A bionic climbing robot

Abstract

The present invention relates to a bionic climbing robot, comprising a gripping structure and a telescopic trunk, wherein the telescopic trunk is interlaced and arranged between the gripping structures; the gripping structure comprises a stepper motor box, a wire rod, a nylon rope, a fixed main connecting rod, two rotating sub-connecting rods, a fixed short arm, a rotating long arm and a gripper, wherein the fixed short arm is respectively mounted at both ends of the fixed main connecting rod, the other end of the fixed short arm is connected to one end of the rotating long arm through the rotating sub-connecting rod, and the ends of the two are meshed, and the gripper is hinged with the rotating long arm; a stepper motor is mounted in the stepper motor box, the stepper motor drives the wire rod to rotate, the first end of the nylon rope is fixedly wound on the wire rod, and the other end passes through the wire holes on the stepper motor box, the fixed main connecting rod and the rotating long arm in sequence, and the stepper motor controls the extension and contraction of the nylon rope and the clamping action of the gripper; the robot's climbing is completed by the clamping action of the gripping structure and the extension and contraction action of the telescopic trunk. The present invention improves the carrying capacity and adaptability of the robot.

Description

Technical Field

[0001] The present invention relates to the technical field of robots, and in particular to a bionic climbing robot. Background Art

[0002] Climbing robots have become an important choice for high-risk operation scenarios such as chemical pipelines, energy pipelines, and cross-river bridges due to their outstanding ability to operate in special environments and their ability to cover vertical space. They have become a typical representative of new quality productivity in the fields of military reconnaissance, high-altitude road and bridge maintenance, forestry exploration, and other online monitoring and early warning, and have been successfully used in the inspection, maintenance, and manufacturing tasks of platforms in various fields. The difference between climbing robots and common ground crawling robots is that the former needs to overcome gravity to achieve vertical movement, so climbing robots have higher requirements for reliability. When traditional climbing robots detect fixed objects such as walls, they mainly use magnetic adsorption and vacuum adsorption, which have specific requirements for the morphological characteristics and materials of the environment. However, such robots generally have problems such as low reliability and small carrying capacity.

[0003] The applicable scenarios and reliability of a climbing robot depend largely on its grasping part. Currently, the grasping part mainly includes two types: soft structure and rigid structure.

[0004] Climbing robots whose gripping parts are composed of soft structures can adapt well to the external shape of the climbing surface, thereby achieving a good gripping effect. With the emergence of bionic robots, a type of soft climbing robots based on bionic adhesive materials has been developed. Existing climbing robots have good climbing and transition capabilities on rough and slippery walls. However, due to the limitation of their stiffness, this type of soft robot is generally only suitable for working scenarios with small loads or even no load.

[0005] In comparison, climbing robots with rigid gripping structures have advantages such as large torque and strong controllability. However, when the climbing surface is irregular or not made of a specific material, the climbing effect of this type of rigid robot will be significantly reduced, or even unable to attach to the climbing surface normally.

[0006] From the above, it can be seen that although the traditional rigid climbing robot has a strong load capacity, its adaptability to the climbing surface is poor; while the soft climbing robot is small in size and has strong environmental adaptability, but its load capacity is limited. Therefore, how to provide a bionic climbing robot that can improve the load capacity and climbing surface adaptability is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0007] The present invention provides a bionic climbing robot to solve the above technical problems.

[0008] In order to solve the above technical problems, the present invention provides a bionic climbing robot, comprising three grasping structures and two telescopic trunks, wherein the telescopic trunks are interspersed between every two grasping structures;

[0009] Each of the gripping structures comprises a stepper motor box, a wire rod, a nylon rope, a fixed main connecting rod, two fixed short arms, two rotating sub-connecting rods, two rotating long arms and two gripping claws, the two fixed short arms are respectively mounted at the two ends of the fixed main connecting rod, the other end of the fixed short arm is connected to one end of the rotating long arm through the rotating sub-connecting rod, and the ends of the two are meshed, and the gripping claw is hinged to the rotating long arm;

[0010] A stepper motor is installed in the stepper motor box, and the stepper motor drives the wire rod to rotate. The first end of the nylon rope is fixedly wound on the wire rod, and the other end passes through the stepper motor box, the fixed main connecting rod and the wire hole on the rotating long arm in sequence. The stepper motor controls the extension and retraction of the nylon rope and the clamping action of the gripper;

[0011] The robot's climbing is accomplished through the clamping action of three grasping structures and the telescopic action of two telescopic trunks.

[0012] Preferably, each of the grippers includes a first parting body, two second parting bodies, four third parting bodies and a soft end, the first and second parting bodies include an arc-shaped sliding surface and a back surface opposite to the sliding surface, and end surfaces on both sides, the third parting body includes an arc-shaped sliding surface and end surfaces on both sides; the back surface of the first parting body is slidably matched with the sliding surface of the rotating long arm, the back surface of the second parting body is slidably matched with the sliding surface of the first parting body, the third parting body is slidably matched with the sliding surface of the second parting body, and the third parting body is installed with the soft end.

[0013] Preferably, the sliding surfaces of the rotating long arm, the first parting body and the second parting body are respectively provided with limiting shoulders for limiting the sliding range, and the back of each of the parting bodies is provided with a back groove matching the limiting shoulder; the end faces of the rotating long arm, the first parting body and the second parting body are respectively provided with end face holes, and the end faces of the first parting body, the second parting body and the third parting body are provided with end face grooves corresponding to the end face holes.

[0014] Preferably, the third parting body is provided with an end limiting cavity, and the end of the soft body is limited to be located in the end limiting cavity.

[0015] Preferably, the assembly gap between each molded body is 1 mm.

[0016] Preferably, the cross-section of the soft body end is trapezoidal and has a thickness of 4 mm.

[0017] Preferably, the soft end is made of silicone with a hardness of 10.

[0018] Preferably, the method for calculating the ideal effective clamping width range of the gripping structure includes:

[0019] Theoretical modeling is performed based on the minimum ideal grasping state and the maximum ideal grasping state of grasping, and the following mathematical assumptions are made to simplify the model structure:

[0020] 1) The selected climbing surface section is a rectangle;

[0021] 2) Simplify the rotating long arm and the rotating joint connecting rod into rods;

[0022] 3) Ignore minor dimensional errors in assembly;

[0023] 4) Establish a rectangular coordinate system. In the minimum grip state, the end face of the soft end coincides with the y-axis, and the rotation pair A is on the x-axis.

