Sma and ipmc driven smart underwater biomimetic soft robots

Abstract

This invention relates to the field of underwater robot technology, and more particularly to an intelligent underwater biomimetic soft robot driven by SMA and IPMC actuators, comprising a fish head, a fish body, and a fish tail; the fish head is fixed to the front end of the fish body, and a pectoral fin is rotatably connected to each side of the fish body, and the pectoral fins are driven by a pectoral fin rotation device to achieve rotation. This invention, through the design of the fish tail and pectoral fins, and driven by SMA and IPMC actuators, enables the swinging of the fish tail and pectoral fins, combined with the angular rotation of the pectoral fins by the pectoral fin rotation device. Under their combined action, the robot can effectively achieve actions such as straight swimming, left and right turns, surfacing and diving. Furthermore, this robot is small in size, lightweight, noiseless, and has good biomimetic effects, making it easier to blend into schools of fish and autonomously navigate when exploring unknown waters.

Description

Technical Field

[0001] This invention relates to the field of underwater robot technology, and more particularly to intelligent underwater biomimetic soft robots driven by SMA and IPMC. Background Technology

[0002] An underwater robot is a complex electromechanical system capable of carrying a certain payload and completing target tasks underwater through human control or autonomous navigation. With the development and maturation of underwater robot technology, it has been widely used in various underwater work fields, such as unknown water exploration, underwater topographic mapping, mine countermeasures, and underwater target detection.

[0003] Traditional underwater robots are mostly powered by motors, which form propellers, jet pumps, and other propulsion devices. They can swim at high speeds and carry heavy objects. However, underwater robots driven in this way also have many disadvantages, such as complex transmission structures, high noise, large size, large weight, and poor biomimetic effects.

[0004] With the emergence of bionic robots, these problems have been gradually solved. Bionic soft robots driven by various smart materials have advantages that traditional underwater robots do not have, such as smaller size, lighter weight, no noise, and better bionic effect. Especially when exploring unknown waters, silent bionic robots are more likely to blend into schools of fish and cruise autonomously.

[0005] Therefore, we designed an underwater intelligent bionic soft robot according to the present invention. Summary of the Invention

[0006] The purpose of this invention is to provide an intelligent underwater biomimetic soft robot driven by SMA and IPMC, which solves the technical problems of existing underwater robots such as complex dynamic structure, high noise, large size, large weight and poor biomimetic effect.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] Intelligent underwater biomimetic soft robots powered by SMA and IPMC, including a fish head, body, and tail;

[0009] The fish head is fixed to the front end of the fish body, and a pectoral fin is rotatably connected to each side of the fish body, and the pectoral fins are driven to rotate by a pectoral fin rotating device.

[0010] Each of the pectoral fins is embedded with at least two IPMC drivers;

[0011] The fish tail includes several main fish bones of different sizes, several secondary fish bones of the same shape, a Flex flexible sensor, a large strain SMA actuator, a fish tail membrane, and a tail fin.

[0012] The main and secondary fish bones are alternately hinged in sequence. The Flex flexible sensor is installed in the four main fish bones near the fish body through square holes. The large strain SMA actuator is a single SMA wire wound back and forth into an "8" shape and installed on both sides of the main and secondary fish bones.

[0013] Furthermore, the shell portion of the fish body is 3D printed using PLA material and sealed and bonded using silicone adhesive.

[0014] Furthermore, the pectoral fin rotating device is driven to rotate by an SMA spring;

[0015] The pectoral fin rotating device includes a rotating end cap, which is assembled with the fish body through a limiting slot and fixed with silicone. The pectoral fin rotating device also includes a main rotating body, one end of which is fixedly connected to the pectoral fin through a rotating shaft. The rotating shaft passes through the fish body shell and is rotatably connected to the fish body. The main rotating body has two arc-shaped sliding grooves inside, and the SMA springs are respectively installed inside the two arc-shaped sliding grooves.

[0016] Two fixing blocks are fixed on one side of the rotating end cover, and the fixing blocks are respectively located inside the two slide grooves. One end of the SMA spring is fixed to the end wall of the slide groove, and the other end is fixed to the fixing block.

[0017] Furthermore, the pectoral fin portion is formed by casting after embedding the IPMC driver;

[0018] The pectoral fins are made of ecflex-0030 silicone with a hardness of 15.

[0019] Furthermore, biomimetic electrodes are installed on both sides of the fish body. The biomimetic electrodes include emitting electrodes and receiving electrodes. The positive and negative poles of the emitting electrodes are distributed on the same side of the fish body, and the receiving electrodes are located on the other side of the fish body.

