A wrist-elbow combined exoskeleton rehabilitation robot and a control method and system thereof

Abstract

The application provides a wrist-elbow combined exoskeleton rehabilitation robot and a control method and system thereof, which comprises a palm platform and an arm platform, the arm platform and the palm platform are rotatably connected through a wrist joint, a steering engine is arranged on the arm platform, the steering engine and the palm platform are connected through a connecting piece to provide power for flexion and extension of the wrist joint, an accommodation space is arranged on the inner side of the arm platform, and the inner side is in an inwardly recessed arc shape, a circular ring is arranged on the outer side of the arm platform, the center of the arm platform and the circular ring is connected, and a connecting shaft is arranged at the center of the circular ring to be connected with an external power mechanism. The robot comprises two degrees of freedom, can realize driving the wrist joint to perform flexion and extension movement, and driving the arm to perform rotation movement, adopts a proportional differential centroid feedback control mode to accurately control the angle and force of the exoskeleton robot, and has important values for rehabilitation treatment, motion perception and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of rehabilitation robot control, and relates to a wrist and elbow combined exoskeleton rehabilitation robot and a control method and system thereof. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] The upper limb is a very important organ in the human body, which has multiple degrees of freedom and various movement modes, so that the human upper limb has a fine and complex muscle nerve network. In daily life, the wrist and elbow often play a major role, and many daily activities need the support of the wrist and elbow. For example, in daily life, extracting an object or most sports need the support of the wrist. However, human aging, body function decline, or some diseases and accidents can cause wrist and elbow function impairment or even loss, seriously affecting the use of the upper limb in daily life and reducing the life quality and happiness index of patients and their families. For example, stroke is one of the common diseases that cause impairment of the upper limb function of the human body. However, many stroke patients will have upper limb movement disorders due to delayed treatment or other reasons. The medical field finds that rehabilitation training in the early stage of disorder can greatly restore the motor ability, and if the rehabilitation training is not timely, the muscles may be fixed and adhered, and the arm will be permanently disabled. Therefore, it is extremely important to grasp the golden period of patient rehabilitation treatment and conduct rehabilitation training on patients. However, there are a large number of stroke patients in China at present, and the number of rehabilitation physicians in China is seriously insufficient, which cannot meet the needs of patients. Due to the reasons such as that the exoskeleton robot can drive the patient to effectively conduct rehabilitation training and has a low price, the method of using the exoskeleton rehabilitation robot for rehabilitation training is widely recognized.

[0004] At present, there are a large number of various types of wrist and elbow exoskeleton robots, but most of the robots can only complete one joint movement, the rehabilitation training mode is single, and the ideal effect cannot be achieved. At the same time, many exoskeletons are not comfortable to wear, the size is fixed and cannot be adjusted, it is difficult to meet the needs of many patients, and the wearing process is relatively complex, which makes the whole training process relatively cumbersome, and the training effect is very limited. It is still difficult to find a wrist and elbow combined exoskeleton rehabilitation robot that is comfortable to wear, can perform multi-degree-of-freedom movement, and is suitable for all patients. SUMMARY

[0005] The present application proposes a wrist-elbow combined exoskeleton rehabilitation robot and a control method and system thereof to solve the above problems.The robot of the present application includes two degrees of freedom, can realize flexion and extension movement of the wrist joint, and can drive the arm to rotate, and adopts proportional differential centroid feedback control to precisely control the angle and force of the exoskeleton robot, which has important value for rehabilitation treatment and motion perception.

[0006] According to some embodiments, the present application adopts the following technical solutions:

[0007] A wrist-elbow combined exoskeleton rehabilitation robot includes a palm platform and an arm platform, the arm platform and the palm platform are rotatably connected through a wrist joint, a steering engine is arranged on the arm platform, the steering engine and the palm platform are connected through a connecting piece to provide power for flexion and extension of the wrist joint.

[0008] The inner side of the arm platform is provided with an accommodation space, and the inner side is recessed in an arc shape; a circular ring is arranged on the outer side of the arm platform, the center of the arm platform and the circular ring are connected, and a connecting shaft is arranged at the center of the circular ring to be connected with an external power mechanism.

[0009] As an optional implementation, the connecting piece includes connecting plates symmetrically distributed on both sides of the palm platform, the connecting plates have a certain arc, one end of the connecting plates is connected to one side of the steering engine, and the other end of the connecting plates is connected to one side of the palm platform.

[0010] As an optional implementation, a plurality of through holes are arranged on the arm platform.