[0024] Through theoretical modeling and geometric analysis of the minimum ideal grasping state and the maximum ideal grasping state, we can obtain:

[0025]

[0026] Among them, L is the ideal effective clamping width range, X1 is the coordinate position of the revolute pair A on the x-axis, L1, L2, and θ3 are all known quantities, and L1 is the size parameter given when designing the revolute long arm, L2 is the size parameter of the revolute pair connecting rod, θ3 is the maximum gripper rotation angle, and X′1 is the distance of the end face of the soft body relative to the revolute pair A in the x-axis direction.

[0027] Preferably, the method for calculating the relationship between the stepper motor input torque and the gripper end force includes:

[0028] Make the following assumptions:

[0029] 1) The selected climbing surface section is a rectangle;

[0030] 2) Ignore the friction between the wire and the fuselage;

[0031] 3) Ignore the diameter of the wire;

[0032] 4) Ignore the clearance of assembly;

[0033] 5) When the gripper rotation angle θ′3 is 0, the position of the rotating long arm is taken as the critical position, and when the rotating long arm is located on the left side of the critical position, the gripper rotation angle takes a negative value, and vice versa.

[0034] Get the relationship:

[0035]

[0036] Among them, F3 is the end force, M1 is the input torque of the stepper motor, Z1 is the number of teeth of the small bevel gear, Z2 is the number of teeth of the large bevel gear, d2 is the diameter of the wire groove, θ 1 is the angle of the nylon rope wrapped around the fixed pulley P, L′1 is the vertical distance from the rotating pair A to the fixed pulley rod, L′2 is the vertical distance from the fixed pulley P to the rotating long arm, θ′3 is the rotation angle of the gripper, L1 and L8 are the dimensional parameters given when designing the rotating long arm, and L6 can be calculated.

[0037] Preferably, the climbing gait of the robot includes the following steps:

[0038] The upper gripping structure is released, and the upper telescopic trunk is extended. When the extension reaches a maximum value, the upper gripping structure is clamped;

[0039] The middle gripping structure is released, the lower telescopic trunk is extended, the upper telescopic trunk is contracted, and the middle gripping structure rises to the maximum value and then clamps;

[0040] The lower gripping structure is released, the lower telescopic trunk contracts, and clamps after the contraction stops.

[0041] Compared with the prior art, the bionic climbing robot provided by the present invention has the following advantages:

[0042] 1. The present invention designs a wire-driven gripping structure, which enhances the adaptability to the climbing surface and the flexibility of gripping;

[0043] 2. Based on the gear transmission principle, the present invention designs a conjugate joint, which enhances the strength of joint rotation and the stability of grasping action;

[0044] 3. The present invention combines the advantages of high load-bearing performance of rigid structures and excellent adhesion of soft structures, and relies on the combination of multiple parting bodies to make the robot have better load-bearing capacity, adaptability and controllability. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the three-dimensional structure of a bionic climbing robot in a specific embodiment of the present invention;

[0046] Figure 2 It is a structural schematic diagram of a gripping structure in a specific embodiment of the present invention;

[0047] Figure 3 It is a schematic diagram of the output transmission of the line drive in a specific embodiment of the present invention;

[0048] Figure 4a An exploded view (front view) of a gripper in a specific embodiment of the present invention;

[0049] Figure 4bAn exploded view (side view) of a gripper in a specific embodiment of the present invention;

[0050] Figure 5 It is a schematic diagram of the gripping of the gripper in a specific embodiment of the present invention;

[0051] Figure 6 A schematic diagram of a climbing gait of a robot in a specific embodiment of the present invention;

[0052] Figure 7 It is a schematic diagram of the minimum gripping state of the gripping structure in a specific embodiment of the present invention;

[0053] Figure 8 It is a schematic diagram of the maximum gripping state of the gripping structure in a specific embodiment of the present invention;

[0054] Fig. 9 A mechanical modeling diagram of a rotating arm in a specific embodiment of the present invention;

[0055] Fig.10 It is a static modeling diagram of a gripper in a specific embodiment of the present invention;

[0056] Fig.11 In one specific embodiment of the present invention, 1 Angle split diagram of

[0057] Fig.12 This is a comparison chart of the theoretical and experimental values ​​of the end force;

[0058] Fig.13 A schematic diagram of a load placement method in a specific implementation manner of the present invention;

[0059] Fig.14 This is a comparison chart of the speed test of the climbing robot;

[0060] Fig.15 The diagram below shows the limit load for climbing pipes with different diameters.

[0061] In the figure: 100-gripping structure, 110-stepping motor box, 111-stepping motor, 112-bevel gear, 113-wire rod, 114-nylon rope, 120-fixed main connecting rod, 130-fixed short arm, 140-rotating secondary connecting rod, 150-rotating long arm, 160-gripping claw, 161-first parting body, 162-second parting body, 163-third parting body, 164-soft end, 165-sliding surface, 166-limiting shoulder, 167-end hole, 168-end groove, 169-end limiting cavity, 200-telescopic trunk, 300-load. DETAILED DESCRIPTION

[0062] In order to describe the technical solution of the above invention in more detail, specific embodiments are listed below to demonstrate the technical effects; it should be emphasized that these embodiments are used to illustrate the present invention but not to limit the scope of the present invention.

[0063] The crab claws are very hard, and they are indispensable for eating, catching prey or defending against enemies. The present invention takes the clamping characteristics of the crab claws as the bionic object, uses wire drive instead of muscle stretching, and designs a bionic climbing robot, the main part of which is designed through the exoskeleton structure of the bionic crab claws.

[0064] The bionic climbing robot provided by the present invention is as follows: Figures 1 to 3 As shown, it includes three gripping structures 100 and two telescopic trunks 200 , and the telescopic trunks 200 are interspersed between every two of the gripping structures 100 .