[0020] Furthermore, the main fish bone, secondary fish bone, and tail fin are directly printed using PLA material via 3D printing.

[0021] Furthermore, the main fishbone and the secondary fishbone are hinged together by a fan-shaped hole and a semi-circular pin, and the ends are limited by a washer and a pin. The sweeping angle on one side of the fan-shaped hole is 8°.

[0022] Furthermore, the fish tail membrane has a corrugated tube-like structure, is made of ecflex-0030 silicone with a hardness of 20 degrees, and is bonded to the fish body and tail fin by silicone.

[0023] Furthermore, four pins are provided on both sides of the main fishbone, which pass through the SMA driver and divide it into three sections.

[0024] The present invention has at least the following beneficial effects:

[0025] This invention designs a biomimetic soft robot based on the shape of a fish. The robot features a fish tail and pectoral fins, driven by SMA and IPMC actuators, enabling the tail and pectoral fins to swing. Combined with a pectoral fin rotation device, the robot can effectively achieve actions such as straight swimming, turning left and right, and surfacing and diving. Furthermore, the robot is small in size, lightweight, noiseless, and has a good biomimetic effect, making it easier to blend into schools of fish and autonomously navigate when exploring unknown waters. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0028] Figure 2 A schematic diagram of the extension and retraction of an SMA spring;

[0029] Figure 3 A schematic diagram of the pectoral fin;

[0030] Figure 4 Schematic diagram of the pectoral fin rotation mechanism Figure 1 ;

[0031] Figure 5 Schematic diagram of the pectoral fin rotation mechanism Figure 2 ;

[0032] Figure 6 This is a schematic diagram of the biomimetic electrode distribution;

[0033] Figure 7 This is a diagram of a fish tail.

[0034] Figure 8 A schematic diagram showing the connection between the main fish bone and the secondary fish bone;

[0035] Figure 9 This is a diagram illustrating the movement of a fish's tail.

[0036] Figure 10 A schematic diagram of a large strain SMA actuator;

[0037] Figure 11 This is a schematic diagram of linear movement;

[0038] Figure 12Diagram showing left and right turns;

[0039] Figure 13 This is a diagram illustrating the ascent and descent.

[0040] Figure 14 This is a schematic diagram of an IPMC driver.

[0041] In the picture:

[0042] 1. Fish head; 2. Fish body; 21. Pectoral fin; 22. Pectoral fin rotating device; 221. Rotating end cap; 222. Main rotating body; 223. Fixing block; 4. Bionic electrode; 3. Fish tail; 31. Main fish bone; 311. Pin; 32. Secondary fish bone; 33. Fish tail membrane; 34. Caudal fin; 35. Flex flexible sensor; 36. Large strain SMA actuator. Implementation

[0043] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Example

[0044] The intelligent underwater biomimetic soft robot of this invention mainly imitates the BCF propulsion method (using the swinging of the main body and tail fin of the fish to achieve swimming) and MPF propulsion method (using the swinging of the front fin and pectoral fin of the fish to achieve forward swimming). Combined with underwater biomimetic electric field sensing technology, the robot can perform close-range detection and sensing in dark and turbid waters, thus improving the robot's intelligence.

[0045] For details, please refer to Figure 1 The intelligent underwater biomimetic soft robot of the present invention has three parts arranged sequentially from front to back: a fish head 1, a fish body 2, and a fish tail 3.

[0046] The shell of the fish body 2 is made of PLA material by 3D printing and sealed with silicone adhesive to improve the overall structure's waterproofness and flexibility.

[0047] The fish head 1 is fixed to the front end of the fish body 2. A pectoral fin 21 is rotatably connected to each side of the fish body 2, and the pectoral fin 21 is driven to rotate by the pectoral fin rotating device 22.

[0048] In one specific embodiment, the pectoral fin rotating device 22 is driven by an SMA spring to rotate. The SMA filament is highly flexible at room temperature and can be made into any shape. After being artificially created with shape memory nodes and deformed by external force, it can increase its hardness and return to its original length at a temperature of approximately 70°C. The driving principle is as follows: Figure 2 As shown. Figure 3 The arc-shaped cavity of the rotating device 22 is equipped with SMA springs for the rotation of the pectoral fins, which can be referred to as SMA-1 and SMA-2.

