Finger exoskeleton unit free of shearing force and self-adaptive to joint rotation center and hand exoskeleton

Abstract

The invention discloses a finger exoskeleton unit free of shear force and self-adaptive to a joint rotation center and a hand exoskeleton, and relates to the technical field of rehabilitation medical instruments. The existing finger exoskeleton can only realize large-angle flexion and extension of a large phalanx and is difficult to realize large-angle flexion and extension of a small phalanx. The end executing mechanism comprises a first connecting rod seat which is assembled to a first phalanx and can move in the length direction of the first phalanx; the transmission connecting rod mechanism comprises a driving connecting rod and a first transmission connecting rod, a second transmission connecting rod, a third transmission connecting rod and a fourth transmission connecting rod which are sequentially connected end to end, a hinge point is formed between every two adjacent transmission connecting rods, and connecting lines of the four hinge points form a deformable parallelogram. The third transmission connecting rod is located at the knuckle position of the first phalanx and fixed, and the tip of the first transmission connecting rod is hinged to the first connecting rod seat; one end of the driving connecting rod is hinged to the fourth transmission connecting rod, and the other end can bear driving force in the length direction of the rod. The hand rehabilitation training device is used for hand rehabilitation training.

Description

Technical Field

[0001] This invention relates to the field of rehabilitation medical device technology, and in particular to a finger exoskeleton unit and a hand exoskeleton that are shear-free and adaptive to the joint rotation center. Background Technology

[0002] Hand dysfunction is widespread among patients with neurological and musculoskeletal disorders such as stroke and spinal cord injury, severely impacting their quality of life. Traditional rehabilitation training methods heavily rely on professional rehabilitation therapists, requiring significant manpower and stringent skill levels. However, a significant gap exists between the number of therapists and patients' rehabilitation needs, often leading to delays in the rehabilitation process and increasing the social burden on healthcare. In contrast, hand exoskeletons demonstrate significant advantages in the field of rehabilitation, offering characteristics such as low labor costs, adjustable training intensity, and precise control of the movement process, providing an effective way to alleviate the shortage of traditional rehabilitation resources.

[0003] Rigid hand exoskeletons can be divided into two types: those with a fixed center of rotation and those with an adaptive center of joint rotation. Exoskeletons with a fixed center of rotation are difficult to adapt to the dynamic changes in the center of joint rotation during hand movement and cannot accommodate differences in finger size between individuals. Exoskeletons with an adaptive center of joint rotation, on the other hand, form a closed-loop kinetic chain with the human hand, and their kinematic model dynamically changes with the position of the finger joints, thus avoiding joint dislocation injuries. Exoskeletons with an adaptive center of joint rotation can be further divided into those with shear force and those without. Exoskeletons with shear force generate a shear force parallel to the phalanges when driving finger movement. Although this stress is perpendicular to the direction of finger movement and does no work, it exerts continuous compression on the phalanges, causing discomfort to the user and even leading to joint fatigue injuries. Exoskeletons without shear force often use a crank-slider mechanism, such as the "Hand Rehabilitation Device and Thumb Control Device Based on Spherical Transmission Linkage Mechanism" disclosed in publication number CN113855482B. Because the slider of this mechanism requires a long track travel to meet the joint's range of motion, it is often used to drive larger joints such as the thumb CMC joint or the four-finger MCP joint, but it is difficult to apply to smaller joints such as PIP. Therefore, there is a lack of a shear-free adaptive joint rotation center exoskeleton device for small-sized joints. Summary of the Invention

[0004] In view of this, the present invention provides a finger exoskeleton unit and a hand exoskeleton that are free from shear force and have an adaptive joint rotation center. It utilizes a four-bar linkage as a transmission linkage mechanism. By constraining the movement of the first transmission link, it forms an orderly rotational motion, so that the driving force of the first transmission link acting on the first link seat is mainly converted into rotational motion, with only a small amount converted into translation of the first link seat. This realizes the adaptive rotational motion of small-sized finger bones under conditions without shear force.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows:

[0006] A finger exoskeleton unit includes an end effector and a transmission linkage mechanism. The end effector includes a first linkage seat, which is assembled to a first phalanx and can reciprocate along the length of the first phalanx. The transmission linkage mechanism includes a drive linkage and transmission linkages. Multiple transmission linkages are provided, respectively designated as a first transmission linkage, a second transmission linkage, a third transmission linkage, and a fourth transmission linkage. The first, second, third, and fourth transmission linkages are connected end-to-end, and a hinge point is formed between two adjacent transmission linkages. The line connecting the four hinge points forms a deformable parallelogram. The third transmission linkage is located at the finger joint of the first phalanx and is fixed. The tip of the first transmission linkage is hinged to the first linkage seat. One end of the drive linkage is hinged to the fourth transmission linkage, and the other end can be subjected to a driving force along the length of the linkage.

[0007] When the drive link is subjected to force, it transmits the driving force to the fourth transmission link and the first transmission link in sequence. Under the constraint of the parallelogram, the first transmission link drives the first link seat. The first link seat drives the first phalanx to rotate around the finger joint while sliding along the length of the finger, so as to realize the adaptive rotation of the first phalanx without shear force.

