CN114888806B - Robust control method and device for under-actuated single-leg supporting hydraulic assistance exoskeleton - Google Patents
Robust control method and device for under-actuated single-leg supporting hydraulic assistance exoskeleton Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
- B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
- B25J9/00—Programme-controlled manipulators
- B25J9/0006—Exoskeletons, i.e. resembling a human figure
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Abstract
The invention relates to a robust control method and a device for an under-actuated single-leg supporting hydraulic power-assisted exoskeleton. The control method comprises the following steps: the method comprises the steps of obtaining state data of the exoskeleton, judging the supporting state of the foot of the exoskeleton leg, correcting the state data in real time according to the supporting state, establishing a physical model of the exoskeleton, converting the physical model into a state equation, obtaining reference displacement according to the state data and the state equation, obtaining expected driving moment according to the reference displacement, obtaining expected flow of an electrohydraulic servo valve according to the expected driving moment, generating a current signal according to the expected flow, driving all joints of the exoskeleton to rotate according to the current signal, and realizing tracking movement of the exoskeleton. Under the condition that the number of hydraulic cylinders is smaller than the number of the freedom degrees of the movements of the exoskeleton, the influence of multi-joint strong coupling of the exoskeleton, high-order nonlinearity of a hydraulic driver and model uncertainty is effectively overcome, and good tracking and power assisting effects of the exoskeleton on the movements of people are achieved.
Description
Technical Field
The invention relates to the field of robot control, in particular to a robust control method and a robust control device for an under-actuated single-leg supporting hydraulic assistance exoskeleton.
Background
The wearable lower limb assistance exoskeleton robot is an intelligent man-machine integrated device for simulating the lower limb structure of a human body, enhancing the walking durability, walking speed, loading capacity and other physical abilities of a wearer, and has important roles in rescue and relief work, building operation, improvement of individual combat capacity and other aspects. The combination of exoskeleton and person can adapt to unstructured environment, has excellent flexibility, and can complete complex work, which is incomparable with other complete mechanical equipment. The hydraulic driver has high power-weight ratio and can output enough force, so that the hydraulic driver is very suitable for a system with compact structure and heavy load, such as a lower limb assistance exoskeleton.
The total drive lower extremity exoskeleton system has the problems of overlarge dead weight and overlarge energy consumption due to the fact that the total drive lower extremity exoskeleton system comprises a plurality of drivers, and the load bearing capacity of the system and the cruising capacity of the portable energy supply system can be limited. In order to further reduce the weight and energy consumption of the assisting exoskeleton robot and enhance the flexibility of human body movement, the underdriven lower limb assisting exoskeleton robot is gradually proposed.
However, the reduction of the number of drivers and the inherent strong coupling high-order nonlinearity of the system and the modeling uncertainty all bring great difficulty to the design of an under-actuated lower limb hydraulic assistance exoskeleton robust control (ARC) algorithm. Specifically, first, the lack of control input to the fully-driven exoskeleton results in a control method for the fully-driven exoskeleton that cannot be directly used in the fully-driven exoskeleton system, as compared to the fully-driven exoskeleton. Secondly, the under-actuated lower limb hydraulic exoskeleton system has strong coupling high-order nonlinearity and various model uncertainties, so that the requirement on the robust performance of a control algorithm is high. The existing under-driven lower limb hydraulic exoskeleton control method is poor in man-machine interaction force control accuracy and weak in system robustness.
Disclosure of Invention
Based on the above, it is necessary to provide a robust control method and device for an under-actuated single-leg support hydraulic power-assisted exoskeleton, aiming at the problem of poor man-machine interaction control precision of the exoskeleton.
A robust control method of an under-actuated single-leg support hydraulic assistance exoskeleton is used for realizing tracking movement of the under-actuated hydraulic assistance exoskeleton. Wherein, underactuated hydraulic assistance exoskeleton includes: the device comprises a right foot plate, a left foot plate, a first rod piece, a second rod piece, a third rod piece, a fourth rod piece, a right leg knee joint hydraulic cylinder, a left leg knee joint hydraulic cylinder, a back plate, a right leg hip joint hydraulic cylinder, a left leg hip joint hydraulic cylinder, an electrohydraulic servo valve, a plurality of sensors and a real-time controller.
The upper end of the backboard is fixedly connected with a back binding belt, and the lower end of the backboard is fixedly connected with a waist binding belt. One end of each of the first rod piece and the third rod piece is rotatably connected with the lower end of the backboard. The other end of the first rod piece is rotatably connected with the top end of the second rod piece, and the other end of the third rod piece is rotatably connected with the top end of the fourth rod piece. The right leg knee joint hydraulic cylinder is connected between the first rod piece and the second rod piece and used for driving the first rod piece and the second rod piece to generate relative rotation. The right leg hip joint hydraulic cylinder is connected between the back plate and the first rod piece and used for driving the back plate and the first rod piece to rotate relatively. The left leg knee joint hydraulic cylinder is connected between the third rod piece and the fourth rod piece and used for driving the third rod piece and the fourth rod piece to generate relative rotation. The left leg hip joint hydraulic cylinder is connected between the back plate and the third rod piece and used for driving the back plate and the third rod piece to rotate relatively. The right foot plate is rotatably connected with the bottom end of the second rod piece. The right foot plate, the first rod piece and the second rod piece jointly form a right leg foot part. The left foot plate is rotatably connected with the bottom end of the fourth rod piece. The left foot plate, the third rod piece and the fourth rod piece jointly form a left leg foot part. The right foot plate is fixedly connected with a first foot binding band, and the left foot plate is fixedly connected with a second foot binding band. The electrohydraulic servo valve is respectively communicated with the right leg knee joint hydraulic cylinder, the left leg knee joint hydraulic cylinder, the right leg hip joint hydraulic cylinder and the left leg hip joint hydraulic cylinder and is used for controlling the running states of the right leg knee joint hydraulic cylinder, the left leg knee joint hydraulic cylinder, the right leg hip joint hydraulic cylinder and the left leg hip joint hydraulic cylinder. The sensors are respectively arranged at different positions of the exoskeleton and are used for collecting state data of the underactuated hydraulic double-leg power-assisted exoskeleton. The real-time controller is used for outputting the control quantity of the hydraulic cylinders according to the state data and controlling the running state of each hydraulic cylinder according to the control quantity of the hydraulic cylinders. The controller comprises an upper controller, a middle controller and a lower controller. The upper controller is used for outputting a human motion prediction track, the middle controller is used for outputting an exoskeleton expected output force, and the lower controller is used for outputting a current signal and controlling the running state of the hydraulic cylinder according to the current signal to realize the track tracking of the exoskeleton.
The robust control method is characterized by comprising the following steps:
s1: setting the sampling period of the real-time controller.
S2: status data of the exoskeleton is obtained. The state data includes feature data and motion data. The motion data includes: back force, foot force, actual angle values of each joint of the exoskeleton, actual pressure of the knee joint hydraulic cylinder, actual pressure of the hip joint hydraulic cylinder and foot supporting force.
S3: and respectively judging the motion states of the left leg foot part and the right leg foot part, and correcting the state data in real time according to the motion states. The method for judging the motion state comprises the following steps: and respectively judging whether the left leg foot part and the right leg foot part exert pressure on the ground, if so, taking the left leg foot part or the right leg foot part as swinging legs, and otherwise, taking the left leg foot part or the right leg foot part as supporting legs.
S4: and establishing a physical model of the under-actuated single-leg supporting hydraulic assistance exoskeleton. The physical model is converted into a state equation based on the state data. The physical model includes: a human-machine interface model, a motion model of an exoskeleton, a complete constraint model, and a dynamics model of a hydraulic drive.
S5: a reference displacement of the exoskeleton is obtained in the upper controller according to the back acting force and the foot acting force. And acquiring the actual displacement of the contact position of the exoskeleton backboard and the swing leg and foot part in the movement model of the exoskeleton according to the actual angle value. And acquiring the expected driving moment in the middle layer controller according to the reference displacement and the actual displacement. And acquiring the actual output force of the knee joint hydraulic cylinder in a dynamic model of the hydraulic driver according to the actual pressure of the knee joint hydraulic cylinder. And acquiring the actual output force of the hip joint hydraulic cylinder in a dynamic model of the hydraulic driver according to the actual pressure of the hip joint hydraulic cylinder. And obtaining the expected flow of the electrohydraulic servo valve in the lower-layer controller according to the expected driving moment, the actual output force of the knee joint hydraulic cylinder and the actual output force of the hip joint hydraulic cylinder.
S6: a voltage signal is generated based on the desired flow rate. And generating a corresponding current signal in the electrohydraulic servo valve according to the voltage signal.
S7: the valve core opening displacement of the corresponding knee joint electrohydraulic servo valve and the corresponding hip joint electrohydraulic servo valve is controlled through the current signals, so that the pressure at two ends of the hydraulic cylinder is controlled, each hydraulic cylinder is pushed to move, each joint of the underactuated single-leg support hydraulic power-assisted exoskeleton is driven to rotate, and the tracking movement of the underactuated single-leg support hydraulic power-assisted exoskeleton is realized.
The invention adopts a force control method, is based on an under-actuated single-leg supporting hydraulic power-assisted exoskeleton overall dynamics model, utilizes a multi-input multi-output self-adaptive robust control algorithm to design an upper controller, a middle controller and a lower controller, effectively overcomes the influence of multi-joint strong coupling and model uncertainty of the under-actuated single-leg supporting hydraulic power-assisted exoskeleton, solves the technical problems of poor man-machine interaction force control precision and weak system robustness of the existing exoskeleton control method, realizes good following and power-assisted effects of the power-assisted exoskeleton on human motions, and has higher application value.
