A soft robot with variable stiffness and multiple motion forms and its operation method

Abstract

The present invention provides a soft robot with variable stiffness and multiple motion forms and an operation method thereof. The robot comprises a bending arm A, a bending arm B, a bending arm C, a bending arm D and a central connecting piece. The structures and sizes of the bending arms A, B, C and D are the same. The bending arm body is made of silicone material, and the central connecting piece is made of rigid material, and the four different faces of the bending arm A, B, C, D and the central connecting piece are fixed. By inflating and deflating the three chambers of different bending arms to make them bend, the multi-directional flipping of the soft robot is achieved; the motor rotation and the bending of the four bending arms can be switched to a four-legged crawling form. By heating and cooling the low-melting-point alloys of the different bending arms, the overall stiffness of the bending arms can be controlled. The invention has a simple structure, strong adaptability, strong stability, strong bending and deformation ability of the soft body, is not limited by traditional mechanical structures and is not easy to damage.

Description

Technical Field

[0001] The present invention belongs to the field of robot technology, and specifically relates to a variable stiffness multi-motion form soft tumbling robot and an operation method thereof. The robot has a tetrahedral form that can realize multi-directional tumbling motion, and also has a quadrupedal form that can realize forward and backward crawling motion. Background Art

[0002] In recent years, the research on robot movement has become one of the hot topics in the field of science and technology. Various mobile robots with rigid structures have been continuously invented, such as wheeled robots, wheel-legged robots and polyhedron robots. These robots have their own advantages in their fields. For example, wheeled robots have fast moving speed on flat ground. Wheel-legged robots have the characteristics of fast moving speed on flat ground of wheeled robots and efficient obstacle crossing ability of legged robots, but each has certain limitations. Chinese patent application CN104118488A discloses a tetrahedron robot that can move and roll autonomously. The robot can realize autonomous movement in any direction by using omnidirectional wheels, and realizes the rolling movement of the robot by using the rotation of multiple servos and the extension and contraction of cylinders. However, the robot mechanism is relatively complex, has poor adaptability, does not have deformability, and has a single motion form.

[0003] Compared with traditional rigid robots, soft robots use soft materials with low elastic film modulus such as silicone, have better flexibility, simple and light structure, strong adaptability, and are not prone to damage to the surrounding environment. Due to their characteristics, they have been widely studied. Chinese patent application CN110774292A proposes a bionic soft tumbling robot with a regular triangular prism shell. The robot can achieve tumbling motion and has the characteristics of light softness and strong adaptability, but cannot achieve multi-directional tumbling. Summary of the invention

[0004] The main purpose of the present invention is to overcome the problems existing in the prior art and to provide a soft tumbling robot with variable stiffness and multiple motion forms and an operation method thereof. Based on the existing purely rigid structure tetrahedron robot, a soft robot with variable stiffness that can realize rolling and crawling motions is developed, and the two forms can be switched with each other during the motion process. The robot has a strong bending and deformation ability and can adapt to various terrains. In addition, variable stiffness control is added to its rolling form and crawling motion form to ensure the stability of the rolling and crawling motions.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A soft robot with variable stiffness and multiple motion forms is composed of four bending arms, namely, bending arm A, bending arm B, bending arm C and bending arm D, connected to a central connecting block; the four bending arms are elastic arms, which are equipped with low-melting-point alloy and silicone rubber heating plates to achieve rigid-flexible conversion; there are three circumferentially evenly distributed long strip air cavities that can be inflated and deflated, so that the robot can bend in three directions, thereby achieving robot crawling;

[0007] The central connecting block is composed of left and right shells, which are equipped with a motor to drive the left and right shells to rotate relative to each other; thereby driving the two bending arms respectively connected to the left and right shells to move relative to each other, thereby realizing the tumbling movement of the robot. The structures and sizes of the four bending arms are the same and are all driven by gas.

[0008] Preferably, each bending arm comprises an elastic layer, a limiting ring, a low melting point alloy, a silicone rubber heating plate, a silicone cover, a fixing frame and three air chambers. The central connecting member comprises a left shell, a motor, a motor fixing member and a right shell.

[0009] Preferably, the low melting point alloy is embedded in the center layer of the elastic layer when in solid state, and the two ends are closed. The low melting point alloy is a tin-bismuth alloy with a melting point of 70°C. The silicone rubber heating plate wraps the low melting point alloy as an intermediate layer, close to the outermost elastic layer. The silicone rubber heating plate, as a heating layer, is composed of a nickel-chromium alloy heating wire and a silicone rubber high-temperature insulating cloth, which can transform the low melting point alloy between solid and liquid states to achieve rigid-flexible conversion. The limiting ring is wrapped around the outside of the elastic layer to limit the radial expansion of the elastic layer so that only axial elongation occurs.

[0010] Preferably, there are three air cavities between the outermost surface of the elastic layer and the silicone rubber heating plate. The end of the elastic layer in contact with the ground is the support end, and the other end is the charging and discharging end to control the bending of the elastic layer in any direction. The silicone cover is bonded to the charging and discharging end of the elastic layer, and the fixing frame is bonded to the silicone cover. The direction of the three air cavities should be aligned with the direction of the other three bending arms, so that each cycle of rolling can be achieved by controlling the air cavities corresponding to the two bending arms respectively.

