CN114469655B - Lower limb exoskeleton gait planning method and system based on gravity center stabilization - Google Patents

Lower limb exoskeleton gait planning method and system based on gravity center stabilization Download PDF

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CN114469655B
CN114469655B CN202210086783.4A CN202210086783A CN114469655B CN 114469655 B CN114469655 B CN 114469655B CN 202210086783 A CN202210086783 A CN 202210086783A CN 114469655 B CN114469655 B CN 114469655B
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gait
lower limb
user
adjustment information
angle adjustment
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CN114469655A (en
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郏云涛
裘焱枫
高熙强
张克勤
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Ningbo Industrial Internet Research Institute Co ltd
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Ningbo Industrial Internet Research Institute 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
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F30/00—Computer-aided design [CAD]
    • G06F30/20—Design optimisation, verification or simulation
    • 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
    • A61H2201/5058—Sensors or detectors
    • A61H2201/5069—Angle sensors
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2111/00—Details relating to CAD techniques
    • G06F2111/04—Constraint-based CAD
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
    • G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation

Abstract

The invention discloses a lower limb exoskeleton gait planning method based on gravity center stabilization, which relates to the technical field of mechanical exoskeleton control and comprises the following steps: according to the spatial relationship among joints of the lower limb exoskeleton, constructing a kinematic model by taking the hip of a user as a reference coordinate system; planning a foot end track of a kinematic model according to gait parameters of a user based on a gravity center stabilization principle in the gait movement process; acquiring angle adjustment information among joints through inverse kinematics analysis according to the planned foot end track; and controlling motors at all joints according to the angle adjustment information to realize gait movement of the lower limb exoskeleton. The invention utilizes the self-adjusting gravity center to realize normal walking to move from a vertical state, so that the gait is more approximate to an actual state, and the problem of the prior art that the gait movement can be performed only by bending legs is solved, thereby being more suitable for rehabilitation treatment of patients with lower limb dysfunction.

Description

Lower limb exoskeleton gait planning method and system based on gravity center stabilization
Technical Field
The invention relates to the technical field of mechanical exoskeleton control, in particular to a lower limb exoskeleton gait planning method and system based on gravity center stabilization.
Background
The lower limb exoskeleton robot is used as a wearable robot, can provide support, assisting and the like for a human body, and interacts with a wearer, so that the exercise capacity of the human body is enhanced, and the wearable robot has obvious social and economic values. On the one hand, the lower limb exoskeleton robot can improve the exercise capacity of the old through assisting the old, such as assisting the old to walk, go up and down stairs and the like, and provides an effective relief scheme for the aged-care social problems caused by the aging of the mouth. On the other hand, the lower limb exoskeleton robot can also face the people with mobility impairment such as lower limb dysfunction people, provide certain supporting assistance for the people, reduce the disease risk caused by excessive atrophy of leg muscles through acquired medical rehabilitation exercise, strengthen the rehabilitation exercise of the lower limbs, and also promote the recovery of walking ability.
However, the multifunctional gait planning needs to be combined with the gait of people in the walking and stair ascending and descending processes, so that the walking process is stable and coordinated, the planning result directly influences the auxiliary walking capability of the lower limb exoskeleton robot, and certain technical difficulty is achieved.
Disclosure of Invention
In order to better provide good walking assistance for the elderly or patients with lower limb dysfunction, the invention provides a lower limb exoskeleton gait planning method based on center of gravity stabilization, which comprises the following steps:
s1: according to the spatial relationship among joints of the lower limb exoskeleton, constructing a kinematic model by taking the hip of a user as a reference coordinate system;
s2: planning a foot end track of a kinematic model according to gait parameters of a user based on a gravity center stabilization principle in the gait movement process;
s3: acquiring angle adjustment information among joints through inverse kinematics analysis according to the planned foot end track;
s4: and controlling motors at all joints according to the angle adjustment information to realize gait movement of the lower limb exoskeleton.
Further, in the step S2, the gait parameters include a step length, a step height, and a gait cycle, and the motion model includes a support phase and a swing phase in one gait cycle, where the periods of the support phase and the swing phase are equal.
Further, in the step S2, the principle of center of gravity stability is: during gait movements, the center of gravity of the user in the horizontal direction is always at the center of the user when the gait cycle is in the supporting phase.