[0008] Furthermore, the end effector also includes a first base, a first finger sleeve, and a first sliding pair. The first base is fitted onto the first finger bone via the first finger sleeve, and the first linkage seat is mounted on the first base via the first sliding pair.

[0009] Furthermore, it also includes a drive mechanism for applying driving force to the drive link. The drive mechanism includes a second link seat, a second finger sleeve, a second base, a second sliding joint, and a cable drive assembly. The second base is fitted onto the second finger bone through the second finger sleeve. The second finger bone is adjacent to the first finger bone and located at the distal end of the fingertip. The second link seat is mounted on the second base through the second sliding joint. The other end of the drive link is hinged to the second link seat.

[0010] Furthermore, the fourth transmission link is a bent link with a bending angle greater than 90°, and the driving link is hinged to the bend of the fourth transmission link.

[0011] Furthermore, the rope drive assembly includes a tendon rope, a steering bearing, and a remote motor. The steering bearing is mounted on the end of the second base near the fingertip. One end of the tendon rope extends away from the fingertip and can be wound or released by the remote motor. The other end passes around the steering bearing and is fixed to the second linkage seat, also extending away from the fingertip, and can also be wound or released by the remote motor. When one end of the tendon rope is wound, the other end is released accordingly.

[0012] Furthermore, the rope drive assembly also includes two cable sleeves, which are fixed to the second base and respectively fitted onto the inlet and outlet ends of the tendon rope.

[0013] Furthermore, the minimum movement distance of the first linkage along the length of the finger is determined based on forward and inverse kinematics, the construction process of which includes:

[0014] Let A be the hinge point between the second connecting rod seat and the drive connecting rod, B be the hinge point between the drive connecting rod and the fourth transmission connecting rod, C be the hinge point between the third and fourth transmission connecting rods, F be the hinge point between the first and fourth transmission connecting rods, E be the hinge point between the first and second transmission connecting rods, O be the hinge point between the second and third transmission connecting rods, G be the hinge point between the first connecting rod seat and the first transmission connecting rod, J be the first finger sleeve, and D be the joint axis of the finger joint; let X be the focus of the right triangle formed by the vertical line passing through point C, the horizontal line passing through point A, and AC; and let X be the distance between any two points. The two dots corresponding to its subscript are represented as follows: The distance between AC. The distance between X and A is... The distance between X and C is represented in the same way as the distance between the other two points; the angle between the three points is represented by... The angle is represented by three points corresponding to its subscript, with the midpoint of these three points being the vertex of the angle. The angle formed by these three points corresponds to an angle less than or equal to 180°. Let ACB be the angle. Let XCA be the angle, and the angles formed by the other three points are represented in the same way;

[0015] Constructing the forward kinematics of the mechanism: the tendon chords drive the translational motion of the second link seat, thereby changing... Length to control finger joint angle That is, the input is The output is The mechanical structure is broken down into four kinematic chains, each of which is solved separately:

[0016] First kinetic chain forward kinematics: The tendon chords drive the translational motion of the second link seat, thereby changing... The length is used to control the angle of the joystick CB. ;

[0017] Given a variable length, find... :

[0018] , , ,

[0019] = , =180-( ;

[0020] Second kinetic chain forward kinematics: Determined by the above formula, For fixed values Given a fixed value, find :

[0021] );

[0022] Third kinetic chain forward kinematics: Based on the above formula, we can find... :

[0023] , ,

[0024] , ,

[0025] , ,

[0026] , ;

[0027] Fourth kinetic chain forward kinematics: Confirmed. Determined, find the finger joint angles. The vertical distance between slider J and the finger joint :

[0028] Establish a Cartesian coordinate system with D as the origin. , , , , This forms a closed-loop kinematic chain, from which the x and y coordinates of point G(x,y) can be obtained:

[0029] ,

[0030] ;

[0031] beg Let the slope of line DJ be K, and let line DJ be Y. Let the distance from point G(x,y) to line Y be D=L. GJ K is obtained from the formula for the distance from point G(x,y) to line Y, and thus the value is determined. And then seek :

[0032] ;

[0033] Constructing inverse kinematics of a mechanism, i.e., input Output , :

[0034] Step 1: Determine the translational motion of the second linkage seat. :based on Seeking Numerical solution;

[0035] Step Two, Find : will be obtained corresponding Substituting the numerical solution into the forward kinematics equations, and then through... Seeking .

[0036] Furthermore, the formula for the distance from point G(x,y) to line Y is obtained...

[0037] ,

[0038] x and y are the x and y coordinates of point G(x,y).

[0039] Furthermore, in determining the minimum travel distance of the first linkage along the length of the finger based on forward and inverse kinematics, the parameters are adjusted using a Pareto front solution set algorithm based on multi-objective optimization, according to the forward and inverse kinematics of the mechanism. Perform multi-objective optimization.

[0040] A hand exoskeleton includes five finger exoskeleton units, each of which is fitted onto one of the five fingers.

