Rigid-flexible hybrid underwater holder and model construction method thereof

Abstract

The invention relates to the technical field of soft robots, and discloses a rigid-flexible hybrid underwater gripper and a model construction method thereof, and the rigid-flexible hybrid underwater gripper is characterized in that connecting rods are arranged on the peripheral sides of flexible fingers, and are respectively hinged with the flexible fingers and a connecting part of a gripper main body; a plurality of protrusions arranged at intervals are arranged on the clamping faces of the flexible fingers. The flexible fingers made of silica gel are matched with the rigid exoskeleton formed by the multiple connecting rods to form the rigid-flexible mixed underwater gripper, namely the soft gripper, the gripper is driven by the driving rope, large-range movement of the flexible fingers is restrained under the condition that local compliance of the flexible fingers is not affected, and the flexible fingers are prevented from being damaged. The stability and the holding power of the clamp holder are improved; the gripper can grab not only fragile objects such as bean curds but also heavy objects such as a barbell of 80 kg, and meanwhile the situation that the gripper loses efficacy due to large-range deformation caused by water power when the gripper moves relative to water flow is avoided. And then the mechanical property of the flexible finger material is analyzed, so that the movement of the flexible finger is conveniently controlled.

Description

Technical Field

[0001] The present invention relates to the technical field of soft robots, and particularly to a rigid-flexible hybrid underwater gripper and a method for constructing a model thereof. Background Art

[0002] With the in-depth development of marine resource exploitation, the performance requirements for grippers in underwater operations are increasing day by day. Existing underwater grippers are mainly divided into two categories: rigid grippers and soft grippers. Although rigid grippers perform excellently in grasping force and stability, they are prone to damage soft objects; while soft grippers have flexibility and agility, but they face problems such as low output force and poor stability, and the control accuracy of soft grippers in related technologies is relatively low, affecting the user experience. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a rigid-flexible hybrid underwater gripper, which effectively solves the technical problems of low output force, poor stability, and low control accuracy of the rigid-flexible hybrid underwater gripper.

[0004] The above technical problem is solved by the following technical solutions:

[0005] A rigid-flexible hybrid underwater gripper, comprising:

[0006] A gripper body, flexible fingers, and connecting rods;

[0007] The gripper body is provided with connecting parts, which are arranged on both sides of the gripper body and extend outward along the side edge end faces of the gripper body;

[0008] The flexible fingers are arranged between the connecting parts and are hinged to the connecting parts;

[0009] The connecting rods are arranged on the circumferences of the flexible fingers and are respectively hinged to the flexible fingers and the connecting parts;

[0010] The flexible fingers include a clamping surface, and a plurality of protrusions arranged at intervals are provided on the clamping surface.

[0011] In one embodiment, the connecting rods include a first connecting rod, a second connecting rod, a third connecting rod, a fourth connecting rod, and a fifth connecting rod, all of which are arranged on the sides of the flexible fingers along the length direction of the flexible fingers;

[0012] The first connecting rod is respectively hinged to the connecting part, the second connecting rod, and the fifth connecting rod; the second connecting rod is respectively hinged to the first connecting rod, the third connecting rod, and the fourth connecting rod; the third connecting rod is respectively hinged to the second connecting rod and the fifth connecting rod; the fourth connecting rod is respectively hinged to the connecting part and the second connecting rod.

[0013] In one embodiment, a first hinge point is formed at the connection between the first connecting rod, the connecting portion and the flexible finger; a second hinge point is formed at the connection between the first connecting rod, the second connecting rod and the flexible finger; a third hinge point is formed at the connection between the second connecting rod, the third connecting rod and the flexible finger; a fourth hinge point is formed at the connection between the third connecting rod and the flexible finger; a fifth hinge point is formed at the connection between the fourth connecting rod, the second connecting rod and the flexible finger; a sixth hinge point is formed at the connection between the fifth connecting rod, the third connecting rod and the flexible finger.

[0014] In one embodiment, it further includes a driving rope. A connection hole is provided on one side of the connecting rod close to the clamping surface, and the driving rope is arranged in the connection hole.

[0015] In one embodiment, it further includes:

[0016] A mounting base, on which the gripper body is arranged;

[0017] A plurality of driving motors, all arranged on the mounting base;

[0018] A plurality of rotating members, which are connected to the driving motors in one-to-one correspondence and are connected to the driving rope.

[0019] In one embodiment, the flexible finger is made of silica gel.