Further, in the step S2, the foot-end trajectory is calculated based on a trajectory constraint equation and a fifth-order polynomial equation, wherein the trajectory constraint equation includes a first radial constraint equation and a first vertical constraint equation based on a step length and a step height, and a second radial constraint equation and a second vertical constraint equation based on a speed and an acceleration under a zero impact principle.
Further, the foot end trajectory may be expressed as the following formula:
wherein x and z are coordinates of the joint under the reference coordinates, S is a step length, T 0 For a gait cycle, H is step height and t is time in one gait cycle.
Further, the angle adjustment information may be expressed as the following formula based on inverse kinematics analysis:
wherein (p) x ,p z ) For the spatial coordinates of the foot end of the exoskeleton of the lower limb in a reference coordinate system, theta 2 For angle adjustment information of hip joint, θ 3 For angle adjustment information of knee joint, L 2 For the length of the user's lower leg, L 3 For the thigh length, s 3 ＝sinθ 3 。
The invention also provides a lower limb exoskeleton gait planning system based on gravity center stabilization, which comprises:
the model building unit is used for building a kinematic model by taking the hip of a user as a reference coordinate system according to the spatial relationship among the joints of the lower limb exoskeleton;
the footprint planning unit is used for planning a foot end track of the kinematic model according to gait parameters of a user based on a gravity center stabilization principle in the gait movement process;
the angle calculation unit is used for acquiring angle adjustment information among all joints through inverse kinematics analysis according to the planned foot end track;
and the motor driving unit is used for controlling the motors at all joints according to the angle adjustment information to realize gait movement of the lower limb exoskeleton.
Further, in the footprint planning unit, the principle of gravity center stability is as follows: during gait movements, the center of gravity of the user in the horizontal direction is always at the center of the user when the gait cycle is in the supporting phase.
Further, the foot end trajectory may be expressed as the following formula:
wherein x and z are coordinates of the joint under the reference coordinates, S is a step length, T 0 For a gait cycle, H is step height and t is time in one gait cycle.
Further, in the angle calculation unit, the angle adjustment information may be expressed as the following formula based on the inverse kinematics analysis:
wherein (p) x ,p z ) For the spatial coordinates of the foot end of the exoskeleton of the lower limb in a reference coordinate system, theta 2 For angle adjustment information of hip joint, θ 3 For angle adjustment information of knee joint, L 2 For the length of the user's lower leg, L 3 For the thigh length, s 3 ＝sinθ 3 。
Compared with the prior art, the invention at least has the following beneficial effects:
(1) According to the lower limb exoskeleton gait planning method and system based on center of gravity stabilization, disclosed by the invention, the gait control of the lower limb exoskeleton can be realized only by conventional data such as step length, step height and gait cycle without additional human body careful data acquisition, and the requirements on experimental equipment and the cost are lower;
(2) The gravity center is automatically adjusted to realize normal walking to move from a vertical state, so that the gait is more approximate to an actual state, and the problem that the gait movement is reversed and conventional only by bending legs in the prior art is solved, so that the device is more suitable for rehabilitation treatment of patients with lower limb dysfunction;
(3) The footprint track planning is firstly carried out based on the gravity center stabilization, and then the angle adjustment information of the joint is obtained through inverse kinematics analysis based on the footprint track, so that the point that the gravity center is stabilized all the time in the joint adjustment process is ensured, and the gravity center stability in the whole gait movement process is ensured.
Drawings
FIG. 1 is a method step diagram of a lower extremity exoskeleton gait planning method based on center of gravity stabilization;
FIG. 2 is a system block diagram of a lower extremity exoskeleton gait planning system based on center of gravity stabilization;
FIG. 3 is a schematic diagram of a kinematic model constructed from the spatial relationships between joints of the lower extremity exoskeleton;
FIG. 4 is a schematic diagram of the principle of gravity stability;
Detailed Description
The following are specific embodiments of the present invention and the technical solutions of the present invention will be further described with reference to the accompanying drawings, but the present invention is not limited to these embodiments.
