the bistable diaphragm 20. Four of the triboelectric non-contact proximity sensing units 1 of the sensing sensors are attached to the claw ventral surface of each of the adaptive capture claws 12.

[0047] Each adaptive capture claw 12 includes a root link, a fingertip link 13, a first back-of-the-finger link 14, a second back-of-the-finger link 15, a low bar 16, a first indexing link 17, and a second indexing link 18. One end of the root link is connected to the outer support frame 11, and the other end of the root link is hinged to one side of one end of the low bar 16. The other side of one end of the low bar 16 is hinged to one end of the second back-of-the-finger link 15, and the other end of the low bar 16 is hinged to one end of the second indexing link 18. The other end of the second finger back link 15 is hinged to one end of the first finger back link 14, and the other end of the second finger indicator link 18 is hinged to one end of the first finger indicator link 17. The fingertip link 13 is a triangular rod, and the other ends of the first finger back link 14 and the first finger indicator link 17 are respectively hinged to two ends of the fingertip link 13. The other end of the fingertip link 13 serves as the fingertip of the adaptive capture claw 12. Both the first finger back link 14 and the second finger back link 15 are located away from the four claws. At the center of module 2, the low lever 16, the first finger indicator link 17, and the second finger indicator link 18 are all close to the center of the four-claw execution module 2. The side of the fingertip link 13, the first back finger link 14, and the second back finger link 15 away from the center of the four-claw execution module 2 serves as the back of the claws of the four-claw execution module 2. The backs of the claws of the fingertip link 13 and the first back finger link 14 are connected by a first small spring. The back of the claw of the second back finger link 15 is connected to one end of the low lever 16 by a second small spring. The side of the fingertip link 13, the first finger indicator link 17, and the second finger indicator link 18 close to the center of the four-claw execution module 2 serves as the ventral surface of the claws of the four-claw execution module 2. The ventral surfaces of the claws of the first finger indicator link 17 and the second finger indicator link 18 are connected by a third small spring. A triboelectric non-contact proximity sensing unit 1 is attached to the ventral surface of the claw of the fingertip link 13. The low lever 16 is tightly attached to the steady-state diaphragm 20, so that the four adaptive capture claws 12 of the four-claw execution module 2 are in an open state. The small spring can absorb some of the energy released by the pneumatic bistable drive module 3, thereby protecting the object to be captured from damage after capture; the small spring can also enable the four-jaw execution module 2 to adjust its own shape according to the shape of the captured object to achieve a more stable grip.

[0048] like Figure 4As shown, the wire-driven robotic arm 4 includes several single-joint connecting plates 23, several universal joints 22, and several large springs 28. The center of each pair of adjacent single-joint connecting plates 23 is connected by a universal joint 22. Four large springs 28 are also connected between each pair of adjacent single-joint connecting plates 23. The four large springs 28 are evenly spaced around the universal joints 22 in the circumferential direction. The two ends of each large spring 28 are respectively connected to the opposite plates of two adjacent single-joint connecting plates 23. Each pair of single-joint connecting plates 23 connected to each large spring 28 has a connecting plate through hole. One single-joint connecting plate 23 at one end of the wire-driven robotic arm 4 is connected to the inner support frame 21 without a connecting plate through hole, and the other single-joint connecting plate 23 at the other end of the wire-driven robotic arm 4 is connected to the base 5. In a specific implementation, twenty-eight large springs 28, six single-joint connecting plates 23, and seven universal joints 22 can be used.