[0020] On the other hand, the present invention also provides a model construction method, which is applied to the rigid-flexible hybrid underwater gripper as described above. The method includes:

[0021] Define a coordinate system O at the central axis of the first hinge point 0 ; Define a coordinate system O at the central axes of the second hinge point, the third hinge point and the fourth hinge point i ; Define a coordinate system O at the central axes of the fifth hinge point and the sixth hinge point j ;

[0022] Obtain the coordinates of the force application points on the flexible finger and determine the target coordinate system where the force application points are located;

[0023] Based on the target coordinate system, determine multiple force application paths from the target coordinate system to the coordinate system O 0 and obtain a plurality of rotation matrices corresponding to the force application paths one by one;

[0024] Based on the multiple rotation matrices, construct the kinematic model of the rigid-flexible hybrid underwater gripper.

[0025] In one embodiment, the method further includes:

[0026] Obtain the strain energy expression after the deformation of the flexible finger, and determine the constraint conditions of the flexible finger;

[0027] Based on the strain energy expression and the constraint conditions, determine the objective function after the deformation of the flexible finger;

[0028] Obtain the strain expression and the bending angle change rate expression of the flexible finger;

[0029] Based on the objective function, simplify the strain expression and the bending angle change rate expression of the flexible finger;

[0030] Based on the simplified strain expression and the bending angle change rate expression of the flexible finger, calculate the strain and the bending angle change rate of the flexible finger.

[0031] In one embodiment, the simplified strain expression and the bending angle change rate expression of the flexible finger are:

[0032]

[0033] where, ε x is the strain of the flexible finger; is the bending angle change rate; σ 0 is the standard deviation of the Gaussian function; are the peak values of the Gaussian function respectively.

[0034] On the other hand, the present invention also provides a computer-readable storage medium, which stores computer instructions for enabling a processor to implement the model construction method as described above when executed.

[0035] The rigid-flexible hybrid underwater gripper provided by the present invention arranges flexible fingers between the connecting parts of the gripper body, and hingedly arranges connecting rods on the circumferential side of the flexible fingers. Without affecting the local compliance of the flexible fingers, it can restrain the large-range movement of the flexible fingers, improve the stability and grasping force of the rigid-flexible hybrid underwater gripper, and avoid the failure of the rigid-flexible hybrid underwater gripper due to large-range deformation caused by hydrodynamic force when moving relative to the water flow. By providing a plurality of spaced protrusions on the clamping surface of the flexible finger, the compliance of the flexible finger is retained. By constructing the kinematic model of the flexible finger, the deformation of the connecting rod can be calculated; and further by calculating the strain and the bending angle change rate of the flexible finger to analyze the mechanical properties of the flexible finger material, so as to facilitate more precise control of the movement of the flexible finger. Description of the Drawings

[0036] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0037] Figure 1 Structural schematic diagram of a rigid-flexible hybrid underwater gripper according to an embodiment of the present invention;

[0038] Figure 2 Three-dimensional structural schematic diagrams of a flexible finger of a rigid-flexible hybrid underwater gripper according to an embodiment of the present invention before and after being stressed;

[0039] Figure 3 For Figure 2 The shown front view;

[0040] Figure 4 Structural schematic diagrams of a flexible finger of a rigid-flexible hybrid underwater gripper according to an embodiment of the present invention after being stressed with and without a connecting rod;

[0041] Figure 5 Three-dimensional structural schematic diagram of a rigid-flexible hybrid underwater gripper according to an embodiment of the present invention;

[0042] Figure 6 For Figure 5 The shown front view;

[0043] Figure 7 Coordinate system schematic diagram in a rigid-flexible hybrid underwater gripper according to an embodiment of the present invention;

[0044] Figure 8 Flow schematic diagram of a model construction method according to an embodiment of the present invention;

[0045] Figure 9 Connecting rod parameter schematic diagram in a rigid-flexible hybrid underwater gripper according to an embodiment of the present invention;

[0046] Figure 10 Structural schematic diagram of an electronic device according to an embodiment of the present invention.