[0011] A control method of the above robot includes the following steps:

[0012] A dynamic equation of the robot is expressed;

[0013] The centroid movement distance of the palm platform in x and y directions is obtained, the contact reaction force between the exoskeleton robot and the human hand is calculated according to the centroid movement, and the contact task is determined;

[0014] The angle information of the exoskeleton robot is obtained for feedback, and a quadratic programming optimization algorithm is used to eliminate the loss in the control process, and the process of calculating the contact reaction force between the exoskeleton robot and the human hand according to the centroid movement is optimized.

[0015] As an optional implementation, the specific process of expressing the dynamic equation of the robot includes expressing the dynamic equation by using the Lagrange method.

[0016] As an optional implementation, the contact reaction force Fr between the exoskeleton robot and the human hand is calculated based on the centroid movement, and the contact reaction force Fr is:

[0017]

[0018] wherein X cm，r is the reference centroid trajectory, X cm is the current centroid, mg is the total mass, K pi and K di are the corresponding PD gain parts.

[0019] As an alternative embodiment, the contact task is:

[0020]

[0021]

[0022] wherein is the reference acceleration of the palm platform, x f is the current position of the palm platform, is the current velocity of the palm platform, is the reference angular acceleration of the arm platform, is the current angular velocity of the arm platform.

[0023] As an alternative embodiment, the specific process of utilizing the acquired angle information of the exoskeleton robot for feedback comprises:

[0024]

[0025] wherein q proj is a predefined wrist joint angle, is the corresponding acceleration of the wrist joint, q is the current position of the wrist joint.

[0026] As an alternative embodiment, the specific process of eliminating the loss of the control process by using a quadratic programming optimization algorithm comprises constructing expressions of momentum loss, contact and arm platform loss, contact force loss and straight arm loss, optimizing to obtain the final optimization result with the sum of all losses as the target.

[0027] A control system of the above robot, comprising:

[0028] a construction module configured to express the dynamic equation of the robot;

[0029] a centroid control module configured to acquire the centroid moving distance of the palm platform in x and y directions, calculate the contact reaction force between the exoskeleton robot and the human hand according to the centroid movement, and determine the contact task;

[0030] an optimization module configured to utilize the acquired angle information of the exoskeleton robot for feedback, eliminate the loss of the control process by using a quadratic programming optimization algorithm, and optimize the process of calculating the contact reaction force between the exoskeleton robot and the human hand according to the centroid movement.

[0031] Compared with the prior art, the present application has the following advantages:

[0032] The exoskeleton is designed as a linkage structure, and the palm platform and the arm platform are rotatably connected, wherein the part in contact with the arm platform is designed as an arc structure to better fit the human body and improve the wearing comfort; the wrist joint movement is driven by two fan leaves to provide sufficient space for the wrist joint movement; the arm platform is driven to rotate by an external large motor, and the circular ring structure can enhance the smoothness of the movement process and reduce the friction during the movement process; a large number of small holes are arranged on the arm platform to not only reduce the weight of the device but also increase the air permeability during wearing.

[0033] The PD centroid feedback controller is designed, and in addition, the controller is improved by position feedback to solve the singular value problem in the controller. In addition, various losses exist in the system, and the quadratic programming (QP) optimization algorithm is used to eliminate the above influences and minimize the losses to obtain good control performance.

[0034] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the following preferred embodiments are described in detail below, and the accompanying drawings are described as follows. BRIEF DESCRIPTION OF DRAWINGS

[0035] The drawings accompanying the specification of the present application form part of the present application and serve to provide a further understanding of the present application, and the illustrative embodiments of the present application and their description serve to explain the present application, and do not constitute an improper limitation of the present application.

[0036] Figure 1 is Figure 1 Structure diagram of a two-degree-of-freedom wearable exoskeleton upper limb rehabilitation robot system of linkage type;

[0037] Figure 2 Kinematics model diagram constructed according to the upper limb exoskeleton robot, wherein 0 is the origin representing the end of the arm platform, and C is the end point of the kinematics model representing the contact point of the fan leaf and the palm platform, thereby completing the modeling of the exoskeleton;

[0038] Figure 3 Projection of the motion modeling diagram in the XOY plane, wherein AD0B0 is the initial state, and ADB is the state after the rotation angle β;

[0039] Figure 4 Controller of the system;

[0040] Figure 5 Flowchart of the operation of the system.

[0041] Wherein, 1 is a fan blade, 2 is a palm platform, 3 is a screw hole, 4 is a steering engine, 5 is a magic tape hole, 6 is a circular ring, 7 is a connecting rod connected with an external motor, 8 is an arm platform, 9 is an arm passing part, 10 is a slide, and 11 is a screw hole. DETAILED DESCRIPTION

[0042] The application will be further described below in conjunction with the drawings and embodiments.

