Force and position sensing method based on wrist-hand exoskeleton robot

Abstract

The present application relates to the technical field of exoskeleton robots, and provides a force and position sensing method based on a wrist-hand exoskeleton robot, which comprises the following steps: building a finger exoskeleton joint kinematic chain and a human finger joint kinematic chain based on D-H criteria, and making the finger exoskeleton joint kinematic chain and the human finger joint kinematic chain form a closed loop chain; based on the closed loop chain, using the principle that the force transmitted by the finger exoskeleton joint is equal to the force borne by the human finger joint, obtaining the kinematic relationship coefficient between the finger exoskeleton joint and the human finger joint; and based on the kinematic relationship coefficient and the first moment of the finger exoskeleton joint, obtaining the second moment of the human finger joint. The force and position sensing method based on the wrist-hand exoskeleton robot can monitor the joint position and human-machine interaction force information in real time, simplifies the difficulty of safety and compliant control, can realize passive rehabilitation training with damping, improves the joint-related muscle strength, and enhances the rehabilitation effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of exoskeleton robots, and particularly relates to a force and position sensing method based on a wrist and hand exoskeleton robot. BACKGROUND

[0002] With the continuous evolution of global population age structure, motor dysfunction diseases represented by stroke and degenerative joint diseases show a significant growth trend. Such pathological conditions often lead to damage to central nervous conduction pathways and degeneration of peripheral musculoskeletal system coordination, and patients face the severe challenge of loss of daily living ability due to lack of motor control ability. The current clinical rehabilitation system mainly relies on repetitive exercise training guided by physical therapists, and its core mechanism is to promote the plasticity reconstruction of damaged neural circuits through proprioceptive stimulation.

[0003] At present, due to the limited number of existing rehabilitation physicians, the rehabilitation demand cannot be met, and therefore the exoskeleton robot for rehabilitation training emerges as the times require. The force applied by the exoskeleton robot on the user is crucial, and if the applied force is too large, it is easy to cause damage to the user; if the applied force is too small, it cannot play a training role, and therefore providing a force and position sensing method has become an urgent problem in the industry. SUMMARY

[0004] The present application provides a force and position sensing method based on a wrist and hand exoskeleton robot to solve the defect that the force actually received by the user cannot be sensed in the prior art.

[0005] The present application provides a force and position sensing method based on a wrist and hand exoskeleton robot, comprising:

[0006] A reference coordinate system of a finger exoskeleton joint motion chain is established, the lengths of each connecting rod in the finger exoskeleton joint motion chain are obtained, and the finger exoskeleton joint motion chain is built by using the D-H criterion based on the lengths of each connecting rod;

[0007] A first coordinate system of a human finger joint motion chain is established, a relative position vector between a first origin of the reference coordinate system and a second origin of the first coordinate system, and a vertical distance and a horizontal distance between a human finger joint center and a finger exoskeleton joint center are obtained, and the human finger joint motion chain is built by using the D-H criterion based on the relative position vector, the vertical distance and the horizontal distance, and the finger exoskeleton joint motion chain and the human finger joint motion chain form a closed loop chain;

[0008] Based on the closed-loop chain, a first transformation matrix of the finger exoskeleton joint kinematic chain is established, and a second transformation matrix of the human finger joint kinematic chain is established. Based on the first transformation matrix and the second transformation matrix, and the principle that the force transmitted by the finger exoskeleton joint is equal to the force borne by the human finger joint, kinematic relationship coefficients between the finger exoskeleton joint and the human finger joint are obtained;

[0009] A first torque is obtained based on Hooke's law, and a second torque of the human finger joint is obtained based on the product of the kinematic relationship coefficient and the first torque, wherein the finger exoskeleton joint includes a first joint and a second joint, the first joint is used to drive the human finger to swing left and right, and the second joint is used to drive the human finger to swing up and down.

[0010] According to a force and position sensing method based on a wrist-hand exoskeleton robot provided by the present invention, the step of obtaining the kinematic relationship coefficients between the finger exoskeleton joints and the human finger joints based on the first transformation matrix and the second transformation matrix, and the principle that the force transmitted by the finger exoskeleton joints is equal to the force borne by the human finger joints, includes: obtaining the forward kinematic relationship formula of the human finger joints based on the first transformation matrix and the second transformation matrix.