[0041] The beneficial effects of this invention compared to the prior art are:

[0042] 1. This invention employs a four-bar linkage as the transmission mechanism. By constraining the movement of the first transmission link, it achieves ordered rotational motion, i.e., simultaneous revolution and rotation along a fixed trajectory. Under this motion, the driving force exerted by the first transmission link on the first link seat is primarily converted into rotational motion, with only a small amount converted into translational motion of the first link seat. This design is particularly suitable for small phalangeal structures such as the thumb's MCP joint and other fingers' PIP joints, ensuring sufficient flexion and extension angles even with limited sliding distance of the first link seat. Furthermore, the translational motion of the first link seat effectively absorbs the shear force generated by the first transmission link on the first phalanx, thus preventing user discomfort or joint fatigue damage caused by shear force. Simultaneously, when driving the first phalanx, the first link seat allows the first phalanx to rotate around its own joint, achieving self-alignment of the joint axis. The finger exoskeleton does not require strict manual alignment during wear and can adapt to fingers of different sizes. It can be seen that this embodiment achieves adaptive rotational motion of small finger bones under conditions without shear force through the synergistic effect of the transmission linkage mechanism and the end effector.

[0043] 2. The present invention determines the minimum moving distance of the first linkage seat along the length direction of the finger based on forward kinematics and inverse kinematics, so that it can still improve the maximum flexion and extension angle of the finger even when the length of the finger bone is small. Attached Figure Description

[0044] The accompanying drawings, which form part of this invention, are provided to give a further understanding of the invention.

[0045] Figure 1 This is a schematic diagram of the hand exoskeleton of the present invention;

[0046] Figure 2 This is an exploded view of a finger exoskeleton unit that is shear-free and adaptively rotates according to the present invention.

[0047] Figure 3 This is a schematic diagram of the index finger of the present invention performing an extension movement under the drive of the finger exoskeleton unit;

[0048] Figure 4 This is a schematic diagram of the index finger bending motion driven by the finger exoskeleton unit of the present invention;

[0049] Figure 5 This is a schematic diagram of the drive mechanism;

[0050] Figure 6 The geometric diagram shows the translational motion of the second slider driven by the tendon ligament.

[0051] Figure 7 This is a schematic diagram of the forward kinematics of the first kinetic chain;

[0052] Figure 8 This is a schematic diagram of the forward kinematic geometry of the second kinetic chain.

[0053] Figure 9 This is a schematic diagram of the positive kinematic geometry of the third kinetic chain.

[0054] Figure 10 This is a schematic diagram of the forward kinematic geometry of the fourth kinetic chain.

[0055] Figure 11 This is a schematic diagram of the inverse kinematics of the mechanism;

[0056] Figure 12 This is a schematic diagram of the optimization process.

[0057] Explanation of reference numerals in the attached figures:

[0058] End effector 1, first linkage seat 11, first finger sleeve 12, first guide rail 13, first slider 14, first base 15;

[0059] Transmission linkage mechanism 2, drive link 21, first transmission link 22, second transmission link 23, third transmission link 24, fourth transmission link 25, first pin 26, second pin 27, third pin 28, fourth pin 29;

[0060] Drive mechanism 3, second linkage seat 31, second finger sleeve 32, second base 33, second guide rail 34, second slider 35, tendon rope 36, steering bearing 37, cable sleeve 38;

[0061] 4. First phalanx; 5. Second phalanx; 6. Finger joint. Detailed Implementation

[0062] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0063] Example 1:

[0064] See Figure 1 , Figure 2 and Figure 3 This embodiment provides a finger exoskeleton unit, including an end effector 1, a transmission linkage mechanism 2, and a drive mechanism 3. The end effector 1 is mounted on a first phalanx 4, which can be a proximal phalanx, middle phalanx, or distal phalanx. The drive mechanism 3 is mounted on a second phalanx 5 or the palm, with the second phalanx 5 adjacent to the first phalanx 4 and located distal to the fingertip. That is, when the end effector 1 is mounted on the middle phalanx, the drive mechanism 3 is mounted on the proximal phalanx. The transmission linkage mechanism 2 connects the end effector 1 and the drive mechanism 3, and transmits the driving force applied by the drive mechanism 3 to the end effector 1, enabling the end effector 1 to drive the first phalanx 4 to rotate around the finger joint 6.

[0065] See Figure 1 , Figure 2 and Figure 3 The end effector 1 in this embodiment includes a first link seat 11, a first finger sleeve 12, a first sliding pair, and a first base 15. The first finger sleeve 12 is installed on the lower side of the first base 15, and the first base 15 is fitted onto the first finger bone 4 through the first finger sleeve 12 and is located on the back of the finger bone 4. The first sliding pair includes a first guide rail 13 and a first slider 14. The first slider 14 is slidably connected to the first guide rail 13. The first guide rail 13 is installed on the upper side of the first base 15 by screws. The first link seat 11 and the first slider 14 are fixedly connected by screws.