[0043] It should be noted that the following detailed description is illustrative only and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0044] It is to be understood that the terminology used herein is for the purpose of describing specific embodiments only and is not intended to be limiting of example embodiments in accordance with the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0045] A multi-degree-of-freedom wearable exoskeleton upper limb rehabilitation robot, such as Figure 1 As shown, it comprises a palm platform 2 (for fixing with the palm and driving the palm to move) and an arm platform 8 (in this embodiment, the arm can be fixed on the arm platform through a magic tape or other fixing mechanism to provide support for the arm).

[0046] The arm platform 8 and the palm platform 2 are rotatably connected through a wrist joint, and the arm platform is provided with a steering engine 4 (in this embodiment, placed in a steering engine groove to provide power for the flexion and extension of the wrist joint), the steering engine and the palm platform 2 are connected through a fan blade 1, the fan blade 1 is used to connect the steering engine and the palm, and transfer the torque provided by the steering engine into a torque for driving the palm to move.

[0047] The fan blade 1 is used as a connecting piece in this embodiment. It can also be replaced by other forms, such as a connecting plate, etc. The fan blade is provided with screw holes 3 and screw holes 11 for connecting the fan blade 1 and the steering engine 4.

[0048] The inner side of the arm platform 8 is provided with a receiving space, i.e. the place where the human arm passes through 9, so that the arm is fixed by being inserted into the device, and there is sufficient space for the arm to pass through, which can ensure that the user's arm can pass through. The inner side is concave in an arc shape, i.e. the surface in contact with the arm is an arc surface, which is more in line with the structure of the human arm; the arm platform 8 has many small holes on the upper surface, which not only reduces its weight, but also increases the air permeability when worn, thus greatly enhancing the comfort of the upper limb exoskeleton robot when worn.

[0049] The outer side of the arm platform is provided with a ring 6, the center of the arm platform and the ring is connected, and a connecting shaft or connecting rod 7 is arranged at the center of the ring, which is used to be connected with an external power mechanism (such as a large steering engine) for driving the movement of the whole arm. The ring 6 mainly plays a role in the rotation of the arm, which can reduce the friction in the rotation process and increase the smoothness of the rotation.

[0050] The Velcro holes 5 include a plurality of holes distributed on the palm platform 2 and the arm platform 8, and the Velcro passes through the holes to connect the arm and the platform. It can be adapted to users of various heights and body shapes.

[0051] The palm platform 2 is provided with a plurality of sliding channels 10 for the position where the long screws of the two leaves 1 pass through. The screw holes 11 on the leaves 1 are fixed together by long screws, and the screws also connect the leaves 1 and the palm platform 2 through the sliding channels 10. The power of the system is provided by the steering engine, the steering engine is powered by an external power source, and the whole system is intelligently controlled by a single-chip microcomputer.

[0052] The existing upper limb exoskeleton robot model is kinematically analyzed and the analysis results are simulated to prove that the above-mentioned robot is available. As shown in Figure 2 The kinematic modeling of the exoskeleton robot is shown in the figure, wherein 0 is the origin representing the end of the arm platform, and C is the end point of the kinematic model representing the contact point of the leaf and the palm platform. After understanding its meaning, first, the kinematic analysis is carried out, because the exoskeleton robot can not only perform wrist joint flexion and extension but also perform rotation, so the kinematic analysis includes translation and rotation.

[0053] Therefore, the formula is established as follows:

[0054]

[0055] Wherein x, y, z are the coordinates of point C in the base coordinate system, and x', y', z' are the coordinates of point C in the coordinate system after transformation at B, and matrix A represents the translation and rotation transformation. Therefore, A and x', y', z' can be represented as:

[0056]

[0057]

[0058] The relationship between the end position of the exoskeleton robot and the rotation angle is established by the above formulas. This is the process of kinematic analysis, and the relationship between the steering angle of the steering engine and the position of the robot end can be directly obtained after the kinematic analysis result, which provides a theoretical basis for subsequent control.

