Force position sensing method based on wrist and hand exoskeleton robot

Abstract

The invention relates to the technical field of exoskeleton robots, and provides a force position sensing method based on a wrist and hand exoskeleton robot, which comprises the following steps: building a finger exoskeleton joint kinematic chain and a human body finger joint kinematic chain based on a D-H criterion, and enabling the finger exoskeleton joint kinematic chain and the human body finger joint kinematic chain to form a closed-loop chain; based on the closed-loop chain, a kinematics relation coefficient between the finger exoskeleton joints and the human body finger joints is obtained according to the principle that force transmitted by the finger exoskeleton joints is equal to force borne by the human body finger joints; based on the kinematics relation coefficient and the first moment of force of the finger exoskeleton joint, obtaining a second moment of force of the finger joint of the human body. According to the force position sensing method based on the wrist and hand exoskeleton robot, the joint position and man-machine interaction force information can be monitored in real time, the difficulty of safety and compliance control is simplified, active and passive rehabilitation training by applying damping can be achieved, the strength of related muscles of the joint is improved, and the rehabilitation effect is enhanced.

Description

Technical Field

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

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

[0003] Currently, due to the limited number of existing rehabilitation physicians, the rehabilitation needs cannot be met. Based on this, exoskeleton robots for rehabilitation training have emerged. The force exerted by the exoskeleton robot on the user is crucial. If the exerted force is too large, it is easy to cause damage to the user; if the exerted force is too small, it cannot play a training role. Therefore, providing a force and position sensing method has become an urgent problem in the industry. Summary of the Invention

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

[0005] The present invention provides a force and position sensing method based on a wrist and hand exoskeleton robot, including: building a finger exoskeleton joint motion chain and a human finger joint motion chain based on the D-H criterion, and forming a closed-loop chain between the finger exoskeleton joint motion chain and the human finger joint motion 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; based on the kinematic relationship coefficient and the first moment of the finger exoskeleton joint, obtaining the second moment of the human finger joint.

[0006] According to the force and position sensing method based on a wrist and hand exoskeleton robot provided by the present invention, the step of building a finger exoskeleton joint motion chain and a human finger joint motion chain based on the D-H criterion and forming a closed-loop chain between the finger exoskeleton joint motion chain and the human finger joint motion chain includes: establishing a reference coordinate system for the finger exoskeleton joint motion chain; based on the D-H criterion and the reference coordinate system, building the finger exoskeleton joint motion chain and the human finger joint motion chain.

[0007] A force and position sensing method based on a wrist and hand exoskeleton robot according to the present invention. Based on the D-H criterion and the reference coordinate system, the steps of building the finger exoskeleton joint kinematic chain include: obtaining the lengths of the connecting rods in the finger exoskeleton joint kinematic chain; and building the finger exoskeleton joint kinematic chain by using the D-H criterion based on the lengths of the connecting rods.

[0008] A force and position sensing method based on a wrist and hand exoskeleton robot according to the present invention. Based on the D-H criterion and the reference coordinate system, the steps of building the human finger joint kinematic chain include: establishing a first coordinate system for the human finger joint kinematic chain; obtaining the relative position vector between the first origin of the reference coordinate system and the second origin of the first coordinate system, as well as the vertical distance and the horizontal distance between the center of the human finger joint and the center of the finger exoskeleton joint; and building the human finger joint kinematic chain by using the D-H criterion based on the relative position vector, the vertical distance and the horizontal distance.

[0009] A force and position sensing method based on a wrist and hand exoskeleton robot according to the present invention. The steps of obtaining the kinematic relationship coefficient between the finger exoskeleton joint and the human finger joint based on the closed-loop chain and the principle that the force transmitted by the finger exoskeleton joint is equal to the force borne by the human finger joint include: establishing a first transformation matrix for the finger exoskeleton joint kinematic chain; establishing a second transformation matrix for the human finger joint kinematic chain; and obtaining the kinematic relationship coefficient between the finger exoskeleton joint and the human finger joint based on the first transformation matrix, 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.

[0010] A force and position sensing method based on a wrist and hand exoskeleton robot according to the present invention. The steps of obtaining the kinematic relationship coefficient between the finger exoskeleton joint and the human finger joint based on the first transformation matrix, 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 include: obtaining the forward kinematic relationship formula of the human finger joint based on the first transformation matrix and the second transformation matrix.

[0011] A force and position sensing method based on a wrist and hand exoskeleton robot according to the present invention. The steps of obtaining the kinematic relationship coefficient between the finger exoskeleton joint and the human finger joint based on the first transformation matrix, 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 further include: obtaining the kinematic relationship coefficient based on the forward kinematic relationship formula and the principle of virtual work.