[0049] like Figure 5 As shown, the base 5 includes a base plate 24, two motors 25, a motor mount 26, two synchronous pulleys 27, and four flexible steel ropes. The motor mount 26 is connected to a single-joint connecting plate 23 at the other end of the linearly driven robotic arm 4 via the base plate 24. Base through holes are provided at positions directly opposite the four connecting plate through holes of the base plate 24 and the single-joint connecting plate 23. The two motors 25 are mounted on the motor mount 26, and their output shafts are parallel to the single-joint connecting plate 23 connected to the base 5. The output shafts of the two motors 25 are perpendicular to each other and arranged opposite each other. The output shafts of the two motors 25 are synchronously connected to a synchronous pulley 27. Two flexible steel ropes are wound around one end of each synchronous pulley 27. The other end of each flexible steel rope passes through the base through hole and then sequentially passes through one connecting plate through hole of each single-joint connecting plate 23 along the arm length direction of the linearly driven robotic arm 4, finally connecting to the surface of a single-joint connecting plate 23 at one end of the linearly driven robotic arm 4 mounted on the inner support frame 21. The two motors 25 are electrically connected to an external data acquisition controller. Four flexible steel cables serve as drive lines, running through the large spring 28 and ultimately driven by the synchronous pulley 27, thereby controlling the degree and direction of bending of the line-driven robotic arm 4.

[0050] The method for fabricating the triboelectric non-contact proximity sensing unit of the soft robot of the present invention includes the following steps:

[0051] Step 1) Template Preparation: First, a 3D printed mold for the triboelectric non-contact proximity sensing unit 1 is prepared using 3D printing. Then, the 3D printed template undergoes surface activation treatment. After treatment, the sensing unit mold is obtained. This treatment facilitates demolding of the substrate later. Specifically, the surface activation treatment involves uniformly spraying RD-518 fluorine release agent onto the surface of the 3D printed mold, then heating it in a 50°C oven for 5 minutes. This spraying and heating process is repeated three times to obtain a sensing unit mold that is easy to demold.

[0052] Step 2) Preparation of PDMS flexible substrate: The PDMS precursor liquid and curing agent are mixed uniformly at a mass ratio of 10:1 and degassed. Then, the mixture is poured into the sensing unit mold, vacuum degassed for 10 min, and dried and cured at 70℃ for 1 h to obtain the PDMS flexible substrate, which is then removed from the sensing unit mold.

[0053] Step 3) Fabrication of the sensing electrode: The sensing electrode is obtained by sputtering one side of the PDMS flexible substrate with the tentacle array structure, and then connected to an external acquisition controller via external leads. Specifically, the sputtering process involves placing the PDMS flexible substrate in a VTC-16-3HD three-target plasma sputtering system, uniformly sputtering the side with the tentacle array structure for 120 seconds using a sputtering target, maintaining a sputtering vacuum of 7 Pa and a sputtering current below 10 mA. After sputtering, the sensing electrode is obtained. In practice, a gold target can be used as the sputtering target, resulting in a uniform gold electrode coating on the surface of the tentacle array.

[0054] Step 4) Preparation of triboelectric non-contact proximity sensing unit 1: BTO nanoparticles were added to PDMS precursor solution at a mass fraction of 15wt% and stirred evenly. Then, the mixture was placed in an ultrasonic cleaner for ultrasonic dispersion treatment for 30 min to obtain a mixed solution. Then, PDMS curing agent with a mass ratio of 10:1 to the mixed solution was added, stirred evenly, and vacuum degassed for 10 min to obtain a particle-doped mixed stock solution. The particle-doped mixed stock solution was evenly spin-coated on one side of the PDMS flexible substrate with a tendril array structure. Then, it was heated and cured at 70℃ in a drying oven for 1 h to obtain triboelectric non-contact proximity sensing unit 1.

[0055] After the BTO nanoparticle-doped PDMS mixture is cured, it serves as a friction layer. The flexible substrate layer 3 of the triboelectric non-contact proximity sensing unit 1 is attached to the claw surface of the adaptive capture gripper 12 of the four-jaw execution module 2. The friction layer of the triboelectric non-contact proximity sensing unit 1 serves as the claw ventral surface of the adaptive capture gripper 12. When the object to be captured approaches, the electrode layer will generate a voltage change and transmit it to the external acquisition control circuit.