In one embodiment, the human interface model is:
wherein F is hm ＝[F hmubx F hmuby τ eubz F hmrx F hmry τ erz ] T Force applied by human machine, F hmubx 、F hmuby Respectively representing components of back man-machine acting force in x and y directions, tau eubz To assume the moment of the human body on the back, F hmrx 、F hmry Respectively representing components of human-machine acting force of leg swinging foot in x and y directions, tau erz To assume the moment of a human body on the foot of the swing leg; k=diag { K ubx ,K uby ,K ubz ,K rx ,K ry ,K rz Human interface stiffness, where K ubx 、K uby 、K ubz 、K rx 、K ry 、K rz The components of the human-machine interface stiffness of the waist and the swing leg foot in the x, y and z directions are respectively; x is x hs ＝[x hubx x huby x hubz x hrx x hry x hrz ] T Is the displacement of the wearer, where x hubx 、x huby 、x hubz Representing the x, y and z three-directional components of the displacement of the wearer's back contactAn amount of; x is x hrx 、x hry 、x hrz Representing the components of the displacement of the contact part of the swing leg and the foot of the wearer in the x, y and z directions respectively, x es ＝[x eubx x euby x eubz x erx x ery x erz ] T For the displacement of exoskeleton, period x eubx 、x euby 、x eubz Respectively representing components of displacement of the waist and back contact part of the exoskeleton in the x, y and z directions; x is x erx 、x ery 、x erz Representing the components of displacement of the foot contact part of the swing leg of the exoskeleton in the x, y and z directions respectively;is a centralized model uncertainty and disturbance on the human-machine interface.
By integration of man-machine forcesInstead of F hm The state equation of the obtained human-machine interface model is:
in one embodiment, the exoskeleton motion model is:
wherein T is act For the driving moment of the joint, Wherein J ub As jacobian matrix at waist, J r Jacobian matrix for foot, q c For the angle of the joint, M Lsp Is an inertial matrix, C Lsp For centrifugal and coriolis force matrices, G Lsp Is a gravity matrix, B is a damping matrix, +.>Is a centralized modeling error, +.>For joint angular velocity>Is the angular acceleration of the joint.
The motion model is further converted into:
in the method, in the process of the invention,F hmubxy ＝[F hmubx F hmuby ] T ；F hmrxy ＝[F hmrx F hmry ] T ，
for the displacement speed of exoskeleton, +.>Is the displacement acceleration of the exoskeleton.
In one embodiment, the complete constraint model is:
x eubz ＝x eubzd (t),x erz ＝x erzd (t)
second derivative of the complete constraint model:
wherein x, y and z are three-dimensional coordinate axis symbols respectively, and x is eubz For the rotation amount in z direction of back contact with human body, x erz For swinging the rotation amount in z direction of the foot contact of the leg and the human body, x eubzd (t) is the known ideal back trajectory, x erzd (t) is a known ideal trajectory for the swing leg foot,is x eubz Second derivative of>Is x eubzd Second derivative of (t)/(t)>Is x erz Second derivative of>Is x erzd (t) a second derivative of (c).
Determination ofBack moment τ eubz Moment tau of swing leg foot erz The method can obtain:
wherein x is ea ＝[x eubx x euby x erx x ery ] T ， U 9 ＝[U 5 U 7 ]，/> 0 1×2 ＝[0 0]，0 1×4 ＝[0 0 0 0]，
In one embodiment, the dynamics model of the hydraulic drive is:
x vi ＝u i ,i＝2,3,4,5
wherein τ 2 、τ 3 、τ 4 、τ 5 Respectively the driving moment of the knee joint of the supporting leg, the hip joint of the swinging leg and the knee joint of the swinging leg, and x Li Is the displacement amount of the hydraulic cylinder,is x Li Regarding q i First order partial derivative of P 1i 、P 2i 、A 1i And A 2i Respectively representing absolute pressure and acting area of two chambers in hydraulic cylinder, V 1i 、V 2i The total volume of the two chambers in the hydraulic cylinder, V h1i 、V h2i Is q i Two-chamber volume of hydraulic cylinder at =0, β e Represents the effective bulk modulus, Q 1i 、Q 2i Respectively the supply and return of the hydraulic cylinder, k q1i 、k q2i The flow gain coefficients of two loops of the hydraulic cylinder are respectively x vi Is the displacement value of the valve core, P s Is the oil supply pressure, P r Is the pressure in the tank, < >>Representing respectively the centralized modeling error and the uncertain disturbance in the dynamics model of the hydraulic driver, tau i For each joint moment, u i For the voltage of both ends of each joint hydraulic valve, delta P 1i For the pressure difference of the left chamber of each hydraulic cylinder, delta P 2i Is the pressure difference of the right chamber of each hydraulic cylinder.
In one embodiment, the state equation is:
T act ＝hF L
Q L ＝K q u
wherein K is xya ＝diag{K ubx ,K uby ,K rx ,K ry }，F hmxy ＝[F hmubx F hmuby F hmrx F hmry ] T ，/>x 4a ＝[P 12 P 13 P 14 P 15 ] T ，x 5a ＝[P 22 P 23 P 24 P 25 ] T ，A 1 ＝diag{A 12 ,A 13 ,A 14 ,A 15 }，A 2 ＝diag{A 22 ,A 23 ,A 24 ,A 25 }，F L ＝A 1 x 4a -A 2 x 5a ，/> Respectively x 1a 、x 2a 、x 3a First derivative of (delta) 1an 、Δ 3an 、Δ 4an A constant part, delta, of the centralized uncertainty of the man-machine interface, the mechanical system and the hydraulic system, respectively 1a 、Δ 3a 、Δ 4a Time-varying part of the centralized uncertainty of man-machine interface, mechanical system and hydraulic system, respectively, +.>Is F L First derivative of Q L For the flow of the hydraulic cylinder, K q ＝diag{K q2 ,K q3 ,K q4 ,K q5 }，/>
In one embodiment, the control method of the upper layer controller includes the following steps:
According to the state equation, a first tracking error z is set 1a Is z 1a ＝x 1a -x 1ad Wherein x is 1a 、x 1ad The integration of the desired human machine effort in the x, y directions for the back and swing legs;
then control the first virtual control input x m The method of (1) is as follows: x is x m ＝x ma +x ms +x msn Wherein, the method comprises the steps of, wherein,x ms ＝K 1 z 1a ，x msn is a first robust feedback term; f (f) θF And Y θF Is composed of x ma Is obtained by linearizing the parameters of K 1 Is a first linear feedback gain matrix, +.>Respectively represent K f 、Δ 1an Estimated value of ∈10->Is theta F Estimate of (2), estimate->In the upper controller, the adaptive rate is +.>Obtained by the method, whereinK θa ＝[1/K ubx 1/K uby 1/K rx 1/K ry ] T ，/>Is K θa Is (t) is (are) the estimated value of (f) 1 Is a first positive gain matrix, +.>Is x 1ad Is a first derivative of (a). />The mapping function of (2) is:
in the formula (I) i As an independent variable, θ Fmaxi ，θ Fmini Respectively is theta F Maximum and minimum values of the i-th element.
According to a first virtual control input x mi I=1, 2,3,4, and performing smoothing treatment through a third-order filter to obtain reference displacement, reference speed and reference acceleration of the exoskeleton; the state equation of the third-order filter is as follows:
i＝1,2,3,4
x i (1)、x i (2)、x i (3) Representing the filtered reference displacement, reference velocity and reference acceleration respectively,is x i (1) First derivative of>Is x i (2) First derivative of>Is x i (3) Let y be i Representing exoskeleton reference displacement, a 1 、a 2 、a 3 Are all control parameters, set y i (s)＝x mi (s), then y i To x i (1) The transfer function G(s) is:
obtaining a desired smoothed exoskeleton reference displacement x by a transfer function i (1)。
In one embodiment, the control method of the middle layer controller includes the following steps:
setting a second tracking errorWherein->Defining a conversion equation:
wherein K is 2 Taking the arbitrary non-negative number of the number,is z 2 First derivative of>Is x r Is the first derivative of z 3 Is a third tracking error; k (K) 2i Represent K 2 Is the i-th element of (a);
let B xea x 3a ＝Y B B θ ，Wherein beta is a model parameter of the mechanical structure, B θ As a matrix of damping coefficients for each joint, B θ ＝[B 1 B 2 B 3 B 4 B 5 B 6 ] T ，B 1 、B 2 、B 3 、B 4 、B 5 、B 6 Respectively represent a supporting leg ankle joint, a supporting leg knee joint, a supporting leg hip joint and a swinging leg hip jointDamping coefficients at the swing leg knee joint and swing leg ankle joint.
Then control tau actd The method of (1) is as follows: τ act ＝τ acta +τ acts +τ actsn Wherein τ actsn For the second robust feedback term,K 3 is a third linear feedback gain matrix, +.> Respectively is beta, B θ 、Δ 3an Estimated value of ∈10->To the parameter theta q Estimate of +.>Minimum value->To the parameter theta q Estimate of +.>Maximum value of θ qmaxi 、θ qmini Respectively is theta q Maximum and minimum values of the i-th element, < ->The value of (2) is determined by the adaptation rate in the lower controller>Obtained by phi 3 ＝[Y Y B I 4×4 ] T ，/>Γ 2 Is a second positive gain matrix. / >The mapping function of (2) is:
in the formula (I) i Is an independent variable.