[0065] Among them, each of the grasping structures 100 includes a stepper motor box 110, a wire rod 113, a nylon rope 114, a fixed main connecting rod 120, two fixed short arms 130, two rotating sub-connecting rods 140, two rotating long arms 150 and two gripping claws 160. The two fixed short arms 130 are respectively installed at the two ends of the fixed main connecting rod 120, and the other end of the fixed short arm 130 is connected to one end of the rotating long arm 150 through the rotating sub-connecting rod 140, and the ends of the two are meshed, and the gripping claw 160 is hinged to the rotating long arm 150.

[0066] The stepper motor box 110 is equipped with a stepper motor 111, and the stepper motor 111 drives the wire rod 113 to rotate. The first end of the nylon rope 114 is fixedly wound on the wire rod 113, and the other end passes through the wire holes on the stepper motor box 110, the fixed main connecting rod 120 and the rotating long arm 150 in sequence. The stepper motor 111 controls the extension and retraction of the nylon rope 114 and the clamping action of the gripper 160. Specifically, in this embodiment, the stepper motor box 110 is divided into an upper and a lower part, and the two ends of the wire rod 113 are restricted in the box body by two micro bearings and the upper and lower parts of the stepper motor box 110. The five degrees of freedom of the wire rod 113 in space are restricted, and only one degree of rotational freedom in the y-axis direction is retained to realize the winding of the nylon rope 114 during line drive. Both the fixed main connecting rod 120 and the rotating long arm 150 have wire holes for routing the wire drive. The four wire holes of the fixed main connecting rod 120 are used to fix the connection and positioning of the short arm 130 while also matching it with the stepper motor box 110. The fixed short arm 130 is matched at both ends of the fixed main connecting rod 120 to increase the clamping range of the gripping structure 100. The rotating secondary connecting rod 140 is used to connect the fixed short arm 130 and the rotating long arm 150. The two arms form a conjugate joint through gear meshing, thereby limiting the rotation angle of the rotating long arm 150 and standardizing the clamping action. In some embodiments, the rotating long arm 150 is coaxially sleeved with a torsion spring with a diameter of 1.5 mm, and the two arms of the torsion spring are confined in the limiting holes of the rotating secondary connecting rod 140 and the rotating long arm 150 to complete the reset.

[0067] The robot's climbing is accomplished through the clamping action of the three grasping structures 100 and the telescopic action of the two telescopic trunks 200 .

[0068] Specifically, the principle of the line drive driving the gripping structure 100 to complete the clamping action is as follows: the closed-loop stepper motor 111 drives the rotation of the bevel gear 112 through serial communication and the fixed torque output mode of the foc algorithm, and transmits the torque to the wire rod 113 after deceleration and torque increase. The wire rod 113 rotates and wraps around the nylon rope 114. The nylon rope 114 passes through the wire hole on the stepper motor box 110, the wire hole on the fixed main connecting rod 120, and the wire hole on the rotating long arm 150 to form a closed loop. During the contraction process, the nylon rope 114 makes the two rotating long arms 150 close under the restriction of the meshing of the rotating secondary connecting rod 140 and the gear. After the clamping action is completed, the stepper motor 111 switches the level to achieve reverse rotation, the nylon rope 114 is relaxed, and the rotating long arm 150 rotates in the opposite direction under the torque of the torsion spring, so that the clamping angle expands back to the initial position, completing a clamping action.

[0069] The present invention designs a wire-driven grasping structure 100, which enhances the adaptability to the climbing surface and the flexibility of grasping; at the same time, based on the gear transmission principle, a conjugate joint is designed to enhance the strength of joint rotation and the stability of the grasping action.

[0070] In some embodiments, please refer to Figure 4a and 4b Each of the grippers 160 includes a first parting body 161, two second parting bodies 162, four third parting bodies 163 and eight soft ends 164. Each parting body includes an arc-shaped sliding surface 165 and a back surface opposite to the sliding surface 165, as well as end surfaces on both sides. The back surface of the first parting body 161 is in sliding cooperation with the sliding surface 165 of the rotating long arm 150, the back surface of the second parting body 162 is in sliding cooperation with the sliding surface 165 of the first parting body 161, the back surface of the third parting body 163 is in sliding cooperation with the sliding surface 165 of the second parting body 162, and the soft end 164 is installed on the third parting body 163. The degree of freedom restriction methods of the three parting bodies are the same, which is to restrict the remaining five degrees of freedom in space and only retain the rotation along the z-axis direction, so as to realize the adaptive grasping of the gripper 160.

[0071] In some embodiments, please refer to Figure 4a and 4bThe sliding surfaces 165 of the rotating long arm 150, the first parting body 161 and the second parting body 162 are respectively provided with limiting shoulders 166 for limiting the sliding range, and the back of each parting body is provided with a back groove (not shown) matching the limiting shoulder 166; the end surfaces of the rotating long arm 150, the first parting body 161 and the second parting body 162 are respectively provided with end holes 167, and the end surfaces of the first parting body 161, the second parting body 162 and the third parting body 163 are provided with end surface grooves 168 corresponding to the end surface holes 167. The end surface grooves 168, the back surface grooves, the back and the matching sliding surface 165 of the parting body, and the limiting shoulders 166 on the sliding surface 165 are all coaxially designed to ensure the reliability of sliding. The back, back groove, and end face groove 168 of the first parting body 161 respectively cooperate with the sliding surface 165, the limiting shoulder 166, and the end face hole 167 of the rotating long arm 150; the back, back groove, and end face groove 168 of the second parting body 162 respectively cooperate with the sliding surface 165, the limiting shoulder 166, and the end face hole 167 of the first parting body 161; the back, back groove, and end face groove 168 of the third parting body 163 respectively cooperate with the sliding surface 165, the limiting shoulder 166, and the end face hole 167 of the second parting body 162. In some embodiments, the third parting body 163 is provided with a terminal limiting cavity 169, and the soft terminal 164 is limited in the terminal limiting cavity 169, that is, the soft terminal 164 cooperates with the third parting body 163 through the terminal limiting cavity 169.

