An adaptive load balancing device for upper extremity exoskeleton

Abstract

The application discloses an upper limb exoskeleton adaptive load balancing device. When the exoskeleton is passively flexed at the hip joint due to the terminal load of the lower arm, the load compensation spring is stretched, and a balance torque is provided. During the flexing process of the hip joint, the increase of the angle drives the feedback adjustment spring to be stretched, the action point of the load compensation spring is changed, the load compensation spring is moved towards the direction in which the force arm of the load compensation spring is increased, so that a greater load compensation torque is generated, the flexing degree of the hip joint is reduced, the working posture is optimized, fatigue is reduced, the exoskeleton can make the human trunk keep in a relatively comfortable vertical state to work under the premise of meeting the external load compensation, and the technical problem that the wearer can only rely on the partial pulling force provided by the back flexor muscles to keep the body balanced when the existing upper limb exoskeleton is used to carry out the hanging rod operation is solved. When the load operation is continuously carried out, the wearer needs to provide the balance pulling force, so that the human muscles are relatively tired after long time work.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of exoskeleton robots, and particularly relates to a self-adaptive load balancing device of an upper limb exoskeleton. BACKGROUND

[0002] An exoskeleton robot system is a kind of man-machine cooperation system, which can enhance the strength of the wearer in various environments. During the process of hanging rod operation, the upper limb exoskeleton needs the back muscles, especially the erector spinae, to provide a pulling force on the trunk to ensure the balance of the human upper limb due to the influence of the load at the end of the upper limb. In order to assist the erector spinae, an auxiliary pulling force is provided in the sagittal plane by wearing an exoskeleton, and the exoskeleton assistance force is parallel to the natural muscle and forms a synergistic effect with the flexor muscle of the human hip joint. At present, the exoskeleton provides a compensation torque through a hip joint auxiliary spring. Since the size of the spring force is approximately linearly related to the bending angle of the human body, in order to provide sufficient auxiliary torque, it is necessary to have sufficient bending angle of the hip joint, and excessive bending angle will affect the operation effect of the human body. In order to not affect the operation efficiency, the wearer can only rely on the partial pulling force provided by the back flexor muscle to maintain the body balance. When continuously performing load operation, the wearer needs to provide a balancing pulling force, which causes the human muscle to be relatively tired after a long time of work. Therefore, it is necessary to design an exoskeleton hanging rod self-balancing technology with feedback, which can still provide auxiliary assistance force when the human body changes the bending angle of the hip joint. SUMMARY

[0003] The present application provides a self-adaptive load balancing device of an upper limb exoskeleton, which is used to solve the technical problem that the wearer can only rely on the partial pulling force provided by the back flexor muscle to maintain the body balance when the existing upper limb exoskeleton performs hanging rod operation, and the wearer needs to provide a balancing pulling force when continuously performing load operation, which causes the human muscle to be relatively tired after a long time of work.

[0004] Therefore, the present application provides a self-adaptive load balancing device of an upper limb exoskeleton, which comprises a load compensation spring, a feedback adjusting spring, a sliding block, a guide rail and a mounting plate.

[0005] The guide rail is movably installed on the sagittal plane of the waist seal position of the upper limb exoskeleton.

[0006] The sliding block is installed on the guide rail.

[0007] The mounting plate is fixed on the upper limb exoskeleton below the guide rail.

[0008] One end of the load compensation spring is connected with the sliding block, and the other end is fixed on the mounting plate.

[0009] One end of the feedback adjusting spring is connected with the sliding block after being bent at an angle parallel to the sliding block, and the other end is fixed on the mounting plate.

[0010] The fixed end of the load compensation spring and the feedback adjusting spring is located on the same horizontal plane, and the connecting angle of the load compensation spring and the feedback adjusting spring is 30-60 degrees.

[0011] Optionally, the rigidity of the load compensation spring and the feedback adjusting spring is determined according to an optimal solution of a target function and a constraint condition, wherein the target function is:

[0012] minF(x)=ω1θ 2 +ω2g(θ)

[0013] The constraint condition is:

[0014] τcos(90-θ)=F1

[0015] τ=(θ(l+s1)+h)k

[0016] F1=(lθ+h1-s1)k1

[0017] Wherein, F(x) is the target function, ω1 and ω2 are weight coefficients, g(θ) is a dual function of compensation torque, θ is the flexion and extension rotation angle of the upper limb exoskeleton hip joint, τ is the force of the load compensation spring, F1 is the force of the feedback adjusting spring, l is the original distance of the sliding block from the rotation center of the upper limb exoskeleton, s1 is the sliding distance of the sliding block, h is the initial pre-tightening length of the load compensation spring, h1 is the initial pre-tightening length of the feedback adjusting spring, k is the rigidity of the load compensation spring, and k1 is the rigidity of the feedback adjusting spring.

[0018] Optionally, the connecting angle of the load compensation spring and the feedback adjusting spring is 45 degrees.