[0012] A force-position sensing method based on a wrist and hand exoskeleton robot provided by the present invention. The step of obtaining the second moment of the human finger joint based on the kinematic relationship coefficient and the first moment of the finger exoskeleton joint includes: obtaining the first moment based on the kinematic relationship coefficient and the angular change amount of the finger exoskeleton joint.

[0013] A force-position sensing method based on a wrist and hand exoskeleton robot provided by the present invention. The step of obtaining the first moment based on the kinematic relationship coefficient and the angular change amount of the finger exoskeleton joint includes: obtaining the input angle and the output angle of the finger exoskeleton joint, and obtaining the angular change amount based on the difference between the input angle and the output angle.

[0014] A force-position sensing method based on a wrist and hand exoskeleton robot provided by the present invention. The finger exoskeleton joint includes a first joint and a second joint. The force-position sensing method further includes: obtaining the moment of the first joint and the moment of the second joint, and obtaining the matrix of the second moment based on the kinematic relationship coefficient, the moment of the first joint, and the moment of the second joint.

[0015] The force-position sensing method based on the wrist and hand exoskeleton robot provided by the present invention can intuitively obtain the actual force borne by the human finger joint, real-time monitor the joint position and the human-machine interaction force information, and can realize the orthogonal two-degree-of-freedom compliant control of the human finger joint through force-position control and impedance control, simplify the difficulty of safety and compliant control, and can realize the application of damped active and passive rehabilitation training, improve the joint-related muscle strength, and enhance the rehabilitation effect. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 It is a flowchart of the force-position sensing method based on the wrist and hand exoskeleton robot provided by the present invention.

[0018] Figure 2 It is a model diagram of the finger exoskeleton joint motion chain and the human finger joint motion chain.

[0019] Figure 3 It is one of the schematic diagrams of the interaction forces between the finger exoskeleton joint and the human finger joint.

[0020] Figure 4It is the second schematic diagram of the interaction force between the finger exoskeleton joint and the human finger joint.

[0021] Reference numerals: 100, base; 101, first joint; 102, second joint; 200, human finger joint. Detailed implementation manners

[0022] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts shall fall within the protection scope of the present invention.

[0023] The following combines Figures 1 - 4 to describe the force and position perception method of the wrist and hand exoskeleton robot of the present invention.

[0024] As Figure 1 shown, the force and position perception method of the wrist and hand exoskeleton robot provided by the embodiment of the present invention includes: Step 301: Build a finger exoskeleton joint kinematic chain and a human finger joint kinematic chain based on the D-H criterion, and form a closed-loop chain with the finger exoskeleton joint kinematic chain and the human finger joint kinematic chain; Step 302: Based on the closed-loop chain, use the principle that the force transmitted by the finger exoskeleton joint is equal to the force borne by the human finger joint to obtain the kinematic relationship coefficient between the finger exoskeleton joint and the human finger joint; Step 303: Based on the kinematic relationship coefficient and the first moment of the finger exoskeleton joint, obtain the second moment of the human finger joint.

[0025] Specifically, the wrist and hand exoskeleton robot can be worn on each finger of the human body to perform rehabilitation training on each finger and the wrist. Since the movements of each finger and the wrist are the same, the embodiments of the present invention will only be described by taking one finger as an example.

[0026] The finger exoskeleton is simplified to a P3RP mechanism, where P represents a prismatic pair and R represents a revolute pair, that is, the finger exoskeleton has two prismatic pairs and three revolute pairs. The joint structure is simplified to a joint with a universal joint. The human finger joint 200 has two rotation axes which are respectively and , 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 that the distance between the rotation center of the human finger joint 200 and the base 100 of the exoskeleton robot is constant. Therefore, the interaction force of the human finger joint 200 can be obtained by the traditional Jacobian matrix method.

[0027] As Figure 3 and Figure 4 shown, and are the interaction forces for the exoskeleton robot to drive the abduction / adduction and flexion / extension of the human finger joint 200, which can be converted into effective work. 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 assisting the human finger movement, the generated constraint torque needs to be concerned, including , , as well as the constraint force . Among them, as well as the torque , , such forces cannot be converted into effective work and are likely to cause damage to the human finger.

[0028] In the embodiment of the present invention, three passive degrees of freedom are designed in the exoskeleton robot, namely , and , which are used to reduce the interaction force. The passive joint effectively eliminates the constraint force by allowing relative displacement between the exoskeleton robot and the human finger. The passive joints and enable relative rotation between the exoskeleton robot and the human finger, eliminating the unexpected torques and . For the unnecessary torque , it can be eliminated by using the flexible nylon fastener belt that bundles the exoskeleton robot to the human finger. From the above analysis, it can be seen that by using the passive joints , , as well as the flexible nylon fastener belt, the interaction force received by the exoskeleton can be reduced.