[0072] The principle of adaptive gripping by the gripper 160 is as follows: when the parting body contacts the external environment, if the contact surface of the external environment is irregular or there is a certain angle between the parting body and the contact surface, it will start to rotate at the moment of contact due to the unevenly distributed reaction force until the contact surface of the parting body and the external environment are fully fitted and the two ends are evenly stressed and then stop rotating. Since the gripping will fail when the rotation angle exceeds a certain range, the rotation angle is limited by the back groove of the parting body and the limiting shoulder 166 on the sliding surface 165. The sliding surface 165 and the end hole 167 limit the freedom of movement of the parting body on the x and y axes, and the two end surfaces limit the freedom of rotation of the parting body on the x and y axes and the freedom of movement on the z axis. When the gripping claw 160 of the gripping structure 100 performs adaptive gripping, the soft end 164 mounted on the third parting body 163 contacts the climbing surface first, and the third parting body 163 rotates under the reaction force of the climbing surface. If the force balance is not reached after reaching the limit position, the force is transmitted to the second parting body 162 through the cooperation between the back groove of the third parting body 163 and the limit shoulder 166 of the second parting body 162 to rotate it. If the force balance is not reached after the second parting body 162 reaches the limit position, the above process is repeated to transmit the force to the first parting body 161 to rotate it. Figure 5It is a schematic diagram of the gripping of the gripper 160. After the gripper 160 clamps the climbing surface, the parting body will automatically adapt and fit onto the climbing surface.

[0073] The robot's climbing gait is Figure 6 As shown, for the convenience of distinction and description, the gripping structures 100 from top to bottom are respectively labeled as the first gripping structure 100A, the second gripping structure 100B and the third gripping structure 100C, and the telescopic trunk 200 from top to bottom is labeled as the first telescopic trunk 200A and the second telescopic trunk 200B.

[0074] The robot's climbing gait includes the following steps:

[0075] The first gripping structure 100A is released, and the small motor drives the screw rod to extend the first telescopic trunk 200A. When the extension reaches the maximum value, the first gripping structure 100A is clamped.

[0076] The second gripping structure 100B is released, the second telescopic trunk 200B is extended, the first telescopic trunk 200A is contracted, and the second gripping structure 100B is clamped after rising to the maximum value;

[0077] The third gripping structure 100C is released, and the second telescopic trunk 200B contracts. After the contraction stops, the third gripping structure 100C is clamped.

[0078] The above actions complete a gait.

[0079] Since the power of the robot linear drive in the present application comes from the stepper motor 111 , in order to enable the body to withstand a larger motor input torque, the present application optimizes the parameters of the gripping structure 100 .

[0080] In some embodiments, the assembly gap between each parting body is 1mm. When designing the gripper 160 of the gripping structure 100, it is necessary to ensure the smoothness of the sliding of the parting body and the compactness of the assembly. If the assembly gap between the end faces is less than 1mm, the sliding of the parting body will be stuck and the gripping cannot be completed normally. Therefore, the present application determines that the assembly gap between the parting bodies is 1mm, and the problem of matching failure will not occur under this assembly gap. In addition, when designing the matching dimensions of the rotating arm, when the assembly gap between the rotating sub-connecting rod 140 and the fixed short arm 130 and the rotating long arm 150 is greater than 0.7mm, a large dislocation will occur at the end of the rotating long arm 150, causing the overall deformation of the rotating arm in the vertical direction to be too large during the alternating gripping process of climbing, thereby reducing the climbing efficiency. When the assembly gap is less than 0.3mm, the rebound of the torsion spring will fail when the rotating arm expands and resets, causing the rotating arm to fail to complete the reset action. Finally, the present application sets the assembly clearance between the rotating secondary connecting rod 140 and the fixed short arm 130 and the rotating long arm 150 to 0.5 mm, thereby ensuring the normal rebound of the torsion spring and reducing the deformation of the rotating arm in the vertical direction.

[0081] Since the driving method of this application adopts gear transmission to drive the line, the structural design includes the selection and modeling of standard parts. The radius of the small bevel gear hole in the selected pair of 1:2 bevel gears is 3mm, and the radius of the rotor of the stepper motor 111 is 2.5mm. The gap between the small bevel gear and the stepper motor rotor is filled by winding a metal gasket with a total length of 240mm and a thickness of 0.03mm on the rotor. The large bevel gear is fixed on the wire rod 113, and the two ends of the wire rod 113 are each equipped with a micro bearing with an inner diameter of 6mm and an outer diameter of 10mm. Since the gap between the small bevel gear and the stepper motor rotor cannot be completely eliminated, the rotation center cannot be completely coaxial, which causes the gear transmission to vibrate, and the wire rod 113 has a certain degree of small up and down swing. If the outer diameter of the micro bearing on the wire rod 113 and the wire rod hole are matched as a transition fit or an interference fit, it will cause the gear transmission to jam and even cause fatigue damage and cracks at the matching point of the stepper motor box 110. To prevent this phenomenon from occurring, we set the diameter of the wire rod hole to 10.16mm and applied lubricating oil to compensate for the clearance fit defect.

[0082] In some embodiments, the cross section of the soft end 164 is a trapezoid and the thickness is 4 mm. Specifically, the soft end 164 is the part where the robot is in direct contact with the climbing surface, and its end face cross section is a trapezoid, which can effectively avoid the occurrence of side overturning while increasing the contact area between the robot and the climbing surface, thereby ensuring the stability of climbing. Experimental verification shows that when the end face thickness is less than 2 mm, tearing is likely to occur, and when the end face thickness is greater than 6 mm, side overturning is likely to occur, causing the grip to fail. Ultimately, this application sets the end face thickness of the soft end 164 to 4 mm, which can effectively avoid the occurrence of side overturning while increasing the strength of the soft end 164.

[0083] The following introduces the mathematical modeling method of the bionic climbing robot.

[0084] The effective clamping width range of the gripping structure 100 refers to the range within which the four soft ends 164 of the gripping claw 160 can fit tightly on the climbing surface. If they cannot fit well, climbing may fail. In order to describe the relationship between the ideal effective clamping width range of the gripping structure 100 and the dimensions of the rotating long arm 150, the gripping claw 160 and the rotating sub-connecting rod 140, and how to determine the dimensions of the fixed short arm 130 given the dimensions of the rotating long arm 150, the gripping claw 160 and the rotating sub-connecting rod 140. This application selects two limit states of gripping for theoretical modeling, and makes the following mathematical assumptions to simplify the model structure:

[0085] 1) The selected climbing surface section is a rectangle;

[0086] 2) Simplify the rotating long arm 150 and the rotating auxiliary connecting rod 140 into rods;

[0087] 3) Ignore minor dimensional errors in assembly;

[0088] 4) Establish a rectangular coordinate system. In the minimum grip state, the end face of the soft end coincides with the y-axis, and the rotation pair A is on the x-axis.