[0049] The specific assembly plan is as follows: Figure 4 and Figure 5 As shown. The rotating device 22 includes a rotating end cap 221, which is assembled with the fish body 2 through a limiting slot and fixed with silicone. The rotating device 22 also includes a main rotating body 222, one end of which is fixedly connected to the pectoral fin 21 through a rotating shaft. The rotating shaft passes through the shell of the fish body 2 and is rotatably connected to the fish body 2. The main rotating body 222 has two arc-shaped sliding grooves inside, and the SMA-1 and SMA-2 are respectively assembled inside the two arc-shaped sliding grooves.

[0050] Two fixing blocks 223 are fixed on one side of the rotating end cover 221, and the fixing blocks 223 are respectively located inside the two slide grooves. One end of SMA-1 and SMA-2 is fixed to the end wall of the slide groove, and the other end is fixed to the fixing block 223.

[0051] Specifically, when SMA-1 and SMA-2 are energized or de-energized, different angles of the pectoral fin 21 can be adjusted, as shown in the following example: In the initial state, both SMA-1 and SMA-2 are de-energized. At this time, both SMA-1 and SMA-2 are at their original lengths, and the pectoral fin 21 is at an angle parallel to the fish body 2. When SMA-2 is energized, it heats up and contracts, simultaneously causing SMA-1 to extend and causing the pectoral fin 21 to rotate along the direction of the solid arrow. Conversely, when SMA-1 is energized again, it heats up and contracts, simultaneously causing SMA-2 to extend and causing the pectoral fin 21 to rotate along the dotted line, as shown below. Figure 5 As shown.

[0052] The pectoral fin 21 is formed by embedding the IPMC actuator and then casting it. Because the IPMC driving force is relatively small, the pectoral fin 21 is made of ecflex-0030 silicone with a hardness of 15 degrees to ensure the normal execution of the pectoral fin's oscillation. When the aforementioned IPMC material is electrically stimulated, it expands near the cathode and contracts near the anode, causing the IPMC to bend towards the anode. Applying a reverse voltage achieves reverse bending, thus achieving the oscillation driving effect. The driving principle is as follows... Figure 14 As shown. See also... Figure 4 At least two IPMC actuators, which can be referred to as IPMC-1 and IPMC-2, are embedded in the pectoral fin 21. Each IPMC actuator is connected to the control module via a metal electrode near the end of the fish body. When powered on, under the action of the control module, it mimics the flapping of the fish fin vertically on the surface of the fin.

[0053] Bionic electrodes 4, including transmitting and receiving electrodes, are installed on both sides of the fish body 2. This allows the generation of a bionic electric field, and the receiving electrodes construct a bionic electric field sensor. By sensing subtle changes in the electric field, the robot obtains information about its surrounding environment, aiding in localization, communication, and autonomous navigation. The distribution of the four electrodes is as follows: Figure 6 As shown. The positive and negative electrodes of the transmitting electrode are located on the same side, and the receiving electrodes 1 and 2 are located on the same side.

[0054] See Figure 7 The fish tail 3 is composed of 9 main fish bones 31 of different sizes, 8 secondary fish bones 32 of the same shape, a Flex flexible sensor 35, a pair of large strain SMA actuators 36, a fish tail membrane 33, and a tail fin 34. The main fish bones 31, secondary fish bones 32 and tail fin 34 are directly printed by 3D printing using PLA material. The main fish bones 31 and secondary fish bones 32 support the entire shape of the tail after being connected, and are connected to the tail fin 34 to generate propulsion force. After the parts are connected, except for the hinged main fish bones 31 and secondary fish bones 32, the rest are all glued and fastened with silicone.

[0055] The main fishbone 31 and the secondary fishbone 32 are alternately hinged in sequence, such as Figure 8 As shown. Specifically, it is hinged to a semi-circular pin through a fan-shaped hole, with the end of the semi-circular pin limited by a washer and a pin; the sweep angle on one side of the fan-shaped hole is 8°, and this design limits the relative rotation between the main and secondary fish bones to ±8°; the main fish bone 31 near the caudal fin 34 is hinged through a semi-circular hole and a semi-circular pin, and the main fish bone 31 near the body 2 is hinged in the same way; the purpose of this design is to allow the maximum sweep angle of the fish tail to be 256° when it swings, such as... Figure 9 As shown.