[0029] In this embodiment, as Figure 2As shown in the figure, a reference coordinate system of the base 100 in the finger exoskeleton joint kinematic chain is established. Based on the D-H criterion and this reference coordinate system, a closed-loop chain of the finger exoskeleton joint kinematic chain and a closed-loop chain of the human finger joint kinematic chain are built. In this embodiment, the force actually received by the human finger joint 200 is set to be equal to the force transmitted by the finger exoskeleton joint. 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. In this embodiment, the finger exoskeleton joint includes a first joint 101 and a second joint 102. The first joint 101 is used to drive the human finger to swing up and down, and the second joint 102 is used to drive the human finger to swing left and right. Based on the product of the kinematic relationship coefficient and the first moment, the second moment of the human finger joint 200 can be obtained. Since the finger exoskeleton has two joints, the second moment of the human finger joint 200 obtained is a matrix.

[0030] The force-position perception method based on the wrist and hand exoskeleton robot provided by the embodiment of the present invention can intuitively obtain the force actually borne by the human finger joint, real-time monitor the joint position and human-machine interaction force information, and can realize the orthogonal two-degree-of-freedom compliant control of the human finger joint through force-position control and impedance control, simplify the difficulty of safety and compliant control, and can realize the application of damped active and passive rehabilitation training, improve the joint-related muscle strength, and enhance the rehabilitation effect.

[0031] As Figure 2 shown, in the embodiment of the present invention, the steps of building a finger exoskeleton joint kinematic chain and a human finger joint kinematic chain based on the D-H criterion and forming a closed-loop chain between the finger exoskeleton joint kinematic chain and the human finger joint kinematic chain include: establishing a reference coordinate system of the finger exoskeleton joint kinematic chain; based on the D-H criterion and the reference coordinate system, building the finger exoskeleton joint kinematic chain and the human finger joint kinematic chain.

[0032] Specifically, as Figure 2 shown, a reference coordinate system of the base 100 in the finger exoskeleton joint kinematic chain is established , the lengths of the connecting rods in the finger exoskeleton joint kinematic chain are obtained, which are respectively and , and based on the lengths of the connecting rods, the finger exoskeleton joint kinematic chain is built using the D-H criterion. As shown in Table 1: Table 1 D-H parameters of the finger exoskeleton joint kinematic chain

[0033] Establish the first coordinate system of the human finger joint kinematic chain , and obtain the relative position vector , the vertical distance between the center of the human finger joint 200 and the center of the finger exoskeleton joint and the horizontal distance , based on the D-H criterion, construct the motion chain of the human finger joint, as shown in Table 2: Table 2 D-H parameters of the motion chain of the human finger joint

[0034] Furthermore, 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, the steps to obtain the kinematic relationship coefficient between the finger exoskeleton joint and the human finger joint include: establishing the first transformation matrix of the finger exoskeleton joint motion chain; establishing the 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 joint is equal to the force borne by the human finger joint 200, that is, the first transformation matrix is equal to the second transformation matrix, to obtain the kinematic relationship coefficient between the finger exoskeleton joint and the human finger joint 200.

[0035] Specifically, define the rotation center of the human finger joint 200 as , set the force transmitted by the finger exoskeleton joint to be equal to the force borne by the human finger joint 200, that is, the kinematics of the finger exoskeleton joint is (1) where 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 joint motion chain, that is, the first transformation matrix, is the transformation matrix of the human finger joint motion chain, that is, the second transformation matrix.

[0036] According to the D-H algorithm, can be written as (2) can be written as (3) where is the homogeneous transformation matrix corresponding to the D-H motion chain.

[0037] , c = cos, s = sin , According to formula (1), it can be obtained that (4) Substitute formulas (2) and (3) into formula (4), and it can be obtained that:

[0038] Solve to get: (5) Equation (5) can be transformed into (6) Define , and we can get: (7) Then equation (6) can be simplified to: (8) Where , , .

[0039] Solving equation (8) gives the forward kinematic relationship of the human finger joint as follows (9) It can be abbreviated as (10) Where and .

[0040] According to equation (10), taking the partial derivatives of the variable with respect to and can be transformed into (11) (12) According to the principle of virtual work, we can get (13) (14) Where is the kinematic relationship coefficient.

[0041] In the embodiment of the present invention, the steps of obtaining the second moment of the human finger joint based on the kinematic relationship coefficient and the first moment of the finger exoskeleton joint include: obtaining the first moment based on the kinematic relationship coefficient and the angular change of the finger exoskeleton joint.