[0066] See Figure 1 , Figure 2 and Figure 3 The transmission linkage mechanism 2 in this embodiment includes a drive linkage 21 and transmission linkages. Multiple transmission linkages are provided, designated as a first transmission linkage 22, a second transmission linkage 23, a third transmission linkage 24, and a fourth transmission linkage 25. Two of each of the second, third, and fourth transmission linkages 23 and 24 are arranged side-by-side. The first, second, third, and fourth transmission linkages 22, 23, 24, and 25 are sequentially hinged end-to-end. Specifically, one end of each of the two second transmission linkages 23 is rotatably connected to the upper middle position of the first transmission linkage 22 via a first pin 26, and the other end of each second transmission linkage 23 is rotatably connected to two other linkages via a second pin 27. One end of the third transmission link 24 and the other ends of the two third transmission links 24 are rotatably connected to one end of the two fourth transmission links 25 via the third pin 28. The two fourth transmission links 25 are rotatably connected to the tail end of the first transmission link 22 via the fourth pin 29. The line connecting the first pin 26, the second pin 27, the third pin 28 and the fourth pin 29 forms a deformable parallelogram. The third transmission link 24 is located at the finger joint 6 of the first phalanx 4 and is fixed. The tip of the first transmission link 22 is hinged to the first link seat 11. One end of the drive link 21 is hinged to the fourth transmission link 25 and the other end is connected to the drive mechanism 3. The drive mechanism 3 can apply a driving force to the drive link 21.

[0067] When the drive mechanism 3 applies a thrust to the drive link 21, the drive link 21 transmits the thrust to the fourth transmission link 25. The fourth transmission link 25 rotates counterclockwise around the third pin 28. The fourth transmission link 25 drives the first transmission link 22 to move. Under the constraint of the second transmission link 23, the first transmission link 22 revolves counterclockwise around the second pin 27 and rotates clockwise around the first pin 26. The first transmission link 22 drives the first phalanx 4 to rotate counterclockwise around the finger joint 6 through the first link seat 11 and slides forward along the length direction of the first base 15. At this time, the first phalanx 4 changes from a straight state to a bent state. Conversely, when the drive mechanism 3 applies a pulling force to the drive link 21, the drive link 21 transmits the pulling force to the fourth transmission link 25. The fourth transmission link 25 rotates clockwise around the third pin 28, and the fourth transmission link 25 drives the first transmission link 22 to move. Under the constraint of the second transmission link 23, the first transmission link 22 revolves clockwise around the second pin 27 and also rotates counterclockwise around the first pin 26. The first transmission link 22 drives the first phalanx 4 to rotate clockwise around the finger joint 6 through the first link seat 11 and slides backward along the length direction of the first base 15. At this time, the first phalanx 4 changes from a bent state to a straight state, thereby realizing the flexion and extension movement of the first phalanx 4.

[0068] This embodiment employs a four-bar linkage as the transmission linkage mechanism 2. By constraining the movement of the first transmission link 22, it achieves an ordered rotational motion, i.e., simultaneously revolving and rotating along a fixed trajectory. Under this motion, the driving force of the first transmission link 22 acting on the first link seat 11 is primarily converted into rotational motion, with only a small amount converted into translation of the first link seat 11. This design is particularly suitable for small-sized phalangeal structures such as the thumb's MCP joint and other fingers' PIP joints, ensuring a large flexion-extension angle even with a limited sliding distance of the first link seat 11. Furthermore, the translational motion of the first link seat 11 effectively absorbs the shear force generated by the first transmission link 22 on the first phalanx 4, thus avoiding user discomfort or joint fatigue damage caused by shear force. Simultaneously, when the first link seat 11 drives the first phalanx 4, it allows the first phalanx 4 to rotate around its own finger joint 6, achieving self-alignment of the joint axis. The finger exoskeleton does not require strict manual alignment during wear and can adapt to fingers of different sizes. It can be seen that this embodiment achieves adaptive rotational motion of small-sized finger bones under conditions without shear force through the coordinated action of the transmission linkage mechanism 2 and the end effector 1.

[0069] See Figure 1 , Figure 2 and Figure 3The drive mechanism 3 in this embodiment includes a second linkage seat 31, a second finger sleeve 32, a second base 33, a second sliding pair, and a rope drive assembly. The second finger sleeve 32 is installed on the lower side of the second base 33, and the second base 33 is fitted onto the second finger bone 5 through the second finger sleeve 32 and is located at the back of the finger of the second finger bone 5. The second sliding pair includes a second guide rail 34 and a second slider 35. The second slider 35 is slidably connected to the second guide rail 34, and the second guide rail 34 is installed on the upper side of the second base 33 by screws. The second linkage seat 31 and the second slider 35 are fixedly connected by screws. The other end of the drive linkage 21 is hinged to the second linkage seat 31.