[0047] Description of the reference numerals: 1. Mounting base; 2. Driving motor; 3. Rotating member; 10. Gripper body; 101. Connecting portion; 11. Flexible finger; 111. Protrusion; 12. First connecting rod; 121. First hinge point; 122. Connecting hole; 13. Second connecting rod; 131. Second hinge point; 132. Third hinge point; 14. Third connecting rod; 141. Fourth hinge point; 15. Fourth connecting rod; 151. Fifth hinge point; 16. Fifth connecting rod; 161. Sixth hinge point; 17. Driving cable; 18. Sixth connecting rod. Detailed implementation manners

[0048] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0049] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes, and cannot be construed as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0050] According to an embodiment of the present invention, as Figures 2 to 6 shown, on the one hand, a rigid-flexible hybrid underwater gripper is provided, including: a gripper body 10, flexible fingers 11, and connecting rods; the gripper body 10 is provided with a connecting portion 101, and the connecting portion 101 is arranged on both sides of the gripper body 10 and extends outward along the side end surface of the gripper body 10; the flexible fingers 11 are arranged between the connecting portions 101 and are hinged to the connecting portions 101; the connecting rods are arranged on the periphery of the flexible fingers 11 and are respectively hinged to the flexible fingers 11 and the connecting portions 101; the flexible fingers 11 include a clamping surface, and a plurality of spaced protrusions 111 are provided on the clamping surface. Further, a driving cable 17 is further included, and a connecting hole 122 is provided on one side of the connecting rod close to the clamping surface, and the driving cable 17 is arranged in the connecting hole 122.

[0051] In this embodiment, connecting portions 101 are provided on both sides of the gripper body 10, and the connecting portions 101 extend away from the side end face along the side end face of the gripper body 10; the flexible fingers 11 are arranged between the connecting portions 101, and the flexible fingers 11 are hingedly connected to the connecting portions 101 through connecting rods. There are multiple connecting rods, all arranged on the circumferential side of the flexible fingers 11 and hinged to the flexible fingers 11; the movement of the connecting rods can drive the movement of the flexible fingers 11, and without affecting the local compliance of the flexible fingers 11, the connecting rods can also restrain the large-range movement of the flexible fingers 11, improving the stability of the rigid-flexible hybrid underwater gripper, i.e., the soft gripper, and preventing the rigid-flexible hybrid underwater gripper from failing due to large-range deformation caused by hydrodynamic forces when moving relative to the water flow. A plurality of spaced protrusions 111 are provided on the clamping surface of the flexible fingers 11 to retain the compliance of the flexible fingers 11 and facilitate the bending movement of the flexible fingers 11. A plurality of connection holes 122 are also provided on one side of the connecting rod close to the clamping surface, and the driving ropes 17 are threaded through the connection holes 122, and the movement of the driving ropes 17 drives the movement of the connecting rods, thereby controlling the movement of the flexible fingers 11. In the present invention, the plurality of spaced protrusions 111 on the clamping surface of the flexible fingers 11 can maintain the local compliance of the flexible fingers 11. And through the restriction of each connecting rod, the overall compliance of the flexible fingers 11 can be ensured. For example, when subjected to an external force F a ′, the deflection δ 1 of the flexible fingers 11 without the connecting rod is significantly greater than the deflection δ 2 of the flexible fingers 11 provided with the connecting rod.

[0052] In one embodiment, the connecting rods include a first connecting rod 12, a second connecting rod 13, a third connecting rod 14, a fourth connecting rod 15, and a fifth connecting rod 16, all arranged on the side of the flexible fingers 11 along the length direction of the flexible fingers 11; the first connecting rod 12 is respectively hinged to the connecting portion 101, the second connecting rod 13, and the fifth connecting rod 16; the second connecting rod 13 is respectively hinged to the first connecting rod 12, the third connecting rod 14, and the fourth connecting rod 15; the third connecting rod 14 is respectively hinged to the second connecting rod 13 and the fifth connecting rod 16; the fourth connecting rod 15 is respectively hinged to the connecting portion 101 and the second connecting rod 13.

[0053] In this embodiment, a first connecting rod 12, a second connecting rod 13, a third connecting rod 14, a fourth connecting rod 15 and a fifth connecting rod 16 are arranged on one side of the flexible finger 11, and are all arranged on the side of the flexible finger 11 along the length direction of the flexible finger 11 to inhibit the large-range movement of the flexible finger 11. Among them, three through holes are provided on each of the first connecting rod 12, the second connecting rod 13 and the third connecting rod 14, and they are all triangular; two through holes are provided on the fourth connecting rod 15 and the fifth connecting rod 16, and they are both L-shaped. By hinging the first connecting rod 12 to the connecting part 101, the second connecting rod 13 and the fifth connecting rod 16 respectively; hinging the second connecting rod 13 to the first connecting rod 12, the third connecting rod 14 and the fourth connecting rod 15 respectively; hinging the third connecting rod 14 to the second connecting rod 13 and the fifth connecting rod 16 respectively; and hinging the fourth connecting rod 15 to the connecting part 101 and the second connecting rod 13 respectively; the connecting rods are wrapped around the circumferential side of the flexible finger 11, thereby reducing the influence of water flow movement on the flexible finger 11. It can be understood that on both sides in the length direction of the flexible finger 11, the structure and connection method of the connecting rods are the same.