[0056] The control method for the soft robot of the present invention includes the following steps:

[0057] The external acquisition controller includes an acquisition module, an ADC (Analog-to-Digital Converter) module, and an MCU (Microcontroller Unit). The acquisition module is electrically connected to five triboelectric non-contact proximity sensing units 1. The output signal of the acquisition module is transmitted to the MCU control unit via the ADC module. The MCU control unit is electrically connected to an external air pump and two motors 25 of the base 5. Initially, the four adaptive capture claws 12 of the four-claw execution module 2 are open. As the object to be captured gradually approaches the five triboelectric non-contact proximity sensing units 1, the five triboelectric non-contact proximity sensing units 1 generate five voltage signals in real time and output them to the acquisition module of the external acquisition control module. The acquisition module sequentially outputs the five voltage signals to the ADC module and the MCU control unit in real time. The MCU control unit compares the magnitude of the five voltage signals received in real time with preset voltage thresholds. When the processed voltage signal reaches the threshold, the MCU control unit determines the voltage threshold. When the magnitude of the pressure signal is greater than the preset voltage threshold, the MCU control unit controls the external air pump to draw out a preset volume of gas from the silicone diaphragm 19 of the pneumatic bistable drive module 3. After the gas is drawn out, the silicone diaphragm 19 drives the bistable diaphragm 20 to contract. The bistable diaphragm 20 quickly drives the four adaptive capture grippers 12 to close, thereby grabbing the object to be captured. Then, the MCU control unit controls the two motors 25 of the base 5 to rotate, which in turn drives the two synchronous pulleys 27 to rotate and pulls the four flexible steel ropes to change the bending degree and bending direction of the linear drive robot arm 4, thereby driving the four-jaw execution module 2 to move to the preset position. Then, the MCU control unit controls the external air pump to inflate the silicone diaphragm 19. After the silicone diaphragm 19 is inflated, it drives the bistable diaphragm 20 to expand. The bistable diaphragm 20 drives the four adaptive capture grippers 12 of the four-jaw execution module 2 from the tightened state to the open state, releasing the object to be captured. The four gripping claws of the four-claw actuator module are repeatedly inflated and deflated by an air pump to return from a tightened state to an open state, and then back to a tightened state. The MCU control unit interacts with the PC via a serial port and outputs to the lower-level machine, i.e., external actuators such as air pumps and motors, through the I / O port.

[0058] like Figure 8 As shown, further, using a 40×40mm FEP film as the approach object of the Bobbit worm-inspired soft robot, the open-circuit voltage of the prepared triboelectric non-contact proximity sensing unit 1 was measured at different intervals, and the relationship between the distance and the sensor's actual output was observed to fit the distance to the approach object. This allows the present invention to perceive approaching objects in advance in a non-contact manner through the triboelectric proximity sensing unit, thereby expanding the sensing range of the soft robot and enabling the bionic robotic hand to perceive the entire process from approach to contact to grasping when capturing an object.

Claims

1. A soft robot inspired by the Bobbit worm, characterized in that: The system includes a sensing sensor, a four-jaw actuator module (2), a pneumatic bistable drive module (3), a wire-driven robotic arm (4), and a base (5). The pneumatic bistable drive module (3) is mounted on the base (5) via the wire-driven robotic arm (4). The root of the four-jaw actuator module (2) is mounted on the pneumatic bistable drive module (3). The sensing sensor is attached to the four-jaw actuator module (2) and the pneumatic bistable drive module (3). The sensing sensor and the base (5) are electrically connected to an external data acquisition controller. The pneumatic bistable drive module (3) is connected to an external air pump. The external data acquisition controller is electrically connected to the external air pump. The sensing sensor includes five triboelectric non-contact proximity sensing units (1), and the pneumatic bistable drive module (3) includes a silicone bladder (19), a bistable diaphragm (20), and an inner support frame (21). The inner support frame (21) is mounted on one end of the wire-driven robotic arm (4), the silicone bladder (19) is mounted on the inner support frame (21) on the side away from the wire-driven robotic arm (4), and one side of the bistable diaphragm (20) is attached to the convex surface of the silicone bladder (19) away from the inner support frame (21). The bistable diaphragm (20) is annularly hollow. The ring-shaped hollow sheet has several triangular pieces extending evenly around the center of the bistable diaphragm (20) along its inner periphery, with each triangular piece not in contact with the others. The four-claw actuator module (2) is fitted onto the outer periphery of the inner support frame (21) and is in close contact with the other side of the bistable diaphragm (20). The center of the bistable diaphragm (20) serves as the claw center of the four-claw actuator module (2). Another triboelectric non-contact proximity sensing unit (1) is attached to the silicone diaphragm (19) at the center of the bistable diaphragm (20). The silicone diaphragm (19) is connected to an external air pump.

