CN111358667A - Method for controlling man-machine interactive motion of lower limb exoskeleton based on joint stress - Google Patents

Method for controlling man-machine interactive motion of lower limb exoskeleton based on joint stress Download PDF

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CN111358667A
CN111358667A CN201811599344.3A CN201811599344A CN111358667A CN 111358667 A CN111358667 A CN 111358667A CN 201811599344 A CN201811599344 A CN 201811599344A CN 111358667 A CN111358667 A CN 111358667A
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leg
exoskeleton robot
exoskeleton
joint
robot
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CN111358667B (en
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王晓峰
曲道奎
邸霈
李刚
宋吉来
刘世昌
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Shenyang Siasun Robot and Automation Co Ltd
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Shenyang Siasun Robot and Automation Co Ltd
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61H—PHYSICAL THERAPY APPARATUS, e.g. DEVICES FOR LOCATING OR STIMULATING REFLEX POINTS IN THE BODY; ARTIFICIAL RESPIRATION; MASSAGE; BATHING DEVICES FOR SPECIAL THERAPEUTIC OR HYGIENIC PURPOSES OR SPECIFIC PARTS OF THE BODY
    • A61H3/00—Appliances for aiding patients or disabled persons to walk about
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61H—PHYSICAL THERAPY APPARATUS, e.g. DEVICES FOR LOCATING OR STIMULATING REFLEX POINTS IN THE BODY; ARTIFICIAL RESPIRATION; MASSAGE; BATHING DEVICES FOR SPECIAL THERAPEUTIC OR HYGIENIC PURPOSES OR SPECIFIC PARTS OF THE BODY
    • A61H1/00—Apparatus for passive exercising; Vibrating apparatus ; Chiropractic devices, e.g. body impacting devices, external devices for briefly extending or aligning unbroken bones
    • A61H1/02—Stretching or bending or torsioning apparatus for exercising
    • A61H1/0237—Stretching or bending or torsioning apparatus for exercising for the lower limbs
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61H—PHYSICAL THERAPY APPARATUS, e.g. DEVICES FOR LOCATING OR STIMULATING REFLEX POINTS IN THE BODY; ARTIFICIAL RESPIRATION; MASSAGE; BATHING DEVICES FOR SPECIAL THERAPEUTIC OR HYGIENIC PURPOSES OR SPECIFIC PARTS OF THE BODY
    • A61H3/00—Appliances for aiding patients or disabled persons to walk about
    • A61H2003/005—Appliances for aiding patients or disabled persons to walk about with knee, leg or stump rests
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61H—PHYSICAL THERAPY APPARATUS, e.g. DEVICES FOR LOCATING OR STIMULATING REFLEX POINTS IN THE BODY; ARTIFICIAL RESPIRATION; MASSAGE; BATHING DEVICES FOR SPECIAL THERAPEUTIC OR HYGIENIC PURPOSES OR SPECIFIC PARTS OF THE BODY
    • A61H3/00—Appliances for aiding patients or disabled persons to walk about
    • A61H2003/007—Appliances for aiding patients or disabled persons to walk about secured to the patient, e.g. with belts
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61H—PHYSICAL THERAPY APPARATUS, e.g. DEVICES FOR LOCATING OR STIMULATING REFLEX POINTS IN THE BODY; ARTIFICIAL RESPIRATION; MASSAGE; BATHING DEVICES FOR SPECIAL THERAPEUTIC OR HYGIENIC PURPOSES OR SPECIFIC PARTS OF THE BODY
    • A61H2201/00—Characteristics of apparatus not provided for in the preceding codes
    • A61H2201/16—Physical interface with patient
    • A61H2201/1657—Movement of interface, i.e. force application means
    • A61H2201/1659—Free spatial automatic movement of interface within a working area, e.g. Robot
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61H—PHYSICAL THERAPY APPARATUS, e.g. DEVICES FOR LOCATING OR STIMULATING REFLEX POINTS IN THE BODY; ARTIFICIAL RESPIRATION; MASSAGE; BATHING DEVICES FOR SPECIAL THERAPEUTIC OR HYGIENIC PURPOSES OR SPECIFIC PARTS OF THE BODY
    • A61H2201/00—Characteristics of apparatus not provided for in the preceding codes
    • A61H2201/50—Control means thereof
    • A61H2201/5023—Interfaces to the user

Abstract

The embodiment of the invention discloses a human-computer interaction control method for a lower limb exoskeleton based on joint stress. The control method comprises the following steps: establishing a leg kinematics model of an exoskeleton robot, the leg comprising a first leg and a second leg; designing a support motion controller model of the exoskeleton robot in a support stage on the basis of the leg kinematics model; designing a swing motion controller model of the exoskeleton robot in a swing stage on the basis of the leg kinematics model; and respectively adopting a support motion controller model or a swing motion controller model to correspondingly control the motion of the first leg or the motion of the second leg according to the different stages of the first leg and the second leg. The control method has the advantages of simple realization process, less number of parameters to be adjusted in the control process and capability of realizing the follow-up control effect.