[0054] In one of the embodiments, the flexible finger 11 is made of silica gel. By using the flexible finger 11 made of silica gel, and then making the flexible finger 11 cooperate with the rigid exoskeleton formed by multiple connecting rods to form a rigid-flexible hybrid underwater gripper, and driving the rigid-flexible hybrid underwater gripper by the driving rope 17, it is possible to inhibit the large-range movement of the flexible finger 11 without affecting the local compliance of the flexible finger 11, and improve the stability and grasping force of the rigid-flexible hybrid underwater gripper; at the same time, avoid the rigid-flexible hybrid underwater gripper from failing due to large-range deformation caused by hydrodynamic force when moving relative to the water flow.

[0055] As Figure 3 shown, further, calculate the degree of freedom of the connecting rod, and the calculation formula is:

[0056] D = 3N - 2P h - P l

[0057] Among them, D is the degree of freedom of the connecting rod; N = 5 is the number of connecting rods; P h = 7 is the number of higher pairs; P l = 0 is the number of lower pairs. Thus, it is calculated that D = 1, that is, one displacement of the driving rope 17 corresponds to a unique deformation of the connecting rod.

[0058] For the third connecting rod 14, when a force F a is applied and the tension of the driving rope 17 is F t , the second connecting rod 13 provides a force F l1 , while the fifth connecting rod 16 provides a force F l2If the third connecting rod 14 is in a state of force balance, the resultant force should be 0, and the resultant moment about point O should be 0, with the expression:

[0059]

[0060] where r i represents the position vector of the force F i relative to point O.

[0061] It can be seen therefrom that the fifth connecting rod 16 is the connecting rod that provides a force in the direction opposite to the external force F a which makes the fifth connecting rod 16 crucial for the stability and load capacity of the rigid-flexible hybrid underwater gripper. Similarly, the fourth connecting rod 15 is also crucial for the stability and load capacity of the rigid-flexible hybrid underwater gripper.

[0062] Furthermore, the connecting rod further includes a sixth connecting rod 18, which is arranged at one end of the flexible finger 11 away from the gripper body 10 and is used to connect the third connecting rods 14 on both sides of the flexible finger 11.

[0063] In one embodiment, a first hinge point 121 is formed at the connection between the first connecting rod 12 and the connection part 101 and the flexible finger 11; a second hinge point 131 is formed at the connection between the first connecting rod 12 and the second connecting rod 13 and the flexible finger 11; a third hinge point 132 is formed at the connection between the second connecting rod 13 and the third connecting rod 14 and the flexible finger 11; a fourth hinge point 141 is formed at the connection between the third connecting rod 14 and the flexible finger 11; a fifth hinge point 151 is formed at the connection between the fourth connecting rod 15 and the second connecting rod 13 and the flexible finger 11; a sixth hinge point 161 is formed at the connection between the fifth connecting rod 16 and the third connecting rod 14 and the flexible finger 11.

[0064] As Figure 1 shown, in one embodiment, it further includes: a mounting base 1, on which the gripper body is arranged; a plurality of drive motors 2, all arranged on the mounting base 1; a plurality of rotating members 3, which are connected to the drive motors 2 in one-to-one correspondence and are connected to the drive ropes 17.

[0065] In this embodiment, the driving motor 2 provides power to drive the rotating member 3 connected to the driving motor 2 to rotate; the driving rope 17 is wound by the rotation of the rotating member 3 to displace the driving rope 17. When the driving rope 17 contracts, the elastic force of the flexible finger 11 is overcome, so that the flexible finger 11 contracts. When the driving rope 17 relaxes, the driving motor 2 releases the driving rope 17 wound on the rotating member 3, and the flexible finger 11 returns to its initial state by using its elastic force. Therefore, the flexible finger 11 does not need to install a spring on the connecting rod, thus simplifying the overall structural design of the flexible finger 11. Moreover, the force can be transmitted through the driving rope 17, and the driving rope 17 can keep complex structures (such as a driving motor or other driving devices) away from the flexible finger 11, thereby simplifying the complexity of the flexible finger 11, which is beneficial to protecting the rigid-flexible hybrid underwater gripper underwater.