2. The Bobbit worm-like soft robot according to claim 1, characterized in that: Each of the triboelectric non-contact proximity sensing units (1) of the aforementioned sensing sensor has a whisker array structure on one side. The other side of four triboelectric non-contact proximity sensing units (1) is attached to the four-claw actuator module (2), and the other side of the other triboelectric non-contact proximity sensing unit (1) is attached to the pneumatic bistable drive module (3). All five triboelectric non-contact proximity sensing units (1) are electrically connected to an external acquisition controller.

3. The Bobbit worm-like soft robot according to claim 1, characterized in that: The four-claw execution module (2) includes an outer support frame (11) and four adaptive capture claws (12). The outer support frame (11) is fitted on the outer periphery of the inner support frame (21). The root ends of the four adaptive capture claws (12) are evenly spaced and circumferentially connected to the side end face of the outer support frame (11) away from the line-driven robotic arm (4) with the center of the bistable diaphragm (20) as the center. The bottom of the four adaptive capture claws (12) is in close contact with the periphery of the bistable diaphragm (20). Four of the triboelectric non-contact proximity sensing units (1) of the sensing sensor are attached to the claw ventral surface of one of the adaptive capture claws (12).

4. A soft robot resembling a Bobbit worm according to claim 3, characterized in that: Each adaptive capture claw (12) includes a root link, a fingertip link (13), a first back-of-the-finger link (14), a second back-of-the-finger link (15), a low bar (16), a first index link (17), and a second index link (18). One end of the root link is connected to the outer support frame (11), and the other end of the root link is hinged to one side of one end of the low bar (16). The other side of one end of the low bar (16) is hinged to one end of the second back-of-the-finger link (15), and the other end of the low bar (16) is hinged to one end of the second index link (18). The other end of the second finger back link (15) is hinged to one end of the first finger back link (14), and the other end of the second finger indicator link (18) is hinged to one end of the first finger indicator link (17). The fingertip link (13) is a triangular rod. The other ends of the first finger back link (14) and the other ends of the first finger indicator link (17) are respectively hinged to two ends of the fingertip link (13). The other end of the fingertip link (13) serves as the fingertip of the adaptive capture claw (12). The first finger back link (14) and the second finger back link (15) are both far away from the four-claw execution module. At the center of block (2), the low rod (16), the first finger indicator link (17), and the second finger indicator link (18) are all close to the center of the four-jaw execution module (2); the side of the fingertip link (13), the first finger back link (14), and the second finger back link (15) away from the center of the four-jaw execution module (2) serves as the back of the claw of the four-jaw execution module (2). The backs of the claws of the fingertip link (13) and the first finger back link (14) are connected by a first small spring, and the back of the claw of the second finger back link (15) is connected to one end of the low rod (16) by a second small spring. The fingertip link (13), the first fingertip link (17), and the second fingertip link (18) are located on the side of the four-claw execution module (2) near the center, which serves as the claw surface of the four-claw execution module (2). The claw surfaces of the first fingertip link (17) and the second fingertip link (18) are connected by a third small spring. A triboelectric non-contact proximity sensing unit (1) is attached to the claw surface of the fingertip link (13). The low rod (16) is attached to the steady-state diaphragm (20), so that the four adaptive capture claws (12) of the four-claw execution module (2) are open.

