Passive ground-contact knee exoskeleton robot and power assistance method thereof

Abstract

This invention relates to a passive ground-contact knee-joint exoskeleton robot and its assistive method, comprising the following components: a thigh mechanism including a thigh rod; a knee joint energy storage mechanism including a knee joint assembly, an elastic rod, and a foot assembly, wherein the upper end of the elastic rod is connected to the knee joint assembly, the lower end of the elastic rod is connected to the foot assembly, and the knee joint assembly is connected to the lower end of the thigh rod; the knee joint energy storage mechanism is used to store and release the gravitational potential energy of the human body during walking; and a lower leg mechanism including a lower leg rod, wherein the upper and lower ends of the lower leg rod are respectively connected to the knee joint assembly and the foot assembly. The device of this invention has a simple structure, is lightweight, easy to wear, stable and reliable, has a reasonable working principle, and provides significant assistance.

Description

Technical Field

[0001] The present invention relates to a passive ground-contacting knee joint exoskeleton robot and a power-assisting method thereof, and in particular to a passive ground-contacting knee joint exoskeleton robot based on elastic rod energy storage and a power-assisting method thereof, belonging to the technical field of passive lower limb exoskeletons. Background Art

[0002] The fundamental difference between humans and animals is that humans are good at making and using tools. Exoskeletons are one of the tools used to expand human body functions and load-bearing capacity. Their advantage over cars, high-speed trains, bicycles and other means of transportation is that they can flexibly follow the movements of human limbs and can provide assistance to the human body under various working conditions including forests, grasslands, beaches, roads, etc.

[0003] The current bottleneck in the development of powered exoskeletons is not in its core algorithm, but in the power module, which is not closely related to the design of the exoskeleton. The reason is that the current battery density is not enough to meet the long-term operation requirements of exoskeleton robots under outdoor conditions. Passive exoskeletons have abandoned this criticism and attempt to help the movement of human limbs by more rationally allocating the body's own energy. At present, the functions realized by most passive exoskeletons are more inclined to assist in sharing the weight carried by the human body, and it is a bit far-fetched when it comes to power assistance functions. At the same time, another advantage of passive exoskeletons over powered exoskeletons is that they are light and flexible. However, some passive mechanisms currently do not have much reflection in this regard. Summary of the invention

[0004] The present invention provides a passive ground-contacting knee joint exoskeleton robot and a power-assisting method thereof. The device has a simple structure, a light body, is easy to wear, is stable and reliable, has a reasonable working principle, and provides obvious power assistance.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A passive ground-contact knee joint exoskeleton robot, comprising the following components:

[0007] A thigh mechanism, including a thigh rod;

[0008] A knee joint energy storage mechanism, comprising a knee joint assembly, an elastic rod and a foot assembly, wherein the upper end of the elastic rod is connected to the knee joint assembly, the lower end of the elastic rod is connected to the foot assembly, the knee joint assembly is connected to the lower end of the thigh rod, and the knee joint energy storage mechanism is used to store and release the gravitational potential energy of the human body during walking;

[0009] The calf mechanism comprises a calf rod, and the upper and lower ends of the calf rod are respectively connected to the knee joint component and the foot component.

[0010] The passive ground-contact knee exoskeleton robot, preferably, the knee joint assembly includes a knee joint outer end cover and a knee joint inner end cover connected thereto, a cavity is formed between the two, a deep groove ball bearing, a cam and a knee joint cam rod are installed in the cavity, the deep groove ball bearing and the cam together constitute a rotating pair, the cam is connected to the lower end of the thigh rod, and the cam and the knee joint cam rod together constitute a cam pair.

[0011] The passive ground-contact knee exoskeleton robot preferably comprises a foot assembly including a linear bearing wrap, a foot push rod and a linear bearing, the upper end of the foot push rod is connected to the lower end of the elastic rod through an ankle joint interface, the linear bearing ring is sleeved on the lower end of the foot push rod to form a cylindrical pair, the lower end of the foot push rod is connected to the linear bearing wrap, and the lower end of the calf rod is connected to the linear bearing wrap.

[0012] The passive ground-contact knee exoskeleton robot, preferably, the foot assembly also includes a shoe cover, the shoe cover is connected to the calf rod through a joint bearing, the upper end of the calf rod is connected to the lower end of the knee joint outer end cover, and the lower end of the calf rod is connected to the shoe cover.

[0013] The passive ground-contact knee exoskeleton robot preferably has an upper end of the elastic rod connected to the knee joint cam rod via a knee joint interface, and the knee joint interface is hinged to the lower end of the knee joint cam rod via a cylindrical pin.