[0066] The rigid-flexible hybrid underwater gripper provided by the present invention can carry a large weight load and can grasp fragile objects such as tofu and raw eggs at the same time; for example, it is known through experiments that the rigid-flexible hybrid underwater gripper can carry a heavy object of at least 80 kg. Moreover, the rigid-flexible hybrid underwater gripper can maintain the grasping stability of the fingers of the rigid-flexible hybrid underwater gripper under the disturbance of high-speed underwater flow (such as 2 m / s). The overall structure of the rigid-flexible hybrid underwater gripper is light, and only 4 servo motors of 23 g are used for the driving motors, which is convenient for the rigid-flexible hybrid underwater gripper to be assembled onto underwater robots of different sizes and different loads.

[0067] As Figures 7 to 9 shown, according to an embodiment of the present invention, on the other hand, a model construction method is provided, which is applied to a rigid-flexible hybrid underwater gripper and includes the following steps:

[0068] Step S100, define a coordinate system O at the central axis of the first hinge point 121 0 ; define a coordinate system O at the central axes of the second hinge point 131, the third hinge point 132, and the fourth hinge point 141 i ; define a coordinate system O at the central axes of the fifth hinge point 151 and the sixth hinge point 161 j ;

[0069] Step S200, obtain the coordinates of the force application points on the flexible finger 11 and determine the target coordinate system where the force application points are located;

[0070] Step S300, based on the target coordinate system, determine multiple force application paths from the target coordinate system to the coordinate system O 0 and obtain a plurality of rotation matrices corresponding to the force application paths one by one;

[0071] Step S400, construct a kinematic model of the rigid-flexible hybrid underwater gripper based on the plurality of rotation matrices.

[0072] In this embodiment, first, a coordinate system O is defined at the central axis of the first hinge point 121 0 , where the x 0 axis points horizontally to the right, the y 0 axis points vertically upward, and the coordinate system O 0 remains fixed during the deformation of the flexible finger 11. Coordinate systems O i are defined at the central axes of the second hinge point 131, the third hinge point 132, and the fourth hinge point 141, where i takes values of 1, 2, 3; the orientation of x i is along the ray direction formed by O i-1 and O i , and the y i axis is perpendicular to the x i axis and points upward; the coordinate system O i moves with the movement of the connecting rod. Coordinate systems O j are defined at the central axes of the fifth hinge point 151 and the sixth hinge point 161, where j takes values of 4, 5; when the flexible finger 11 is undeformed, the axis of the coordinate axis O j is consistent with the length direction of the connecting rod, the x j axis is parallel to the long side of the connecting rod, and the y j axis is perpendicular to the x j axis and points upward; the coordinate system O j moves with the movement of the connecting rod.

[0073] Furthermore, the rotation angle of each connecting rod is characterized by the angle formed by its axis x i and the axis x i-1 of another connecting rod, denoted as θ i , where i takes values of 1, 2, 3; the rotation angle of the coordinate system O 4 is characterized by its rotation angle relative to the initial position, denoted as θ 4 , and the rotation angle of the coordinate system O 5 is characterized by its rotation angle relative to the coordinate system O 1 , denoted as θ 5 .

[0074] Taking the force application point P in the coordinate system O 3 as an example, the coordinates of P in the coordinate system O 3 are and the coordinates of P in the coordinate system O 0 are Then there is:

[0075] p 0p = T 03 × p 3p (1)

[0076] In the formula, represents the transformation from O 3 to O 0The rotation matrix, through different force paths, can be respectively expressed as:

[0077]

[0078] According to Equation (2), we can obtain:

[0079] T 12 T 23 = T 15 T 53 (3)

[0080] Expanding Equation (3), we can get:

[0081]

[0082] Further simplifying Equation (3) using trigonometric functions, we obtain a system of linear equations in three variables:

[0083]

[0084] where θ = θ 2 + θ 3 , moving all terms with θ 5 to the left side of the equation and the remaining terms to the right side of the equation, taking the square of both sides of the equation and then adding the two equations, and substituting the special condition l 1 = l 2 , we simplify to get:

[0085]

[0086] Equation (7) describes the relationship between θ 2 and θ 3 . Repeating the above steps, it is easy to prove that the relationship between θ 1 and θ 2 is exactly the same as the relationship between θ 2 and θ 3 . Substituting the relevant parameters L 1 = 45, L 2 = 18, l 0 = 24, l 1 = 15, l 2 = 15, l 3 = 18, l 4 = 3mm, further simplifying Equation (7) we get:

[0087]

[0088] When one of the quantities of θ 2 or θ 3 is known, Equation (8) can be expressed by Equation (9):

[0089]

[0090] Among them, is an unknown angular measure, A, B, and D are all known coefficients, and the general solution of Equation (12) is:

[0091]

[0092] It is also known that 0° ≤ θ 1,2,3 < 90°, so that the other two values can be calculated based on any value of θ 1,2,3 .