[0059] In addition, inverse kinematics analysis of the exoskeleton robot is needed, which is a process of deducing the rotation angle of the servo from the end position. In this process, the kinematics model is projected to the XOY plane to solve the angle, as shown in Figure 3 . Figure 2 and Figure 3 , the relationship between the end position C(x c , y c , z c ) and the rotation angle α, β is as follows:

[0060] l5·cosα+l1=z c (4)

[0061]

[0062]

[0063] The above three formulas are the relationship between the end position C(x c , y c , z c ) and the rotation angle α, β according to the geometric relationship in the kinematics model, wherein formula 4 is obtained according to the attached Figure 2 , formula 5 and formula 6 are obtained according to the attached Figure 3 . Solving the above three formulas can obtain the following two relationship formulas, which are the results of inverse kinematics, as follows:

[0064]

[0065]

[0066] The two formulas obtained above are the results of inverse kinematics calculation. Through the inverse kinematics results, we can directly obtain the rotation angle of the servo according to the end position, which provides a theoretical basis for subsequent control. In addition, due to the limitation of some mechanical structures, we can limit the value range of x c , y c , z c in the end position, as follows:

[0067] 0<x c <l3 (9)

[0068] l4-l1-l5<y c <l4+l5·sin30°-l1(10)

[0069] -l5<z c <l2+l5 (11)

[0070] In order to verify the reliability of the model, the simulation verification is also carried out after the controversial kinematics analysis of the upper limb exoskeleton robot is completed. The control signal obtained by modulation is input into the simulation system, and the formula calculated by kinematics analysis is used to drive the exoskeleton robot to move. It is found through simulation that the established kinematics model is accurate and reliable.

[0071] The control strategy of the robot is shown in Figure 4 . First, the dynamic equation of the robot can be obtained by the Lagrange method, as shown in equation (12). Where M is the mass matrix, b is the Coriolis matrix, g is the gravity term, S is the selection matrix, is the contact Jacobian matrix, B is the Jacobian matrix from the generalized frame to the center of mass, τ is the torque, and p is the generalized force.

[0072]

[0073] A PD center of mass feedback controller is designed for the system, as shown in equation (13). The controller needs to obtain the palm platform x and y direction center of mass moving distance, and based on the center of mass movement, the contact reaction force Fr between the exoskeleton robot and the human hand is calculated. In the formula, X cm，r is the reference center of mass trajectory, X cm is the current center of mass, and mg is the total mass. In equations (13)-(15), K pi and K di are the respective PD gain parts.

[0074]

[0075] The contact task between the hand and the exoskeleton can be formulated as (14), where is the reference acceleration, x f is the current position, is the current velocity, is the reference angular acceleration of the trunk, is the current angular velocity of the trunk.

[0076]

[0077]

[0078] When only the above controller is used to form the lifting movement, the singular value problem will be encountered. In order to solve this problem, the sensor obtained angle information of the exoskeleton robot is fed back to optimize the controller, as shown in equation (15). Where q proj is the predefined joint angle, is the corresponding acceleration of the joint, and q is the current joint position.

[0079]

[0080] In the control process, there will be some loss terms, for this design a QP optimization algorithm to eliminate these effects as much as possible, as shown in equation (16). Where v is the generalized velocity, is the generalized acceleration, A is the center of mass momentum matrix, W g and W grf are the gravity moment and contact force moment respectively, p is the required motion vector, P h , P J and P ρ are weights, in the last arm straightening loss formula (straight arm loss formula), J is the Jacobian matrix of motion in the Cartesian coordinate system, J task is the contact Jacobian matrix.

[0081]

[0082]

[0083] ρ min ≤ρ≤ρ max ,τ min ≤τ≤τ max ,

[0084] Momentum loss: where

[0085] Contact and whole torso loss:

[0086] Contact force loss: J ρ =||P ρ ρ|| 2 ,

[0087] Straight arm loss: where J task = [(SA) T J T ] T

[0088] Finally, the improved and ρ are brought into equation (12), and the final dynamics equation is obtained as shown in equation (17), which solves the problem of singular values existing in the motion process.

[0089]

[0090] The controller solves the problem of singular values existing in the motion process, and ensures the smoothness of the whole system during operation. In addition, by optimizing we minimize the loss in the robot motion process, improve the efficiency of the system, and have beneficial effects.

[0091] like Figure 5 As shown in the figure, to begin training, the patient first needs to put on the upper limb robot and secure the arm to the exoskeleton using Velcro. After putting on the robot, the patient needs to set the number of rehabilitation training sessions and then begin the rehabilitation process. During this process, the controller processes the information obtained by the motion capture system and then controls the two servos of the exoskeleton. Finally, these two servos rotate together to drive the exoskeleton upper limb rehabilitation robot to move, thus allowing the patient to receive rehabilitation training while wearing the exoskeleton. The entire exoskeleton robot system is powered by an external power supply. After completing the set number of training sessions, the patient decides whether to continue training. If so, the patient resets the number of training sessions and repeats the above steps. Otherwise, the training ends.