[0070] Combination Figure 1 and Figure 3 The cable-driven assembly includes a tendon cable 36, a steering bearing 37, a remote motor (not shown in the figure), and two cable sleeves 38. Two third transmission links 24 are vertically mounted on the end of the second base 33 near the fingertip and are integrally formed with the second base 33. The steering bearing 37 is fitted onto the third pin 28 and is located between the two third transmission links 24. A support post 331 is provided at the end of the second base 33 away from the fingertip. The support post 331 has two through holes, and both cable sleeves 38 are fixed to the support post 33. 1. Align the two wire holes on the top and bottom respectively; the remote motor is set on the back of the hand or arm. One end of the tendon cord 36 passes through a wire hole and a wire sleeve 38 on the support column 331 and is wrapped around the motor shaft of the remote motor. It can be wound or released by the motor shaft of the remote motor. The other end passes around the steering bearing 37 and is fixed on the second connecting rod seat 31. Then it passes through another wire hole and another wire sleeve 38 on the support column 331 and is wrapped around the motor shaft of the remote motor in the opposite direction. It can also be wound or released by the motor shaft of the remote motor.

[0071] When one end of the tendon cord 36 is wound up and the other end is released, the tendon cord 36 drives the second link seat 31 to move forward along the length of the second base 33, and the second link seat 31 generates a thrust on the drive link 21. Conversely, when one end of the tendon cord 36 is released and the other end is wound up, the tendon cord 36 drives the second link seat 31 to move backward along the length of the second base 33, and the second link seat 31 generates a tension on the drive link 21.

[0072] Furthermore, to avoid interference between the drive linkage 21 and the second base 33, which would affect the range of motion of the first phalanx 4, see [reference needed]. Figure 1 , Figure 2 and Figure 3In this embodiment, the fourth transmission link 25 is a bent rod structure with a bending angle greater than 90°. The drive link 21 is hinged to the bend of the fourth transmission link 25. When the drive link 21 drives the fourth transmission link 25 to rotate, the drive link 21 gradually flips downwards as the fourth transmission link 25 rotates. When the hinge point between the drive link 21 and the fourth transmission link 25 is lower than the hinge point between the drive link 21 and the second link seat 31, the drive link 21 will interfere with the second base 33, causing the fourth transmission link 25 to be unable to continue moving, thus affecting the flexion-extension angle of the first phalanx 4. Therefore, this embodiment designs the fourth transmission link 25 as a bent rod structure, which increases the height of the hinge point between the drive link 21 and the fourth transmission link 25, avoiding the aforementioned problem.

[0073] The sliding distance of the first link seat 11 directly affects the flexion and extension angle of the finger. When the phalanx length is small, this sliding distance may limit the maximum flexion and extension range of the finger. To improve the maximum flexion and extension angle of the finger, this embodiment optimizes the transmission linkage mechanism to minimize the sliding distance of the first link seat 11 while ensuring that the finger flexion and extension angle is not affected. The specific optimization process is as follows: A schematic diagram of the geometric relationship extracted based on the finger exoskeleton unit is shown below. Figure 6 As shown, the hinge point between the second connecting rod seat 31 and the drive connecting rod 21 is denoted as A, the hinge point between the drive connecting rod 21 and the fourth transmission connecting rod 25 is denoted as B, the hinge point between the third transmission connecting rod 24 and the fourth transmission connecting rod 25 is denoted as C, the hinge point between the first transmission connecting rod 22 and the fourth transmission connecting rod 25 is denoted as F, the hinge point between the first transmission connecting rod 22 and the second transmission connecting rod 23 is denoted as E, the hinge point between the second transmission connecting rod 23 and the third transmission connecting rod 24 is denoted as O, the hinge point between the first connecting rod seat 11 and the first transmission connecting rod 22 is denoted as G, the first finger sleeve 12 is denoted as J, and the joint axis of the finger joint is denoted as D.

[0074] Let the horizontal distance between AC be denoted as Let the vertical distance between AC be denoted as Constructing the forward kinematics of the mechanism: The tendon chords drive the translational motion of the second link seat 31, thereby changing... Length to control finger joint angle That is, the input is The output is To facilitate the solution, the mechanical structure is broken down into four kinematic chains, which are solved separately.

[0075] First kinetic chain forward kinematics: The tendon cord drives the second slider in translational motion, by changing... The length is used to control the angle of the joystick CB. ,like Figure 7 As shown.

[0076] Given a variable length, find... :

[0077] (1)

[0078] (2)

[0079] (3)

[0080] (4)

[0081] (5)

[0082] Second kinetic chain positive kinematics: such as Figure 8 As shown, From the above formula, it is known that... For fixed values Given a fixed value, find :

[0083] (6)

[0084] Third kinetic chain positive kinematics: such as Figure 9 As shown, Given, find :

[0085] (7)

[0086] (8)

[0087] (9)

[0088] (10)

[0089] (11)

[0090] (12)

[0091] (13)

[0092] (14)

[0093] Fourth kinetic chain forward kinematics: such as Figure 10 As shown, It is known that Given the angles of the finger joints, find the angles of the finger joints. The vertical distance between slider J and the finger joint :

[0094] Establish a Cartesian coordinate system with D as the origin. , , , , Forming a closed-loop kinetic chain:

[0095] (15)

[0096] (16)

[0097] (17)

[0098] beg Let the slope of line DJ be K, and let the line be Y=KX. Let the distance from point G(x,y) to line Y=KX be D=L. GJ From the formula for the distance from point G(x,y) to the line Y=KX, we get...