Description

Method for controlling man-machine interactive motion of lower limb exoskeleton based on joint stress
Technical Field
The invention relates to the technical field of rehabilitation engineering, in particular to a method for controlling man-machine interactive motion of a lower limb exoskeleton based on joint stress.
Background
The exoskeleton walking-aid robot is a high-tech achievement integrating multiple disciplinary knowledge such as human body information detection, robot automatic control, neural engineering and the like. The robot design and research aim to realize the preset human body movement function by adopting a machine movement auxiliary technology, and the complete function of the robot is realized by three key nodes of intention generation, intention identification and feedback stimulation. The control process of the exoskeleton walking robot can be described as: first generating an athletic intent by the wearer; then capturing the movement intention of the person by a sensor on the robot, and classifying and quantifying the movement intention of the person by utilizing various recognition algorithms; and finally, adjusting each joint motor of the robot by a joint controller of the robot according to the recognition result of the human motion intention, thereby realizing the function of assisting the human motion. The human exoskeleton and the robot exoskeleton are two different dynamic systems, and when a person wears the exoskeleton to walk, the person and the exoskeleton need to cooperate with each other to achieve the purpose of common walking. Therefore, human-machine collaboration needs to be divided into two parts: one of them is the control method of the exoskeleton robot, and the other is to transmit the movement intention of the person to the exoskeleton.
Currently, methods for controlling the joints of an exoskeleton walking aid robot include a phase sequence control method, a control method based on a preset gait and a sensitivity amplification control method. The phase sequence control method comprises the steps of firstly dividing the activities (such as walking, standing, climbing stairs and the like) of the lower limbs of a human body into different phase stages, setting phase transition time for switching adjacent phases, then setting auxiliary force to be applied by the robot aiming at different phases, determining the phase stage of the current activity of the robot by a controller according to feedback information of a sensor in the running process of the robot, and then applying influence on the human body according to the auxiliary force set in advance to realize the function of providing assistance for the activities of the lower limbs of the human body. The phase sequence control method sets the magnitude of the auxiliary force aiming at different stages of different activities of the lower limbs of the human body, and can realize various auxiliary functions; however, each phase assist force parameter is complex to set and difficult to implement, and the set assist force is relatively fixed and lacks flexibility, and needs to be customized for different users. The control method based on the preset gait adjusts the auxiliary moment according to the deviation of the current joint activity state and the predefined reference joint angle and the reference angular velocity after acquiring the motion intention of the human, and if the current robot activity state is consistent with the predefined reference state, the auxiliary force is zero. The control method based on the preset gait avoids the limitation that the phase sequence control method sets a fixed auxiliary torque for each phase, and can dynamically adjust the size of the auxiliary torque according to the running state of the robot; however, the requirement for designing the reference trajectory is high, a fixed reference trajectory is difficult to adapt to the auxiliary operations of different users under different environmental conditions, and the auxiliary force cannot be dynamically adjusted according to the walking desire of the users in the exercise process. The sensitivity amplification control method defines the transfer function of human applied force to the exoskeleton output as a sensitivity function, and aims to maximize the sensitivity function through the design of the controller, so that the action of the exoskeleton can be changed with small force. The sensitivity amplification control method does not need to install a sensor between human and machines, can still control the exoskeleton to move along with a wearer, but strictly depends on the accuracy of an inverse dynamics model of the exoskeleton.
Therefore, in order to solve the problems of the existing joint control method for the exoskeleton walking-assisted robot, a man-machine interaction control method which can adjust the exoskeleton robot during walking and realize coordinated movement between a user and the robot is needed to be provided.