[0014] The passive ground-contact knee exoskeleton robot is preferably provided with a roller bearing between the cam and the knee cam rod, so as to prevent the knee cam rod from moving downward due to gravity during the swinging period, causing the gap between the cam pairs to be too large.

[0015] In the passive ground-contact knee exoskeleton robot, preferably, the knee cam rod is in contact with the knee outer end cover through two groups of roller bearings, and each group contains at least two roller bearings.

[0016] The passive ground-contact knee exoskeleton robot preferably comprises a foot assembly further comprising a ground contact disc, wherein the ground contact disc is mounted on the lower end of the linear bearing wrapper.

[0017] In the passive ground-contact knee exoskeleton robot, preferably, the thigh mechanism further comprises a thigh fixing piece, and the thigh fixing piece is provided with a strap hole for accommodating a strap to pass through so as to bind the thigh rod to the thigh of the human body;

[0018] The calf mechanism also includes a calf fixing piece, and the calf fixing piece is also provided with a strap hole for accommodating the passing of a strap so as to bind the calf rod to the calf of a human body.

[0019] Based on the above passive ground-contact knee exoskeleton robot, the present invention also provides a power assisting method of the robot, comprising the following steps:

[0020] When a patient wearing the passive ground-contact knee exoskeleton robot walks, as the heel of the supporting leg of the human body gradually and completely contacts the ground, the ground contact circle and the sole push rod move upward relative to the human body to compress the elastic rod to deform. At this time, the bending degree of the elastic rod increases, and the knee joint interface rotates counterclockwise relative to the knee joint cam rod due to the bending of the elastic rod, and the ankle joint interface rotates clockwise relative to the upper end of the sole push rod. This process not only realizes the pre-deformation of the elastic rod, but also recovers the part of the human body and the weight it carries that reduces the gravitational potential energy.

[0021] When the knee joint of the human body's supporting leg further bends backward, the knee joint cam rod rolls clockwise around the cam under the action of the calf mechanism through the roller bearing. During this process, since the radius of curvature of the knee joint cam rod and the cam at the contact point continues to increase, the lower end of the knee joint cam rod moves downward relative to the calf mechanism. At the same time, since the ground contact circle contacts the ground, the spatial position of the foot push rod is fixed, which further causes the bending deformation of the elastic rod to achieve the purpose of storing energy when the knee joint of the human body's supporting leg is bent backward by the passive ground-contact knee joint exoskeleton robot.

[0022] When the human body's supporting leg is further transformed into a swinging leg, during the process of the heel leaving the ground, the pressure of the push rod on the elastic rod gradually decreases, and the elastic rod provides the human body with a power assistance compensation in the direction of leaving the ground through the foot assembly. This process feeds back to the human body part of the gravitational potential energy reduced by the human body and the weight it carries before the passive ground-contacting knee exoskeleton robot retracts its legs and enters the supporting period.

[0023] The present invention adopts the above technical solution, which has the following advantages:

[0024] 1. The knee joint energy storage mechanism of the present invention has a clutch function and an energy storage function. The knee joint energy storage mechanism uses the heel-touching phenomenon as a clutch control signal, and realizes energy storage by converting the displacement of the knee joint cam rod in the inverted cam pair and the compression of the elastic rod during the support period. When the clutch is disengaged during the swing period, it ensures that the exoskeleton does not significantly interfere with the human knee joint.

[0025] 2. The knee joint cam rod in the knee joint assembly of the present invention contacts the outer end cover of the knee joint through two groups of four roller bearings. The purpose of this structural design is to transform the complex spatial contact force between the two into two component forces in the sagittal plane and the coronal plane respectively, which are borne by two groups of bearings to prevent the two components from getting stuck due to the complex contact force.

[0026] 3. The compression amount of the elastic rod in the present invention is adjustable, and the assistance effect of the knee joint can be adjusted according to different people. The knee joint energy storage mechanism can recover the gravitational potential energy that drops when the supporting leg lands and provide assistance when the supporting leg leaves the ground.