[0093] When deriving the value of θ i+1 from θ i , i takes values 1, 2, takes θ i , A takes the value of (720 + 90cosθ i+1 - 270sinθ i+1 ), B takes the value of (720 + 90sinθ i+1 + 270cosθ i+1 ), D takes the value of (1278 + 144sinθ i+1 - 288cosθ i+1 ), then

[0094] When calculating the value of θ i from θ i - 1, i takes 2 or 3, takes θ i , A takes (-144 + 90cosθ i-1 - 270sinθ i-1 ), B takes (288 + 90sinθ i-1 + 270cosθ i-1 ), D takes (1278 - 720sinθ i-1 - 720cosθ i-1 ), then

[0095] Furthermore, the change length of the driving rope 17 can be calculated through the above kinematic model to facilitate better precise control of the flexible finger 11.

[0096] In one of the embodiments, it further includes: obtaining the strain energy expression after the deformation of the flexible finger 11, and determining the constraint conditions of the flexible finger 11; based on the strain energy expression and the constraint conditions, determining the objective function after the deformation of the flexible finger 11; obtaining the strain expression and the bending angle change rate expression of the flexible finger 11; simplifying the strain expression and the bending angle change rate expression of the flexible finger 11 based on the objective function; calculating the strain and the bending angle change rate of the flexible finger 11 based on the simplified strain expression and the bending angle change rate expression of the flexible finger 11.

[0097] In this embodiment, first, obtain the strain energy expression after the deformation of the flexible finger 11:

[0098]

[0099] where E is the Young's modulus of the flexible finger 11; T, H, and L are the thickness, height, and length of the flexible finger 11 respectively; ε x is the strain of the flexible finger 11; is the bending angle change rate of the flexible finger 11; ΔL is the displacement magnitude of the driving rope 17; W p is the strain energy; F is the tensile force.

[0100] Because during the deformation of the flexible finger 11, the bottom of the flexible finger 11 is always connected to the connecting rod, the constraint conditions of the flexible finger 11 can be obtained:

[0101]

[0102] According to the principle of minimum energy, and combining the strain energy expression and the constraint conditions, the objective function after the deformation of the flexible finger 11 is obtained as:

[0103] min W p s.t.formula(12) 13)

[0104] Since the forms of the strain ε x of the flexible finger 11 and the bending angle change rate of the flexible finger 11 are still unknown. Therefore, by observing the finite element simulation results, it is determined that the deformation of the flexible finger 11 is mainly concentrated at the hinge joint with the connecting rod, and the positions far from the hinge joint hardly deform, and the closer to the hinge joint, the greater the deformation.

[0105] Therefore, assume that the forms of ε x and are:

[0106]

[0107] where ε x and All are composed of 4 Gaussian functions. The centers of the Gaussian functions are located at 0, l, 2l, and 3l respectively, that is, at the 4 hinge joints of the connecting rod. The standard deviations of the Gaussian functions are σ 1,2 ,..., 8 , and the peak values of the Gaussian functions are all greater than 0.

[0108] The Gaussian function can be approximated as 0 when deviating from the center position by ±3 i After that, that is, when the standard deviation σ i of the Gaussian function is relatively small, ε x and In the expressions, multiple Gaussian functions are independent of each other. ε x and composed of multiple Gaussian functions can actually be regarded as a piecewise function, so as to simplify the complexity of mathematical operations in integral operations through the form of piecewise functions.

[0109] In the process of actual operation, to solve the constraint conditions, it is necessary to first perform an indefinite integral on , and then perform a definite integral with the result of the indefinite integral. It is known that there is no analytical solution for the indefinite integral of the Gaussian function, so numerical integration can be used to solve it; by traversing the values of parameters ai and bi, the numerical integration results are output one by one to detect whether the constraint conditions are satisfied.

[0110] It is known that ε x and are composed of the superposition of multiple Gaussian functions, and can be calculated segment by segment when calculating the constraint conditions. In fact, for each small segment of the Gaussian function in ε x and , only the right part can be calculated, that is, the part on the right side of the symmetry axis of the Gaussian function. Since the flexible finger 11 is deformed under the influence of the connecting rod, the connecting rod remains relatively fixed at the bottom of the flexible finger 11, and the part of the connecting rod at the front end of the flexible finger 11 is deformed. After each section of the connecting rod is deformed, it causes the flexible finger 11 to deform. This section of the flexible finger 11 often completes a large amount of deformation near the rear end of this section of the connecting rod, and only a small amount of deformation occurs at the front end of the connecting rod. The part corresponding to the right side of each section of the Gaussian function participates in the calculation, and the left part is ignored. Therefore, when calculating a certain section of the constraint conditions, only the right half of a section of the Gaussian function needs to be calculated, which simplifies the calculation complexity and is also more in line with the actual situation.