Disclosure of Invention
Aiming at the problems of the existing joint control method of the exoskeleton walking aid robot, the embodiment of the invention provides a lower limb exoskeleton man-machine interaction control method based on joint stress. The lower limb exoskeleton man-machine interaction control method based on joint stress is simple in implementation process, few in number of parameters needing to be adjusted in the control process, and capable of achieving follow-up control effect.
The specific scheme of the lower limb exoskeleton man-machine interaction control method based on joint stress is as follows: a human-computer interaction control method for a lower limb exoskeleton based on joint stress comprises the following steps: establishing a leg kinematics model of an exoskeleton robot, the leg comprising a first leg and a second leg; designing a support motion controller model of the exoskeleton robot in a support stage on the basis of the leg kinematics model; designing a swing motion controller model of the exoskeleton robot in a swing stage on the basis of the leg kinematics model; and respectively adopting a support motion controller model or a swing motion controller model to correspondingly control the motion of the first leg or the motion of the second leg according to the different stages of the first leg and the second leg.
Preferably, the leg kinematics model of the first leg and the leg kinematics model of the second leg are the same.
Preferably, when the first leg is in the support stage, the motion of the first leg is controlled by using a support motion controller model; and when the second leg is in a swinging stage, controlling the movement of the second leg by adopting a swinging movement controller model.
Preferably, when the first leg is in the swing stage, the swing motion controller model is adopted to control the motion of the first leg; and when the second leg is in the supporting stage, the movement of the second leg is controlled by adopting a supporting movement controller model.
Preferably, the leg kinematics model is a relationship between the ankle joint end velocity and each joint angular velocity of the exoskeleton robot, and the relational expression is as follows:
Figure BDA0001922066510000031
wherein A isy＝Lusin(θ1)+Ldsin(θ1-θ2)，Az＝-Lucos(θ1)-Ldcos(θ1-θ2)，AyIndicating the coordinate of the ankle joint in the Y-axis, AzIndicating the coordinate of the ankle joint in the Z-axis, LuIs the thigh length, L, of the exoskeleton robotdThe length of the lower leg of the exoskeleton robot, theta1Angle of rotation, theta, for lifting the leg forward of the exoskeleton robot's hip joint2Is the bending angle of the knee joint of the exoskeleton robot.
Preferably, a Jacobian matrix of the leg of the exoskeleton robot can be derived according to the leg kinematics model, and the expression of the Jacobian matrix is as follows:
Figure BDA0001922066510000032
wherein J is Jacobian matrix, LuIs the thigh length, L, of the exoskeleton robotdThe length of the lower leg of the exoskeleton robot, theta1Angle of rotation, theta, for lifting the leg forward of the exoskeleton robot's hip joint2For the angle of knee joint bending of exoskeleton robot
Preferably, the support motion controller model is a support desired angular velocity of a leg joint of the exoskeletal robot in a support phase, and the expression of the support desired angular velocity is as follows:
Figure BDA0001922066510000033
wherein the content of the first and second substances,
Figure BDA0001922066510000034
desired angular velocities for support of leg joints of the exoskeleton robot; tau ishThe moment is the interaction moment between the human body and the exoskeleton robot borne by hip joints and knee joints of the exoskeleton robot; j is a Jacobian matrix which is obtained by the derivation of a leg kinematics model; a. the0Reference coordinates of the ankle joint of the exoskeleton robot in a supporting stage; a is the current desired speed of the ankle joint of the exoskeleton robot; k1Is a rigidity coefficient for adjusting the restoring force applied to the ankle joint when the ankle joint deviates from the reference posture; k2Is the elastic coefficient used to adjust the current desired velocity level of the ankle joint.
Preferably, the swing motion controller model is a swing desired angular velocity of a leg joint of the exo-skeletal robot in a swing phase, the swing desired angular velocity being expressed by the following equation:
Figure BDA0001922066510000041
wherein the content of the first and second substances,
Figure BDA0001922066510000042
desired angular velocities for the oscillations of the exoskeleton robot's leg joints; tau ishThe moment is the interaction moment between the human body and the exoskeleton robot borne by hip joints and knee joints of the exoskeleton robot; j is a Jacobian matrix which is obtained by the derivation of a leg kinematics model; a. therReference coordinates of the ankle joint of the exoskeleton robot in a swing stage; a is the current desired speed of the ankle joint of the exoskeleton robot; k1Is a rigidity coefficient for adjusting the restoring force applied to the ankle joint when the ankle joint deviates from the reference posture; k2Is the elastic coefficient used to adjust the current desired velocity level of the ankle joint.