[0019] From the above technical solution, the upper limb exoskeleton self-adaptive load balancing device provided by the application has the following advantages:

[0020] The upper limb exoskeleton self-adaptive load balancing device provided by the application, when the exoskeleton is passively flexed at the hip joint due to the terminal load of the forearm, drives the load compensation spring to stretch, provides a balancing torque, and during the flexion of the hip joint, the increase of the angle drives the feedback adjusting spring to stretch, changes the action point of the load compensation spring, and moves it towards the direction of the increase of the force arm of the load compensation spring, thereby generating a greater load compensation torque, thereby reducing the flexion degree of the hip joint, optimizing the working posture and reducing fatigue, enabling the human body trunk to be kept in a relatively comfortable vertical state for work under the premise of meeting the external load compensation, and solving the technical problem that the wearer can only rely on the partial tension provided by the back flexor muscles to maintain body balance when the existing upper limb exoskeleton is working on the hanging rod, and the wearer needs to provide a balancing tension when continuously working on the load, resulting in relatively tired muscles after long time work. BRIEF DESCRIPTION OF DRAWINGS

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of an adaptive load balancing device for an upper limb exoskeleton provided in this invention, installed on an upper limb exoskeleton;

[0023] Figure 2 This is a simplified structural diagram of an adaptive load balancing device for an upper limb exoskeleton, as provided in this invention, mounted on an upper limb exoskeleton.

[0024] The attached figures are labeled as follows:

[0025] 1. Guide rail; 2. Slider; 3. Load compensation spring; 4. Feedback adjustment spring; 5. Mounting plate. Detailed Implementation

[0026] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] For easier understanding, please refer to Figure 1 and Figure 2 The present invention provides an embodiment of an adaptive load balancing device for an upper limb exoskeleton, including a load compensation spring 3, a feedback adjustment spring 4, a slider 2, a guide rail 1, and a mounting plate 5;

[0028] The guide rail 1 is movably mounted on the sagittal plane at the waist of the upper limb exoskeleton;

[0029] Slider 2 is mounted on guide rail 1;

[0030] Mounting plate 5 is fixed to the upper limb exoskeleton below the guide rail 1;

[0031] One end of the load compensation spring 3 is connected to the slider 2, and the other end is fixed on the mounting plate 5;

[0032] One end of the feedback adjustment spring 4 is bent at an angle parallel to the slider 2 and connected to the slider 2, while the other end is fixed on the mounting plate 5;

[0033] The fixed end of the load compensation spring 3 and the feedback adjusting spring 4 is located on the same horizontal plane, and the connection angle of the load compensation spring 3 and the feedback adjusting spring 4 is 30-60 degrees.

[0034] It should be noted that the movable guide rail 1 is installed on the sagittal plane of the upper limb exoskeleton waist sealing position, and the guide rail 1 can be angularly inclined with the bending of the upper limb exoskeleton. The guide rail 1 is provided with a sliding block 2. An installation plate 5 is arranged on the upper limb exoskeleton below the guide rail 1, and the installation plate 5 is used to fix the load compensation spring 3 and the feedback adjusting spring 4. One end of the load compensation spring 3 is connected with the sliding block 2, and the other end is fixed on the installation plate 5. One end of the feedback adjusting spring 4 is bent to be parallel to the sliding block 2 and then connected with the sliding block 2, and the other end is fixed on the installation plate 5. The fixed end of the load compensation spring 3 and the feedback adjusting spring 4 is located on the same horizontal plane, and the connection angle of the load compensation spring 3 and the feedback adjusting spring 4 is 30-60 degrees, and the optimal angle is 45 degrees. When the human body drives the exoskeleton hip joint to flex, the flexion angle is used as a feedback variable, the feedback adjusting spring 4 is pulled, the larger the angle, the greater the feedback, so that the load compensation spring 3 moves in the direction of increasing the moment, and finally reduces the bending angle of the exoskeleton hip joint, so as to realize the external load moment compensation with a smaller angle.

[0035] The upper limb exoskeleton adaptive load balancing device provided by the application can provide a balance moment when the exoskeleton hip joint is passively flexed due to the small arm terminal load, drive the load compensation spring 3 to stretch, provide a balance moment, and change the action point of the load compensation spring 3 to move in the direction of increasing the force arm of the load compensation spring 3, so that a larger load compensation moment is generated, thereby reducing the hip joint flexion degree, optimizing the working posture, reducing fatigue, enabling the human body to keep in a more comfortable vertical state to work under the premise of meeting the external load compensation, and solving the technical problem that the wearer can only rely on the partial pulling force provided by the back flexor muscle to keep the body balanced when the existing upper limb exoskeleton is used for hanging rod operation, and the wearer needs to provide a balance pulling force when continuously performing load operation, resulting in that the human body muscle is relatively tired after a long time of work.

[0036] The application provides an upper limb exoskeleton based on structural feedback, and designs a moment compensation structure scheme. During hanging rod operation, a certain moment compensation is provided based on the load size, the human body burden is reduced, the sliding block 2 structure is ingeniously designed as the force action point, and real-time adjustable moment balancing compensation is realized.