In one embodiment, the control method of the lower controller includes the following steps:
definition of fourth tracking error z 4 ＝F L -F Ld Wherein F L For the actual output force of the hydraulic cylinder, F Ld Is the desired output force of the hydraulic cylinder;
the error equation at this stage is written as:wherein->Is F Ld Is the first derivative of (a);
control Q L The method of (1) is as follows: q (Q) Ld ＝Q Lda +Q Lds Wherein Q is Ld For the desired flow rate of the hydraulic cylinder, Q Lda Providing robust feedback term for flow, Q Lds Robust feedback terms are reflowed for traffic.K 4 Is a fourth linear feedback gain matrix, beta emin Is beta e Is a minimum of (2). Phi (phi) 4c ＝[-q v I 4×4 ] T ，/>φ 4 ＝[Q Lda -q v I 4×4 ] T ，/>Is to beta e 、Δ 4an Estimated value of θ u ＝[β e Δ 4an T ] T ；/>Wherein Q is Ldsn For the third robust feedback term, +.>To the parameter theta u Estimate of +.>Minimum value->To the parameter theta u Estimate of +.>Is the maximum value of (2); estimate->The value of (2) is determined by the adaptation rate in the lower controller>Obtained by the method, whereinΓ 3 Is a third positive gain matrix, +.>The mapping function of (2) is:
in θ umaxi ，θ umini Respectively is theta u Maximum value of ith elementAnd minimum, · i Is an independent variable;
and generating a voltage signal according to the expected flow, and generating a corresponding current signal in the electrohydraulic servo valve according to the voltage signal. Let Q Ld ＝[Q Ld2 Q Ld3 Q Ld4 Q Ld5 ] T Wherein Q is Ld2 、Q Ld3 、Q Ld4 、Q Ld5 The expected output flow of the knee joint servo valve of the supporting leg, the expected output flow of the hip joint servo valve of the supporting leg, the expected output flow of the knee joint servo valve of the swinging leg and the expected output flow of the hip joint servo valve of the swinging leg are respectively calculated according to the virtual control input Q L The control voltage u of the electro-hydraulic servo valve is obtained as follows:
the invention also provides a robust control device of the under-actuated single-leg supporting hydraulic assistance exoskeleton, which comprises: the system comprises a data acquisition module, an initialization module, a model establishment module, a data processing module, a current signal generation module and a tracking control module.
The data acquisition module is used for acquiring the status data of the exoskeleton. The state data includes feature data and motion data. The motion data includes: back force, foot force, actual angle values of each joint of the exoskeleton, actual pressure of the knee joint hydraulic cylinder, actual pressure of the hip joint hydraulic cylinder and foot supporting force. The characteristic data comprise man-machine interface rigidity, waist rigidity, leg and foot rigidity, chamber volume of the hydraulic cylinder and damping coefficients of all joints.
The support state judging module is used for judging whether the left leg foot part and the right leg foot part exert pressure on the ground or not respectively, if yes, the left leg foot part or the right leg foot part is taken as a swinging leg, and if not, the left leg foot part or the right leg foot part is taken as a support leg.
The initialization module is used for initializing the sampling period of the real-time controller. The initialization module is also used for controlling the foot plate to rotate to a horizontal position and controlling the first rod piece, the second rod piece and the back to rotate to a vertical position.
The model building module is used for building a physical model of the exoskeleton according to the characteristic data and converting the physical model into a state equation. Wherein the physical model comprises: a human-machine interface model, a motion model of an exoskeleton, a dynamics model of a hydraulic drive, a complete constraint model.
The data processing module is used for acquiring reference displacement of the exoskeleton in the upper-layer controller according to the back acting force and the foot acting force, acquiring actual displacement of the backboard in the motion model of the exoskeleton according to the actual angle value, and acquiring expected driving moment according to the reference displacement and the actual displacement. The data processing module is also used for obtaining the actual output force of the knee joint hydraulic cylinder in the dynamic model of the hydraulic driver according to the actual pressure of the knee joint hydraulic cylinder, obtaining the actual output force of the hip joint hydraulic cylinder in the dynamic model of the hydraulic driver according to the actual pressure of the hip joint hydraulic cylinder, and obtaining the expected flow of the electrohydraulic servo valve according to the expected driving moment, the actual output force of the knee joint hydraulic cylinder and the actual output force of the hip joint hydraulic cylinder.
The current signal generation module is used for generating corresponding current signals according to the expected flow of the electrohydraulic servo valve.
The tracking control module is used for controlling the rotation of each joint of the exoskeleton according to the current signals, so that the track tracking of the exoskeleton is realized.
Compared with the existing exoskeleton control method, the robust control method of the underactuated single-leg support hydraulic assistance exoskeleton has the following beneficial effects:
1. the invention adopts a force control method, utilizes a multi-input multi-output self-adaptive robust control algorithm, and adopts a cascade force control method to design an upper-layer controller, a middle-layer controller and a lower-layer controller. Under the condition that the number of control inputs is less than the number of the degrees of freedom of the movements of the exoskeleton, the influence of strong coupling of multiple joints and uncertainty of the model of the exoskeleton is effectively overcome, feedforward compensation is performed on the control model to ensure zero tracking error under static state, dynamic characteristics and stability of the exoskeleton are ensured through designed robust feedback, the technical problems of poor man-machine interaction force control precision and weak system robust performance of the existing control method of the hydraulic assistance exoskeleton of the lower limbs are solved, good tracking and assistance effects of the assistance exoskeleton on human movements are achieved, and high application value is achieved.
2. The exoskeleton power system adopts a hydraulic driving mode which has the characteristics of small volume, light weight, flexible layout, compact mechanism, capability of outputting larger force or torque, sensitive action response, easiness in control and the like.
3. The sensor system of the invention mainly realizes more effective and reliable man-machine interaction by the force sensor and the rotary encoder, and aims at exoskeleton reinforcement and tracking problems, and the exoskeleton is converted into a full-drive system by considering the complete constraint provided by a wearer.
4. In the exoskeleton, the ankle joint is driven passively, and a driver is not arranged, so that the exoskeleton has lighter weight, better cruising ability of a portable energy supply system and higher load performance.
5. The invention fully considers the control action of the wearer on the exoskeleton, reduces the use of the hydraulic cylinder and the energy consumption, is effective and reliable in man-machine interaction problem, and has the characteristic of quick response to the movement intention of the human body.
6. In the invention, the exoskeleton wearer is taken as a participant for system control, and in a walking plane, the wearer can ensure the forward and backward walking balance of the whole system, so that the exoskeleton is prevented from falling down. Meanwhile, the control method of the invention designs the upper, middle and lower controllers by utilizing a cascade control strategy, realizes track planning and track tracking of the under-actuated power-assisted exoskeleton, has simple realization, is easy for engineering realization and is flexible to control.
Drawings
Fig. 1 is a schematic perspective view of an under-actuated hydraulic assist exoskeleton according to embodiment 1 of the present invention.
Fig. 2 is a schematic diagram of the front view of the under-actuated hydraulic assist exoskeleton of fig. 1.
Fig. 3 is a control flow chart of a robust control method of the under-actuated single-leg support hydraulic assist exoskeleton of embodiment 1 of the present invention.
Fig. 4 is a step diagram of a robust control method of an under-actuated single-leg support hydraulic assist exoskeleton of embodiment 1 of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It is noted that when an element is referred to as being "mounted to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "secured to" another element, it can be directly secured to the other element or intervening elements may also be present.
Unless defined otherwise, 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 invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or/and" as used herein includes any and all combinations of one or more of the associated listed items.
Referring to fig. 1 and 2, fig. 1 is a schematic perspective view of an under-actuated hydraulic power-assisted exoskeleton according to embodiment 1 of the present invention; fig. 2 is a schematic diagram of the front view of the under-actuated hydraulic assist exoskeleton of fig. 1. The under-actuated hydraulic assistance exoskeleton comprises: the device comprises a right foot plate, a left foot plate, a first rod piece, a second rod piece, a third rod piece, a fourth rod piece, a right leg knee joint hydraulic cylinder, a left leg knee joint hydraulic cylinder, a back plate, a right leg hip joint hydraulic cylinder, a left leg hip joint hydraulic cylinder, an electrohydraulic servo valve, a plurality of sensors and a real-time controller.
The upper end of the backboard is fixedly connected with a back binding belt, and the lower end of the backboard is fixedly connected with a waist binding belt. One end of each of the first rod piece and the third rod piece is rotatably connected with the lower end of the backboard. The other end of the first rod piece is rotatably connected with the top end of the second rod piece, and the other end of the third rod piece is rotatably connected with the top end of the fourth rod piece. The right leg knee joint hydraulic cylinder is connected between the first rod piece and the second rod piece and used for driving the first rod piece and the second rod piece to generate relative rotation. The right leg hip joint hydraulic cylinder is connected between the back plate and the first rod piece and used for driving the back plate and the first rod piece to rotate relatively. The left leg knee joint hydraulic cylinder is connected between the third rod piece and the fourth rod piece and used for driving the third rod piece and the fourth rod piece to generate relative rotation. The left leg hip joint hydraulic cylinder is connected between the back plate and the third rod piece and used for driving the back plate and the third rod piece to rotate relatively. The right foot plate is rotatably connected with the bottom end of the second rod piece. The right foot plate, the first rod piece and the second rod piece jointly form a right leg foot part. The left foot plate is rotatably connected with the bottom end of the fourth rod piece. The left foot plate, the third rod piece and the fourth rod piece jointly form a left leg foot part. The right foot plate is fixedly connected with a first foot binding band, and the left foot plate is fixedly connected with a second foot binding band. The back binding band is bound on the back of a human body, and the waist binding band is bound on the waist of the human body, so that the exoskeleton is worn on the human body. The first and second back straps and the waist strap of the foot strap can be elastic straps, so that when the exoskeleton fails, the wearer can quickly take off the exoskeleton, and damage to the human body caused by the exoskeleton in an emergency situation is prevented. The connection between the right foot plate and the second rod piece is defined as a right ankle joint, the connection between the left foot plate and the fourth rod piece is defined as a left ankle joint, the connection between the first rod piece and the second rod piece is defined as a right leg knee joint, the connection between the third rod piece and the fourth rod piece is defined as a left leg knee joint, the connection between the first rod piece and the back plate is defined as a right leg hip joint, and the connection between the third rod piece and the back plate is defined as a left leg hip joint. The right foot plate, the first rod piece and the second rod piece jointly form a right leg foot part, and the left foot plate, the third rod piece and the fourth rod piece jointly form a left leg foot part. The junction of the exoskeleton and the waist of the wearer is defined as the exoskeleton waist. The junction of the back plate and the wearer is defined as the exoskeleton back.