Preferably, said τ ishObtained by numerical calculations taken by pressure sensors mounted at the thigh and calf.
Preferably, the exoskeleton robot comprises: the leg part is used for assisting the legs of the person to walk; the motor is connected with the leg part and is used for driving the leg part to move; a wearable part connected with the leg part and the motor and used for fixing the exoskeleton robot to a human body; a foot portion connected to the leg portion for supporting a foot of a person; and the pressure sensor is used for acquiring pressure information of the exoskeleton robot in the walking process.
According to the technical scheme, the embodiment of the invention has the following advantages:
the embodiment of the invention provides a lower limb exoskeleton man-machine interactive motion control method based on joint stress, which divides the walking process of an exoskeleton robot assisting a human to walk into a supporting stage and a swinging stage, and the control process does not need to establish a complex dynamic model for the exoskeleton robot, does not need to set the movement track of the exoskeleton in advance, and only needs to control the exoskeleton robot according to the current interaction state of the human and the exoskeleton, so that the control process is easier to realize. Further, the lower limb exoskeleton man-machine interaction motion control method based on joint stress provided by the embodiment of the invention has the advantages of less quantity of parameters required to be adjusted, simple and intuitive modeling process and easiness in understanding. Further, the embodiment of the invention provides a control method for human-computer interaction motion of the lower extremity exoskeleton based on joint stress, which can achieve multiple control effects by adjusting control parameters of the same controller.
Drawings
Fig. 1 is a schematic flowchart illustrating steps of a method for controlling human-computer interaction motion of a lower extremity exoskeleton based on joint stress according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of the exoskeleton robot employed in the embodiment of FIG. 1;
FIG. 3 is a schematic diagram illustrating an assisted walking gesture using the exoskeleton robot of FIG. 2;
FIG. 4 is a block diagram of a human-computer interaction controller in the embodiment shown in FIG. 1.
Description of the reference symbols in the drawings:
100. exoskeleton robot 10, wearing part 20, and leg part
21. First leg 23, second leg 30 motor
40 foot 41, first foot 43, second foot
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The terms "first," "second," "third," "fourth," and the like in the description and in the claims, as well as in the drawings, if any, are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It will be appreciated that the data so used may be interchanged under appropriate circumstances such that the embodiments described herein may be practiced otherwise than as specifically illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
As shown in fig. 1, a flow step schematic diagram of a method for controlling human-computer interaction motion of a lower extremity exoskeleton based on joint stress according to an embodiment of the present invention is provided. In the embodiment, the human-computer interaction motion control method for the lower limb exoskeleton based on joint stress comprises four steps.
Step S1: a leg kinematics model of an exoskeleton robot is established, the leg comprising a first leg and a second leg. The first leg may also be referred to as the left leg and the second leg may also be referred to as the right leg. In this embodiment, the leg kinematics model of the first leg and the leg kinematics model of the second leg are the same.
Referring to fig. 2, exoskeleton robot 100 used in the embodiment of the present invention is schematically configured. The exoskeleton robot 100 comprises a leg portion 20 for assisting a human leg to walk, a motor 30 connected to the leg portion 20 for driving the leg portion 20 to move, a wearing portion 10 connected to the leg portion 20 and the motor 30 for fixing the exoskeleton robot 100 to a human body, a foot portion 40 connected to the leg portion 20 for supporting a human foot, and a pressure sensor (not shown) for collecting pressure information of the exoskeleton robot 100 during walking.
Further, the leg portion 20 includes a first leg portion 21 and a second leg portion 23, and the first leg portion 21 and the second leg portion 23 are identical in structural design. Each leg comprises a thigh part, a lower leg part, a knee joint connecting the thigh part and the lower leg part, and a hip joint above the thigh part. Preferably, the outer sides of the thighs and the shanks of the exoskeleton robot are provided with straps. The lower limbs of the human body are fixed on the legs of the exoskeleton robot through the binding bands. The foot 40 includes a first foot 41 and a second foot 43. The first foot 41 is connected to the first leg 21, and an ankle joint is provided at the connection between the first foot and the first leg. The second foot 43 is connected to the second leg 23, and an ankle joint is provided at the connection between the two.