[0011] Preferably, the motor is stuck in the groove of the left shell, the motor fixing part is fixed to the motor by bolt connection, and the motor fixing part is fixed to the outer edge of the left shell groove by welding. The motor output shaft adopts a D-shaped shaft, which is tightly connected with the D-shaped groove of the right shell. The rotation of the motor will drive the right shell to rotate.

[0012] Preferably, the bending arm includes a first air chamber, a second air chamber and a third air chamber, which are evenly distributed on the circumference of the elastic layer and are both air inlet and air outlet. The first air chamber is connected to an external air source or the atmosphere through a pneumatic hose to achieve inflation and deflation of the first air chamber; the second air chamber is connected to an external air source or the atmosphere through a pneumatic hose to achieve inflation and deflation of the second air chamber; the third air chamber is connected to an external air source or the atmosphere through a pneumatic hose to achieve inflation and deflation of the third air chamber. The structure of air chamber No. 1 is a hollow fan-shaped cavity. By inflating air into air chamber No. 1, the bending arm bends toward the inner side of air chamber No. 1, and by deflating air into air chamber No. 1, the bending arm returns to its original straight state; the structure of air chamber No. 2 is a hollow fan-shaped cavity. By inflating air into air chamber No. 2, the bending arm bends toward the inner side of air chamber No. 2, and by deflating air into air chamber No. 2, the bending arm returns to its original straight state; the structure of air chamber No. 3 is a hollow fan-shaped cavity. By inflating air into air chamber No. 3, the bending arm bends toward the inner side of air chamber No. 3, and by deflating air into air chamber No. 3, the bending arm returns to its original straight state.

[0013] Preferably, by inflating and deflating the No. 1 and No. 2 air chambers, adjusting the inflation amount and inflation sequence of the No. 1 and No. 2 air chambers, a bending range of nearly 120° from the inner side of the No. 1 air chamber to the inner side of the No. 2 air chamber can be achieved; by inflating and deflating the No. 1 and No. 3 air chambers, adjusting the inflation amount and inflation sequence of the No. 1 and No. 3 air chambers, a bending range of nearly 120° from the inner side of the No. 1 air chamber to the inner side of the No. 3 air chamber can be achieved; by inflating and deflating the No. 2 and No. 3 air chambers, adjusting the inflation amount and inflation sequence of the No. 2 and No. 3 air chambers, a bending range of nearly 120° from the inner side of the No. 2 air chamber to the inner side of the No. 3 air chamber can be achieved. The bending arm A realizes omnidirectional bending.

[0014] The fixing frames of the A bending arm, the B bending arm, the C bending arm and the D bending arm of the present invention are respectively fixed to four different surfaces of the central connecting member by bolt connection.

[0015] Through the above connection, a soft robot with variable stiffness and multiple motion forms is constructed.

[0016] A method for operating a soft robot with variable stiffness and multiple motion forms, using the robot of the present invention for operation, comprising:

[0017] 1) Through the following sequential control method, a soft robot with variable stiffness and multiple motion forms can switch between its rolling and crawling motion forms.

[0018] Step 1: The support ends of the A bending arm, the B bending arm, the C bending arm, and the D bending arm are naturally straightened. The low melting point alloys in the A bending arm, the B bending arm, the C bending arm, and the D bending arm are all in solid state. At this time, the robot is in the initial state of the tumbling mode.

[0019] Step 2, the motor output shaft rotates 90 degrees, driving the A bending arm and the B bending arm to rotate 90 degrees. The A bending arm, the B bending arm, the C bending arm, and the D bending arm are on the same plane. At this time, the low melting point alloys in the A bending arm, the B bending arm, the C bending arm, and the D bending arm are all in a solid state.

[0020] Step 3, power on the silicone rubber heating plates in the A bending arm, B bending arm, C bending arm, and D bending arm to heat the low melting point alloy therein and melt it into a liquid state, and then inflate the A bending arm, B bending arm, C bending arm, and D bending arm to bend inward, at which point they become the initial form of the quadruped crawling mode.

[0021] Step 4, the motor output shaft continues to rotate 90 degrees, driving the A bending arm and the B bending arm to rotate 90 degrees, and the A bending arm, the B bending arm, the C bending arm, and the D bending arm continue to maintain the bending shape of step 3. At this time, the low melting point alloy in the A bending arm, the B bending arm, the C bending arm, and the D bending arm still remains in liquid state.

[0022] Step 5, restore the A, B, C and D bending arms to their normal straight state by releasing air, stop heating the low melting point alloy in the A, B, C and D bending arms, and solidify the low melting point alloy. At this time, the robot has switched from the quadruped crawling form to the polyhedron rolling form.

[0023] By switching between the tumbling and crawling motion modes of the soft robot, the flexibility of the robot during movement is greatly increased. In different environments, the robot can selectively switch its motion mode to improve its motion efficiency.

[0024] 2) Realize the robot's flipping function, including the following control steps.

[0025] Step 1: The A bending arm, the B bending arm, the C bending arm, and the D bending arm are naturally straightened. The low melting point alloys in the A bending arm, the B bending arm, the C bending arm, and the D bending arm are all in a solid state. At this time, the robot is in an initial state.