[0099] (18)

[0100] Simplify to get

[0101] (19)

[0102] (20)

[0103] Seeking 𝐿 DJ :

[0104] (twenty one)

[0105] (twenty two)

[0106] Constructing inverse kinematics of a mechanism: such as Figure 11 As shown, input Output , :

[0107] Step 1: Determine the translational motion of the slider. :

[0108] Since the analytical solution for the inverse kinematics of a series mechanism is complex, therefore, based on Calculated using MATLAB Numerical solution. The MATLAB calculation uses equation (20) obtained by substituting equations (1)-(19) step by step and expanding them.

[0109] Step Two, Find :

[0110] Due to the complexity of the geometric configuration, it is difficult to establish directly. and The functional relationship between them, therefore, will be obtained corresponding Substituting the numerical solution into the forward kinematics equations, and then through... Seeking . Substituting the numerical solution into the forward kinematics equation (22) yields In the actual MATLAB calculation, equation (22) is obtained by substituting equations (1)-(17) and (22) step by step and expanding them.

[0111] Based on the forward and inverse kinematics of the mechanism, the parameter x of the main link is optimized using the Pareto front solution set algorithm based on multi-objective optimization. The minimum movement distance of the first slider 14 is determined based on the optimized x.

[0112] Parameters to be optimized: Parameters of the main links affecting kinematics

[0113]

[0114] Fixed parameters: Linkage parameters determined by the dimensions of standard parts and the size of the fingers themselves. ;

[0115] Constraints: Range of finger movement driven by the exoskeleton Greater than or equal to 90° of the natural range of motion of the finger joints:

[0116]

[0117] Objective function 1: To enable the placement of a slider guide rail in small joints (such as the middle phalanx joint), it is necessary to minimize the displacement Δ of slider J during the process of the exoskeleton driving the finger from a naturally extended state to its maximum range of motion. The objective function is as follows:

[0118] =Δ =max -min

[0119] Objective function 2: To reduce the mass of the exoskeleton and ensure the mechanism's portability, the link length needs to be minimized. The objective function is as follows:

[0120] =

[0121] like Figure 12 As shown, the specific optimization process includes the following steps:

[0122] Step S1: Input the initial CAD solution:

[0123] Obtain the initial design variable vector based on the organization's CAD model:

[0124]

[0125] Note: This initial solution may not satisfy the constraint of a motion range ≥ 90°, but it is usually close to the feasible region.

[0126] Step S2: Initialize the population:

[0127] by Centered on a random perturbation, a subset of individuals is generated:

[0128]

[0129] in It is a random perturbation vector.

[0130] The remaining individuals are randomly generated within the allowable range of variables, and the final composition size is initial population .

[0131] Step S3: Constraint handling:

[0132] (1) Calculate the range of motion:

[0133] For each design solution The range of motion is calculated using the inverse kinematics model of the mechanism. The specific method is as follows:

[0134] 1.1) From the joint angle Initially, the judgment is based on the inverse kinematics model equations of the mechanism. obtained Does a real numerical solution exist?

[0135] 1.2) If it exists, then use Incrementing step size ,until achieve Continue until the model has no solution.

[0136] 1.3) Final Record The value is the solution of this design. range of motion .

[0137] (2) Constraint expression:

[0138] Kinematic constraints can be written as:

[0139]

[0140] (3) Violation calculation:

[0141]

[0142] when When is a feasible solution, This is an infeasible solution.

[0143] (4) Penalty function for infeasible solutions:

[0144] To ensure that infeasible solutions do not affect the Pareto boundary, a penalty term is added to the objective function:

[0145] ,

[0146] ;

[0147] in A sufficiently large penalty coefficient is used to automatically disadvantage infeasible solutions.

[0148] (5) Feasibility first principle:

[0149] When sorting, follow these rules:

[0150] Feasible solution ( ) takes precedence over infeasible solutions ( );

[0151] Infeasible solutions according to degree of violation Sort by size from smallest to largest.

[0152] Step S4: Non-dominated Sorting:

[0153] (1) Mathematical definition of dominance relationship:

[0154] For two solutions and If the following conditions are met:

[0155]

[0156] Then it is said:

[0157]

[0158] That is, "solution a dominates solution b".

[0159] (2) Sorting rules:

[0160] ① Non-dominated sorting of feasible solutions:

[0161] All feasible solutions are based on the true objective value. Perform a non-dominated sort to obtain a feasible solution non-dominated sequence:

[0162] First-level Front (Rank 1): All solutions that are not dominated by any other solution.

[0163] Second-level Front (Rank2): The solution obtained by performing a non-dominated sort on the remaining solutions after removing the first-level solution;

[0164] The Nth level Front (Rank N) follows the same pattern.

[0165] ② Infeasible solution violation ranking:

[0166] All infeasible solutions are sorted in ascending order of violation degree to obtain the infeasible solution violation degree sequence;

[0167] ③ Final sorting:

[0168] The final sorted sequence is composed of two parts: the non-dominated sequence of feasible solutions and the violation sequence of infeasible solutions. First, the Front sequences (Rank 1 to Rank N) of all feasible non-dominated sequences are sorted, followed by the violation sequence of infeasible solutions.