The pressure sensors may include a plurality of different pressure sensors disposed at different locations of exoskeleton robot 100. Specifically, the pressure sensor is arranged between a thigh part and a shank part of the exoskeleton robot and is used for acquiring interaction force information of the thigh and the shank of the human body and an exoskeleton of the exoskeleton robot; the pressure sensor is arranged on the foot and used for collecting the pressure of the sole of the foot so as to detect the motion state change information of the human body.
The motor 30 is a dc motor. The motor 30 is adjusted by the lower extremity exoskeleton man-machine interaction control method based on joint stress provided by the embodiment of the invention, so as to provide power assistance for walking of a user wearing the exoskeleton robot 100.
In the embodiment of the present invention, the leg kinematics model of the first leg is the same as the leg kinematics model of the second leg, and therefore, the embodiment of the present invention is only described by using the modeling process of the leg kinematics model of the first leg. Referring to fig. 3, the hip joint rotation center point is set to H, the knee joint rotation center point is set to K, the ankle joint rotation center point is set to a, and the exoskeleton robot thigh length is set to L in the exoskeleton supporting stateuThe length of the exoskeleton robot shank is set to be LdThe rotation angle of the hip joint for lifting the leg forward is set to theta1The angle of knee joint flexion is set to theta2The interaction force in the leg-lifting direction on the thigh is Fu1The interaction force in the leg falling direction on the thigh is Fu2The interaction force of the lower leg in the kicking direction is Fd1The interaction force of the lower leg in the leg bending direction is Fd2Knee joint reference point when exoskeleton robot lifts legThe position is K ', and the position of the ankle joint reference point when the exoskeleton robot lifts the leg is A'.
And establishing a reference coordinate system by taking the point H as an origin, taking the vertical direction as the Z-axis direction and the inward direction of the hip joint rotating shaft as the X-axis direction. At this time, the coordinate of the ankle joint on the Y-axis is as shown in formula 1:
Ay＝Lusin(θ1)+Ldsin(θ1-θ2) (formula 1)
At this time, the coordinate of the ankle joint on the Z-axis is as shown in equation 2:
Az＝-Lucos(θ1)-Ldcos(θ1-θ2) (formula 2)
According to the formula 1 and the formula 2, the relationship between the ankle joint terminal velocity and the angular velocity of each joint is calculated and obtained as shown in the formula 3:
Figure BDA0001922066510000071
equation 3 is the leg kinematics model. As can be derived from equation 3, the jacobian matrix for the exoskeleton leg is shown in equation 4:
Figure BDA0001922066510000072
step S2: and designing a support motion controller model of the exoskeleton robot in a support stage on the basis of the leg kinematics model. In the supporting stage, the reference coordinate of the ankle joint is A0(Ay0,Az0) Then the interaction between the person and the exoskeleton robot can be described by equation 5:
Figure BDA0001922066510000073
wherein F is the desired interaction force,
Figure BDA0001922066510000074
for the currently desired velocity of the ankle joint, K1Is the coefficient of stiffness, K2Is the elastic coefficient. K1For adjusting the restoring force applied to the ankle joint when it deviates from the reference attitude, and K1＞0。K2For adjusting the current desired velocity of the ankle joint, and K2Is greater than 0. The desired interaction force F can be converted to the respective joint by means of a Jacobian matrix (tau)h＝JTF) In that respect The currently desired speed A can also be converted to the respective joint by means of a Jacobian matrix
Figure BDA0001922066510000075
Therefore, equation 5 can also be rewritten as equation 6:
Figure BDA0001922066510000076
wherein the content of the first and second substances,
Figure BDA0001922066510000077
desired angular velocities for support of exoskeleton leg joints; tau ishThe interaction torque between the person and the exoskeleton born by the hip joint and the knee joint of the exoskeleton can be calculated by the numerical value obtained by the pressure sensors arranged at the thigh and the shank; j is a Jacobian matrix and is derived from the exoskeleton kinematics model. Equation 6 is the mathematical model of the support motion controller.