Example 1
In order to better provide good walking assistance for the elderly or patients with lower limb dysfunction, and simultaneously, the lower limb exoskeleton robot better accords with the form of normal gait movement in the gait movement, as shown in fig. 1, the invention provides a lower limb exoskeleton gait planning method based on center of gravity stabilization, which comprises the following steps:
s1: according to the spatial relationship among joints of the lower limb exoskeleton, constructing a kinematic model by taking the hip of a user as a reference coordinate system;
s2: planning a foot end track of a kinematic model according to gait parameters of a user based on a gravity center stabilization principle in the gait movement process;
s3: acquiring angle adjustment information among joints through inverse kinematics analysis according to the planned foot end track;
s4: and controlling motors at all joints according to the angle adjustment information to realize gait movement of the lower limb exoskeleton.
In order to better simulate the track of the lower limb exoskeleton in the gait movement process, firstly, a kinematic model is constructed according to the spatial relationship between joints of the lower limb exoskeleton by taking the hip bone of a user as a reference coordinate system (taking the center point of the hip bone as an origin) (as shown in fig. 3, setting X as the gait movement direction on a horizontal plane, Z as the vertical direction vertical to the horizontal plane and Y as the direction vertical to the XZ plane), so that a personalized gait planning scheme of the user is obtained on the basis of the model.
For the lower limb exoskeleton robot, when the movement of the robot is a supporting phase (one gait cycle is divided into the supporting phase and the swinging phase), the center of gravity of the robot is required to be ensured to be the most stable in the center of a human body, as shown in fig. 4, the lower limb exoskeleton robot can make a rectangular step length at the foot end of the lower limb exoskeleton from top to bottom, can make the center of gravity change from starting to stopping, always keeps at the center position and is the most stable, and foot end track planning is performed according to the principle of center of gravity stability.
Therefore, in the invention, in order to make the gait movement effect finally obtained more fit the effect in the actual walking process, the stability of the center of gravity is ensured. The invention takes the stability of the gravity center as the key point, proposes planning of foot-end tracks based on the principle of the stability of the gravity center, and then reversely pushes angle adjustment information among all joint points through inverse kinematics analysis according to the foot-end tracks. Based on the above, the design scheme of the invention is only available.
In the gait planning, in order to provide angle adjustment information for each joint of the lower limb exoskeleton, different requirements of a human body in normal walking, ascending and descending stairs and other conventional movement scenes are fully considered in the gait movement process, so that the step length S, the step height H and the gait cycle T are adopted 0 The (including the two periods of the support phase and the swing phase, which are set equal in the present invention) and the step height h also need to be added to the planning element of the foot-end trajectory planning. Under the limitation of these planning elements, we first fully understand the pose relationship that the lower extremity exoskeleton should be in between the legs in one gait cycle after trajectory planning in different walking states, wherein:
normal walking gait: the whole double legs are firstly in a standing and resting stage, then the left leg starts, the right leg steps, the left leg steps, the right leg stops, and finally the double legs are in a standing and resting stage. Specifically, the left leg falls to the ground after starting, the planned foot end swing phase track point is at a height which maintains a walking state relative to a reference coordinate system in the vertical direction, the improvement of the foot end track is equivalent to the lowering of the whole gravity center, and the right leg support phase track point is also at the height relative to the reference coordinate system in the vertical direction, so that the two legs of the exoskeleton robot are in a normal walking state; the swing phase and support phase track points in the middle walking stage take the height as a starting point, and track points of alternate walking of the right leg and the left leg are planned; the right leg falls to the ground after stopping, the planned foot end swing phase track point is at the height when keeping a static standing state relative to a reference coordinate system in the vertical direction, the drop of the foot end track corresponds to the rise of the integral mass center, and the left leg support phase track point is also dropped relative to the reference coordinate system in the vertical direction, so that the two legs of the exoskeleton robot are in the static standing state.
Gait of going upstairs: the whole double legs are firstly in a standing and resting stage, the left leg starts firstly, the right leg takes a step, the left leg takes a step, the right leg stops at last, and finally the double legs are in a standing and resting stage. Specifically, the left leg starts to swing to the first stair (the height h is higher than the step height h), the swing phase track point falls on the first stair height, and the right leg is in a static state; in the middle stage, the right leg is stepped up, the swing phase track point falls on the second stair height, the left leg support phase track point falls to the original point from the second stair height, and the alternate ascending stair track point of which the difference between the right leg and the left leg is one stair height is planned; the right leg falls to the ground after stopping the walking, the swing phase track point is lowered to the original point from the position higher than the height of the stairs, and the left leg support phase track point is also lowered to the original point, so that the two legs of the exoskeleton robot are in a static standing state.