[0011] According to a force and position sensing method based on a wrist-hand exoskeleton robot provided by the present invention, the step of obtaining the kinematic relationship coefficient between the finger exoskeleton joints and the human finger joints based on the first transformation matrix and the second transformation matrix, and the principle that the force transmitted by the finger exoskeleton joints is equal to the force borne by the human finger joints, also includes: obtaining the kinematic relationship coefficient based on the forward kinematic relationship and the principle of virtual work.

[0012] According to a force and position sensing method based on a wrist-hand exoskeleton robot provided by the present invention, the finger exoskeleton joint includes a first joint and a second joint, and the force and position sensing method also includes: obtaining the torque of the first joint and the torque of the second joint, and obtaining the matrix of the second torque based on the kinematic relationship coefficient, the torque of the first joint and the torque of the second joint.

[0013] The force-position sensing method based on the wrist-hand exoskeleton robot provided by the present invention can intuitively obtain the actual force borne by the human finger joints, monitor the joint position and human-computer interaction force information in real time, and realize orthogonal two-degree-of-freedom compliant control of the human finger joints through force-position control and impedance control, thereby simplifying the difficulty of safety and compliant control, and realizing active and passive rehabilitation training by applying damping, thereby improving the strength of joint-related muscles and enhancing the rehabilitation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 This is a flow chart of the force-position sensing method based on the wrist-hand exoskeleton robot provided by the present invention.

[0016] Figure 2 It is a model diagram of the finger exoskeleton joint motion chain and the human finger joint motion chain.

[0017] Figure 3 This is one of the schematic diagrams of the interaction forces between the finger exoskeleton joints and the human finger joints.

[0018] Figure 4 This is the second schematic diagram of the interaction forces between the finger exoskeleton joints and the human finger joints.

[0019] Reference numerals:

[0020] 100. Base; 101. First joint; 102. Second joint; 200. Human finger joint. DETAILED DESCRIPTION

[0021] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0022] The following combination Figure 1-Figure 4 The force and position sensing method based on the wrist-hand exoskeleton robot of the present invention is described.

[0023] like Figure 1 As shown, the force and position sensing method based on the wrist-hand exoskeleton robot provided by the embodiment of the present invention includes: step 301: constructing a finger exoskeleton joint motion chain and a human finger joint motion chain based on the DH criterion, and making the finger exoskeleton joint motion chain and the human finger joint motion chain form a closed-loop chain; step 302: based on the closed-loop chain, using the principle that the force transmitted by the finger exoskeleton joint is equal to the force borne by the human finger joint, obtaining the kinematic relationship coefficient between the finger exoskeleton joint and the human finger joint; step 303: obtaining the second torque of the human finger joint based on the kinematic relationship coefficient and the first torque of the finger exoskeleton joint.

[0024] Specifically, the wrist-hand exoskeleton robot can be worn on each finger of the human body to perform rehabilitation training on each finger and wrist. Since the movements of each finger and wrist are the same, the embodiment of the present invention only uses one finger as an example to illustrate.

[0025] The finger exoskeleton is simplified to a P3RP mechanism, where P represents a translation pair and R represents a rotation pair. That is, the finger exoskeleton has two translation pairs and three rotation pairs. The joint structure is simplified to a joint with a universal joint. The human finger joint 200 has two rotation axes, and , the rotation center of the human finger joint 200 is defined as Because the exoskeleton robot is fixed on the human finger, we can consider the distance between the rotation center of the human finger joint 200 and the base 100 of the exoskeleton robot to be constant, so the interaction force of the human finger joint 200 can be obtained using the traditional Jacobian matrix method.

[0026] like Figure 3 and Figure 4 As shown, and It is the interaction force of the exoskeleton robot driving the abduction, adduction, flexion and extension of the human finger joints 200, which can be converted into effective work. It is the constraint force along the direction of the guide rail slider of the human finger and the exoskeleton robot, which will cause the human finger to bear shear force. When discussing the exoskeleton robot to assist the movement of the human finger, it is necessary to pay attention to the constraint torque generated, including 、 、 and binding force ,in, and torque 、 、 This type of force cannot be converted into effective work and is likely to cause damage to human fingers.

[0027] In the embodiment of the present invention, three passive degrees of freedom are designed in the exoskeleton robot, namely 、 and , used to reduce the interaction force. Passive joint By allowing relative displacement between the exoskeleton robot and the human fingers, the restraint force is effectively eliminated. Passive joints and , which enables relative rotation between the exoskeleton robot and the human finger, eliminating unexpected torque and For unnecessary torque The flexible Velcro band that binds the exoskeleton robot to the human finger can be used to eliminate it. 、 、 and the flexible Velcro band, the interaction force borne by the exoskeleton can be reduced.