[0169] First-level Front (Rank 1): All solutions that are not dominated by any other solution;

[0170] Second-level Front (Rank2): The solution obtained by performing a non-dominated sort on the remaining solutions after removing the first-level solution;

[0171] The Nth level Front (Rank N) follows the same pattern.

[0172] All infeasible solutions are added to the frontier of feasible solutions in order of violation degree.

[0173] The first front (Rank 1) of the final sorted sequence constitutes the Pareto front solution set;

[0174] Step S5: Crowding Distance Calculation:

[0175] Within each frontier layer, to maintain the uniformity of solution distribution, the crowding degree of each solution is calculated:

[0176]

[0177] in: =2 represents the number of objective functions; In the first The objective function values ​​of two adjacent solutions on each objective.

[0178] The greater the congestion, the sparser the solution, and the more preferred the solution becomes.

[0179] Step S6: Parent selection:

[0180] Select from the population according to the following rules One parent individual:

[0181] 1. First sort by non-dominant level;

[0182] 2. Within the same level, sort by congestion level from highest to lowest;

[0183] 3. If they are still the same, then choose randomly.

[0184] Step S7: Crossover and Mutation:

[0185] Generate offspring using genetic operators:

[0186] (1) Simulated binary cross (SBX):

[0187] Generate a new solution for simulating binary crossover:

[0188]

[0189] in These are the weighting coefficients that follow an SBX distribution.

[0190] (2) Polynomial Mutation:

[0191] Perform the following for each simulated binary crossover new solution:

[0192]

[0193] A new solution for polynomial mutation is obtained. ,in Generates according to a multinomial distribution.

[0194] Step S8: Merge and Update

[0195] Parent generation with offspring merge:

[0196]

[0197] right Execute again:

[0198] Constraint evaluation (degree of violation);

[0199] Non-dominated sorting;

[0200] Crowding calculation;

[0201] Choose from Individuals constitute the next generation .

[0202] Step S9: Termination condition determination:

[0203] (1) Hard termination condition:

[0204] The evolutionary process terminates directly when the following conditions are met:

[0205] Current Algebra Reaching the preset maximum algebra (1000 generations);

[0206] (2) Soft termination condition:

[0207] This embodiment introduces an intergenerational convergence metric to determine the stability and convergence of the Pareto front. When the following metrics are met, and the convergence is continuous... generation (e.g.) If the evolutionary process remains stable, it can be determined that the evolutionary process has converged and terminated.

[0208] Generational distance stability:

[0209] Record No. The Rank-1 set of the generation is

[0210]

[0211] Each of them target vector The generation distance between generations is defined as:

[0212]

[0213] If continuous Substitute to satisfy

[0214]

[0215] For example Therefore, it is believed that the position of the Pareto front tends to stabilize.

[0216] (3) Termination rules:

[0217] This embodiment employs the following comprehensive termination strategy:

[0218] If any hard termination condition is met, the process terminates directly.

[0219] If any soft termination criterion is met, and continuously The generation remains stable → terminated;

[0220] After termination, output the current generation Rank-1 solution set as the final Pareto front.

[0221] (4) Post-termination result processing:

[0222] Output: The first-level (Rank 1) Pareto front solution set of the final sorted sequence obtained after step S4;

[0223] When the termination rule is met, the first-level (Rank 1) Pareto front solution set of the final sorted sequence obtained through step S4 of the current generation is output as the final Pareto front. Based on experience, the solution corresponding to a point on the final Pareto front is selected. = This serves as the final output of the optimization model.

[0224] Example 2:

[0225] See Figure 1 This embodiment provides a hand exoskeleton, including five finger exoskeleton units as described in Embodiment 1, which are respectively fitted onto the five fingers. When the five finger exoskeleton units are activated simultaneously, flexion and extension movements of the entire hand can be achieved.

[0226] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions created by the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions created by the present invention without departing from the essence and scope of the technical solutions created by the present invention.

Claims

1. A finger exoskeleton unit, characterized in that, The device includes an end effector and a transmission linkage mechanism. The end effector includes a first linkage seat, which is assembled to the first phalanx and can reciprocate along the length of the first phalanx. The transmission linkage mechanism includes a drive linkage and transmission linkages. There are multiple transmission linkages, which are respectively designated as a first transmission linkage, a second transmission linkage, a third transmission linkage, and a fourth transmission linkage. The first, second, third, and fourth transmission linkages are connected end to end in sequence, and a hinge point is formed between two adjacent transmission linkages. The line connecting the four hinge points forms a deformable parallelogram. The third transmission linkage is located at the joint of the first phalanx and is fixed. The tip of the first transmission linkage is hinged to the first linkage seat. One end of the drive linkage is hinged to the fourth transmission linkage, and the other end can be subjected to a driving force along the length of the linkage. When the drive link is subjected to force, it transmits the driving force to the fourth transmission link and the first transmission link in sequence. Under the constraint of the parallelogram, the first transmission link drives the first link seat. The first link seat drives the first phalanx to rotate around the finger joint while sliding along the length of the finger, so as to realize the adaptive rotation of the first phalanx without shear force.