[0027] 4. The device of the present invention has a simple structure, is light in size, easy to wear, stable and reliable, has a reasonable working principle, and provides obvious assistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of the overall structure of a passive ground-contact knee exoskeleton robot provided by an embodiment of the present invention;

[0029] Figure 2 An exploded view of the components of the passive ground contact knee exoskeleton provided for this embodiment of the present invention around the knee joint gathering area (knee joint assembly);

[0030] Figure 3 An exploded view of the components of the passive ground contact knee exoskeleton around the foot gathering area (foot assembly) provided for this embodiment of the present invention;

[0031] Figure 4 An exploded view of the passive ground contact knee exoskeleton provided by the embodiment of the present invention;

[0032] The marks in the figure are as follows:

[0033] 1-thigh mechanism, 101-thigh rod, 102-thigh fixing part; 2-knee joint assembly; 3-elastic rod; 4-calf mechanism, 401-calf rod, 402-calf fixing part; 5-foot assembly; 6-shoe cover; 7-knee joint interface; 8-roller bearing; 9-knee joint outer end cover; 10-Saida screw; 11-knee joint cam rod; 12-cam; 13-deep groove ball bearing; 14-knee joint inner end cover; 15-hexagon socket flat round head screw; 16-linear bearing wrap; 17-foot push rod; 18-linear bearing; 19-ankle joint interface; 20-joint bearing; 21-screw; 22-slotted pan head self-tapping screw; 23-ground contact disc. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention is described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in the art without creative work are within the scope of protection of the present invention.

[0035] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meanings understood by persons with ordinary skills in the field to which the present invention belongs. The words "first", "second", "third", "fourth" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Words such as "include" or "comprise" and the like mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" and the like are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0036] like Figure 1 As shown, the passive ground-contact knee joint exoskeleton robot provided by the present invention includes the following components:

[0037] The thigh mechanism 1 includes a thigh rod 101; the knee joint energy storage mechanism includes a knee joint assembly 2, an elastic rod 3 and a foot assembly 5, the upper end of the elastic rod 3 is connected to the knee joint assembly 2, the lower end of the elastic rod 3 is connected to the foot assembly 5, the knee joint assembly 2 is connected to the lower end of the thigh rod 101, and the knee joint energy storage mechanism is used to store and release the gravitational potential energy of the human body during walking; the shank mechanism 4 includes a shank rod 401, and the upper and lower ends of the shank rod 401 are respectively connected to the knee joint assembly 2 and the foot assembly 5. The elastic rod 3 in the present invention is any elastic element with bending elastic energy storage, including a spring rigid rod, a carbon fiber rod, a high elastic composite material, etc.

[0038] like Figure 1 As shown, the calf mechanism 4 is composed of a calf rod 401 and two calf fixings 402 fixed to each other by screws, and the strap passes through the slender strap holes of the two calf fixings 402 to tie the calf mechanism 4 parallel to the outside of the human calf. During the bending process, the elastic rod 3 will give the cam 12 a vertical upward external force, which is transmitted to the fixed body of the inner end cover 14 of the knee joint and the outer end cover 9 of the knee joint through the deep groove ball bearing 13. Since the two ends of the calf mechanism 4 are connected to the outer end cover 9 of the knee joint and the shoe cover 6, the external force will eventually be transmitted from the outer end cover 9 of the knee joint to the sole of the foot through the calf rod 401, and the deformation reaction force of the elastic rod 3 is overcome by the human body stepping down, so as to overcome the disadvantage of the unreliable binding of the strap.

[0039] like Figure 1 As shown, the thigh mechanism 1 is composed of a thigh rod 101 and two thigh fixing parts 102 which are fixed to each other by screws. The strap passes through the slender strap holes of the two thigh fixing parts 102 to bind the thigh mechanism parallel to the outer side of the human thigh. The lower end of the thigh rod 101 is connected to the cam 12 in the knee joint assembly 2 by screws, so as to keep the cam 12, the thigh mechanism 1 and the human thigh fixed to each other.