[0028] In the embodiment, as shown in Figure 2 , the reference coordinate of the base 100 in the finger exoskeleton kinematic chain is established, and the closed loop chain of the finger exoskeleton joint kinematic chain and the closed loop chain of the human finger joint kinematic chain are built based on the D-H criterion and the reference coordinate system. In the embodiment, the force actually borne by the human finger joint 200 is set to be equal to the force transmitted by the finger exoskeleton joint, and based on this, the kinematic relationship coefficient between the finger exoskeleton joint and the human finger joint 200 can be calculated. The first moment of the finger exoskeleton joint is calculated based on Hooke's law, and in the embodiment, the finger exoskeleton joint includes the first joint 101 and the second joint 102, the first joint 101 is used to drive the human finger to swing left and right, and the second joint 102 is used to drive the human finger to swing up and down. The second moment of the human finger joint 200 can be obtained based on the product of the kinematic relationship coefficient and the first moment. Since the finger exoskeleton has two joints, the second moment of the human finger joint 200 obtained is a matrix.

[0029] The force and position sensing method based on the wrist and hand exoskeleton robot provided by the embodiment can intuitively obtain the actual force borne by the human finger joint, monitor the joint position and human-machine interaction force information in real time, realize the orthogonal two-degree-of-freedom compliant control of the human finger joint through force and position control and impedance control, simplify the difficulty of safety and compliant control, and realize the application of damping passive rehabilitation training, improve the joint related muscle strength, and enhance the rehabilitation effect.

[0030] As shown in Figure 2 , in the embodiment of the application, the reference coordinate system of the finger exoskeleton joint kinematic chain is established, and the finger exoskeleton joint kinematic chain and the human finger joint kinematic chain are built based on the D-H criterion and the reference coordinate system.

[0031] Specifically, as shown in Figure 2 , the reference coordinate system of the base 100 in the finger exoskeleton joint kinematic chain is established , the lengths of each connecting rod in the finger exoskeleton joint kinematic chain are obtained, which are 、 、 and Based on the length of each link, the DH principle is used to build the finger exoskeleton joint kinematic chain. As shown in Table 1:

[0032] Table 1 DH parameters of the finger exoskeleton joint kinematic chain

[0033]

[0034] Establish the first coordinate system of the human finger joint kinematic chain , get the relative position vector between the first origin of the reference coordinate system and the second origin of the first coordinate system , the vertical distance between the center of the human finger joint 200 and the center of the finger exoskeleton joint and horizontal distance , the human finger joint kinematic chain is constructed based on the DH criterion, as shown in Table 2:

[0035] Table 2 DH parameters of human finger joint kinematic chain

[0036]

[0037] Furthermore, based on the closed-loop chain, utilizing the principle that the force transmitted by the finger exoskeleton joints is equal to the force borne by the human finger joints, the steps of obtaining the kinematic relationship coefficients between the finger exoskeleton joints and the human finger joints include: establishing a first transformation matrix of the finger exoskeleton joint motion chain; establishing a second transformation matrix of the human finger joint motion chain; based on the first transformation matrix and the second transformation matrix, and the principle that the force transmitted by the finger exoskeleton joints is equal to the force borne by the human finger joints 200, that is, the first transformation matrix is ​​equal to the second transformation matrix, obtaining the kinematic relationship coefficients between the finger exoskeleton joints and the human finger joints 200.

[0038] Specifically, the rotation center of the human finger joint 200 is defined as , the force transmitted by the finger exoskeleton joint is assumed to be equal to the force borne by the human finger joint 200, that is, the kinematics of the finger exoskeleton joint is,

[0039] (1)

[0040] in, is the rotation angle of the finger exoskeleton joint, is the rotation angle of the human finger joint, is the transformation matrix of the finger exoskeleton kinematic chain, that is, the first transformation matrix, It is the transformation matrix of the human finger joint kinematic chain, that is, the second transformation matrix.

[0041] According to the DH algorithm, It can be written as,

[0042] (2)

[0043] can be written as,

[0044] (3)

[0045] where, is the homogeneous transformation matrix corresponding to the D-H chain.