[0111] To further simplify the calculation, considering the deformation situation of a small element of the flexible finger 11, it is determined that the length of this small element is dx, the distance from the bending position to the center position is h, and the local bending angle Since is very small, the strain Since the connecting rod hardly deforms, and the length of the flexible finger 11 connected to the connecting rod remains basically unchanged before and after deformation, it can be assumed that the distance h between the center of the hinge point and the center position of the flexible finger 11 is a constant. Then So i = 1, 2, 3, 4 = 5, 6, 7, 8.

[0112] Finally, considering the standard deviation of each small Gaussian function, for reasonable simplification of the calculation, the value of the standard deviation is taken as a fixed value of 8. After simplifying Equation (14), the strain expression and the bending angle change rate expression of the flexible finger 11 are:

[0113]

[0114] where ε x is the strain of the flexible finger 11; is the bending angle change rate; σ 0 is the standard deviation of the Gaussian function; are the peak values of the Gaussian function, respectively.

[0115] In summary, the rigid-flexible hybrid underwater gripper provided by the present invention suppresses the large-range movement of the flexible finger 11 without affecting the local compliance of the flexible finger 11 by arranging the flexible finger 11 between the connecting parts 101 of the gripper body 10 and hinging a connecting rod on the circumferential side of the flexible finger 11, improving the stability of the rigid-flexible hybrid underwater gripper and avoiding the failure of the rigid-flexible hybrid underwater gripper due to large-range deformation caused by hydrodynamic force when moving relative to the water flow. By providing a plurality of spaced protrusions 111 on the clamping surface of the flexible finger 11, the compliance of the flexible finger 11 is retained. By constructing the kinematic model of the flexible finger 11, the deformation of the connecting rod can be calculated; and further, by calculating the strain and the bending angle change rate of the flexible finger 11, the mechanical properties of the material of the flexible finger 11 can be analyzed, so as to facilitate more precise control of the movement of the flexible finger 11.

[0116] Figure 10 The structural schematic diagram of the embodiment of the electronic device provided by the embodiment of the present invention is shown. The specific implementation of the electronic device is not limited in the specific embodiments of the present invention.

[0117] As Figure 10 shown, the electronic device may include: a processor 502, a communications interface 504, a memory 506, and a communication bus 508.

[0118] Among them: The processor 502, the communication interface 504, and the memory 506 communicate with each other through the communication bus 508. The communication interface 504 is used to communicate with network elements of other devices such as clients or other servers. The processor 502 is used to execute the program 510, and specifically can execute the relevant steps in the above-mentioned method embodiments for model construction.

[0119] Specifically, the program 510 may include program code, and the program code includes computer-executable instructions.

[0120] The processor 502 may be a central processing unit CPU, or a specific integrated circuit ASIC (Application Specific Integrated Circuit), or one or more integrated circuits configured to implement the embodiments of the present invention. One or more processors included in the electronic device may be of the same type of processor, such as one or more CPUs; or may be of different types of processors, such as one or more CPUs and one or more ASICs.

[0121] The memory 506 is used to store the program 510. The memory 506 may include high-speed RAM memory, and may also include non-volatile memory, such as at least one disk memory.

[0122] The program 510 can specifically be called by the processor 502 to make the electronic device execute the relevant steps in the above-mentioned method embodiments for model construction.

[0123] Those of ordinary skill in the art can understand that Figure 10 The structure shown is only schematic and does not limit the structure of the above-mentioned device. For example, the electronic device may further include more or fewer components than those shown Figure 10 in the figure, or have a different configuration from that shown Figure 10 in the figure.

[0124] Embodiments of the present invention also provide a computer-readable storage medium. The method according to the embodiments of the present invention can be implemented in hardware, firmware, or be implemented as computer code that can be recorded on a storage medium, or be implemented as computer code that is originally stored in a remote storage medium or a non-transitory machine-readable storage medium and downloaded through a network and will be stored in a local storage medium, so that the method described herein can be stored in such software processes on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. Among them, the storage medium can be a magnetic disk, an optical disk, a read-only memory, a random access memory, a flash memory, a hard disk, or a solid-state drive, etc.; further, the storage medium can also include a combination of the above-mentioned types of memories. It can be understood that a computer, a processor, a microprocessor controller, or programmable hardware includes a storage component that can store or receive software or computer code. When the software or computer code is accessed and executed by the computer, the processor, or the hardware, the method shown in the above embodiments is implemented.