Step S3: and designing a swing motion controller model of the exoskeleton robot in a swing stage on the basis of the leg kinematics model. Similarly, in the swing stage, if the reference coordinate of the ankle joint is A, as in the design process in step S2r(Ayr,Azr) At this time, the mathematical model of the swing motion controller of the exoskeleton robot can be described as shown in equation 7:
Figure BDA0001922066510000081
wherein the content of the first and second substances,
Figure BDA0001922066510000082
is outsideThe swing of the leg joints of the skeletal robot is at a desired angular velocity. Equations 7 and 6 are essentially the same mathematical model of the controller, but with different reference coordinates.
Step S4: and respectively adopting a support motion controller model or a swing motion controller model to correspondingly control the motion of the first leg or the motion of the second leg according to the different stages of the first leg and the second leg. The control mode specifically includes: when the first leg is in the supporting stage, controlling the movement of the first leg by adopting a supporting movement controller model; when the second leg is in the swing phase, the swing motion controller model is used to control the motion of the second leg. When the first leg is in a swinging stage, controlling the movement of the first leg by adopting a swinging movement controller model; when the second leg is in the support phase, the motion of the second leg is controlled using the support motion controller model.
Referring to fig. 3, a schematic diagram of the exoskeleton robot performing the walking assistance posture in the embodiment of the present invention is shown. If the human body wears the exoskeleton robot to walk, the first leg is taken along first, and the first leg is a swing leg and the second leg is a supporting leg in the starting stage. The control procedure for this phase can be described as follows:
the reference point of the first leg ankle joint is point A' in FIG. 3, and the coordinate of the point is set as Ar(Ayr,Azr) Then equation 6 is adopted as the controller of the first leg of the exoskeleton at this stage, and the moment τ of man-machine interaction is obtainedhIs zero. Under the action of the controller, virtual spring damping between the current point and the reference point of the ankle joint can generate a desired movement speed, so that the first leg of the exoskeleton generates a movement trend towards the reference point. Subsequently, the man-machine interaction moment τhWill gradually increase, if the person wearing the exoskeleton robot does not want to move, the resulting final state is τh＝JTK1(Ar-a) when the desired speed of movement output by the controller is zero, but there is always a tendency to move towards the reference point. If the person wearing the exoskeleton robot wants to take a first leg, the moment τ is interactedhWill fall and the controller will produce a desired velocity toward the reference point and the first leg of the exoskeleton is controlled by the underlying controllerThe movement is performed until the first leg reaches the reference point. When the ankle joint of the first leg reaches the designated reference point, the damping effect of the virtual spring is weakened, a person wearing the exoskeleton robot can operate the first leg of the exoskeleton robot through the man-machine interaction torque to finish landing, and the switching of the motion state of the first leg from the swinging stage to the supporting stage is realized.
In the first leg swing stage, the second leg is the support stage, the reference point of the ankle joint of the second leg is point A in fig. 3, and the coordinate of the point is set as A0(Ay0,Az0) Then equation 7 is used as the controller for the second leg of the phase. Since the current second leg ankle joint is at the reference point and the second leg ankle joint will always move around the reference point during the support phase, the effect of the virtual spring damping is weak and the reference speed generated by the controller is dominated by the human-machine interaction moment of the second leg. When the first leg is transited from the swing leg to the supporting leg, the second leg also moves to the maximum amplitude of the supporting leg, and a certain movement trend is accumulated, so that the second leg cannot generate large sudden change in the transition process from the supporting leg to the swing leg, and the transition stability is ensured.
By repeating the cycle, the motion controller provided by the embodiment of the invention realizes the function of assisting the exoskeleton walking robot in the motion of wearing the exoskeleton robot by switching the reference points between the first leg supporting stage and the second leg supporting stage and the swinging stage.
The supporting motion controller or the swinging motion controller provided by the embodiment of the invention forms a virtual spring damper between the ankle joint and the reference point of the exoskeleton robot, and the spring damper can be adjusted on line, so that the aim of assisting the movement of a wearer by the exoskeleton robot is fulfilled.