[0026] Step 2, energize the silicone rubber heating plate in the B bending arm to heat the low melting point alloy therein and melt it into a liquid state, and then inflate the B bending arm to bend inward, while the A bending arm, the C bending arm and the D bending arm remain stationary.

[0027] Step 3, powering up the silicone rubber heating plate in the A bending arm to heat the low melting point alloy therein and melt it into a liquid state, and then inflating the A bending arm to bend inward.

[0028] Step 4: When the A bending arm is bent to a certain angle, the center of gravity of the tumbling robot becomes unstable, causing the support end of the A bending arm to fall to the ground and the support end of the B bending arm to rise, and then proceed to the next operation after it stabilizes.

[0029] Step 5, restore the bending arm to a normal straight state by releasing air, stop heating the low melting point alloy in the bending arm A, and solidify it.

[0030] Step 6, restore the bending arm to a normal straight state by releasing air, stop heating the low melting point alloy in the B bending arm, and solidify the low melting point alloy.

[0031] The above are the control steps for the robot to roll over once. By controlling the bending of any two of the four bending arms, the robot can roll over in any three directions. After multiple rolls, it can reach the specified position.

[0032] 3) Realize the robot's crawling function, including the following control steps in sequence.

[0033] Step 1, the A bending arm, the B bending arm, the C bending arm, and the D bending arm are bent inward, and the low melting point alloy in the A bending arm, the B bending arm, the C bending arm 3 and the D bending arm 4 remain in liquid state. This is the initial form in the quadruped crawling mode.

[0034] Step 2, deflate the B bending arm and the D bending arm, so that the B bending arm and the D bending arm are lifted up and suspended in the air, while the A bending arm and the C bending arm remain stationary.

[0035] Step 3, inflate the air cavities of the A bending arm and the C bending arm to move the B bending arm and the D bending arm forward.

[0036] Step 4, inflate the B curved arm and the D curved arm so that the supporting ends of the B curved arm and the D curved arm fall to the ground and support the entire structure.

[0037] Step 5, deflate the A-bend arm and the C-bend arm so that they are suspended in the air, and then inflate them so that the A-bend arm and the C-bend arm move forward to a position perpendicular to the ground.

[0038] Step 6, inflate the A-bend arm and the C-bend arm so that the supporting ends of the A-bend arm and the C-bend arm fall to the ground and support the entire structure.

[0039] The above are the control steps for the robot to crawl once, which is suitable for movement on flat roads. By switching between the crawling and rolling modes, the efficiency of the movement can be significantly improved.

[0040] Compared with the prior art, the present invention has the following obvious outstanding substantial features and significant advantages:

[0041] 1. The present invention has a simple structure, strong adaptability, strong stability, strong bending and deformation ability of the soft body, is not restricted by traditional mechanical structures and is not easy to damage. It also has a soft robot that can roll in a normal form and a four-legged soft robot that can crawl after rotation.

[0042] 2. The present invention realizes multi-directional flipping of the soft robot by inflating and deflating the three chambers of different bending arms to make them bend; the rotation of the motor and the bending of the four bending arms can be switched to a four-legged crawling form;

[0043] 3. The present invention can achieve the effect of controlling the overall stiffness of the bending arm by heating and cooling the low melting point alloy of different bending arms. The invention has a simple structure, strong adaptability, strong stability, strong bending deformation ability of the soft body, is not limited by the traditional mechanical structure and is not easy to damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1A This is a structural diagram of the variable stiffness and multi-motion morphology soft robot of the present invention.

[0045] Figure 1B This is a module breakdown diagram of the variable stiffness, multi-motion morphology soft robot of the present invention.

[0046] Figure 2 It is a schematic diagram of the transverse structure of the bending arm of the present invention.

[0047] Figure 3 Based Figure 2 AA section view.

[0048] Figure 4 Based Figure 2 Enlarged BB cross-section view.

[0049] Figure 5 It is an exploded view of the central connecting member of the present invention.

[0050] Figure 6 It is a schematic diagram of the process of switching between the motion forms of the robot of the present invention.

[0051] Figure 7 Schematic diagram of the tumbling motion process of the robot of the present invention.

[0052] Figure 8 Schematic diagram of the crawling motion process of the robot of the present invention.

[0053] In the figure: 1. A bending arm, 11. elastic layer, 11a. No. 1 air chamber, 11b. No. 2 air chamber, 11c. No. 3 air chamber, 12. restriction ring, 13. low melting point alloy, 14. silicone rubber heating plate, 15. silicone cover, 16. fixing frame; 2. B bending arm; 3. C bending arm; 4. D bending arm; 5. central connecting piece, 51. left shell, 52. motor, 53. motor fixing piece, 54. right shell. DETAILED DESCRIPTION

[0054] The present invention will be further described below through preferred embodiments in conjunction with the accompanying drawings.