The electrohydraulic servo valve is respectively communicated with the right leg knee joint hydraulic cylinder, the left leg knee joint hydraulic cylinder, the right leg hip joint hydraulic cylinder and the left leg hip joint hydraulic cylinder and is used for controlling the running states of the right leg knee joint hydraulic cylinder, the left leg knee joint hydraulic cylinder, the right leg hip joint hydraulic cylinder and the left leg hip joint hydraulic cylinder. The sensors are respectively arranged at different positions of the exoskeleton and are used for collecting state data of the underactuated hydraulic double-leg power-assisted exoskeleton. The plurality of sensors includes a back force sensor, a foot force sensor, a rotary encoder, a knee hydraulic cylinder actual pressure sensor, a hip hydraulic cylinder actual pressure sensor, and a foot support force sensor. The back force sensor is mounted on the back plate for acquiring back force. The foot force sensor is mounted on the foot plate for acquiring foot force. A rotary encoder is mounted at each joint of the exoskeleton for acquiring the actual angles of each joint of the exoskeleton. The knee joint hydraulic cylinder actual pressure sensors are arranged at the left leg knee joint and the right leg knee joint and are used for acquiring the actual pressures of the right leg knee joint hydraulic cylinder and the left leg knee joint hydraulic cylinder. The actual pressure sensors of the hip joint hydraulic cylinders are arranged at the positions of the right leg hip joint and the left leg hip joint and are used for acquiring the actual pressures of the right leg hip joint hydraulic cylinders and the left leg hip joint hydraulic cylinders. The foot support force sensor is installed on the right foot plate and the left foot plate and is used for acquiring right foot support force and left foot support force. The real-time controller is used for outputting the control quantity of the hydraulic cylinders according to the state data and controlling the running state of each hydraulic cylinder according to the control quantity of the hydraulic cylinders. The controller comprises an upper controller, a middle controller and a lower controller. The upper controller is used for outputting a human motion prediction track, the middle controller is used for outputting an exoskeleton expected output force, and the lower controller is used for outputting a current signal and controlling the running state of the hydraulic cylinder according to the current signal to realize the track tracking of the exoskeleton.
Referring to fig. 3 and 4, fig. 3 is a control flow chart of a robust control method of the under-actuated single-leg supporting hydraulic assistance exoskeleton of the present embodiment; fig. 4 is a step diagram of a robust control method of the under-actuated single-leg support hydraulic assist exoskeleton of the present embodiment. The robust control method comprises the following steps:
s1: setting the sampling period of the real-time controller. The exoskeleton is adjusted to an initialized state, namely the foot plate is controlled to rotate to a horizontal position, and the first rod piece, the second rod piece and the back are controlled to rotate to a vertical position. In this embodiment, the sampling period is set to between 10-20 ms.
S2: status data of the exoskeleton is obtained. The state data includes feature data and motion data. The motion data includes: back force, foot force, actual angle values of each joint of the exoskeleton, actual pressure of the knee joint hydraulic cylinder, actual pressure of the hip joint hydraulic cylinder and foot supporting force. The characteristic data includes: man-machine interface stiffness, waist stiffness, leg-foot stiffness, chamber volume of the hydraulic cylinder, and joint damping coefficients.
S3: and respectively judging the motion states of the left leg foot part and the right leg foot part, and correcting the state data in real time according to the motion states. The method for judging the motion state comprises the following steps: and respectively judging whether the left leg foot part and the right leg foot part exert pressure on the ground, if so, taking the left leg foot part or the right leg foot part as swinging legs, and otherwise, taking the left leg foot part or the right leg foot part as supporting legs. In the process of movement of the human body, the left leg or the right leg of the human body can be in a supporting state or a swinging state, namely, the left leg or the right leg of the human body can be used as a supporting leg at a certain moment or can be used as a swinging leg. The pressure signals of the two legs of the human body are obtained in real time by installing foot pressure sensors under the feet or the foot plates of the exoskeleton of the human body, so that the two legs and the leg parts of the exoskeleton of the human body are judged to be in a supporting state or a swinging state.
S4: and establishing a physical model of the under-actuated single-leg supporting hydraulic assistance exoskeleton, and converting the physical model into a state equation according to the state data. The physical model includes: a human-machine interface model, a motion model of an exoskeleton, a complete constraint model, and a dynamics model of a hydraulic drive.
Wherein, the human-machine interface model can be expressed as:
wherein F is hm To correspond to the man-machine acting force of the back and the leg of the swing leg, F hm ＝[F hmubx F hmuby τ eubz F hmrx F hmry τ erz ] T ，F hmubx 、F hmuby Respectively representing components of back man-machine acting force in x and y directions, tau eubz For back moment, F hmrx 、F hmry Respectively representing components of human-machine acting force of leg swinging foot in x and y directions, tau erz For swinging leg and foot moment. K=diag { K ubx ,K uby ,K ubz ,K rx ,K ry ,K rz (where K) ubx 、K uby 、K ubz 、K rx 、K ry 、K rz The components of the waist and swing leg foot human-machine interface stiffness in the x, y, z directions, x hs For displacement of the wearer, x es For displacement of exoskeleton, x hs ＝[x hubx x huby x hubz x hrx x hry x hrz ] T ，x es ＝[x eubx x euby x eubz x erx x ery x erz ] T The method comprises the steps of carrying out a first treatment on the surface of the Wherein x is hubx 、x huby 、x hubz Representing components of displacement in three directions of x, y and z at the back contact of the wearer respectively; x is x hrx 、x hry 、x hrz Representing components of the foot displacement of the swing leg of the wearer in the x, y and z directions respectively; x is x eubx 、x euby 、x eubz Representing the components of the exoskeleton waist displacement in the x, y and z directions respectively; x is x erx 、x ery 、x erz Representing the components of foot displacement of the swing leg of the exoskeleton in the x, y and z directions respectively; Is a centralized model uncertainty and disturbance on the human-machine interface.
By integration of man-machine forcesInstead of F hm The state equation of the obtained human-machine interface model is:
the kinematic model of the exoskeleton can be expressed as:
wherein x, y and z are three-dimensional coordinate axis symbols respectively, T act ＝[τ 2 τ 3 τ 4 τ 5 ] T Is the joint driving moment, wherein tau 2 、τ 3 、τ 4 、τ 5 Respectively the driving moment of the knee joint of the supporting leg, the hip joint of the swinging leg and the knee joint of the swinging leg,wherein J ub 、J r Jacobian matrices at waist and swing legs, respectively, q c ＝[q 1 q 2 q 3 q 4 q 5 q 6 ] T Is the joint angle, wherein q 1 、q 2 、q 3 、q 4 、q 5 、q 6 The rotation angles of the supporting leg ankle joint, the supporting leg knee joint, the supporting leg hip joint, the swinging leg knee joint and the swinging leg ankle joint are respectively M Lsp Is an inertial matrix, C Lsp Is a matrix of centrifugal and coriolis forces, G Lsp Is a gravity matrix, B is a damping matrix, +.>Is a centralized modeling error, +.>For angular velocity +.>Is angular acceleration.
The motion model is further converted into:
in the method, in the process of the invention,F hmubxy ＝[F hmubx F hmuby ] T ；F hmrxy ＝[F hmrx F hmry ] T ，/>for the displacement speed of exoskeleton, +.>Is the displacement acceleration of the exoskeleton.
The complete constraint model can be expressed as:
x eubz ＝x eubzd (t),x erz ＝x erzd (t)
second derivative of the complete constraint model:
wherein x is eubz For the rotation amount in z direction of back contact with human body, x erz For swinging the rotation amount in z direction of the foot contact of the leg and the human body, x eubzd (t) is the known ideal back trajectory, x erzd (t) is a known ideal trajectory for the swing leg foot,is x eubz Second derivative of>Is x eubzd Second derivative of (t)/(t)>Is x erz Is used for the first derivative of (c),is x erzd (t) a second derivative of (c).
Determination ofBack moment τ eubz Moment tau of foot erz The method can obtain:
wherein x is ea ＝[x eubx x euby x erx x ery ] T ，Is x ea Second derivative of>Is x ea First derivative of>/> 0 1×2 ＝[0 0]，0 1×4 ＝[0 0 0 0]，/>Is x eubz First derivative of>Is x erz Is used as a first derivative of (a),
the dynamics model of the hydraulic drive can be expressed as:
x vi ＝u i ,i＝2,3,4,5
wherein x is Li Is the displacement amount of the hydraulic cylinder,is x Li Regarding q i First order partial derivative of P 1i 、P 2i 、A 1i And A 2i Respectively representing absolute pressure and acting area of two chambers in hydraulic cylinder, V 1i And V 2i The total volume of the two chambers in the hydraulic cylinder, V 1i ＝V h1i +A 1i x Li ，V 2i ＝V h2i +A 2i x Li ，V h1i 、V h2i Is q i Two-chamber volume of hydraulic cylinder at =0, β e Represents the effective bulk modulus, Q 1i 、Q 2i Respectively the supply and return of the hydraulic cylinder, k q1i 、k q2i The flow gain coefficients of two loops of the hydraulic cylinder are respectively x vi Is the displacement value of the valve core, P s Is the oil supply pressure, P r Is the pressure in the tank, < >>Representative of concentrated modeling errors and uncertain disturbances in a hydraulic drive dynamics model, τ i For each joint moment, u i For the voltage of both ends of each joint hydraulic valve, delta P 1i For the pressure difference of the left chamber of each hydraulic cylinder, delta P 2i Is the pressure difference of the left chamber of each hydraulic cylinder.