[0037] In one embodiment, the stiffness of the load compensation spring 3 and the feedback adjusting spring 4 is determined according to an optimal solution of a target function and a constraint condition, wherein the target function is:

[0038] min F(x) = ω1θ2 + ω2g (θ)

[0039] The constraint condition is:

[0040] τcos (90- θ) = F1

[0041] τ= (θ (l + s1) + h) k

[0042] F1= (l θ + h1 - s1) k1

[0043] Wherein, F (x) is the objective function, ω1 and ω2 are weight coefficients, g (θ) is the dual function of compensation torque, θ is the upper limb exoskeleton hip flexion and extension rotation angle, τ is the load compensation spring 3 acting force, F1 is the feedback adjustment spring 4 acting force, l is the original distance of the slider 2 from the rotation center of the upper limb exoskeleton (that is, the load compensation spring 3 and the feedback adjustment spring 4 are in the original state, and no deformation occurs), s1 is the sliding distance of the slider 2, h is the initial pre-tightening length of the load compensation spring 3, h1 is the initial pre-tightening length of the feedback adjustment spring 4, k is the stiffness of the load compensation spring 3, and k1 is the stiffness of the feedback adjustment spring 4.

[0044] It should be noted that, as shown in Figure 2 The upper limb exoskeleton hip flexion and extension rotation angle is θ, and the load compensation spring 3 acting force is:

[0045] τ= (θ (l + s1) + h) k

[0046] Wherein, θ is the upper limb exoskeleton hip flexion and extension rotation angle, τ is the load compensation spring 3 acting force, h is the initial pre-tightening length of the load compensation spring 3, k is the stiffness of the load compensation spring 3, s1 is the sliding distance of the slider 2, and l is the original distance of the slider 2 from the rotation center of the upper limb exoskeleton.

[0047] The feedback adjustment spring 4 acting force is:

[0048] F1= (l θ + h1 - s1) k1

[0049] Wherein, F1 is the feedback adjustment spring 4 acting force, h1 is the initial pre-tightening length of the feedback adjustment spring 4, and k1 is the stiffness of the feedback adjustment spring 4.

[0050] To ensure that the upper limb exoskeleton meets certain torque compensation during operation, the displacement is minimized, therefore, the design objective function is:

[0051] min F (x) = ω1θ 2 + ω2g (θ)

[0052] The constraint condition is:

[0053] τcos (90- θ) = F1

[0054] wherein F(x) is the objective function, ω1 and ω2 are weight coefficients, and g(θ) is the dual function of the compensation torque.

[0055] Two parts are planned in the objective function, wherein the first part is the flexion angle of the hip joint, and the flexion angle is required to be as small as possible during the operation process, and the second part represents the compensation torque, because the compensation torque is required to be as large as possible during the operation process, and the dual function is taken here. ω1 and ω2 represent the weights of the two parts, respectively. The minimum parameters of the above equation are solved according to the gradient descent method. The stiffness k1 and k of the spring are a pair of combined parameters, if k1 is too large, the slider 2 is moved, which causes the action point of the load compensation spring 3 to move too much, if k1 is too small, which causes the action point of the load compensation spring 3 to move insufficiently. If the exoskeleton cannot provide sufficient compensation torque during the operation process, the flexion angle of the exoskeleton hip joint part is too large, and the too large flexion angle will affect the comfort of task completion, and even cause muscle fatigue during operation. The optimal stiffness combination is calculated and solved, that is, the required optimal stiffness combination parameters.

[0056] The above-described and above-mentioned embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An adaptive load balancing device for an upper limb exoskeleton, characterized in that, Includes load compensation springs, feedback adjustment springs, sliders, guide rails, and mounting plates; The guide rail is movably mounted on the sagittal plane at the waist of the upper limb exoskeleton; The slider is mounted on the guide rail; The mounting plate is fixed to the upper limb exoskeleton below the guide rail; One end of the load compensation spring is connected to the slider, and the other end is fixed to the mounting plate; One end of the feedback adjustment spring is bent at an angle parallel to the slider and connected to the slider, while the other end is fixed to the mounting plate. The fixed ends of the load compensation spring and the feedback adjustment spring are located on the same horizontal plane, and the connection angle between the load compensation spring and the feedback adjustment spring is 30°~60°. The stiffness of the load compensation spring and the feedback adjustment spring are determined by finding the optimal solution based on the objective function and constraints. The objective function is: ； The constraints are: ； ； ； in, Let be the objective function. and These are the weighting coefficients. For the dual function of the compensating torque, The hip joint flexion-extension-rotation angle of the upper limb exoskeleton. To compensate for the spring force under load, To provide feedback for adjusting the spring force, This represents the original distance between the slider and the center of rotation of the upper limb exoskeleton. The distance the slider slides. The initial preload length of the load compensation spring. To provide feedback for adjusting the initial preload length of the spring, To compensate for the load, the spring stiffness, The spring stiffness is adjusted based on feedback.

2. The adaptive load balancing device for the upper limb exoskeleton according to claim 1, characterized in that, The connection angle between the load compensation spring and the feedback adjustment spring is 45°.

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