[0055] Embodiment 1:

[0056] See also Figure 1A and Figure 1B , a soft robot with variable stiffness and multiple motion forms, is composed of four bending arms A bending arm 1, B bending arm 2, C bending arm 3 and D bending arm 4 connected to a central connecting block 5. It is characterized by:

[0057] The four bending arms are elastic arms, which are equipped with a low melting point alloy 13 and a silicone rubber heating plate 14 to achieve rigid-flexible conversion; there are three inflatable and deflated long strip air cavities evenly distributed in the circumference, so that the arms can be bent in three directions, thereby achieving robot crawling;

[0058] The central connecting block 5 is composed of left and right shells 51 and 54, and a motor 52 is installed therein to drive the left and right shells 51 and 54 to rotate relative to each other; thereby driving the two bending arms respectively connected to the left and right shells 51 and 54 to move relative to each other, thereby realizing the tumbling movement of the robot.

[0059] The variable stiffness multi-motion form soft tumbling robot of the present embodiment is a soft robot with variable stiffness capable of tumbling and crawling motions, based on the existing purely rigid structure tetrahedron robot. The robot has strong bending and deformation capabilities and can adapt to a variety of terrains. In addition, variable stiffness control is added to its rolling and crawling motion forms to ensure the stability of the tumbling and crawling motions.

[0060] Embodiment 2:

[0061] In this embodiment, a soft robot with variable stiffness and multiple motion forms, such as Figure 1A and Figure 1B As shown, the robot comprises an A bending arm, a B bending arm, a C bending arm, a D bending arm and a central connecting piece, wherein the structures and sizes of the A bending arm, the B bending arm, the C bending arm and the D bending arm are the same.

[0062] The fixing frames 16 of the A bending arm 1 , the B bending arm 2 , the C bending arm 3 , and the D bending arm 4 are respectively fixed to four different surfaces of the central connecting member 5 by means of bolt connection.

[0063] Through the above connection, a soft robot with variable stiffness and multiple motion forms is constructed.

[0064] like Figure 3 and Figure 4 As shown, the A bending arm includes an elastic layer 11, a limiting ring 12, a low melting point alloy 13, a silicone rubber heating plate 14, a silicone cover 15, a fixing frame 16, a No. 1 air chamber 11a, a No. 2 air chamber 11b, and a No. 3 air chamber 11c;

[0065] like Figure 5 As shown, the central connecting member includes a left shell 51, a motor 52, a motor fixing member 53, and a right shell 54;

[0066] The elastic layer 11 is made of highly elastic silicone material. The low melting point alloy 13 is embedded in the central layer of the elastic layer 11 when it is solid, and the two ends are closed. The low melting point alloy 13 is a tin-bismuth alloy with a melting point of 70°C. The silicone rubber heating plate 14 wraps the low melting point alloy 13 as an intermediate layer, close to the outermost elastic layer 11. The silicone rubber heating plate 14, as a heating layer, is composed of a nickel-chromium alloy heating wire and a silicone rubber high-temperature insulating cloth, which can transform the low melting point alloy 13 between solid and liquid states to achieve rigid-flexible conversion. The limiting ring 12 is wrapped around the outside of the elastic layer 11 to limit the radial expansion of the elastic layer 11 so that only axial elongation occurs.

[0067] There are three air cavities between the outermost surface of the elastic layer 11 and the silicone rubber heating plate 14. The end of the elastic layer 11 in contact with the ground is the support end, and the other end is the charging and discharging end, which controls the bending of the elastic layer 11 in any direction. The silicone cover 15 is bonded to the charging and discharging end of the elastic layer 11, and the fixing frame 16 is bonded to the silicone cover 15. The directions of the three air cavities should be aligned with the directions of the other three bending arms, so that each cycle of rolling can be achieved by controlling the air cavities corresponding to the two bending arms respectively.

[0068] The A bending arm includes a first air chamber 11a, a second air chamber 11b, and a third air chamber 11c, which are evenly distributed on the circumference of the elastic layer 11 and are both air inlet and air outlet. The first air chamber 11a is connected to an external air source or the atmosphere through a pneumatic hose to achieve inflation and deflation of the first air chamber 11a; the second air chamber 11b is connected to an external air source or the atmosphere through a pneumatic hose to achieve inflation and deflation of the second air chamber 11b; the third air chamber 11c is connected to an external air source or the atmosphere through a pneumatic hose to achieve inflation and deflation of the third air chamber 11c. The structure of the No. 1 air chamber 11a is a hollow fan-shaped cavity. By inflating the No. 1 air chamber 11a of the A bending arm, the A bending arm is bent toward the inner side of the No. 1 air chamber 11a. By deflating the No. 1 air chamber 11a of the A bending arm, the A bending arm is restored to its original straight state. The structure of the No. 2 air chamber 11b is a hollow fan-shaped cavity. By inflating the No. 2 air chamber 11b of the A bending arm, the A bending arm is bent toward the inner side of the No. 1 air chamber 11a. The No. 2 air chamber 11b is bent toward the inner side, and by releasing air into the No. 2 air chamber 11b of the A bending arm, the A bending arm is restored to its original straight state; the structure of the No. 3 air chamber 11c is a hollow fan-shaped cavity, and by inflating air into the No. 3 air chamber 11c of the A bending arm, the A bending arm is bent toward the inner side of the No. 3 air chamber 11c, and by releasing air into the No. 3 air chamber 11c of the A bending arm, the A bending arm is restored to its original straight state.