The method for converting the physical model into the state equation comprises the following steps:
let state variablesWherein F is hmxy ＝[F hmubx F hmuby F hmrx F hmry ] T ，/>x 4a ＝P 1 ＝[P 12 P 13 P 14 P 15 ] T ，x 5a ＝P 2 ＝[P 22 P 23 P 24 P 25 ] T ，，/>Is x ea Is a first derivative of (a).
Set up centralized model uncertaintyThe method comprises the following steps:
wherein delta is in And delta i Respectively representConstant part and time-varying part of +.>Respectively a man-machine interface, a mechanical system and a liquidCentralized uncertainty of the compression system, set +.> Wherein K is θa Is a rigid matrix, K θa ＝[1/K ubx 1/K uby 1/K rx 1/K ry ] T ，Δ 1an ＝[Δ 1anxub Δ 1anyub Δ 1anxr Δ 1anyr ] T Wherein delta is 1anxub ,Δ 1anyub ,Δ 1anxr ,Δ 1anyr Respectively represent delta 1an Components in the x, y directions of the back and swing leg foot; beta= [ M ] 0 Y 1 Y 2 Y 3 X 4 Y 4 Y 5 Y 6 Y 7 J 1 J 2 J 3 J 4 J 5 J 6 J 7 ] T Is a system parameter of the exoskeleton, wherein M 0 、Y 1 、Y 2 、Y 3 、X 4 、Y 4 、Y 5 、Y 6 、Y 7 、J 1 、J 2 、J 3 、J 4 、J 5 、J 6 、J 7 System parameters for exoskeleton support legs; b (B) θ ＝[B 1 B 2 B 3 B 4 B 5 B 6 ] T ，B 1 、B 2 、B 3 、B 4 、B 5 、B 6 Damping coefficients of joint rotation at the positions of the support leg ankle joint, the support leg knee joint, the support leg hip joint, the swing leg knee joint and the swing leg ankle joint are respectively; delta 3an ＝[Δ 3anxub Δ 3anyub Δ 3anxr Δ 3anyr ] T Wherein delta is 3anxub 、Δ 3anyub 、Δ 3anxr 、Δ 3anyr The sub-table represents delta 3an Components in the x, y directions of the back and swing leg foot; delta 4an ＝[Δ 4an1 Δ 4an2 Δ 4an3 Δ 4an4 ] T Wherein delta is 4an1 、Δ 4an2 、Δ 4an3 、Δ 4an4 The sub-table shows the concentrated disturbances at the knee joint of the support leg, hip joint of the swing leg and knee joint of the swing leg, delta 1a 、Δ 3a 、Δ 4a Centralized uncertainties, delta, for man-machine interfaces, mechanical systems and hydraulic systems, respectively 1an 、Δ 3an 、Δ 4an The concentrated disturbances of the man-machine interface, the mechanical system and the hydraulic system, respectively.
The state equation is:
T act ＝hF L
Q L ＝K q u
wherein,,respectively x 1a 、x 2a 、x 3a K is the first derivative of (1) xya ＝diag{K ubx ,K uby ,K rx ,K ry }，/>Is x L2 Regarding q 2 First order partial derivative of>Is x L3 Regarding q 3 First order partial derivative of>Is x L4 Regarding q 4 First order partial derivative of>Is x L5 Regarding q 5 First order partial derivative of F L For hydraulic rigid output force F L ＝A 1 x 4a -A 2 x 5a ，A 1 ＝diag{A 12 ,A 13 ,A 14 ,A 15 }，A 2 ＝diag{A 22 ,A 23 ,A 24 ,A 25 }，/>Is F L Is used as a first derivative of (a),Q 12 、Q 22 、Q 13 、Q 23 、Q 14 、Q 24 、Q 15 、Q 25 two-cavity flow for each joint; k (K) q ＝diag{K q2 ,K q3 ,K q4 ,K q5 }， Respectively q 2 、q 3 、q 4 、q 5 U is the control voltage of the hydraulic valve.
S5: a reference displacement of the exoskeleton is obtained in the upper controller according to the back acting force and the foot acting force. And acquiring the actual displacement of the contact position of the exoskeleton backboard and the swing leg and foot part in the movement model of the exoskeleton according to the actual angle value. And acquiring the expected driving moment in the middle layer controller according to the reference displacement and the actual displacement. And acquiring the actual output force of the knee joint hydraulic cylinder in a dynamic model of the hydraulic driver according to the actual pressure of the knee joint hydraulic cylinder. And acquiring the actual output force of the hip joint hydraulic cylinder in a dynamic model of the hydraulic driver according to the actual pressure of the hip joint hydraulic cylinder. And acquiring the flow of the knee joint hydraulic cylinder and the flow of the hip joint hydraulic cylinder in the lower-layer controller according to the expected driving moment, the actual output force of the knee joint hydraulic cylinder and the actual output force of the hip joint hydraulic cylinder.
The control method of the upper layer controller comprises the following steps:
according to the state equation of the physical model, the first tracking error is set as z 1a ＝x 1a -x 1ad Wherein x is 1ad The integral of the man-machine acting force in the x and y directions is expected for the back and the swing legs and feet, and the value is 0; let x be m For the first virtual control input, a first virtual control input x m First tracking error z for human-machine effort 1a Rapidly trending towards zero;
control x m The method of (1) is as follows: x is x m ＝x ma +x ms +x msn Whereinx ms ＝K 1 z 1a ，x msn For the first robust feedback term, f θF And Y θF Is composed of x ma Is obtained by linearizing the parameters of (f) θF ＝[0000]T， Desired ergonomic forces in x, y directions for waist and leg foot, respectively, K 1 Is the first linear feedback gain momentArray, K in this embodiment 1 ＝diag{12,12,12,12}，/>Respectively represent K f 、Δ 1an Is a function of the estimated value of (2); />Is K θa Is a function of the estimated value of (2); />Is theta F And the range of the estimated values is: />In this embodiment, the initial value is taken asWherein->To the parameter theta F Estimate of +.>In the present embodiment, +.>To the parameter theta F Estimate of +.>In the present embodiment, +.>Estimate->In the upper controller, the adaptive rate is +.>Obtained by->Γ 1 Is a first positive gain matrix, taking Γ in this embodiment 1 ＝diag{0,0,0,0,36,36,36,36}，/>The mapping function of (2) is:
in the formula (I) i As an independent variable, θ Fmaxi ，θ Fmini Respectively is theta F Maximum and minimum values of the i-th element; x is x msn The method meets the following conditions:
in the method, in the process of the invention,is an estimated value +.>Subtracting the actual value theta F ，/>ε 1 Is a threshold and is any non-negative number; in this embodiment, ε is selected 3 ＝[1 1 1 1] T Selecting τ actsn ＝[0 0 0 0] T 。
According to a first virtual control input x mi I=1, 2,3,4, and smoothing by a third order filterObtaining reference displacement, reference speed and reference acceleration of the exoskeleton; the state equation of the third-order filter is as follows:
i＝1,2,3,4
x i (1)、x i (2)、x i (3) Representing the filtered reference displacement, reference velocity and reference acceleration respectively,is x i (1) First derivative of>Is x i (2) First derivative of>Is x i (3) A is the first derivative of a 1 、a 2 、a 3 All are control parameters, and are obtained through pole allocation. Let y i Representing exoskeleton reference displacement, let y i (s)＝x mi (s), then y i To x i (1) The transfer function G(s) is:
obtaining x through transfer function mi Conversion to the desired smoothed exoskeleton reference displacement x i (1). In this embodiment, the closed loop pole is set to 20 radians per second to obtaina 1 、a 2 、a 3 The values of (a) are respectively a 1 ＝80,a 2 ＝2400,a 3 =32000, and may not be limited thereto in practice.
The control method of the middle layer controller comprises the following steps:
setting a second tracking errorWherein->Defining a conversion equation:
wherein K is 2 Taking an arbitrary non-negative number, in this embodiment, K is selected 2 ＝diag{30,30,30,30}，z 3 Is a third tracking error; z 2 And z 3 Is of the transfer function of
Let B xea x 3a ＝Y B B θ ，Wherein K is 2i Represent K 2 Is the i-th element of (2), beta= [ M 0 Y 1 Y 2 Y 2 Y 2 X 4 Y5 Y6 Y7 J1 J2 J3 J4 J5 J6 J7] T ,M 0 、Y 1 、Y 2 、Y 3 、Y 4 、X 4 、Y 5 、Y 6 、Y 7 、J 1 、J 2 、J 3 、J 4 、J 6 、J 7 Model parameters of mechanical structure, B θ As a matrix of damping coefficients for each joint, B θ ＝[B 1 B 2 B 3 B 4 B 5 B 6 ] T ，B 1 、B 2 、B 3 、B 4 、B 5 、B 6 Respectively represent damping coefficients of the ankle joint of the supporting leg, the knee joint of the supporting leg, the hip joint of the swinging leg, the knee joint of the swinging leg and the ankle joint of the swinging leg.