[0042] Specifically is the output force and torque for driving the finger exoskeleton joint, is the moment vector applied to the human finger joint 200.

[0043] The first moment , where is the stiffness coefficient of the Archimedes spiral spring, is the input angle of the outer ring of the Archimedes spiral spring, is the output angle of the inner ring of the Archimedes spiral spring.

[0044] According to the mapping relationship between the finger exoskeleton joint and the human finger joint 200 in formula (15), the second moment received by the human finger joint 200 can be obtained , that is: .

[0045] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some 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 invention.

Claims

1. A force and position sensing method based on a wrist and hand exoskeleton robot, characterized in that including: Constructing a finger exoskeleton joint kinematic chain and a human finger joint kinematic chain based on the D-H criterion, and forming a closed-loop chain between the finger exoskeleton joint kinematic chain and the human finger joint kinematic 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; Based on the kinematic relationship coefficient and the first moment of the finger exoskeleton joint, obtaining the second moment of the human finger joint.

2. The force and position sensing method based on the wrist and hand exoskeleton robot according to claim 1, wherein The step of constructing a finger exoskeleton joint kinematic chain and a human finger joint kinematic chain based on the D-H criterion, and forming a closed-loop chain between the finger exoskeleton joint kinematic chain and the human finger joint kinematic chain includes: Establishing a reference coordinate system for the finger exoskeleton joint kinematic chain; Based on the D-H criterion and the reference coordinate system, constructing the finger exoskeleton joint kinematic chain and the human finger joint kinematic chain.

3. The force and position sensing method based on a wrist and hand exoskeleton robot according to claim 2, wherein The step of constructing the finger exoskeleton joint kinematic chain based on the D-H criterion and the reference coordinate system includes: Obtaining the lengths of the connecting rods in the finger exoskeleton joint kinematic chain; Based on the lengths of the connecting rods, using the D-H criterion to construct the finger exoskeleton joint kinematic chain.

4. The force and position perception method based on the wrist and hand exoskeleton robot according to claim 2, characterized in that, The step of constructing the human finger joint kinematic chain based on the D-H criterion and the reference coordinate system includes: Establishing a first coordinate system for the human finger joint kinematic chain; Obtaining the relative position vector between the first origin of the reference coordinate system and the second origin of the first coordinate system, as well as the vertical distance and horizontal distance between the center of the human finger joint and the center of the finger exoskeleton joint; Based on the relative position vector, the vertical distance and the horizontal distance, using the D-H criterion to construct the human finger joint kinematic chain.

5. The force-position perception method based on the wrist and hand exoskeleton robot according to claim 2, wherein The step of obtaining the kinematic relationship coefficient between the finger exoskeleton joint and the human finger joint 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 includes: Establishing a first transformation matrix for the finger exoskeleton joint kinematic chain; Establishing a second transformation matrix for the human finger joint kinematic chain; 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, obtaining the kinematic relationship coefficient between the finger exoskeleton joint and the human finger joint.

6. The force and position sensing method based on the wrist and hand exoskeleton robot according to claim 5, characterized in that, The step of obtaining the kinematic relationship coefficient between the finger exoskeleton joint and the human finger joint 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 includes: Obtaining the forward kinematic relationship formula of the human finger joint based on the first transformation matrix and the second transformation matrix.

7. The force and position sensing method based on the wrist and hand exoskeleton robot according to claim 6, characterized in that The step of obtaining the kinematic relationship coefficient between the finger exoskeleton joint and the human finger joint 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 further includes: Based on the forward kinematic relationship formula and the principle of virtual work, obtaining the kinematic relationship coefficient.

8. The force and position perception method based on the wrist and hand exoskeleton robot according to claim 1, characterized in that, The steps of obtaining the second moment of the human finger joint based on the kinematic relationship coefficient and the first moment of the finger exoskeleton joint include: Obtaining the first moment based on the kinematic relationship coefficient and the angle change amount of the finger exoskeleton joint.

9. The force and position sensing method based on the wrist and hand exoskeleton robot according to claim 8, characterized in that, The steps of obtaining the first moment based on the kinematic relationship coefficient and the angle change amount of the finger exoskeleton joint include: Obtaining the input angle and the output angle of the finger exoskeleton joint, and obtaining the angle change amount based on the difference between the input angle and the output angle.

10. The force and position perception method based on the wrist and hand exoskeleton robot according to claim 1, characterized in that, The finger exoskeleton joint includes a first joint and a second joint, and the force-position sensing method further includes: Obtaining the moment of the first joint and the moment of the second joint, Based on the kinematic relationship coefficient, the moment of the first joint, and the moment of the second joint, obtaining the matrix of the second moment.

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