[0089] Figure 7 is the minimum grasping state of the grasping structure 100, L1, L2, L8, D, R, θ3, d1 are known quantities, and the rest are unknown quantities.

[0090] From the geometric relationship, we can get:

[0091] X1=-(L3+L2·cosθθ4) (1)

[0092] L3+L2·cosθ4=L5·cosθ5+D-R+L4 (2)

[0093] In formula (1) and formula (2), X1 is the coordinate position of the revolute pair A on the x-axis, D is the lateral length when the parting surfaces of the gripper 160 are parallel to each other, and R is the back radius of the first parting body 161. Next, θ4 and θ5 are solved. Because the maximum gripper rotation angle θ3 of the first parting body 161 has been determined during the structural parameter design, and θ3 and θ5 are mutually complementary, we can get:

[0094] θ5=90°-θ3 (3)

[0095] From the rotation characteristics of the conjugate joint θ1=θ2, and the complementarity of θ4 and θ2, we can get:

[0096] θ4+θ5=θ1=θ2 (4)

[0097] θ4=180°-θ2 (5)

[0098] Combining equations (2) and (3) we get:

[0099]

[0100] d1 is the arch height, and according to the principle of similar triangles:

[0101] θ6=θ3 (7)

[0102]

[0103] Combining equations (7) and (8) we get:

[0104]

[0105] The chord length L8 is known, and L4 obtained from equation (7) can be obtained:

[0106]

[0107]

[0108] From equations (8) and (9), we can deduce:

[0109]

[0110] Substituting equations (3), (6), (9), and (12) into equation (2), we can obtain:

[0111]

[0112] In formula (13), L3 is the distance between the symmetry axis of the fixed main connecting rod 120 and the revolute pair B.

[0113] Substituting equations (6) and (13) into (1), we obtain:

[0114]

[0115] The maximum gripping state of the gripping structure 100 is as follows Figure 8 As shown, the rotating long arm 150 reaches the maximum grasping state after rotating 2θ3 counterclockwise. Since the rotating joint is a conjugate joint, θ1=θ2 always holds true, so when the rotating long arm 150 rotates to change θ1, the rotating secondary connecting rod 140 will also rotate to change the angle θ2.

[0116] The rotation of the revolving pair connecting rod 140 will change the position of the revolving pair A, so firstly perform a geometric analysis on the revolving pair A. At this time, θ3 and θ7 are internal angles, and we can get:

[0117] θ3=θ7 (15)

[0118] θ7+90°+θ′4=180°-θ′4 (16)

[0119] Combining equations (15) and (16) we get:

[0120]

[0121] From equation (6) and equation (17), we can get:

[0122]

[0123] In formula (18), ΔL is the change of the revolute pair A on the x-axis.

[0124] Next, the position of the rotating long arm 150 relative to the rotating pair A is analyzed. From the geometric relationship, it can be obtained that

[0125] X′1=D+L4-L 10 -R (19)

[0126] X′1 is the distance of the end surface of the soft body relative to the revolute pair A in the x-axis direction. Among them, L4, D, and R are known. 10 To solve.

[0127]

[0128] Substituting formula (20) into formula (19), we get:

[0129]

[0130] Through the above theoretical modeling and geometric analysis of the minimum ideal grasping state and the maximum ideal grasping state, we can obtain:

[0131]

[0132] In formula (22), L is the ideal effective clamping width range.

[0133] At this point, when the dimensions of the rotating long arm 150, the gripping claw 160 and the rotating secondary connecting rod 140 are known, the design dimensions of the fixed main connecting rod 120 and the fixed short arm 130 and the ideal effective clamping width range of the gripping structure 100 can be calculated. The actual effective clamping width range of the gripping structure 100 will be greater than the ideal effective clamping width range, because the climbing surface in the actual application scenario has a certain thickness, so the setting L When the size is 3, it can be larger than the size obtained by theoretical calculation, so that the maximum clamping width is increased. If the climbing surface is changed to a cylindrical climbing surface with a larger diameter, the soft end 164 can also be completely fitted on the climbing surface to achieve normal grip.

[0134] In order to further accurately describe the gripping posture of the gripping structure during climbing, and the relationship between the closed-loop stepper motor input torque and the gripping claw end force, the present application also performs a mechanical modeling of the gripping structure 100. First, the following assumptions are made:

[0135] 1) The selected climbing surface section is a rectangle;

[0136] 2) Ignore the friction between the wire and the fuselage;

[0137] 3) Ignore the diameter of the wire;

[0138] 4) Ignore assembly clearance.

[0139] 5) When the gripper rotation angle θ′3 is 0, the position of the rotating long arm is taken as the critical position, and when the rotating long arm is located on the left side of the critical position, the gripper rotation angle takes a negative value, and vice versa.

[0140] Please focus on Figure 3 The input torque of the stepping motor 111 is converted into the torque of the wire rod 113 through gear transmission, and the wire rod 113 pulls the nylon rope 114 to generate tension.

[0141] It is known that the input torque of the closed-loop stepper motor 111 is M1, the number of teeth of the small bevel gear is Z1, and the number of teeth of the large bevel gear is Z2, and the following relationship can be obtained:

[0142]

[0143] In formula (23), M2 is the torque on the wire rod 113. Since the torque on the same rod is equal everywhere, when the diameter d2 of the wire groove is known, the magnitude of the force on the wire can be calculated:

[0144]

[0145] In formula (24), F1 is the magnitude of the force exerted on the nylon rope 114 when it is wound around the wire groove with a diameter of d2 on the wire rod 113.

[0146] Fig. 9 The figure is the mechanical modeling diagram of the rotating arm, which describes the vector value of the force of the line drive on the fixed pulley at point P. Since the line drive in this design only uses one rope and there is no knot on the rope, the force on the taut rope is equal everywhere.