[0046] , c = cos, s = sin,

[0047] According to formula (1), we can get,

[0048] (4)

[0049] Bring formula (2) and (3) into formula (4), we can get:

[0050]

[0051] The solution is:

[0052] (5)

[0053] Formula (5) can be transformed into,

[0054] (6)

[0055] Definition , we can get:

[0056] (7)

[0057] Then formula (6) can be simplified as:

[0058] (8)

[0059] where, , , .

[0060] Solving formula (8) can get, the forward kinematics relationship of human finger joints is as follows,

[0061] (9)

[0062] Can be written as,

[0063] (10)

[0064] where and .

[0065] According to formula (10), the variables are calculated with respect to and The partial derivative of can be transformed into,

[0066] (11)

[0067] (12)

[0068] According to the principle of virtual work, we can get:

[0069] (13)

[0070] (14)

[0071] in, is the kinematic relationship coefficient.

[0072] In an embodiment of the present invention, the step of obtaining the second torque of the human finger joint based on the kinematic relationship coefficient and the first torque of the finger exoskeleton joint includes: obtaining the second torque based on the kinematic relationship coefficient and the angle change of the finger exoskeleton joint.

[0073] Specifically, is the output force and torque that drives the finger exoskeleton joints, is the torque vector applied to the human finger joint 200.

[0074] First moment (15),

[0075] in is the stiffness coefficient of the Archimedean coil spring, is the input angle of the outer ring of the Archimedean coil spring, is the output angle of the inner coil of the Archimedean coil spring.

[0076] According to the mapping relationship between the finger exoskeleton joint and the human finger joint 200, the second moment of the human finger joint 200 can be calculated: ,Right now:

[0077]

[0078]

[0079] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A force-position sensing method based on a wrist-hand exoskeleton robot, characterized in that: include: Establish a reference coordinate system for the finger exoskeleton joint motion chain, obtain the length of each link in the finger exoskeleton joint motion chain, and use the DH criterion to build the finger exoskeleton joint motion chain based on the length of each link; Establishing a first coordinate system for a human finger joint kinematic chain, obtaining a relative position vector between a first origin of the reference coordinate system and a second origin of the first coordinate system, and a vertical distance and a horizontal distance between a center of a human finger joint and a center of a finger exoskeleton joint, and constructing a human finger joint kinematic chain using the DH criterion based on the relative position vector, the vertical distance, and the horizontal distance, so that the finger exoskeleton joint kinematic chain and the human finger joint kinematic chain form a closed-loop chain; Based on the closed-loop chain, a first transformation matrix of the finger exoskeleton joint kinematic chain is established, and a second transformation matrix of the human finger joint kinematic chain is established. Based on the first transformation matrix and the second transformation matrix, and the principle that the force transmitted by the finger exoskeleton joint is equal to the force borne by the human finger joint, kinematic relationship coefficients between the finger exoskeleton joint and the human finger joint are obtained; A first torque is obtained based on Hooke's law, and a second torque of the human finger joint is obtained based on the product of the kinematic relationship coefficient and the first torque, wherein the finger exoskeleton joint includes a first joint and a second joint, the first joint is used to drive the human finger to swing left and right, and the second joint is used to drive the human finger to swing up and down.

2. The force position sensing method based on the wrist-hand exoskeleton robot according to claim 1 is characterized in that: The step of obtaining kinematic relationship coefficients between the finger exoskeleton joints and the human finger joints based on the first transformation matrix and the second transformation matrix and the principle that the force transmitted by the finger exoskeleton joints is equal to the force borne by the human finger joints comprises: A forward kinematics relationship of the human finger joints is obtained based on the first transformation matrix and the second transformation matrix.

3. The force-position sensing method based on the wrist-hand exoskeleton robot according to claim 2 is characterized in that: The step of obtaining kinematic relationship coefficients between the finger exoskeleton joints and the human finger joints based on the first transformation matrix and the second transformation matrix and the principle that the force transmitted by the finger exoskeleton joints is equal to the force borne by the human finger joints further includes: Based on the forward kinematics relationship and the principle of virtual work, the kinematics relationship coefficient is obtained.

4. The force-position sensing method based on the wrist-hand exoskeleton robot according to claim 1 is characterized in that: The force position sensing method further includes: Obtain the torque of the first joint and the torque of the second joint, A matrix of the second moment is obtained based on the kinematic relationship coefficient, the moment of the first joint, and the moment of the second joint.

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