2. The finger exoskeleton unit according to claim 1, characterized in that, The end effector also includes a first base, a first finger sleeve, and a first sliding pair. The first base is fitted onto the first finger bone via the first finger sleeve, and the first connecting rod seat is mounted on the first base via the first sliding pair.

3. A finger exoskeleton unit according to claim 2, characterized in that, It also includes a drive mechanism for applying driving force to the drive link. The drive mechanism includes a second link seat, a second finger sleeve, a second base, a second sliding joint, and a rope drive assembly. The second base is fitted onto the second finger bone through the second finger sleeve. The second finger bone is adjacent to the first finger bone and located at the distal end of the fingertip. The second link seat is mounted on the second base through the second sliding joint. The other end of the drive link is hinged to the second link seat.

4. A finger exoskeleton unit according to claim 3, characterized in that, The fourth transmission link is a bent link with a bending angle greater than 90°, and the drive link is hinged to the bend of the fourth transmission link.

5. A finger exoskeleton unit according to claim 3, characterized in that, The rope drive assembly includes a tendon rope, a steering bearing, and a remote motor. The steering bearing is mounted on the end of the second base near the fingertip. One end of the tendon rope extends away from the fingertip and can be wound or released by the remote motor. The other end passes around the steering bearing and is fixed to the second link seat, also extending away from the fingertip and can be wound or released by the remote motor. When one end of the tendon rope is wound, the other end is released accordingly.

6. A finger exoskeleton unit according to claim 5, characterized in that, The cable drive assembly also includes two cable sleeves, which are fixed to the second base and respectively fitted onto the inlet and outlet ends of the tendon cable.

7. A finger exoskeleton unit according to any one of claims 5 or 6, characterized in that, The minimum movement distance of the first linkage along the length of the finger is determined based on forward and inverse kinematics, the construction process of which includes: Let A be the hinge point between the second connecting rod seat and the drive connecting rod, B be the hinge point between the drive connecting rod and the fourth transmission connecting rod, C be the hinge point between the third and fourth transmission connecting rods, F be the hinge point between the first and fourth transmission connecting rods, E be the hinge point between the first and second transmission connecting rods, O be the hinge point between the second and third transmission connecting rods, G be the hinge point between the first connecting rod seat and the first transmission connecting rod, J be the first finger sleeve, and D be the joint axis of the finger joint; let X be the focus of the right triangle formed by the vertical line passing through point C, the horizontal line passing through point A, and AC; and let X be the distance between any two points. The two dots corresponding to its subscript are represented as follows: The distance between AC. The distance between X and A is... The distance between X and C is represented in the same way as the distance between the other two points; the angle between the three points is represented by... The angle is represented by three points corresponding to its subscript, with the midpoint of these three points being the vertex of the angle. The angle formed by these three points corresponds to an angle less than or equal to 180°. Let ACB be the angle. Let XCA be the angle, and the angles formed by the other three points are represented in the same way; Constructing the forward kinematics of the mechanism: the tendon chords drive the translational motion of the second link seat, thereby changing... Length to control finger joint angle That is, the input is The output is The mechanical structure is broken down into four kinematic chains, each of which is solved separately: First kinetic chain forward kinematics: The tendon chords drive the translational motion of the second link seat, thereby changing... The length is used to control the angle of the joystick CB. ; Given a variable length, find... : ， ， ， ， ； Second kinetic chain forward kinematics: Determined by the above formula, For fixed values Given a fixed value, find : )； Third kinetic chain forward kinematics: Based on the above formula, we can find... : ， ， ， ， ， ， ， ； Fourth kinetic chain forward kinematics: Confirmed. Determined, find the finger joint angles. The vertical distance between slider J and the finger joint : Establish a Cartesian coordinate system with D as the origin. , , , , This forms a closed-loop kinematic chain, from which the x and y coordinates of point G(x,y) can be obtained: ， ； beg Let the slope of line DJ be K, and let line DJ be Y. Let the distance from point G(x,y) to line Y be D=L. GJ K is obtained from the formula for the distance from point G(x,y) to line Y, and thus the value is determined. And then seek : ； Constructing inverse kinematics of a mechanism, i.e., input Output , : Step 1: Determine the translational motion of the second linkage seat. :based on Seeking Numerical solution; Step Two, Find : will be obtained corresponding Substituting the numerical solution into the forward kinematics equations, and then through... Seeking .

8. A finger exoskeleton unit according to claim 7, characterized in that, The formula for the distance from point G(x,y) to line Y is obtained x and y are the x and y coordinates of point G(x,y).

9. A finger exoskeleton unit according to claim 7, characterized in that, In determining the minimum travel distance of the first linkage along the length of the finger based on forward and inverse kinematics, the parameters are adjusted using a Pareto front solution set algorithm based on multi-objective optimization, according to the forward and inverse kinematics of the mechanism. Perform multi-objective optimization.

10. A hand exoskeleton, characterized in that, It includes five finger exoskeleton units as described in any one of claims 1 to 9, each of which is fitted onto one of the five fingers.

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