[0069] By inflating and deflating the No. 1 and No. 2 air chambers 11a and 11b, and adjusting the inflation amount and inflation sequence of the No. 1 and No. 2 air chambers 11b, a bending range of nearly 120° from the inner side of the No. 1 air chamber 11a to the inner side of the No. 2 air chamber 11b can be achieved; by inflating and deflating the No. 1 and No. 3 air chambers 11c, and adjusting the inflation amount and inflation sequence of the No. 1 and No. 3 air chambers 11a and 11c, a bending range of nearly 120° from the inner side of the No. 1 air chamber 11a to the inner side of the No. 3 air chamber 11c can be achieved; by inflating and deflating the No. 2 and No. 3 air chambers 11b and 11c, and adjusting the inflation amount and inflation sequence of the No. 2 and No. 3 air chambers 11c, a bending range of nearly 120° from the inner side of the No. 2 air chamber 11b to the inner side of the No. 3 air chamber 11c can be achieved.

[0070] The motor 52 is stuck in the groove of the left shell 51, and the motor fixing part 53 is fixed to the motor 52 by bolt connection. The motor fixing part 53 is fixed to the outer edge of the groove of the left shell 51 by welding. The output shaft of the motor 52 adopts a D-shaped shaft, which is tightly connected with the D-shaped groove of the right shell 54. The rotation of the motor 52 will drive the right shell 54 to rotate.

[0071] The bending arm A has the ability to bend in all directions. The tumbling motion of the variable stiffness soft robot can be achieved by controlling the bending of the four bending arms, and the forward and backward crawling motion of the variable stiffness soft robot can be achieved by controlling the rotation of the motor and the bending of the four bending arms.

[0072] The robot of this embodiment can bend the three chambers of different bending arms by inflating and deflating them, thus realizing multi-directional flipping of the soft robot; the motor rotation and the bending of the four bending arms can be switched to a four-legged crawling form. By heating and cooling the low-melting-point alloys of the different bending arms, the overall stiffness of the bending arms can be controlled. The invention has a simple structure, strong adaptability, strong stability, and a strong bending and deformation ability of the soft body. It is not limited by traditional mechanical structures and is not easy to be damaged.

[0073] Embodiment three:

[0074] In this embodiment, a method for operating a soft robot with variable stiffness and multiple motion forms is performed using the above robot:

[0075] 1) To switch between rolling and crawling motion, the control method includes the following sequence:

[0076] Step 1: If Figure 6 In the state shown in Figure a, the support ends of the A bending arm 1, B bending arm 2, C bending arm 3, and D bending arm 4 remain naturally straight. The low melting point alloys in the A bending arm 1, B bending arm 2, C bending arm 3, and D bending arm 4 are all in solid state. At this time, the robot is in the initial state of the tumbling mode.

[0077] Step 2: If Figure 6 As shown in Figure b, the output shaft of the motor 52 rotates 90 degrees, driving the A bending arm 1 and the B bending arm 2 to rotate 90 degrees. The A bending arm 1, the B bending arm 2, the C bending arm 3, and the D bending arm 4 are on the same plane. At this time, the low melting point alloys in the A bending arm 1, the B bending arm 2, the C bending arm 3, and the D bending arm 4 are all in a solid state.

[0078] Step 3: If Figure 6 As shown in Figure c, the silicone rubber heating plates 14 in the A bending arm 1, B bending arm 2, C bending arm 3, and D bending arm 4 are energized to heat the low melting point alloy 13 therein and melt it into a liquid state, and then the A bending arm 1, B bending arm 2, C bending arm 3, and D bending arm 4 are bent inward by inflation, and at this time they become the initial form of the four-legged crawling mode.

[0079] Step 4: Figure 6As shown in Figure d, the output shaft of the motor 52 continues to rotate 90 degrees, driving the A bending arm 1 and the B bending arm 2 to rotate 90 degrees, and the A bending arm 1, the B bending arm 2, the C bending arm 3, and the D bending arm 4 continue to maintain the bending shape of step 3. At this time, the low melting point alloy in the A bending arm 1, the B bending arm 2, the C bending arm 3, and the D bending arm 4 still remains in liquid state.

[0080] Step 5: Figure 6 As shown in Figure e, the A bending arm 1, B bending arm 2, C bending arm 3, and D bending arm 4 are restored to a normal straight state by releasing air, and the heating of the low melting point alloy 13 in the A bending arm 1, B bending arm 2, C bending arm 3, and D bending arm 4 is stopped to solidify the low melting point alloy 13. At this time, the robot has switched from the quadruped crawling form to the polyhedron rolling form.

[0081] By switching between the tumbling and crawling motion modes of the soft robot, the flexibility of the robot during movement is greatly increased. In different environments, the robot can selectively switch its motion mode to improve its motion efficiency.

[0082] 2) The variable stiffness multi-motion morphology soft robot realizes its rolling function, which includes the following control steps in sequence:

[0083] Step 1: If Figure 7 In the state shown in Figure a, the support ends of the A bending arm 1, the B bending arm 2, the C bending arm 3, and the D bending arm 4 remain naturally straight. The low melting point alloys in the A bending arm 1, the B bending arm 2, the C bending arm 3, and the D bending arm 4 are all in solid state. At this time, the robot is in the initial state.