[0147] At point O, the lines that were originally parallel are separated. Since they are the same line, and the sum of the forces in the two directions must be equal to F1, the forces in each direction are Let the angle of the winding be θ 1 , from the geometric relationship, we can get the force F acting on point P t for:

[0148]

[0149] Fig.10 It is a static modeling diagram of the gripper 160. Fig.10 It can be seen that the gripper 160 and the rotating long arm 150 are finally subjected to only the tensile force F t Static equilibrium is achieved under the reaction force of the climbing surface.

[0150] The horizontal component of the climbing surface reaction force is taken as the value of the gripper end output force F3, so F t The torque of the horizontal component of force on the revolute pair A is equal to the torque of the output force F3 at the end of the gripper on the revolute pair A, and the following formula is obtained:

[0151]

[0152]

[0153] F2·L′3=F3·L′4 (29)

[0154] In the above formulas (26) and (27): L′1 is the vertical distance from the rotating pair A to the fixed pulley rod, L′2 is the vertical distance from the fixed pulley to the rotating long arm 150, L′3 is the force arm of the force F2 on the rotating pair A, L′4 is the force arm of the end force F3 on the rotating pair A, and the rotating long arm 150 is positive on the left side of the critical position and negative otherwise.

[0155] Combining equations (23) to (29) yields:

[0156]

[0157] The above formula (30) is the terminal force F3 and the angle θ 1 The relationship between the rotation angle θ′3 of the gripper and the rotation angle of the long arm 150 is positive on the left side of the critical position, and negative on the contrary.

[0158] Fig.11 is θ 1The angle split diagram is used to establish the relationship between θ′3 and θ 1 θ 1 Split into θ that can be represented by θ′3 (1) and θ (2) .

[0159] From the geometric relationship of the rotating arm, we can get:

[0160] θ 1 =θ (1) +θ (2) (31)

[0161]

[0162] Combining equations (31) to (33) yields:

[0163]

[0164] In formula (34) and formula (35), d (1) is the center distance between the two fixed pulleys, d (2) It is the vertical distance from the line connecting the two fixed pulleys to the wire hole. And the rotating long arm 150 takes a negative value on the left side of the critical position, and vice versa.

[0165] Substituting equations (34) and (35) into equation (36), we can obtain the relationship between θ′3 and θ1.

[0166] Substituting formula (36) into formula (30) yields:

[0167]

[0168] The above results in the end force F3, the grip rotation angle θ′3 and d (1) ,d (2) For equation (37), the rotation of the long arm 150 is positive on the left side of the critical position, and negative on the contrary.

[0169] Substituting equations (34) and (35) into (37), we can obtain the relationship between the input torque of the closed-loop stepper motor and the output force at the end when the gripper rotation angle is known.

[0170]

[0171] In formula (38): if the rotating long arm 150 is on the left side of the critical position, the first sign is negative, the second sign is positive, and the third sign is positive, otherwise the signs are opposite.

[0172] Next, the bionic climbing robot proposed in this application is experimentally verified.

[0173] Since the robot in this application relies on grasping to climb, the climbing force comes entirely from the friction between the robot's gripper and the climbing surface, the selected material must have a large friction coefficient with the climbing surface, have adhesion and be able to adapt to the shape changes of the climbing surface to a certain extent. Therefore, this application chooses silicone as the manufacturing material of the terminal structure, which is very convenient in terms of both the difficulty of obtaining the material and the molding method.

[0174] In order to select the silicone with the best parameters and molding profile, a silicone friction test experiment was conducted. The experimental results show that the lower the degree (hardness) and the silicone surface without dents, the greater the friction. Because the silicone surface of the silicone molding with lower degree is softer, it fits more tightly with the contact surface and has a greater friction coefficient. The dents will reduce the fit between the silicone surface and the contact surface, thereby reducing the friction coefficient.

[0175] However, silicone with too low a degree will be too soft overall, causing large deformation during clamping, resulting in side overturning and clamping failure. In order to maximize the friction between the end and the climbing surface without causing clamping failure, this application selected silicone with a degree of 10.

[0176] Specifically, the production process of the soft end 164 is as follows: mix POSILICONE-10A glue and B glue in a ratio of 1:1 and stir evenly, put them into a vacuum barrel for vacuum degassing, apply silicone release agent on the printed mold, inject the degassed mixed silicone into the mold with a syringe and put the mold into a drying oven, and the molded soft end 164 can be obtained after 1 hour.

[0177] In the present application, the overall design of the gripping structure 100 can be realized by SolidWorks. In some embodiments, each component of the bionic climbing robot can be made by 3D printing technology to obtain a solid structure. Among them, if the wire rod 113 is printed according to normal strength, it will be sheared and broken due to the tension of the wire when in use. Therefore, in the slicing process before the wire rod 113 is printed, the filling degree needs to be adjusted to 100% to ensure that the wire rod 113 will not fail due to the breakage during climbing.

[0178] In order to verify the relationship between the motor input torque M1 and the end force F3 derived from the mechanical model, and to test the end force output performance, an experimental platform was established. It includes two test platforms, (a) the gripper end output force test platform, and (b) the motor input torque test platform. Both platforms include pressure sensors and display controllers. The end force test platform is designed with corresponding pressure plates and pressure test frames according to the size of the gripper. The torque test platform is designed with corresponding toothed groove force arms and torque test frames according to the size of the motor being tested.

[0179] During the test, the display controller needs to be short-circuited for 1 second to ensure the accuracy of the test. Multiple sets of experimental data are obtained by inputting increasing current into the stepper motor.

[0180] Changes in the gripper rotation angle and the stepper motor input torque will cause changes in the end force. In order to study the relationship between the gripper rotation angle θ′3, the stepper motor input torque M1 and the end force F3, the experimental platform tested and obtained the gripper rotation angle θ′3 of -13°-9° and -5°, and the stepper motor 111 input torque and the corresponding end force after 7 groups of currents of 500mA, 750mA, 1000mA, 1250mA, 1500mA, 1750mA and 2000mA were input to the stepper motor 111.