Referring to fig. 4, a schematic block diagram of a structure of a human-computer interaction controller in the embodiment of the present invention. The process of human-computer interaction by a human-computer interaction controller (namely a motion controller) is specifically as follows: determining reference point position Ar and impedance control parameters K1 and K2 of ankle joint, and obtaining desired angular velocity of exoskeleton through motion controller of formula 6 or formula 7
Figure BDA0001922066510000091
And performing control, wherein the control process is closed-loop control. In the control process, the man-machine interaction torque tauhAnd the current state of each joint of the exoskeleton (including reference point a and jacobian matrix J) as a closed-loop feedback parameter. The lower controller is used for controlling the lower layer controller according to the desired angular velocity of the exoskeleton
Figure BDA0001922066510000092
And controlling the motion of the exoskeleton robot.
In this embodiment, the support motion controller model and the swing motion controller model are substantially the same mathematical model, and the design process is similar. Therefore, in other embodiments, the order of step S2 and step S3 may be interchanged or unified into one step.
The lower limb exoskeleton man-machine interaction motion control method based on joint stress provided by the embodiment of the invention divides the walking process of an exoskeleton robot assisting a human to be two stages: one is a support phase and one is a swing phase. The same motion controller is used for the support phase and the swing phase, but the control parameters of the motion controller are different.
In the supporting stage (including single-leg support and double-leg support), the impedance controller is designed by taking H-K-A in fig. 3 as a reference posture, a virtual spring damping is added between the current posture and the reference posture of the exoskeleton robot, so that when the leg of the exoskeleton robot deviates from the reference posture, the controller can provide acting force returning to the reference posture for the exoskeleton robot, and the acting force and the interaction force between the robot and the exoskeleton robot are differentiated to jointly complete the motion regulation of the leg of the exoskeleton robot.
In the swing stage, H-K '-A' in fig. 3 is taken as a reference posture, an impedance controller is designed, a virtual spring damping is added between the current posture and the reference posture of the exoskeleton robot, when the leg of the exoskeleton robot deviates from the reference posture, the controller can provide acting force returning to the reference posture for the exoskeleton robot, and the acting force and the interaction force between the robot and the exoskeleton robot are differentiated to jointly complete the motion regulation of the leg of the exoskeleton robot.
Compared with the existing control method, the human-computer interaction motion control method for the lower limb exoskeleton based on joint stress provided by the embodiment of the invention is simpler to realize, does not need to establish a complex dynamic model for the exoskeleton robot, does not need to set the motion track of the exoskeleton in advance, and only controls the exoskeleton robot according to the current interaction state of a human and the exoskeleton.
Further, compared with the existing control method, the lower limb exoskeleton human-computer interaction motion control method based on joint stress provided by the embodiment of the invention has the advantages of less required adjustment parameters, simplicity, intuition and easiness in understanding. In practical operation, the method for controlling the human-computer interaction motion of the lower extremity exoskeleton based on the joint stress provided by the embodiment of the invention only needs to adjust three parameters: a. therFor the reference posture position of the ankle joint in the interactive motion control process, the function of the parameter is that the current position of the ankle joint and the reference posture position ArA virtual spring damper is set, so that the farther the ankle joint deviates from the position, the greater the auxiliary force is exerted; k1The stiffness coefficient is used for adjusting the proportion of the influence of the deviation between the current position of the ankle joint and the reference position and the interaction moment on the expected speed of the exoskeleton; k2Is a damping coefficient which regulates the effect of the relevant parameters on the desired movement velocity of the exoskeleton, the larger the damping coefficient, the smaller the influence of the relevant parameters.
Furthermore, the method for controlling the human-computer interaction motion of the lower extremity exoskeleton based on joint stress provided by the embodiment of the invention is realized by changing K1Zero is set to achieve the follow-up control effect. Will K1Assistance with respect to the reference point can be achieved by setting to a certain value. By adjusting the control parameters, the same controller can achieve multiple control effects.
In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims (10)

1. A human-computer interaction control method for a lower limb exoskeleton based on joint stress is characterized by comprising the following steps:
establishing a leg kinematics model of an exoskeleton robot, the leg comprising a first leg and a second leg;
designing a support motion controller model of the exoskeleton robot in a support stage on the basis of the leg kinematics model;
designing a swing motion controller model of the exoskeleton robot in a swing stage on the basis of the leg kinematics model;
and respectively adopting a support motion controller model or a swing motion controller model to correspondingly control the motion of the first leg or the motion of the second leg according to the different stages of the first leg and the second leg.