[0084] Step 2: Power on the silicone rubber heating plate 14 in the B bending arm 2 to heat the low melting point alloy 13 therein and melt it into a liquid state, and then inflate the B bending arm 2 to bend inward, while the A bending arm 1, the C bending arm 3 and the D bending arm 4 remain stationary. Figure 7 The state shown in Figure b.

[0085] Step 3: Power is supplied to the silicone rubber heating plate 14 in the bending arm 1 of A to heat the low melting point alloy 13 therein and melt it into a liquid state, and then the bending arm 1 of A is bent inward by inflation, as shown in FIG. Figure 7 The state shown in Figure c.

[0086] Step 4: When the bending arm 1 of A is bent to a certain angle, the center of gravity of the tumbling robot becomes unstable, causing the support end of the bending arm 1 of A to fall to the ground and the support end of the bending arm 2 of B to rise. After it stabilizes, the next operation is performed. Figure 7 The state shown in Figure d.

[0087] Step 5: The bending arm 1 is restored to a normal straight state by releasing air, and the heating of the low melting point alloy 13 in the bending arm 1 is stopped to solidify it. Figure 7 The state shown in Figure e.

[0088] Step 6: The bending arm 2 is restored to a normal straight state by releasing air, and the heating of the low melting point alloy 13 in the bending arm 2 is stopped to solidify the low melting point alloy 13. Figure 7 The state shown in Figure f.

[0089] The above are the control steps for the robot to roll over once. By controlling the bending of any two of the four bending arms, the robot can roll over in any three directions. After multiple rolls, it can reach the specified position.

[0090] 3) The variable stiffness multi-motion morphology soft robot realizes its crawling function, including the following control steps in sequence:

[0091] Step 1: If Figure 8 In the state shown in Figure a, A bending arm 1, B bending arm 2, C bending arm 3, and D bending arm 4 bend inward, and the low-melting-point alloy in A bending arm 1, B bending arm 2, C bending arm 3, and D bending arm 4 remain in liquid state. This is the initial form of the four-legged crawling mode.

[0092] Step 2: If Figure 8 In the state shown in Figure b, the B bending arm 2 and the D bending arm 4 are deflated so that the B bending arm 2 and the D bending arm 4 are lifted up and suspended in the air, while the A bending arm 1 and the C bending arm 3 remain stationary.

[0093] Step 3: If Figure 8 In the state shown in Figure c, the air cavities of the A bending arm 1 and the C bending arm 3 are inflated to move the B bending arm 2 and the D bending arm 4 forward.

[0094] Step 4: Figure 8 In the state shown in Figure d, the B curved arm 2 and the D curved arm 4 are inflated so that the supporting ends of the B curved arm 2 and the D curved arm 4 fall to the ground and support the entire structure.

[0095] Step 5: Figure 8 In the state shown in Figure e, the A curved arm 1 and the C curved arm 3 are deflated so that the A curved arm 1 and the C curved arm 3 are suspended in the air, and then the A curved arm 1 and the C curved arm 3 are inflated so that the A curved arm 1 and the C curved arm 3 move forward to a position perpendicular to the ground.

[0096] Step 6: Figure 8 In the state shown in Figure f, the A curved arm 1 and the C curved arm 3 are inflated so that the supporting ends of the A curved arm 1 and the C curved arm 3 fall to the ground and support the entire structure.

[0097] The above are the control steps for the robot to crawl once, which is suitable for movement on flat roads. By switching between the crawling and rolling modes, the efficiency of the movement can be significantly improved.

[0098] The operating method of the soft robot with variable stiffness and multiple motion forms in this embodiment is to develop a soft robot with variable stiffness that can realize rolling and crawling motions based on the existing pure rigid structure tetrahedron robot, and the two forms can be switched with each other during the motion. The robot has strong bending and deformation capabilities and can adapt to various terrains. In addition, variable stiffness control is added to its rolling form and crawling motion form to ensure the stability of the rolling and crawling motions.

[0099] The above describes the embodiments of the present invention in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made according to the purpose of the invention. Any changes, modifications, substitutions, combinations or simplifications made according to the spirit and principle of the technical solution of the present invention should be equivalent replacement methods. As long as they meet the purpose of the invention and do not deviate from the technical principles and inventive concepts of the present invention, they belong to the protection scope of the present invention.