[0181] Comparison between theoretical and experimental values ​​of end force Fig.12 It can be seen that the trend of the theoretical data is consistent with the experimental data. The theoretical data increases linearly with the increase of the motor output torque. As the gripper rotation angle θ′3 increases, the theoretical and experimental values ​​of the end force F3 decrease. Fig.12 It can also be seen that there is a certain error between the theoretical value and the actual value. In order to quantitatively describe the error between theory and experiment, the following related differences are defined:

[0182]

[0183] In the above formula (39), d p is the correlation difference, is the theoretical value of the end force, is the experimental value of the end force.

[0184] The summary table of the relevant differences is shown in Table 1. It can be seen from the table that the relevant differences are on a downward trend as a whole. The reduction of the gripper rotation angle θ′3 and the increase of the motor input torque M1 will reduce the relevant differences, and the theoretical value of the end force will be closer to the actual value. The reason why the relevant difference is reduced by the reduction of the gripper rotation angle may be that the reduction of the gripper rotation angle will gradually reset the torsion spring, reduce the reaction force of the torsion spring, and reduce the error; the reason why the relevant difference is reduced by the increase of the motor input torque may be that the error caused by the torsion spring is a constant value without changing the rotation angle, and the increase of the motor input torque makes the error caused by the torsion spring less and less, and the relevant difference is also getting smaller and smaller.

[0185] Table 1. Table of terminal force related differences

[0186]

[0187] There is a certain error between the theoretical value of the end force and the actual measured value. The possible causes of the error are: the friction between the nylon rope 114 and the wire hole, the friction between the bevel gear 112 transmission, the size error of the assembly, the deformation error of the soft end 164, etc. The difference between the theoretical end force and the actual end force increases with the increase of the motor input torque, but the relevant difference has only a small amplitude and a regular decreasing change, which proves to a certain extent the correctness of the relationship (37) between the motor output torque M1, the gripper rotation angle θ′3 and the end force F3 derived from the mechanical model.

[0188] The completion of a climbing gait requires three extensions and retractions of the telescopic trunk 200 and three resets and clamps of the gripping structure 100, and the vertical ascent distance is 75 mm. Under no-load conditions, the theoretical time for a single extension and retraction of the telescopic trunk 200 is 12.5 seconds, and the time for a single reset and clamp of the gripping structure 100 is 3 seconds. The theoretical climbing speed is 1.613 mm / s. To verify the climbing speed of the robot, incremental loads 300 are placed on the top, middle, and bottom of the telescopic trunk 200, and the speed of the climbing gait is recorded. The loads 300 are placed as follows: Fig.13 shown.

[0189] Fig.14 This is a comparison chart of the speed test of climbing robots. Fig.14 It can be seen that as the load 300 increases, the climbing speed of the robot decreases. When the load 300 is placed in the middle of the trunk, the robot's climbing speed decreases the least. The reason may be that the middle of the trunk is pulled by two push rods at the same time, the driving force is greater, and the impact of the load is smaller; when the load 300 is placed at the top and bottom of the trunk, the robot's climbing speed decreases by a similar amount. The reason is that the top and bottom are each pulled by a push rod and do not interfere with each other. Therefore, the speed suppression effect produced by the same size of load 300 is consistent.

[0190] In order to more specifically express the degree of load suppression on the robot's climbing speed, the speed suppression rate is defined:

[0191]

[0192] In formula (40), d v is the speed suppression rate, v0 is the climbing speed when the robot load is 0, and v n is the climbing speed of the robot when the load is n, where n is the applied load. Table 2 shows that under the dynamic load within the robot's tolerable range, the load has a small suppression rate on the speed. Since the trunk uses a screw drive, it has a strong traction force, but when the motion load increases to 5kg, the 3D printed shell of the trunk will break and fail.

[0193] Table 2. Load and speed suppression rate relationship table

[0194]

[0195] To verify the robot's load-bearing capacity, the robot's limit load capacity when climbing pipes of different diameters was tested. Since the fuselage is prone to fatigue fracture when the input current of the stepper motor 111 exceeds 2000mA, the current was uniformly controlled at 2000mA during the experiment. Eight groups of load-bearing capacity test experiments were conducted on eight pipes with increasing diameters, and each group of experiments was repeated four times and the average value was taken.

[0196] A load frame is installed on the top of the fuselage, and weights and iron blocks are placed. Each iron block weighs about 2 kg and is used for coarse adjustment. The weights are smaller and can be used for fine adjustment. When the gripping structure 100 begins to slide slightly after continuous load application, the current load is taken as the limit load. Finally, Table 3 is obtained.

[0197] Table 3. Comparison of extreme loads

[0198]

[0199]

[0200] In order to more directly represent the robot's ultimate load under climbing pipes of different diameters, the pipe diameters and corresponding ultimate load data in the above table are plotted in a dotted line graph. Fig.15 As shown in the figure, when the diameter of the climbing pipe is 110mm, the robot's limit load reaches a maximum value of 10.5kg, and then the limit load decreases whether the diameter of the climbing pipe is increased or decreased. Therefore, the optimal climbing diameter of the robot is between 80mm and 140mm. When the diameter of the climbing pipe increases to 260mm, the robot's limit load is reduced to the minimum, and when the pipe diameter increases to 290mm, the robot cannot be attached to the pipe normally.

[0201] In order to intuitively evaluate the load-bearing performance of the robot, the load-bearing ratios of the same type of bionic climbing robots are compared, as shown in Table 4. It can be seen that the load-bearing ratio of the climbing robot designed in the present application is 1.1 to 10.6 times that of the same type of climbing robots.

[0202] Table 4. Comparison of performance indicators of climbing robots of the same type

[0203]

[0204] In order to verify the reliability and adaptability of the robot, climbing experiments were conducted on the robot under various complex climbing surfaces, including water pipes, flat aluminum alloys, wooden doors, fire pipes, and tree trunks. The transverse sections of these climbing objects have arcs, rectangles, polygons, and irregular shapes. Most climbing robots have a single usage scenario and can only complete climbing tasks for one type of climbing surface. The climbing robot designed in this application can cope with a variety of complex climbing surfaces.

[0205] The experimental results show that through simple motor control and wire-driven traction grippers, the designed climbing robot can climb on various complex climbing surfaces with stable climbing movements.