Control τ act The determining method of (1) comprises the following steps: τ act ＝τ acta +τ acts +τ actsn Wherein τ actsn For the second robust feedback term,K 3 is a third linear feedback gain matrix, in this embodiment, K is taken 3 ＝diag{6300,6300,6300,6300}，/>Respectively is beta, B θ 、Δ 3an Is used for the estimation of the (c),wherein Y is B From B xea x 3a Linearizing the parameters to obtain f 0 Y is composed ofLinearization of parameters to give->To the parameter theta q Estimate of +.>In the present embodiment, the initial value is [69.988-11.585-33.7026-26.8827-8.95152.37443.12121.20040.03336.362134.437217.75436.41141.63770.48130.0073140140140140140140000 ]]，/>To the parameter theta q Estimate of +.>In the present embodiment, the maximum value of [139.976-2.317-6.74052-5.37654-1.79034.74886.24242.40080.0667.2724268.874435.508612.82283.27540.96260.0146280280280280280280100100100100 ]]；θ qmini For theta q The minimum value of the i-th element, in this example, is [13.9976-23.17-67.4052-53.7654-17.9030.474880.624240.240080.00660.7272426.887443.550861.282280.327540.096260.00146141414141414-100-100-100-100 ] ]；/>The value of (2) is determined by the adaptation rate in the lower controller>Obtained by, among others, Γ 2 Is a second positive gain matrix, and in this embodiment, Γ is selected 2 ＝[1678 1×10 0 1×2 1678 1×4 0 1×6 1678 1×4 ] T ，1678 1×10 ＝[1678 1678 1678 1678 1678 1678 1678 1678 1678 1678],0 1×2 ＝[0 0],1678 1×4 ＝[1678 1678 1678 1678]，0 1×6 ＝[0 0 0 0 0 0]，/>The mapping function of (2) is:
in the formula (I) i Is an independent variable;
order theτ actsn The method meets the following conditions: />
In the method, in the process of the invention,is an estimated value +.>Subtracting the actual value theta q I.e. +.>I 4*4 Is a fourth-order identity matrix epsilon 3 Is a threshold and is arbitrary non-negative. In this embodiment, ε is selected 3 ＝[1 1 1 1] T Selecting τ actsn ＝[0 0 0 0] T 。
The control method of the lower controller comprises the following steps:
definition of fourth tracking error z 4 ＝F L -F Ld Wherein F L For the actual output force of the hydraulic cylinder, F Ld For the desired output force of the hydraulic cylinder, F Ld ＝h -1 τ actd ，For the first derivative of F, in conjunction with the dynamic modeling of this stage, the error equation of this stage is written: />Is z 4 First derivative of Q L Is the flow of the hydraulic cylinder.
Control Q L The method of (1) is set as follows: q (Q) Ld ＝Q Lda +Q Lds Wherein Q is Ld For the desired flow rate of the hydraulic cylinder, Q Lda Providing robust feedback term for flow, Q Lds For the flow back robust feedback term, K 4 is a fourth linear feedback gain matrix, beta emin Is beta e Is a minimum of (2). In the present embodiment, K is taken 4 ＝[100 100 100 100] T 。φ 4c ＝[-q v I 4×4 ] T ，/>φ 4 ＝[Q Lda -q v I 4×4 ] T ，/>Is to beta e 、Δ 4an Estimated value of θ u ＝[β e Δ 4an T ] T In the present embodiment, the initial value is θ u ＝[8.7*10 7 0 0 0 0] T ；Wherein Q is Ldsn For the third robust feedback term, +.>To the parameter theta u Estimate of +.>Minimum value- >To the parameter theta u Estimate of +.>Is the maximum value of (2); in the present embodiment, the selection range isEstimate->The value of (2) is determined by the adaptation rate in the lower controller>Obtained by->Γ 3 Is a third positive gain matrix, in this embodiment, chosen as Γ 3 ＝[250000 0 0 0 0] T ，/>The mapping function of (2) is:
in θ umaxi ，θ umini Respectively is theta u Maximum and minimum values of the i-th element, · i Is an independent variable;
Q Ldsn the method meets the following conditions:
z 4 β e Q Ldsn ≤0
in the method, in the process of the invention,is an estimated value +.>Subtracting the actual value theta u ，/>ε 4 Is a threshold and is any non-negative number; in this embodiment, ε is selected 4 ＝[1 1 1 1] T Q is selected Ldsn ＝[0 0 0 0] T 。
S6: generating electricity from a desired flowAnd generating a corresponding current signal in the electrohydraulic servo valve according to the voltage signal. Let Q Ld ＝[Q Ld2 Q Ld3 Q Ld4 Q Ld5 ] T Wherein Q is Ld2 、Q Ld3 、Q Ld4 、Q Ld5 The expected output flow of the knee joint servo valve of the supporting leg, the expected output flow of the hip joint servo valve of the supporting leg, the expected output flow of the knee joint servo valve of the swinging leg and the expected output flow of the hip joint servo valve of the swinging leg are respectively calculated according to the virtual control input Q L The control voltage u of the electro-hydraulic servo valve is obtained as follows:
s7: the valve core opening displacement of the corresponding knee joint electrohydraulic servo valve and the corresponding hip joint electrohydraulic servo valve is controlled through the current signals, so that the pressure at two ends of the hydraulic cylinder is controlled, each hydraulic cylinder is pushed to move, each joint of the underactuated single-leg support hydraulic power-assisted exoskeleton is driven to rotate, and the tracking movement of the underactuated single-leg support hydraulic power-assisted exoskeleton is realized.
The robust control apparatus includes: the system comprises a data acquisition module, an initialization module, a model establishment module, a data processing module, a current signal generation module and a tracking control module.
The data acquisition module is used for acquiring the status data of the exoskeleton. The state data includes feature data and motion data. The motion data includes: back force, foot force, actual angle values of each joint of the exoskeleton, actual pressure of the knee joint hydraulic cylinder, actual pressure of the hip joint hydraulic cylinder and foot supporting force. The characteristic data includes: man-machine interface stiffness, waist stiffness, leg-foot stiffness, chamber volume of the hydraulic cylinder, and joint damping coefficients. The data acquisition module may include a plurality of sensors including a back force sensor, a foot force sensor, a rotary encoder, a knee hydraulic cylinder actual pressure sensor, a hip hydraulic cylinder actual pressure sensor, and a foot support force sensor.
The support state judging module is used for judging whether the left leg foot part and the right leg foot part exert pressure on the ground or not respectively, if yes, the left leg foot part or the right leg foot part is taken as a swinging leg, and if not, the left leg foot part or the right leg foot part is taken as a support leg. And switching the input state data in real time according to the supporting state of the left leg foot part or the right leg foot part.
The initialization module is used for initializing the sampling period of the real-time controller, and the sampling period is set between 10 ms and 20 ms. The initialization module is also used for controlling the foot plate to rotate to a horizontal position and controlling the first rod piece, the second rod piece and the back to rotate to a vertical position.
The model building module is used for building a physical model of the exoskeleton and converting the physical model into a state equation according to the characteristic data. Wherein the physical model comprises: a human-machine interface model, a motion model of an exoskeleton, a dynamics model of a hydraulic drive, a complete constraint model.
The data processing module is used for acquiring reference displacement of the exoskeleton in the upper-layer controller according to the back acting force and the foot acting force, acquiring actual displacement of the backboard in the motion model of the exoskeleton according to the actual angle value, and acquiring expected driving moment in the middle-layer controller according to the reference displacement and the actual displacement. The back force can be obtained by real-time monitoring with a back force sensor mounted on the back plate. The actual angle values may be obtained by real-time monitoring with a rotary decoder mounted at each joint. The data processing module is also used for acquiring the actual output force of the knee joint hydraulic cylinder in the dynamic model of the hydraulic driver according to the actual pressure of the knee joint hydraulic cylinder, acquiring the actual output force of the hip joint hydraulic cylinder in the dynamic model of the hydraulic driver according to the actual pressure of the hip joint hydraulic cylinder, and acquiring the flow of the knee joint hydraulic cylinder and the flow of the hip joint hydraulic cylinder in the lower controller according to the expected driving moment, the actual output force of the knee joint hydraulic cylinder and the actual output force of the hip joint hydraulic cylinder. The actual pressure of the knee cylinder may be obtained by an actual pressure sensor of the knee cylinder. The actual pressure of the hip joint hydraulic cylinder can be obtained through real-time monitoring of an actual pressure sensor of the hip joint hydraulic cylinder.
The current signal generation module is used for generating corresponding voltage signals according to the expected flow of the electrohydraulic servo valve, and further generating corresponding current signals.
The tracking control module is used for controlling the rotation of each joint of the exoskeleton according to the current signals, so that the track tracking of the exoskeleton is realized. The input end of the electrohydraulic servo valve is current, and the output end is flow. The electrohydraulic servo valve receives current to drive the valve core opening to displace so as to control the pressure at two ends of the hydraulic cylinder, thereby driving each hydraulic cylinder to move and realizing real-time track tracking of the exoskeleton.
The present embodiment also provides a computer terminal comprising a memory, a processor, and a computer program stored on the memory and executable on the processor. The steps of the robust control method of the underactuated single-leg support hydraulic assistance exoskeleton of the embodiment are realized when the processor executes a program. When the control method is applied, the control method can be applied in the form of software, such as a program designed to run independently, and is installed on a computer terminal, wherein the computer terminal can be a computer, a smart phone, a control system, other Internet of things equipment and the like. The control method can also be designed into an embedded running program which is installed on a computer terminal, such as a singlechip.
The present embodiment also provides a computer-readable storage medium having a computer program stored thereon. When the program is executed by the processor, the steps of the robust control method of the underactuated single-leg support hydraulic assistance exoskeleton of the embodiment are realized. When the control method is applied, the control method can be applied in the form of software, such as a program designed to be independently operated by a computer readable storage medium, wherein the computer readable storage medium can be a U disk, the U disk is designed as a U shield, and the program for starting the whole method through external triggering is designed through the U disk.