Claims

1. A soft robot with variable stiffness and multiple motion forms, comprising four bending arms, namely, an A bending arm (1), a B bending arm (2), a C bending arm (3) and a D bending arm (4), connected to a central connecting block (5); characterized in that: The four bending arms are elastic arms, which are equipped with a low melting point alloy (13) and a silicone rubber heating plate (14) to achieve rigid-flexible conversion; there are three inflatable and deflated long strip air cavities evenly distributed in the circumference, so that the arms can be bent in three directions, thereby achieving robot crawling; The central connecting block (5) is composed of a left shell and a right shell (51, 54), and a motor (52) is installed therein to drive the left shell and the right shell (51, 54) to rotate relative to each other; thereby driving the two bending arms respectively connected to the left shell and the right shell (51, 54) to move relative to each other, so as to realize the tumbling movement of the robot; The structures and dimensions of the A bending arm (1), the B bending arm (2), the C bending arm (3) and the D bending arm (4) are the same; Each bending arm includes an elastic layer (11), a limiting ring (12), a low melting point alloy (13), a silicone rubber heating plate (14), a silicone cover (15), and a fixing frame (16); the central connecting block includes a left shell (51), a motor (52), a motor fixing member (53), and a right shell (54); The low melting point alloy (13) is embedded in the central layer of the elastic layer (11) when in solid state, and its two ends are closed. The low melting point alloy (13) is a tin-bismuth alloy with a melting point of 70°C. The silicone rubber heating plate (14) wraps the low melting point alloy (13) as an intermediate layer, which is closely attached to the outermost elastic layer (11). The silicone rubber heating plate (14) serves as a heating layer and is composed of a nickel-chromium alloy heating wire and a silicone rubber high-temperature insulating cloth, which can transform the low melting point alloy (13) between solid and liquid states to achieve rigid-flexible conversion. The limiting ring (12) is wrapped around the outside of the elastic layer (11) to limit the elastic layer ( 11) radial expansion, thereby only axial elongation occurs; there are three air cavities between the outermost surface of the elastic layer (11) and the silicone rubber heating plate (14); the end of the elastic layer (11) in contact with the ground is the support end, and the other end is the inflation and deflation end, which controls the bending of the elastic layer (11) in any direction; the silicone cover (15) is bonded to the inflation and deflation end of the elastic layer (11), and the fixing frame (16) is bonded to the silicone cover (15); the directions of the three air cavities are aligned with the directions of the other three bending arms, so that each cycle of rolling can be achieved by controlling the air cavities corresponding to the two bending arms respectively; The A-bending arm (1) comprises a first air chamber (11a), a second air chamber (11b) and a third air chamber (11c), which are evenly distributed on the circumference of the elastic layer (11) and are both air inlet and air outlet. The first air chamber (11a) is connected to an external air source or the atmosphere via a pneumatic hose to achieve inflation and deflation of the first air chamber (11a). The second air chamber (11b) is connected to an external air source or the atmosphere via a pneumatic hose to achieve inflation and deflation of the second air chamber (11b). The third air chamber (11c) is connected to an external air source or the atmosphere via a pneumatic hose to achieve inflation and deflation of the third air chamber (11c). The structure of the first air chamber (11a) is a hollow fan-shaped cavity. By inflating the first air chamber (11a), the A-bending arm (1) is The curved arm is bent toward the inner side of the first air chamber (11a), and the curved arm A is restored to its original straight state by releasing air into the first air chamber (11a); the second air chamber (11b) is a hollow fan-shaped cavity, and the curved arm A is bent toward the inner side of the second air chamber (11b) by inflating air into the second air chamber (11b), and the curved arm A is restored to its original straight state by releasing air into the second air chamber (11b); the third air chamber (11c) is a hollow fan-shaped cavity, and the curved arm A is bent toward the inner side of the third air chamber (11c) by inflating air into the third air chamber (11c), and the curved arm A is restored to its original straight state by releasing air into the third air chamber (11c); By inflating and deflating the No. 1 air chamber (11a) and the No. 2 air chamber (11b), and adjusting the inflation amount and inflation order of the No. 1 air chamber (11a) and the No. 2 air chamber (11b), a bending range of nearly 120° from the inner side of the No. 1 air chamber (11a) to the inner side of the No. 2 air chamber (11b) can be achieved; by inflating and deflating the No. 1 air chamber (11a) and the No. 3 air chamber (11c), and adjusting the inflation amount and inflation order of the No. 1 air chamber (11a) and the No. 3 air chamber (11c), a bending range of nearly 120° from the inner side of the No. 1 air chamber (11a) to the inner side of the No. 2 air chamber (11b) can be achieved. By adjusting the inflation sequence, a bending range of nearly 120° from the inner side of the No. 1 air chamber (11a) to the inner side of the No. 3 air chamber (11c) can be achieved; by inflating and deflating the No. 2 air chamber (11b) and the No. 3 air chamber (11c), and adjusting the inflation amount and inflation sequence of the No. 2 air chamber (11b) and the No. 3 air chamber (11c), a bending range of nearly 120° from the inner side of the No. 2 air chamber (11b) to the inner side of the No. 3 air chamber (11c) can be achieved; the A bending arm achieves omnidirectional bending.

2. The variable stiffness multi-motion morphology soft robot according to claim 1, characterized in that: The motor (52) is stuck in the groove of the left shell (51), and the motor fixing member (53) is fixed to the motor (52) by bolt connection. The motor fixing member (53) is fixed to the outer edge of the groove of the left shell (51) by welding. The output shaft of the motor (52) adopts a D-shaped shaft, which is tightly matched with the D-shaped groove of the right shell (54). The rotation of the motor (52) will drive the right shell (54) to rotate.

3. The variable stiffness multi-motion morphology soft robot according to claim 1, characterized in that: The fixing frames (16) of the A bending arm (1), the B bending arm (2), the C bending arm (3) and the D bending arm (4) and the central connecting block (5) are fixed by bolt connection at four different surfaces.