Gait of going downstairs: the whole double legs are firstly in a standing and resting stage, the left leg starts firstly, the right leg takes a step, the left leg takes a step, the right leg stops at last, and finally the double legs are in a standing and resting stage. Specifically, the left leg starts to take off the first stair, the swing phase track point reaches a certain height higher than the stair and falls on the original point, the right leg support phase track point vertically rises to a stair height from the original point, and the advancing direction is separated from the original point by half a step length; intermediate stage: the right leg steps up and down two stairs, the trace point of the swing phase reaches a certain height higher than the stairs and falls on the original point, the trace point of the left leg support phase rises to a stair height from the original point in the vertical direction, the advancing direction is separated from the original point by half a step length, and the trace point of alternate downstairs of which the right leg and the left leg differ by a stair height is planned; the right leg falls to the ground after stopping the step, the swing phase track point reaches a certain height higher than the stairs and falls to the origin, and the left leg supporting phase track point also falls to the origin, so that the two legs of the exoskeleton robot are in a static standing state.
After the overall movement track target of the leg is clear, it can be seen that during the movement process of the leg, the track of the foot end has a certain constraint in practice, such as: under gait parameter constraint, step length constraint causes the movement length of the foot end to be limited, and step height constraint causes the movement height of the foot end to be limited; and under the constraint of a zero impact principle (the speed and the acceleration are zero when the motion state of the foot end is changed), the speed constraint causes the speed of the foot end at the starting point, the speed of the foot end at the high point and the speed of the foot end at the end point are zero, and the acceleration constraint causes the acceleration of the foot end at the starting point, the speed of the foot end at the high point and the speed at the end point are zero.
Then, under gait parameter constraints, the constraint equation of the gait motion direction X can be expressed as:
the constraint equation for the vertical direction Z can be expressed as:
meanwhile, under the constraint of the zero impact principle, the constraint equation of the gait motion direction X can be expressed as:
the constraint equation for the vertical direction Z can be expressed as:
based on the constraint equation, the conventional foot end track calculation method comprises a cycloid equation and a pentagram polynomial curve, and the track obtained by planning the cycloid equation is not round enough for the lower limb exoskeleton of the invention, the speed in the process can not be controlled, the solution of the pentagram polynomial is solved according to a displacement constraint equation and an acceleration constraint equation, the speed and the acceleration are controllable, and meanwhile, the constraint conditions available in the gait motion of the lower limb exoskeleton are met, so the invention solves the problem here through the pentagram polynomial based on the constraint conditions.
For the fifth order polynomial, the fifth order polynomial equation for the gait movement direction X is:
x＝at 5 +bt 4 +ct 3 +dt 2 +et+f (7)
and (3) conducting derivative calculation on the formula (7), and obtaining a motion equation:
six unknowns exist in the fifth-order polynomial equation, so six constraint equations are needed, and the trajectory curve equation in the horizontal X direction can be obtained by solving the constraint equations given in the previous section:
for the vertical direction Z, the segmentation is needed to be carried out five times moreWhen T is more than or equal to 0 and less than or equal to T 0 At/2, the fifth order polynomial equation is:
z＝At 5 +Bt 4 +Ct 3 +Dt 2 +Et+F (10)
then, according to formulas (2), (5) and (6), the foot-end trajectory equation in the vertical Y direction can be solved as:
the same thing can solve for when T 0 /2＜t≤T 0 When the foot-end trajectory equation in the vertical Y direction is:
thus, the foot end trajectory can be expressed as the following formula:
after foot end track planning, according to the planned foot end track, the angle adjustment information of each joint is needed to be solved by an inverse kinematics equation and is input into a joint motor of the lower limb exoskeleton robot to realize gait operation of the lower limb exoskeleton robot. The inverse kinematics is to solve the motion track of the joint at the known motion track of the foot end, the equation is derived from the forward kinematics, the forward kinematics is to solve the foot end position at the known angle of each joint, the forward kinematics equation is obtained according to the D-H parameter coordinate method, and the model of the D-H parameter coordinate method of the lower limb exoskeleton robot is shown in fig. 3. How to derive this is not repeated here, and the person skilled in the art can make a evidence according to the prior art. Then according to the positive kinematics equation of the two joints, the inverse kinematics solution equation of the lower limb exoskeleton robot can be obtained by solving by using an analytic method, and the inverse kinematics solution equation is as follows:
wherein (p) x ,p z ) For the spatial coordinates of the foot end of the exoskeleton of the lower limb in a reference coordinate system, theta 2 For angle adjustment information of hip joint, θ 3 For angle adjustment information of knee joint, L 2 For the length of the user's lower leg, L 3 For the thigh length, s 3 ＝sinθ 3 。
In a preferred embodiment, considering the possibility of a triple joint, the inverse kinematics solution equation for the case of a triple joint is further obtained as:
wherein (p) x ,p y ,p z ) For the spatial coordinates of the foot end of the exoskeleton of the lower limb in a reference coordinate system, theta 1 To newly add angle adjustment information at the joint, L 1 To newly increase the length between the joint and the hip bone c 1 ＝cosθ 1 ，s 1 ＝sinθ 1 。
In summary, the lower limb exoskeleton gait planning method and system based on the gravity center stabilization disclosed by the invention can realize gait control of the lower limb exoskeleton only by conventional data such as step length, step height and gait cycle without additional human body careful data acquisition, and are lower in experimental equipment requirement and cost.
The gravity center is automatically adjusted to realize normal walking to move from a vertical state, so that the gait is closer to an actual state, and the problem that the gait movement is reversed and conventional only by bending legs in advance in the prior art is solved, so that the device is more suitable for rehabilitation treatment of patients with lower limb dysfunction.
The footprint track planning is firstly carried out based on the gravity center stabilization, and then the angle adjustment information of the joint is obtained through inverse kinematics analysis based on the footprint track, so that the point that the gravity center is stabilized all the time in the joint adjustment process is ensured, and the gravity center stability in the whole gait movement process is ensured.
Example two
For a better understanding of the technical content of the present invention, the present embodiment illustrates the present invention by way of a system structure, as shown in fig. 2, a lower extremity exoskeleton gait planning system based on center of gravity stabilization, comprising:
the model building unit is used for building a kinematic model by taking the hip of a user as a reference coordinate system according to the spatial relationship among the joints of the lower limb exoskeleton;
the footprint planning unit is used for planning a foot end track of the kinematic model according to gait parameters of a user based on a gravity center stabilization principle in the gait movement process;
the angle calculation unit is used for acquiring angle adjustment information among all joints through inverse kinematics analysis according to the planned foot end track;
and the motor driving unit is used for controlling the motors at all joints according to the angle adjustment information to realize gait movement of the lower limb exoskeleton.
Further, in the footprint planning unit, the principle of center of gravity stability is as follows: during gait movements, the center of gravity of the user in the horizontal direction is always at the center of the user when the gait cycle is in the supporting phase.
Further, the foot end trajectory can be expressed as the following formula:
wherein x and z are coordinates of the joint under the reference coordinates, S is a step length, T 0 For a gait cycle, H is step height and t is time in one gait cycle.
Further, in the angle calculation unit, the angle adjustment information based on the inverse kinematics analysis may be expressed as the following formula:
wherein (p) x ,p z ) For the spatial coordinates of the foot end of the exoskeleton of the lower limb in a reference coordinate system, theta 2 For angle adjustment information of hip joint, θ 3 For angle adjustment information of knee joint, L 2 For the length of the user's lower leg, L 3 For the thigh length, s 3 ＝sinθ 3 。
It should be noted that all directional indicators (such as up, down, left, right, front, and rear … …) in the embodiments of the present invention are merely used to explain the relative positional relationship, movement, etc. between the components in a particular posture (as shown in the drawings), and if the particular posture is changed, the directional indicator is changed accordingly.