The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The foregoing examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (2)
1. A robust control method of an under-actuated single-leg support hydraulically assisted exoskeleton for effecting tracking motion of the under-actuated hydraulically assisted exoskeleton, the under-actuated hydraulically assisted exoskeleton comprising:
a back plate;
the two ends of the back binding band are fixedly connected to the upper end of the backboard;
the two ends of the waist binding belt are fixedly connected with the lower end of the backboard;
the top end of the first rod piece is rotatably connected with one side of the lower end of the back plate;
the top end of the second rod piece is rotatably connected with the lower end of the first rod piece;
the right foot plate is rotatably connected with the bottom end of the second rod piece; the right foot plate, the first rod piece and the second rod piece jointly form a right leg foot part;
the two ends of the foot binding belt I are fixedly connected to the right foot plate;
the right leg knee joint hydraulic cylinder is used for driving the first rod piece and the second rod piece to rotate relatively;
the right leg hip joint hydraulic cylinder is used for driving the back plate and the first rod piece to rotate relatively;
the top end of the third rod piece is rotatably connected with the other side of the lower end of the back plate;
the top end of the fourth rod piece is rotatably connected with the lower end of the third rod piece;
The left foot plate is rotatably connected with the bottom end of the fourth rod piece; the left foot plate, the third rod piece and the fourth rod piece jointly form a left leg foot part;
two ends of the foot binding band II are fixedly connected to the left foot plate;
the left leg knee joint hydraulic cylinder is used for driving the third rod piece and the fourth rod piece to rotate relatively;
the left leg hip joint hydraulic cylinder is used for driving the backboard and the third rod piece to generate relative rotation;
the electrohydraulic servo valve is used for controlling the running states of the right leg knee joint hydraulic cylinder, the right leg hip joint hydraulic cylinder, the left leg knee joint hydraulic cylinder and the left leg hip joint hydraulic cylinder;
a plurality of sensors for acquiring status data of the exoskeleton; and
the real-time controller is used for outputting a control quantity according to the state data and controlling the running state of the electrohydraulic servo valve according to the control quantity; the real-time controller comprises an upper layer controller, a middle layer controller and a lower layer controller; the upper controller is used for outputting a human motion prediction track; the middle layer controller is used for outputting expected output force of the exoskeleton; the lower controller is used for outputting a current signal and controlling the running state of the electrohydraulic servo valve according to the current signal so as to realize the track tracking of the exoskeleton;
The control method is characterized by comprising the following steps:
s1: setting a sampling period of the real-time controller;
s2: acquiring state data of the exoskeleton; the state data includes feature data and motion data; the motion data includes: back acting force, foot acting force, actual angle values of all joints of the exoskeleton, actual pressure of a knee joint hydraulic cylinder and actual pressure of a hip joint hydraulic cylinder;
s3: respectively judging the motion states of the left leg foot part and the right leg foot part; correcting the state data in real time according to the motion state; the method for judging the motion state comprises the following steps: judging whether the left leg foot part and the right leg foot part apply pressure to the ground or not respectively; if yes, taking the left leg foot part or the right leg foot part as a swinging leg; otherwise, taking the left leg foot part or the right leg foot part as a supporting leg;
s4: establishing a physical model of the under-actuated hydraulic assistance exoskeleton; converting the physical model into a state equation according to the state data; the physical model includes: a human-machine interface model, a motion model of an exoskeleton, a dynamics model of a hydraulic driver, and a complete constraint model;
S5: acquiring reference displacement of the exoskeleton in the upper controller according to the back acting force and the foot acting force; acquiring actual displacement of the backboard in a motion model of the exoskeleton according to the actual angle value; acquiring expected driving moment in the middle-layer controller according to the reference displacement and the actual displacement; acquiring the actual output force of the knee joint hydraulic cylinder in a dynamic model of the hydraulic driver according to the actual pressure of the knee joint hydraulic cylinder; acquiring the actual output force of the hip joint hydraulic cylinder in a dynamic model of the hydraulic driver according to the actual pressure of the hip joint hydraulic cylinder; acquiring the expected flow of the electrohydraulic servo valve in a lower controller according to the expected driving moment, the actual output force of the knee joint hydraulic cylinder and the actual output force of the hip joint hydraulic cylinder;
s6: generating a voltage signal according to the desired flow rate; generating a corresponding current signal in the electrohydraulic servo valve according to the voltage signal;
s7: controlling the running state of the electrohydraulic servo valve through the current signal to control the pressure at two ends of the hydraulic cylinder, pushing each hydraulic cylinder to move, and further driving each joint of the underactuated single-leg support hydraulic power-assisted exoskeleton to rotate, so as to realize the tracking movement of the underactuated single-leg support hydraulic power-assisted exoskeleton;
Wherein, in S4, the human-machine interface model is:
wherein F is hm ＝[F hmubx F hmuby τ eubz F hmrx F hmry τ erz ] T Force applied by human machine, F hmubx 、F hmuby Respectively representing components of back man-machine acting force in x and y directions, tau eubz To assume the moment of the human body on the back, F hmrx 、F hmry Respectively representing components of human-machine acting force of leg swinging foot in x and y directions, tau erz To assume the moment of a human body on the foot of the swing leg; k=diag { K ubx ,K uby ,K ubz ,K rx ,K ry ,K rz Human interface stiffness, where K ubx 、K uby 、K ubz 、K rx 、K ry 、K rz The components of the human-machine interface stiffness of the waist and the swing leg foot in the x, y and z directions are respectively; x is x hs ＝[x hubx x huby x hubz x hrx x hry x hrz ] T Is the displacement of the wearer, where x hubx 、x huby 、x hubz Representing components of displacement in three directions of x, y and z at the back contact of the wearer respectively; x is x hrx 、x hry 、x hrz Representing the components of the displacement of the contact part of the swing leg and the foot of the wearer in the x, y and z directions respectively, x es ＝[x eubx x euby x eubz x erx x ery x erz ] T For the displacement of exoskeleton, period x eubx 、x euby 、x eubz Respectively representing components of displacement of the waist and back contact part of the exoskeleton in the x, y and z directions; x is x erx 、x ery 、x erz Representing the components of displacement of the foot contact part of the swing leg of the exoskeleton in the x, y and z directions respectively;for centralized model uncertainty and interference on human-machine interfaces;
by integration of man-machine forcesInstead of F hm The state equation for obtaining the human-machine interface model is：
In S4, the motion model of the exoskeleton is:
Wherein T is act For the driving moment of the joint,wherein J ub As jacobian matrix at waist, J r Jacobian matrix for foot, q c For the angle of the joint, M Lsp Is an inertial matrix, C Lsp For centrifugal and coriolis force matrices, G Lsp Is a gravity matrix, B is a damping matrix, +.>Is a centralized modeling error, +.>For joint angular velocity>Is joint angular acceleration;
the motion model is further converted into:
in the method, in the process of the invention,F hmubxy ＝[F hmubx F hmuby ] T ；F hmrxy ＝[F hmrx F hmry ] T ，/>for the displacement speed of exoskeleton, +.>Displacement acceleration for exoskeleton;
in S4, the complete constraint model is:
x eubz ＝x eubzd (t),x erz ＝x erzd (t)
second derivative of the complete constraint model:
wherein x, y and z are three-dimensional coordinate axis symbols respectively, and x is eubz For the rotation amount in z direction of back contact with human body, x erz For swinging the rotation amount in z direction of the foot contact of the leg and the human body, x eubzd (t) is the known ideal back trajectory, x erzd (t) is a known ideal trajectory for the swing leg foot,is x eubz Second derivative of>Is x eubzd Second derivative of (t)/(t)>Is x erz Second derivative of>Is x erzd (t) the second derivative;
determination ofBack moment τ eubz Moment tau of swing leg foot erz The method can obtain:
wherein x is ea ＝[x eubx x euby x erx x ery ] T ， U 9 ＝[U 5 U 7 ]， 0 1×2 ＝[0 0]，0 1×4 ＝[0 0 0 0]，
In S4, the dynamics model of the hydraulic actuator is:
x vi ＝u i ,i＝2,3,4,5
wherein τ 2 、τ 3 、τ 4 、τ 5 Respectively the driving moment of the knee joint of the supporting leg, the hip joint of the swinging leg and the knee joint of the swinging leg, and x Li Is the displacement amount of the hydraulic cylinder,is x Li Regarding q i First order partial derivative of P 1i 、P 2i 、A 1i And A 2i Respectively representing absolute pressure and acting area of two chambers in hydraulic cylinder, V 1i 、V 2i The total volume of the two chambers in the hydraulic cylinder, V h1i 、V h2i Is q i Two-chamber volume of hydraulic cylinder at =0, β e Represents the effective bulk modulus, Q 1i 、Q 2i Respectively the supply and return of the hydraulic cylinder, k q1i 、k q2i The flow gain coefficients of two loops of the hydraulic cylinder are respectively x vi Is the displacement value of the valve core, P s Is the oil supply pressure, P r Is the pressure in the tank, < >>Representing respectively the centralized modeling error and the uncertain disturbance in the dynamics model of the hydraulic driver, tau i For each joint moment, u i For the voltage of both ends of each joint hydraulic valve, delta P 1i For the pressure difference of the left chamber of each hydraulic cylinder, delta P 2i The pressure difference of the right chamber of each hydraulic cylinder is;