5. A soft robot resembling a Bobbit worm according to claim 1, characterized in that: The wire-driven robotic arm (4) includes several single-joint connecting plates (23), several universal joints (22), and several large springs (28). The center of the plate surface of each two adjacent single-joint connecting plates (23) is connected by a universal joint (22). Four large springs (28) are also connected between the plate surfaces of each two adjacent single-joint connecting plates (23). The four large springs (28) are evenly spaced around the universal joints (22) in the circumferential direction. The two ends of each large spring (28) are respectively connected to the opposite plate surfaces of two adjacent single-joint connecting plates (23). A connecting plate through hole is opened at the plate surface of the two single-joint connecting plates (23) connected to each large spring (28). One single-joint connecting plate (23) at one end of the wire-driven robotic arm (4) is connected to the inner support frame (21) without a connecting plate through hole. One single-joint connecting plate (23) at the other end of the wire-driven robotic arm (4) is connected to the base (5).

6. A soft robot resembling a Bobbit worm according to claim 5, characterized in that: The base (5) includes a base plate (24), two motors (25), a motor mount (26), two synchronous pulleys (27), and four flexible steel ropes. The motor mount (26) is connected to a single-joint connecting plate (23) at the other end of the online drive robotic arm (4) via the base plate (24). Base through holes are provided on the base plate (24) and at positions directly opposite to the four connecting plate through holes of the single-joint connecting plate (23). The two motors (25) are mounted on the motor mount (26), and the output shafts of the two motors (25) are parallel to the single-joint connecting plate (23) connected to the base (5). The output shafts of the two motors (25) are perpendicular to each other and arranged opposite each other. The output shafts of the two motors (25) are synchronously connected to a synchronous pulley (27). Two flexible steel ropes are wound around one end of each synchronous pulley (27). The other end of each flexible steel rope passes through the through hole of the base and then passes through one of the connecting plate through holes of each single joint connecting plate (23) along the arm length direction of the line-driven robotic arm (4). Finally, it is connected to the plate surface of a single joint connecting plate (23) at one end of the line-driven robotic arm (4) installed on the inner support frame (21). The two motors (25) are electrically connected to an external acquisition controller.

7. The method for fabricating a triboelectric non-contact proximity sensing unit for a soft robot according to any one of claims 1-6, characterized in that: The method includes the following steps: Step 1) Template preparation: First, a 3D printing mold of the triboelectric non-contact proximity sensing unit (1) is prepared by 3D printing. Then, the 3D printing template is subjected to surface activity treatment. After the treatment is completed, the sensing unit mold is obtained. Step 2) Preparation of PDMS flexible substrate: After uniformly mixing the PDMS precursor liquid and curing agent, degas the mixture and pour it into the sensing unit mold. After vacuum degassing and constant temperature drying and curing, a PDMS flexible substrate with a tendril array structure is obtained and removed from the sensing unit mold. Step 3) Fabrication of sensing electrodes: The sensing electrodes are obtained by sputtering one side of the PDMS flexible substrate with the tendril array structure, and then connected to an external acquisition controller through external leads. Step 4) Preparation of triboelectric non-contact proximity sensing unit (1): BTO nanoparticles are added to PDMS precursor solution and stirred evenly. Then, ultrasonic dispersion is performed to obtain a mixed solution. PDMS curing agent is added and stirred evenly and vacuum degassed to obtain particle-doped mixed stock solution. The particle-doped mixed stock solution is evenly spin-coated on one side of the PDMS flexible substrate with a tendril array structure. Then, it is heated at a constant temperature to cure and obtain triboelectric non-contact proximity sensing unit (1).