[0092] The exoskeleton upper limb rehabilitation robot designed in this invention has two degrees of freedom, allowing for different movements. Therefore, during rehabilitation training, the exoskeleton robot can comprehensively train the patient's wrist joint and arm rotation function, making it of great significance in the field of upper limb rehabilitation training.

[0093] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0094] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0095] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 one or more processes and / or functions described in the one or more blocks. Figure 1 one or more blocks or multiple blocks.

[0096] These computer program instructions can also be loaded into a computer or other programmable data processing devices, so that a series of operational steps are performed on the computer or other programmable data processing devices to generate a computer implemented process, so that the instructions executed on the computer or other programmable data processing devices provide steps for implementing the function described in the one or more processes and / or functions described in the one or more blocks. Figure 1 one or more processes and / or functions described in the one or more blocks. Figure 1 one or more blocks or multiple blocks.

[0097] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0098] Although the specific embodiments of the present application are described above in combination with the drawings, it is not intended to limit the protection scope of the present application. Those skilled in the art should understand that various modifications or changes made on the basis of the technical solutions of the present application without creative labor are still within the protection scope of the present application.

Claims

1. A control system for a wrist-elbow combined exoskeleton rehabilitation robot, comprising: A building module is configured to express a dynamic equation of a wrist-elbow combined exoskeleton rehabilitation robot; the wrist-elbow combined exoskeleton rehabilitation robot includes a palm platform and an arm platform, the arm platform and the palm platform are rotatably connected via a wrist joint, a servo is provided on the arm platform, and the servo is connected to the palm platform via a connector to provide power for flexion and extension of the wrist joint; The inner side of the arm platform is provided with a receiving space, and the inner side is in an inwardly concave arc shape; the outer side of the arm platform is provided with a circular ring, the arm platform is connected to the center of the circular ring, and a connecting shaft is provided at the center of the circular ring for connecting to an external power mechanism; The center of mass control module is configured to obtain the center of mass movement distance of the palm platform in the x and y directions, calculate the contact reaction force between the wrist-elbow combined exoskeleton rehabilitation robot and the human hand based on the center of mass movement, and determine the contact task; The optimization module is configured to use the acquired angle information of the wrist-elbow combined exoskeleton rehabilitation robot for feedback, and use the quadratic programming optimization algorithm to eliminate the loss of the control process, and optimize the process of calculating the contact reaction force between the wrist-elbow combined exoskeleton rehabilitation robot and the human hand based on the movement of the center of mass.

2. The control system of the wrist-elbow combined exoskeleton rehabilitation robot according to claim 1, characterized in that: The connecting member includes connecting plates symmetrically distributed on both sides of the palm platform. The connecting plate has a certain curvature, one end of which is connected to one side of the steering gear, and the other end of which is connected to one side of the palm platform.

3. The control system of the wrist-elbow combined exoskeleton rehabilitation robot according to claim 1, characterized in that: A plurality of through holes are provided on the arm platform.

4. The control system of the wrist-elbow combined exoskeleton rehabilitation robot according to claim 1, characterized in that: The specific process of expressing the dynamic equations of the wrist-elbow combined exoskeleton rehabilitation robot includes using the Lagrangian method to express the dynamic equations.

5. The control system of the wrist-elbow combined exoskeleton rehabilitation robot according to claim 1, characterized in that: The contact reaction force between the wrist-elbow combined exoskeleton rehabilitation robot and the human hand is calculated based on the center of mass movement. The contact reaction force Fr is: Where, is the reference center-of-mass trajectory, is the current center of mass, mg is the total mass, and is the corresponding PD gain part.

6. The control system of the wrist-elbow combined exoskeleton rehabilitation robot according to claim 1, characterized in that: The contact tasks are: in is the base acceleration of the palm platform, The current location of the palm platform, is the current speed of the palm platform, is the reference angular acceleration of the arm platform, is the current angular velocity of the arm platform, 、 、 is the corresponding PD gain part.

7. The control system of the wrist-elbow combined exoskeleton rehabilitation robot according to claim 1, characterized in that: The specific process of using the acquired angle information of the wrist-elbow combined exoskeleton rehabilitation robot for feedback includes: in, is the predefined wrist joint angle, is the corresponding acceleration of the wrist joint, q is the current position of the wrist joint, and is the corresponding PD gain part.

8. The control system of the wrist-elbow combined exoskeleton rehabilitation robot according to claim 1, characterized in that: The specific process of using the quadratic programming optimization algorithm to eliminate the loss of the control process includes constructing expressions for momentum loss, contact and arm platform loss, contact force loss and straight arm loss, and optimizing with the goal of minimizing the sum of all losses to obtain the final optimization result.

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