in S4, the state equation is:
T act ＝hF L
Q L ＝K q u
wherein K is xya ＝diag{K ubx ,K uby ,K rx ,K ry }，F hmxy ＝[F hmubx F hmuby F hmrx F hmry ] T ，/>x 4a ＝[P 12 P 13 P 14 P 15 ] T ，x 5a ＝[P 22 P 23 P 24 P 25 ] T ，A 1 ＝diag{A 12 ,A 13 ,A 14 ,A 15 }，A 2 ＝diag{A 22 ,A 23 ,A 24 ,A 25 }，F L ＝A 1 x 4a -A 2 x 5a ， Respectively x 1a 、x 2a 、x 3a First derivative of (delta) 1an 、Δ 3an 、Δ 4an A constant part, delta, of the centralized uncertainty of the man-machine interface, the mechanical system and the hydraulic system, respectively 1a 、Δ 3a 、Δ 4a Time-varying part of the centralized uncertainty of man-machine interface, mechanical system and hydraulic system, respectively, +.>Is F L First derivative of Q L For the flow of the hydraulic cylinder, K q ＝diag{K q2 ,K q3 ,K q4 ,K q5 }， In S5, the control method of the upper layer controller includes the following steps:
According to the state equation, a first tracking error z is set 1a Is z 1a ＝x 1a -x 1ad Wherein x is 1a 、x 1ad The integration of the desired human machine effort in the x, y directions for the back and swing legs;
then control the first virtual control input x m The method of (1) is as follows: x is x m ＝x ma +x ms +x msn Wherein, the method comprises the steps of, wherein,x ms ＝K 1 z 1a ，x msn is a first robust feedback term; f (f) θF And Y θF Is composed of x ma Is obtained by linearizing the parameters of K 1 Is a first linear feedback gain matrix, +.>Respectively represent K f 、Δ 1an Estimated value of ∈10->Is theta F Estimate of (2), estimate->In the upper controller, the adaptive rate is +.>Obtained by the method, whereinK θa ＝[1/K ubx 1/K uby 1/K rx 1/K ry ] T ，/>Is K θa Is (t) is (are) the estimated value of (f) 1 Is a first positive gain matrix, +.>Is x 1ad Is the first derivative of (a); />The mapping function of (2) is:
in the formula (I) i As an independent variable, θ Fmaxi ，θ Fmini Respectively is theta F Maximum and minimum values of the i-th element;
according to a first virtual control input x mi I=1, 2,3,4, and performing smoothing treatment through a third-order filter to obtain reference displacement, reference speed and reference acceleration of the exoskeleton; the state equation of the third-order filter is as follows:
i＝1,2,3,4
x i (1)、x i (2)、x i (3) Representing the filtered reference displacement, reference velocity and reference acceleration respectively,is x i (1) First derivative of>Is x i (2) First derivative of>Is x i (3) Let y be i Representing exoskeleton reference displacement, a 1 、a 2 、a 3 Are all control parameters, set y i (s)＝x mi (s), then y i To x i (1) The transfer function G(s) is:
obtaining a desired smoothed exoskeleton reference displacement x by a transfer function i (1)；
In S5, the control method of the middle layer controller includes the following steps:
setting a second tracking errorWherein->Defining a conversion equation:
wherein K is 2 Taking the arbitrary non-negative number of the number,is z 2 First derivative of>Is x r Is the first derivative of z 3 Is a third tracking error; k (K) 2i Represent K 2 Is the i-th element of (a);
let B xea x 3a ＝Y B B θ ，Wherein beta is a model parameter of the mechanical structure, B θ As a matrix of damping coefficients for each joint, B θ ＝[B 1 B 2 B 3 B 4 B 5 B 6 ] T ，B 1 、B 2 、B 3 、B 4 、B 5 、B 6 Respectively representing damping coefficients of the ankle joint of the supporting leg, the knee joint of the supporting leg, the hip joint of the swinging leg, the knee joint of the swinging leg and the ankle joint of the swinging leg;
then control tau actd The method of (1) is as follows: τ act ＝τ acta +τ acts +τ actsn Wherein τ actsn For the second robust feedback term,K 3 is a third linear feedback gain matrix, +.> Respectively is beta, B θ 、Δ 3an Estimated value of ∈10->To the parameter theta q Estimate of +.>Minimum value->To the parameter theta q Estimate of +.>Maximum value of θ qmaxi 、θ qmini Respectively is theta q Maximum and minimum values of the i-th element, < ->The value of (2) is determined by the adaptation rate in the lower controller>Obtained by phi 3 ＝[Y Y B I 4×4 ] T ，/>Γ 2 Is a second positive fixed gain matrix; />The mapping function of (2) is:
In the formula (I) i Is an independent variable;
in S5, the control method of the lower controller includes the following steps:
definition of fourth tracking error z 4 ＝F L -F Ld Wherein F L For the actual output force of the hydraulic cylinder, F Ld Is the desired output force of the hydraulic cylinder;
the error equation at this stage is written as:wherein->Is F Ld Is the first derivative of (a);
control Q L The method of (1) is as follows: q (Q) Ld ＝Q Lda +Q Lds Wherein Q is Ld For the desired flow rate of the hydraulic cylinder, Q Lda Providing robust feedback term for flow, Q Lds A robust feedback term is returned for the flow;K 4 is a fourth linear feedback gain matrix, beta emin Is beta e Is the minimum of (2); phi (phi) 4c ＝[-q v I 4×4 ] T ，/>φ 4 ＝[Q Lda -q v I 4×4 ] T ，/>Is to beta e 、Δ 4an Estimated value of θ u ＝[β e Δ 4an T ] T ；/>Wherein Q is Ldsn For the third robust feedback term,/>to the parameter theta u Estimate of +.>Minimum value->To the parameter theta u Estimate of +.>Is the maximum value of (2); estimate->The value of (2) is determined by the adaptation rate in the lower controller>Obtained by the method, whereinΓ 3 Is a third positive gain matrix, +.>The mapping function of (2) is:
in θ umaxi ，θ umini Respectively is theta u Maximum and minimum values of the i-th element, · i Is an independent variable;
generating a voltage signal according to the expected flow, and generating a corresponding current signal in the electrohydraulic servo valve according to the voltage signal; let Q Ld ＝[Q Ld2 Q Ld3 Q Ld4 Q Ld5 ] T Wherein Q is Ld2 、Q Ld3 、Q Ld4 、Q Ld5 The expected output flow of the knee joint servo valve of the supporting leg, the expected output flow of the hip joint servo valve of the supporting leg, the expected output flow of the knee joint servo valve of the swinging leg and the expected output flow of the hip joint servo valve of the swinging leg are respectively calculated according to the virtual control input Q L The control voltage u of the electro-hydraulic servo valve is obtained as follows:
2. a robust control apparatus for an under-actuated single-leg-supported hydraulically assisted exoskeleton, configured to implement the robust control method for an under-actuated single-leg-supported hydraulically assisted exoskeleton of claim 1, comprising:
the data acquisition module is used for acquiring the state data of the exoskeleton; the state data includes feature data and motion data; the motion data includes: back acting force, actual angle values of all joints of the exoskeleton, actual pressure of a knee joint hydraulic cylinder, actual pressure of a hip joint hydraulic cylinder and foot supporting force; the characteristic data comprise man-machine interface rigidity, waist rigidity, leg and foot rigidity, chamber volume of the hydraulic cylinder and damping coefficients of all joints;
a support state judgment module for judging whether or not the left leg foot and the right leg foot exert pressure on the ground, respectively; if yes, taking the left leg foot part or the right leg foot part as a swinging leg; otherwise, taking the left leg foot part or the right leg foot part as a supporting leg;
an initialization module for initializing a sampling period of the real-time controller; the initialization module is also used for controlling the foot plate to rotate to a horizontal position and controlling the first rod piece, the second rod piece and the back to rotate to a vertical position;
The model building module is used for building a physical model of the exoskeleton according to the characteristic data and converting the physical model into a state equation; wherein the physical model comprises: a human-machine interface model, a motion model of an exoskeleton, a dynamics model of a hydraulic driver, and a complete constraint model;
the data processing module is used for acquiring the reference displacement of the exoskeleton in the upper-layer controller according to the back acting force and the foot acting force; acquiring actual displacement of the backboard in a motion model of the exoskeleton according to the actual angle value; acquiring expected driving moment according to the reference displacement and the actual displacement; acquiring the actual output force of the knee joint hydraulic cylinder in a dynamic model of the hydraulic driver according to the actual pressure of the knee joint hydraulic cylinder; acquiring the actual output force of the hip joint hydraulic cylinder in a dynamic model of the hydraulic driver according to the actual pressure of the hip joint hydraulic cylinder; acquiring the expected flow of the electrohydraulic servo valve according to the expected driving moment, the actual output force of the knee joint hydraulic cylinder and the actual output force of the hip joint hydraulic cylinder;
The current signal generation module is used for generating a corresponding current signal according to the expected flow of the electrohydraulic servo valve;
and the tracking control module is used for controlling the rotation of each joint of the exoskeleton according to the current signals so as to realize the track tracking of the exoskeleton.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105116728A (en) * | 2015-08-14 | 2015-12-02 | 上海申磬产业有限公司 | A method for single-joint power-assisting exoskeleton inversion self-adaptive robust force control |
| CN105137972A (en) * | 2015-08-14 | 2015-12-09 | 浙江大学 | Adaptive robustness cascading force controlling method for single-joint powered exoskeleton |
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| CN105116728A (en) * | 2015-08-14 | 2015-12-02 | 上海申磬产业有限公司 | A method for single-joint power-assisting exoskeleton inversion self-adaptive robust force control |
| CN105137972A (en) * | 2015-08-14 | 2015-12-09 | 浙江大学 | Adaptive robustness cascading force controlling method for single-joint powered exoskeleton |
| CN112775937A (en) * | 2021-01-07 | 2021-05-11 | 合肥工业大学 | Self-adaptive robust control method and device for under-actuated hydraulic single-leg power-assisted exoskeleton |
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