[0056] The outer part of the fish tail 3 is the fish tail membrane of the intelligent bionic soft robot. Its shape is similar to a corrugated tube structure. It is made of ecflex-0030 silicone with a hardness of 20 degrees. It is bonded to the fish body 2 and the tail fin through silicone, which can fit the fish bones well and ensure the flexibility of the tail drive. When the fish tail is subjected to force and swings, the corrugated fish tail membrane can be compressed and folded or stretched and unfolded on one side.

[0057] The Flex flexible sensor 35 is installed through square holes in the four main fish bones 31 near the fish body. This is a resistive flexible thin-film pressure sensor that generates a change in resistance when it bends and deforms, and then converts the change into a corresponding electrical signal change and feeds it back to the control system. The control system analyzes the signal and determines the bending state of the fish tail and predicts the posture of the fish tail.

[0058] The large strain SMA actuator 36 is formed by winding a single SMA wire back and forth into a figure-eight shape, and is divided into three sections by four pins (311) fixed on both sides of the main fishbone 31, and then installed on both sides of the main fishbone 31 and the secondary fishbone 32, as shown. Figure 7 As shown in the magnified section, the design of adding pin 311 is mainly to prevent the large strain SMA actuator 36 from shifting during elongation and compression.

[0059] This design enables the actuator to have a strain capacity of 38% and generate a large driving force, meeting the tail-driven requirements of the robot during underwater movement. The large-strain SMA actuator 36 is divided into three sections; the driving principle analysis is performed on the first section closest to the fish's body, as follows... Figure 10 As shown.

[0060] Specifically, the robot's swimming, turning, surfacing and diving, acceleration, sudden stop, and autonomous cruising methods are as follows:

[0061] Straight-line swimming

[0062] The robot swims in a straight line by swinging its tail 3 left and right. The large-strain SMA actuator 36 is controlled using a polling heating method, meaning the two large-strain SMA actuators 36 are energized and heated at different times. For example, after the left large-strain SMA actuator 36 reaches its phase transition temperature and cools for a period of time, the right large-strain SMA actuator 36 is energized and heated, and this cycle is repeated to achieve the left-right swinging effect of the tail 3. Combined with a Flex flexible sensor, when the sensor generates resistance due to the bending and deformation of the tail, the energizing time of the SMA actuator is controlled based on the feedback electrical signal, thereby controlling the swinging angle of the tail within the maximum rotation angle. Figure 11 As shown.

[0063] Turn left and right

[0064] When performing left and right turns, the robot can achieve rapid turning movements by coordinating its pectoral fins 21 and tail 3. Taking a left turn as an example: When the control integration receives a left turn command, it first stops the tail-driven oscillation. Based on the electrical signal from the Flex flexible sensor, it determines whether the tail has returned to its initial state. Once it returns to its initial state, the right pectoral fin rotation device drives the pectoral fin to rotate 90°. Then, the IPMC drivers embedded in the pectoral fin 21, designated IPMC-3 and IPMC-4, are energized to oscillate, thereby driving the pectoral fin to flap. The left pectoral fin remains in its initial position. While the pectoral fins are oscillating, the tail fin oscillates frequently to the left under a specific heating sequence command. When the turn command is completed, the right pectoral fin rotation device drives the right pectoral fin back to its initial state. The specific process is as follows: Figure 12 As shown.

[0065] Ascending and Diving

[0066] The robot's ascent and descent are primarily related to the movement of its pectoral fins. Upon receiving an ascent command, the four IPMCs in both pectoral fins are simultaneously energized, driving a 1 / 4 cycle sinusoidal AC voltage signal. With the clamping electrodes positioned as anodes on top and cathodes on the bottom, the pectoral fins bend upwards. Once the desired pose is achieved, the voltage is switched back to a normal sinusoidal voltage. The robot's descent principle is the same, except that initially, the bottom of the pectoral fin is the anode and the top the cathode, adjusting the voltage polarity. During the oscillation, the tail actuator can simultaneously execute the energizing sequence for linear cruising, thus achieving rapid ascent or descent. Figure 13 As shown.

[0067] Acceleration, sudden stop

[0068] When the robot needs to accelerate, the polling and heating conversion frequency driven by the tail increases, which in turn increases the left and right swinging frequency of the tail, causing the tail fin to swing within a small angle. When the robot needs to decelerate or stop suddenly, the polling and heating conversion time driven by the tail increases, and the pectoral fin rotates 90 degrees and bends and swings in the direction the robot is moving, generating a reverse thrust in the opposite direction of movement until the expected swimming speed is reached.