2. The method of claim 1, wherein the leg kinematics model of the first leg is the same as the leg kinematics model of the second leg.
3. The method of claim 1, wherein the motion of the first leg is controlled using a support motion controller model while the first leg is in a support phase; and when the second leg is in a swinging stage, controlling the movement of the second leg by adopting a swinging movement controller model.
4. The method of claim 1, wherein the first leg is in a swing phase, and a swing motion controller model is used to control the motion of the first leg; and when the second leg is in the supporting stage, the movement of the second leg is controlled by adopting a supporting movement controller model.
5. The method of claim 1, wherein the leg kinematics model is a relationship between an ankle joint end velocity and each joint angular velocity of the exoskeleton robot, and the relationship is expressed by the following expression:
Figure RE-FDA0001990588430000011
wherein A isy＝Lusin(θ1)+Ldsin(θ1-θ2)，Az＝-Lucos(θ1)-Ldcos(θ1-θ2)，AyIndicating the coordinate of the ankle joint in the Y-axis, AzIndicating the coordinate of the ankle joint in the Z-axis, LuIs the thigh length, L, of the exoskeleton robotdThe length of the lower leg of the exoskeleton robot, theta1Angle of rotation, theta, for lifting the leg forward of the exoskeleton robot's hip joint2Is the bending angle of the knee joint of the exoskeleton robot.
6. The method of claim 5, wherein a Jacobian matrix for the legs of the exoskeleton robot is derived from the leg kinematics model, and is expressed as follows:
Figure RE-FDA0001990588430000021
wherein J is Jacobian matrix, LuIs the thigh length, L, of the exoskeleton robotdThe length of the lower leg of the exoskeleton robot, theta1Angle of rotation, theta, for lifting the leg forward of the exoskeleton robot's hip joint2Is the bending angle of the knee joint of the exoskeleton robot.
7. The method of claim 1, wherein the support motion controller model is a support desired angular velocity of a leg joint of the exoskeleton robot during a support phase, and the support desired angular velocity is expressed by the following equation:
Figure RE-FDA0001990588430000022
wherein, thetaZDesired angular velocities for support of leg joints of the exoskeleton robot; tau ishThe moment is the interaction moment between the human body and the exoskeleton robot borne by hip joints and knee joints of the exoskeleton robot; j is a Jacobian matrix which is obtained by the derivation of a leg kinematics model; a. the0Reference coordinates of the ankle joint of the exoskeleton robot in a supporting stage; a is the current desired speed of the ankle joint of the exoskeleton robot; k1Is a rigidity coefficient for adjusting the restoring force applied to the ankle joint when the ankle joint deviates from the reference posture; k2Is the elastic coefficient used to adjust the current desired velocity level of the ankle joint.
8. The method of claim 1, wherein the swing motion controller model is a desired swing angular velocity of a leg joint of the exoskeleton robot during a swing phase, and the desired swing angular velocity is expressed by the following equation:
Figure RE-FDA0001990588430000023
wherein, thetaBDesired angular velocities for the oscillations of the exoskeleton robot's leg joints; tau ishThe moment is the interaction moment between the human body and the exoskeleton robot borne by hip joints and knee joints of the exoskeleton robot; j is a Jacobian matrix which is obtained by the derivation of a leg kinematics model; a. therReference coordinates of the ankle joint of the exoskeleton robot in a swing stage; a is the current desired speed of the ankle joint of the exoskeleton robot; k1Is a rigidity coefficient for adjusting the restoring force applied to the ankle joint when the ankle joint deviates from the reference posture; k2Is the elastic coefficient used to adjust the current desired velocity level of the ankle joint.
9. The method for controlling human-computer interaction of the lower extremity exoskeleton of claim 7 or claim 8, wherein τ is a function of joint stresshObtained by numerical calculations taken by pressure sensors mounted at the thigh and calf.
10. The method of claim 1, wherein the exoskeleton robot comprises:
the leg part is used for assisting the legs of the person to walk;
the motor is connected with the leg part and is used for driving the leg part to move;
a wearable part connected with the leg part and the motor and used for fixing the exoskeleton robot to a human body;
a foot portion connected to the leg portion for supporting a foot of a person;
and the pressure sensor is used for acquiring pressure information of the exoskeleton robot in the walking process.
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