8. The method for preparing the triboelectric non-contact proximity sensing unit (1) for a soft robot according to claim 7, characterized in that: In step 1), the surface activity treatment specifically involves uniformly spraying RD-518 fluorine release agent onto the surface of the 3D printed mold, then placing it in an oven at 50°C and heating it for 5 minutes. The above spraying and heating operations are repeated 3 times to obtain the sensing unit mold. In step 2), the PDMS precursor liquid and curing agent are mixed uniformly at a mass ratio of 10:1 and degassed. Then, the mixture is poured into the sensing unit mold, vacuum degassed for 10 minutes, and dried and cured at 70°C for 1 hour to obtain the PDMS flexible substrate. In step 3), the sputtering process specifically involves placing the PDMS flexible substrate into a VTC-16-3HD three-target plasma sputtering coating instrument, uniformly sputtering one side with the tendril array structure for 120 seconds using a sputtering target, with a sputtering vacuum of 7 Pa and a sputtering current of less than 10 mA, and obtaining the sensing electrode after sputtering. In step 4), BTO nanoparticles are added to PDMS precursor solution at a mass fraction of 15wt% and stirred evenly. Then, the solution is placed in an ultrasonic cleaner for ultrasonic dispersion treatment for 30 minutes to obtain a mixed solution. Then, PDMS curing agent with a mass ratio of 10:1 to the mixed solution is added, stirred evenly, and vacuum degassed for 10 minutes to obtain a particle-doped mixed stock solution. The particle-doped mixed stock solution is evenly spin-coated on one side of the PDMS flexible substrate with a tendril array structure. Then, it is heated and cured at a constant temperature of 70℃ in a drying oven for 1 hour to obtain a triboelectric non-contact proximity sensing unit (1).

9. The control method for a soft robot according to any one of claims 1-6, characterized in that: The method includes the following steps: The external acquisition controller includes an acquisition module, an ADC analog-to-digital converter module, and an MCU control unit. The acquisition module is electrically connected to five triboelectric non-contact proximity sensing units (1). The output signal of the acquisition module is transmitted to the MCU control unit via the ADC analog-to-digital converter module. The MCU control unit is electrically connected to the external air pump and two motors (25) of the base (5). In the initial state, the four adaptive capture claws (12) of the four-claw execution module (2) are in an open state. When the object to be captured gradually approaches the five triboelectric non-contact proximity sensing units (1), the five triboelectric non-contact proximity sensing units (1) generate five voltage signals in real time and output them to the acquisition module of the external acquisition control module. The acquisition module outputs the five voltage signals sequentially to the ADC analog-to-digital converter module and the MCU control unit in real time. The MCU control unit compares the magnitude of the five voltage signals received in real time with the preset voltage threshold. When the magnitude of the processed voltage signals is greater than the preset voltage threshold, the signal is considered to be captured. When the preset voltage threshold is reached, the MCU control unit controls the external air pump to draw out a preset volume of gas from the silicone membrane bladder (19) of the pneumatic bistable drive module (3). After the gas is drawn out, the silicone membrane bladder (19) causes the bistable diaphragm (20) to contract. The bistable diaphragm (20) quickly drives the four adaptive capture grippers (12) to close, thereby grabbing the object to be captured. Then, the MCU control unit controls the two motors (25) of the base (5) to rotate, which in turn drives the two synchronous pulleys (27) to rotate and pulls the four flexible steel ropes to change the bending degree and bending direction of the line-driven robotic arm (4), thereby driving the four-jaw execution module (2) to move to the preset position. Then, the MCU control unit controls the external air pump to inflate the silicone membrane bladder (19). After the gas is inflated, the silicone membrane bladder (19) causes the bistable diaphragm (20) to expand. The bistable diaphragm (20) causes the four adaptive capture grippers (12) of the four-jaw execution module (2) to go from the tightened state to the open state, releasing the object to be captured.

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