4. A method for operating a soft robot with variable stiffness and multiple motion forms, using the soft robot with variable stiffness and multiple motion forms according to claim 1, characterized in that include: 1) The robot switches between rolling and crawling motions, which includes the following steps: Step 1: The supporting ends of the A bending arm (1), the B bending arm (2), the C bending arm (3), and the D bending arm (4) are kept naturally straight; the low melting point alloys in the A bending arm (1), the B bending arm (2), the C bending arm (3), and the D bending arm (4) are all in a solid state; at this time, the robot is in the initial state of the tumbling mode; Step 2: The output shaft of the motor (52) rotates 90 degrees, driving the A bending arm (1) and the B bending arm (2) to rotate 90 degrees, so that the A bending arm (1), the B bending arm (2), the C bending arm (3), and the D bending arm (4) are on the same plane. At this time, the low melting point alloy in the A bending arm (1), the B bending arm (2), the C bending arm (3), and the D bending arm (4) are all in a solid state; Step 3: The silicone rubber heating plates (14) in the A bending arm (1), the B bending arm (2), the C bending arm (3), and the D bending arm (4) are energized to heat the low melting point alloy (13) therein and melt it into a liquid state, and then the A bending arm (1), the B bending arm (2), the C bending arm (3), and the D bending arm (4) are bent inward by inflation, and at this time, they become the initial form of the quadruped crawling mode; Step 4: The output shaft of the motor (52) continues to rotate 90 degrees, driving the A bending arm (1) and the B bending arm (2) to rotate 90 degrees, and the A bending arm (1), the B bending arm (2), the C bending arm (3), and the D bending arm (4) continue to maintain the bending shape of step 3. At this time, the low melting point alloy in the A bending arm (1), the B bending arm (2), the C bending arm (3), and the D bending arm (4) still remains in liquid state; Step 5: The A bending arm (1), the B bending arm (2), the C bending arm (3), and the D bending arm (4) are restored to a normal straight state by releasing air, and the heating of the low melting point alloy (13) in the A bending arm (1), the B bending arm (2), the C bending arm (3), and the D bending arm (4) is stopped to solidify the low melting point alloy (13). At this time, the robot has switched from the quadruped crawling form to the polyhedron rolling form; By switching between the rolling and crawling motion modes of the soft robot, the flexibility of the robot during motion is greatly increased. In different environments, the robot can selectively switch its motion mode to improve its motion efficiency. 2) To realize the robot's rolling function, the following steps are included; Step 1: The A bending arm (1), the B bending arm (2), the C bending arm (3), and the D bending arm (4) are naturally straightened; the low melting point alloy in the A bending arm (1), the B bending arm (2), the C bending arm (3), and the D bending arm (4) are all in a solid state; at this time, the robot is in an initial state; Step 2: The silicone rubber heating plate (14) in the B bending arm (2) is energized to heat the low melting point alloy (13) therein and melt it into a liquid state, and then the B bending arm (2) is bent inward by inflation, while the A bending arm (1), the C bending arm (3) and the D bending arm (4) remain stationary; Step 3: The silicone rubber heating plate (14) in the bending arm (1) is energized to heat the low melting point alloy (13) therein and melt it into a liquid state, and then the bending arm (1) is bent inward by inflation; Step 4: When the A bending arm (1) is bent to a certain angle, the center of gravity of the tumbling robot becomes unstable, causing the support end of the A bending arm (1) to fall to the ground and the support end of the B bending arm (2) to rise, and then proceed to the next operation after it stabilizes; Step 5: The A bending arm (1) is restored to a normal straight state by releasing air, and the heating of the low melting point alloy (13) in the A bending arm (1) is stopped to solidify it; Step 6: The B bending arm (2) is restored to a normal straight state by releasing air, and the heating of the low melting point alloy (13) in the B bending arm (2) is stopped to solidify the low melting point alloy (13); The above are the control steps for the robot to roll over once. By controlling the bending of any two of the four bending arms, the robot can roll over in any three directions. After multiple rolls, it can reach the specified position. 3) To realize the crawling function of the robot, the following steps are included; Step 1: The A bending arm (1), the B bending arm (2), the C bending arm (3), and the D bending arm (4) bend inwards, and the low melting point alloy in the A bending arm (1), the B bending arm (2), the C bending arm (3), and the D bending arm (4) remains in a liquid state, which is the initial state of the quadruped crawling mode; Step 2: Deflate the B bending arm (2) and the D bending arm (4) so ​​that the B bending arm (2) and the D bending arm (4) are lifted up and suspended in the air, while the A bending arm (1) and the C bending arm (3) remain stationary; Step 3: Inflate the air cavities of the A curved arm (1) and the C curved arm (3) to move the B curved arm (2) and the D curved arm (4) forward; Step 4: Inflate the B curved arm (2) and the D curved arm (4) so ​​that the supporting ends of the B curved arm (2) and the D curved arm (4) fall to the ground and support the entire structure; Step 5: Deflate the A-bend arm (1) and the C-bend arm (3) to make them suspended in the air, and then inflate them to make the A-bend arm (1) and the C-bend arm (3) move forward to a position perpendicular to the ground; Step 6: Inflate the A-bend arm (1) and the C-bend arm (3) so that the supporting ends of the A-bend arm (1) and the C-bend arm (3) fall to the ground and support the entire structure.

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