[0069] Autonomous cruise

[0070] The robot's autonomous navigation relies on a biomimetic electric field sensing device. When the robot receives an autonomous navigation command, it senses changes in its own biomimetic electric field caused by the surrounding environment to achieve the purpose of guidance and drive. For example, if the robot is set to perform the following commands, it will approach the nearest swimming object at a normal speed when it senses a change in the electric field. The motion execution state is as follows: when the robot senses a corresponding change in the electric field through the biomimetic electric field sensing device underwater, it will first turn to align with the target, and then use its tail fin to drive closer to the target. If commands such as surfacing or diving are required, the robot will be controlled through a predetermined program.

[0071] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention. The scope of protection claimed by the appended claims and their equivalents is defined.

Claims

1. An intelligent underwater biomimetic soft robot driven by SMA and IPMC, characterized in that, Includes the fish head (1), the fish body (2), and the fish tail (3); The fish head (1) is fixed to the front end of the fish body (2), and a pectoral fin (21) is rotatably connected to each side of the fish body (2), and the pectoral fin (21) is driven to rotate by the pectoral fin rotating device (22). At least two IPMC drivers are embedded within each of the pectoral fins (21); The fish tail (3) includes several main fish bones (31) of different sizes, several secondary fish bones (32) of the same type, a Flex flexible sensor (35), a large strain SMA actuator (36), a fish tail membrane (33) and a tail fin (34). The main fish bone (31) and the secondary fish bone (32) are alternately hinged in sequence. The Flex flexible sensor (35) is installed in the four main fish bones (31) near the fish body through square holes. The large strain SMA actuator (36) is made by winding a single SMA wire back and forth into an "8" shape and is installed on both sides of the main fish bone (31) and the secondary fish bone (32). The pectoral fin rotating device (22) is driven to rotate by an SMA spring; The pectoral fin rotating device (22) includes a rotating end cap (221), which is assembled with the fish body (2) through a limiting slot and fixed with silicone. The pectoral fin rotating device (22) also includes a main rotating body (222), one end of which is fixedly connected to the pectoral fin (21) through a rotating shaft. The rotating shaft passes through the fish body (2) shell and is rotatably connected to the fish body (2). The main rotating body (222) has two arc-shaped sliding grooves inside, and the SMA springs are respectively installed inside the two arc-shaped sliding grooves. Two fixing blocks (223) are fixed on one side of the rotating end cover (221), and the fixing blocks (223) are located inside the two slide grooves respectively. One end of the SMA spring is fixed to the end wall of the slide groove, and the other end is fixed to the fixing block (223).

2. The intelligent underwater biomimetic soft robot driven by SMA and IPMC according to claim 1, characterized in that, The shell part of the fish body (2) is made of PLA material by 3D printing and sealed with silicone adhesive.

3. The intelligent underwater biomimetic soft robot driven by SMA and IPMC according to claim 1, characterized in that, The pectoral fin (21) portion is formed by casting after embedding the IPMC driver; The pectoral fin (21) is made of ecflex-0030 silicone with a hardness of 15 degrees.

4. The intelligent underwater biomimetic soft robot driven by SMA and IPMC according to claim 1, characterized in that, Both sides of the fish body (2) are also equipped with biomimetic electrodes (4). The biomimetic electrodes (4) include emitting electrodes and receiving electrodes. The positive and negative electrodes of the emitting electrodes are distributed on the same side of the fish body (2), and the receiving electrodes are located on the other side of the fish body (2).

5. The intelligent underwater biomimetic soft robot driven by SMA and IPMC according to claim 1, characterized in that, The main fish bone (31), secondary fish bone (32) and caudal fin (34) are directly printed by 3D printing using PLA material.

6. The intelligent underwater biomimetic soft robot driven by SMA and IPMC according to claim 1, characterized in that, The main fishbone (31) and the secondary fishbone (32) are hinged together by a fan-shaped hole and a semi-circular pin. The ends are limited by a washer and a pin. The sweeping angle on one side of the fan-shaped hole is 8°.

7. The intelligent underwater biomimetic soft robot driven by SMA and IPMC according to claim 1, characterized in that, The fish tail membrane (33) has a corrugated tube-like structure and is made of ecflex-0030 silicone with a hardness of 20 degrees. It is bonded to the fish body (2) and tail fin by silicone.

8. The intelligent underwater biomimetic soft robot driven by SMA and IPMC according to claim 1, characterized in that, The main fishbone (31) is also provided with four pins on both sides, which pass through the SMA driver (36) and divide it into three sections.

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