Furthermore, descriptions such as those referred to herein as "first," "second," "a," and the like are provided for descriptive purposes only and are not to be construed as indicating or implying a relative importance or an implicit indication of the number of features being indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
In the present invention, unless specifically stated and limited otherwise, the terms "connected," "affixed," and the like are to be construed broadly, and for example, "affixed" may be a fixed connection, a removable connection, or an integral body; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In addition, the technical solutions of the embodiments of the present invention may be combined with each other, but it is necessary to be based on the fact that those skilled in the art can implement the technical solutions, and when the technical solutions are contradictory or cannot be implemented, the combination of the technical solutions should be considered as not existing, and not falling within the scope of protection claimed by the present invention.

Claims (2)

1. The lower limb exoskeleton gait planning method based on gravity center stabilization is characterized by comprising the following steps of:
s1: according to the spatial relationship among joints of the lower limb exoskeleton, constructing a kinematic model by taking the hip of a user as a reference coordinate system;
s2: planning a foot end track of a kinematic model according to gait parameters of a user based on a gravity center stabilization principle in the gait movement process;
s3: acquiring angle adjustment information among joints through inverse kinematics analysis according to the planned foot end track;
s4: controlling motors at all joints according to the angle adjustment information to realize gait movement of the lower limb exoskeleton;
in the step S2, the gait parameters comprise a step length, a step height and a gait cycle, and the kinematic model comprises a supporting phase and a swinging phase in one gait cycle, wherein the periods of the supporting phase and the swinging phase are equal;
in the step S2, the principle of center of gravity stability is as follows: in the gait movement process of the lower limb exoskeleton, when the gait cycle is in a supporting phase, the gravity center of a user in the horizontal direction is always in the center of the user;
in the step S2, the foot end track is solved based on a track constraint equation and a quintic polynomial equation, wherein the track constraint equation comprises a first radial constraint equation and a first vertical constraint equation based on step length and step height, and a second radial constraint equation and a second vertical constraint equation based on speed and acceleration under the zero impact principle;
the foot end trajectory may be expressed as the following formula:
wherein x and z are coordinates of the joint under the reference coordinates, S is a step length, T 0 The gait cycle is that H is the step height, and t is the time in one gait cycle;
the angle adjustment information may be expressed as the following formula based on inverse kinematics analysis:
in the method, in the process of the invention,for the spatial coordinates of the exoskeleton foot end of the lower limb in the reference coordinate system, +.>For angle adjustment information of the hip joint, +.>For angle adjustment information of knee joint, +.>For the user's calf length, < >>For the thigh length of the user->。
2. A lower extremity exoskeleton gait planning system based on center of gravity stabilization, comprising:
the model building unit is used for building a kinematic model by taking the hip of a user as a reference coordinate system according to the spatial relationship among the joints of the lower limb exoskeleton;
the footprint planning unit is used for planning a foot end track of the kinematic model according to gait parameters of a user based on a gravity center stabilization principle in the gait movement process;
the angle calculation unit is used for acquiring angle adjustment information among all joints through inverse kinematics analysis according to the planned foot end track;
the motor driving unit is used for controlling the motors at all joints according to the angle adjustment information to realize gait movement of the lower limb exoskeleton;
in the footprint planning unit, the principle of gravity center stability is as follows: in the gait movement process of the lower limb exoskeleton, when the gait cycle is in a supporting phase, the gravity center of a user in the horizontal direction is always in the center of the user;
the foot end trajectory may be expressed as the following formula:
wherein x and z are coordinates of the joint under the reference coordinates, S is a step length, T 0 The gait cycle is that H is the step height, and t is the time in one gait cycle;
in the angle calculation unit, the angle adjustment information may be expressed as the following formula based on the inverse kinematics analysis:
in the method, in the process of the invention,for the spatial coordinates of the exoskeleton foot end of the lower limb in the reference coordinate system, +.>For angle adjustment information of the hip joint, +.>For angle adjustment information of knee joint, +.>For the user's calf length, < >>For the thigh length of the user->。
CN202210086783.4A 2022-01-25 2022-01-25 Lower limb exoskeleton gait planning method and system based on gravity center stabilization Active CN114469655B (en)

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WO2022012491A1 (en) * 2020-07-13 2022-01-20 Angelexo Scientific Co., Ltd Single-lower-limb rehabilitation exoskeleton apparatus and control method

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