[0206] In summary, the bionic climbing robot provided by the present invention utilizes the line drive principle, and designs a new type of adaptive soft-attached bionic climbing robot by conceiving the grasping structure 100 of the climbing robot and optimizing the size parameters of the entire fuselage. At the same time, theoretical modeling, experimental verification and actual climbing tests of the robot are carried out, including verification of the relationship between the motor torque and the end force and adaptive climbing tests of climbing surfaces with different shapes. The designed robot has the characteristics of simple control, rapid clamping, strong bearing capacity and stability, and its maximum load capacity can reach 10.5kg, the maximum clampable diameter is 290mm, and the maximum vertical climbing speed is 1.593mm / s. Compared with other climbing robots of the same type, the robot can carry a load that is 3.5 times heavier than the fuselage, showing excellent bearing capacity. The robot can be competent for climbing tasks on various complex climbing surfaces such as pipes, wooden doors, irregularly shaped tree trunks, uneven walls, etc., and has strong environmental adaptability.

[0207] Obviously, those skilled in the art can make various changes and modifications to the invention without departing from the spirit and scope of the invention. Thus, if these modifications and variations of the invention fall within the scope of the claims of the invention and their equivalents, the invention is also intended to include these modifications and variations.

Claims

1. A bionic climbing robot, characterized in that: It comprises three gripping structures and two telescopic trunks, wherein the telescopic trunk is interspersed between every two of the gripping structures; Each of the gripping structures comprises a stepper motor box, a wire rod, a nylon rope, a fixed main connecting rod, two fixed short arms, two rotating sub-connecting rods, two rotating long arms and two gripping claws, the two fixed short arms are respectively mounted at the two ends of the fixed main connecting rod, the other end of the fixed short arm is connected to one end of the rotating long arm through the rotating sub-connecting rod, and the ends of the two are meshed, and the gripping claw is hinged to the rotating long arm; A stepper motor is installed in the stepper motor box, and the stepper motor drives the wire rod to rotate. The first end of the nylon rope is fixedly wound on the wire rod, and the other end passes through the stepper motor box, the fixed main connecting rod and the wire hole on the rotating long arm in sequence. The stepper motor controls the extension and retraction of the nylon rope and the clamping action of the gripper; The robot's climbing is accomplished through the clamping action of three grasping structures and the telescopic action of two telescopic trunks; each of the grippers comprises a first parting body, two second parting bodies, four third parting bodies and a soft end; the first and second parting bodies comprise an arc-shaped sliding surface and a back surface opposite to the sliding surface, as well as end surfaces on both sides; the third parting body comprises an arc-shaped sliding surface and end surfaces on both sides; the back surface of the first parting body is in sliding cooperation with the sliding surface of the rotating long arm, the back surface of the second parting body is in sliding cooperation with the sliding surface of the first parting body, the third parting body is in sliding cooperation with the sliding surface of the second parting body, and the third parting body is installed with the soft end; The method for calculating the ideal effective clamping width range of the gripping structure includes: Theoretical modeling is performed based on the minimum ideal grasping state and the maximum ideal grasping state of grasping, and the following mathematical assumptions are made to simplify the model structure: 1) The selected climbing surface section is a rectangle; 2) Simplify the rotating long arm and the rotating joint connecting rod into rods; 3) Ignore minor dimensional errors in assembly; 4) Establish a rectangular coordinate system. In the minimum grip state, the end face of the soft end coincides with the y-axis, and the revolute pair A is on the x-axis. Through theoretical modeling and geometric analysis of the minimum ideal grasping state and the maximum ideal grasping state, we can obtain: in, For the ideal effective clamping width range, is the coordinate position of the revolute pair A on the x-axis, , are all known quantities, and is the dimension parameter of the connecting rod of the revolute pair, is the maximum gripper rotation angle, It is the distance between the end face of the soft body and the revolute pair A in the x-axis direction.

2. The bionic climbing robot according to claim 1, characterized in that: The sliding surfaces of the rotating long arm, the first parting body and the second parting body are respectively provided with limiting shoulders for limiting the sliding range, and the back of each parting body is provided with a back groove matching the limiting shoulder; the end faces of the rotating long arm, the first parting body and the second parting body are respectively provided with end face holes, and the end faces of the first parting body, the second parting body and the third parting body are provided with end face grooves corresponding to the end face holes.

3. The bionic climbing robot according to claim 1, characterized in that: The third parting body is provided with an end limiting cavity, and the end limit of the soft body is located in the end limiting cavity.

4. The bionic climbing robot according to claim 1, characterized in that: The assembly gap between each parting body is 1mm.

5. The bionic climbing robot according to claim 1, characterized in that: The cross section of the soft body end is trapezoidal and has a thickness of 4 mm.

6. The bionic climbing robot according to claim 1, characterized in that: The end of the soft body is made of silicone with a hardness of 10.

7. The bionic climbing robot according to claim 1, characterized in that: The method for calculating the relationship between the stepper motor input torque and the gripper end force includes: Make the following assumptions: 1) The selected climbing surface section is a rectangle; 2) Ignore the friction between the wire and the fuselage; 3) Ignore the diameter of the wire; 4) Ignore the clearance of assembly; 5) Grip rotation angle When is 0, the position of the rotating long arm is taken as the critical position, and when the rotating long arm is on the left side of the critical position, the gripper rotation angle takes a negative value, and vice versa, and the relationship is obtained: in, is the end force, is the input torque of the stepper motor, is the number of teeth of the small bevel gear, is the number of teeth of the large bevel gear, is the diameter of the wire trough, is the angle of the nylon rope wrapped around the fixed pulley P, is the vertical distance from the revolving pair A to the fixed pulley rod, is the vertical distance from the fixed pulley P to the rotating long arm, For the gripper rotation angle, and For the given dimensional parameters when designing the rotating long arm, It can be found by calculation.

8. The bionic climbing robot according to claim 1, characterized in that: The robot's climbing gait includes the following steps: The upper gripping structure is released, and the upper telescopic trunk is extended. When the extension reaches a maximum value, the upper gripping structure is clamped; The middle gripping structure is released, the lower telescopic trunk is extended, the upper telescopic trunk is contracted, and the middle gripping structure rises to the maximum value and then clamps; The lower gripping structure releases, the lower telescopic trunk contracts, and clamps after the contraction stops.

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