[0125] In the specific content of the above specific embodiments, the technical features can be combined arbitrarily without contradiction. For the sake of brevity of description, not all possible combinations of the above technical features are described. However, as long as the combinations of these technical features do not exist in contradiction, they should be considered to be within the scope described in this specification.

[0126] The specific content of the above specific embodiments only expresses several embodiments of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

1. A rigid-flexible hybrid underwater gripper, characterized in that: include: Gripper body, flexible fingers and connecting rods; The gripper body is provided with a connecting portion, which is arranged on both sides of the gripper body and extends outward along the side end surface of the gripper body; The flexible fingers are arranged between the connecting parts and are hinged to the connecting parts; The connecting rod is arranged on the peripheral side of the flexible finger and is hinged to the flexible finger and the connecting part respectively; The flexible finger comprises a clamping surface, on which a plurality of protrusions arranged at intervals are disposed.

2. The rigid-flexible hybrid underwater gripper according to claim 1, characterized in that: The connecting rods include a first connecting rod, a second connecting rod, a third connecting rod, a fourth connecting rod and a fifth connecting rod, all of which are arranged on the side of the flexible finger along the length direction of the flexible finger; The first connecting rod is hinged to the connecting part, the second connecting rod and the fifth connecting rod respectively; the second connecting rod is hinged to the first connecting rod, the third connecting rod and the fourth connecting rod respectively; the third connecting rod is hinged to the second connecting rod and the fifth connecting rod respectively; the fourth connecting rod is hinged to the connecting part and the second connecting rod respectively.

3. The rigid-flexible hybrid underwater gripper according to claim 2, characterized in that: The connection between the first connecting rod and the connecting part and the flexible finger forms a first hinge; the connection between the first connecting rod and the second connecting rod and the flexible finger forms a second hinge; the connection between the second connecting rod and the third connecting rod and the flexible finger forms a third hinge; the connection between the third connecting rod and the flexible finger forms a fourth hinge; the connection between the fourth connecting rod and the second connecting rod and the flexible finger forms a fifth hinge; the connection between the fifth connecting rod and the third connecting rod and the flexible finger forms a sixth hinge.

4. The rigid-flexible hybrid underwater gripper according to claim 1, characterized in that: It also includes a driving rope. A connecting hole is provided on one side of the connecting rod close to the clamping surface, and the driving rope is arranged in the connecting hole.

5. The rigid-flexible hybrid underwater gripper according to claim 4, characterized in that: Also includes: A mounting base, wherein the gripper body is arranged on the mounting base; A plurality of driving motors are arranged on the mounting base; A plurality of rotating members are connected to the driving motors in a one-to-one correspondence and are connected to the driving ropes.

6. The rigid-flexible hybrid underwater gripper according to claim 1, characterized in that: The flexible finger is made of silica gel.

7. A model building method, characterized in that: Applied to the rigid-flexible hybrid underwater gripper according to any one of claims 1 to 6, the method comprises: The coordinate system O0 is defined at the center axis of the first hinge point; the coordinate system O is defined at the center axis of the second hinge point, the third hinge point, and the fourth hinge point. i ; Define the coordinate system O at the center axis of the fifth and sixth hinge points j ; Obtaining the coordinates of the force-bearing point on the flexible finger, and determining the target coordinate system where the force-bearing point is located; Based on the target coordinate system, multiple force paths from the target coordinate system to the coordinate system O0 are determined, and multiple rotation matrices corresponding to the force paths are obtained; Based on the multiple rotation matrices, a kinematic model of the rigid-flexible hybrid underwater gripper is constructed.

8. The model building method according to claim 7, characterized in that: Also includes: Obtaining a strain energy expression of the flexible finger after deformation, and determining a constraint condition of the flexible finger; Determining the objective function of the flexible finger after deformation based on the strain energy expression and the constraint condition; Obtaining a strain expression and a bending angle change rate expression of the flexible finger; Simplifying the strain expression and bending angle change rate expression of the flexible finger based on the objective function; Based on the simplified strain expression and bending angle change rate expression of the flexible finger, the strain and bending angle change rate of the flexible finger are calculated.

9. The model building method according to claim 7, characterized in that: The simplified strain expression and bending angle change rate expression of the flexible finger are: Among them, ε x is the strain of the flexible finger; is the bending angle change rate; σ0 is the standard deviation of the Gaussian function; are the peak values ​​of the Gaussian function.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the model building method according to any one of claims 7 to 9 when executed.

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