[0040] like Figure 2 As shown, the knee joint assembly in the knee joint energy storage mechanism includes: a knee joint interface 7, a roller bearing 8, a knee joint outer end cover 9, a sata screw 10, a knee joint cam rod 11, a cam 12, a deep groove ball bearing 13, a knee joint inner end cover 14 and a hexagon socket round head screw 15. The cam 12 is connected to the thigh mechanism 1 through the hexagon socket round head screw 15. In the initial working state, it is inclined at an angle of 30 degrees to the horizontal ground. The knee joint outer end cover 9 and the knee joint inner end cover 14 are connected and fixed by the hexagon socket round head screw 15. The deep groove ball bearing 13 and the cam 12 together form a revolute pair. The knee joint interface 7 is hinged to the lower end of the knee joint cam rod 11 and connected to the upper end of the elastic rod 3 through a thread. A roller bearing 8 is fixed to the right plane of the cam 12 through the hexagon socket round head screw 15 to prevent the knee joint cam rod 11 from moving downward due to gravity during the swing period, resulting in an excessive gap between the cam pair (knee joint cam rod 11 and cam 12). The inner diameter of the deep groove ball bearing 13 is not only interference fit with the left cylinder of the cam 12, but also squeezed together by four hexagon socket flat round head screws 15 that are screwed out of the left cylinder of the cam 12 from the inside to the outside to ensure a tight fit between the components. The outer diameter of the deep groove ball bearing 13 is not only clearance fit with the inner end cover 14 of the knee joint, but also squeezed together by four hexagon socket flat round head screws 15 that are screwed into the inner end cover 14 of the knee joint from the outside to the inside to ensure a tight fit between the components. The purpose of the knee joint cam rod 11 contacting the outer end cover 9 of the knee joint through two groups of four roller bearings 8 is to transform the complex spatial contact force of the two into two component forces in the sagittal plane and the coronal plane, respectively, which are borne by the two groups of bearings to prevent the two components from getting stuck due to the complex contact force.

[0041] like Figure 3As shown, the foot assembly in the knee joint energy storage mechanism includes: a linear bearing wrap 16, a sole push rod 17, a linear bearing 18, an ankle joint interface 19 and a ground contact disc 23. The ankle joint interface 19 is hinged to the upper end of the sole push rod 17 and connected to the lower end of the elastic rod 3 through a thread. The linear bearing wrap 16 is fixed to the calf rod 401 through four hexagon socket flat round head screws 15, and is fixed to the linear bearing 18 through four front and rear slotted pan head self-tapping screws 22. The linear bearing 18 and the sole push rod 17 form a cylindrical pair. The ground contact disc 23 is connected to the sole push rod 17 through the hexagon socket flat round head screw 15; the shoe cover 6 is connected to the calf 401 through the joint bearing 20 and three hexagon socket flat round head screws 15.

[0042] like Figure 3 As shown, the shoe cover 6 is connected to the calf rod 401 through the joint bearing 20 and is tied to the human foot with a strap. Specifically, slender strap holes are dug out in the left and right front structural beams, the left and right front quarter protruding pancake-shaped structures and the back, and weight-reducing holes are dug out in the remaining positions.

[0043] like Figure 3 As shown, a roller bearing 8 is fixed to the right plane of the cam 12 by a hexagon socket flat round head screw 15, so the downward movement of the knee joint cam rod 11 during the swing period will be hindered by the roller bearing 8, which ensures that the gap between the cam pair (knee joint cam rod 11 and cam 12) will not be too large. When the human knee joint is further extended, the lower limb exoskeleton accompanies the human body to start the next physique cycle.

[0044] like Figure 4 As shown, the energy storage principle of the knee joint energy storage mechanism is to realize energy storage by utilizing the mutual conversion of the stroke of the knee joint cam rod 11 in the inverted cam pair (knee joint cam rod 11 and cam 12) and the vertical compression amount of the elastic rod 3. The cam 12 is connected to the thigh rod 101 by bolts, and has a certain inclined angle in the initial working state. The inner and outer end covers of the knee joint are relatively fixed after being connected by bolts, and together with the cam 12, a deep groove ball bearing 13 forms a rotating pair, the knee joint interface 7 is hinged to the lower end of the knee joint cam rod 11 by a cylindrical pin, and is connected to the upper end of the elastic rod 3 by a thread, the ankle joint interface 19 is hinged to the upper end of the sole push rod 17 by a bolt connection, and is connected to the lower end of the elastic rod 3 by a thread, the linear bearing wrapper 16 is fixed to the calf rod 401 by screws, and further forms a cylindrical pair with the sole push rod 17 through a linear bearing 18, and the ground contact disk 23 is connected to the sole push rod 17 by a countersunk bolt.

[0045] In addition, the knee joint energy storage mechanism recovers the reduced gravitational potential energy of the human body and the weights it carries before entering the support period, and provides assistance compensation to the human body in the direction of leaving the ground through the foot assembly 5 and the elastic rod 3 when the heel leaves the ground later. Specifically, since the thigh mechanism 1 and the calf mechanism 4 are respectively tied to the thigh and calf of the human body by straps, the rotation angle of the knee joint outer end cover 9 and the knee joint inner end cover 14 together with the cam 12 will be determined by the human knee joint. In the process of the heel of the supporting leg gradually and completely contacting the ground, the ground contact circle 23 and the foot push rod 17 move upward relative to the human body to compress the elastic rod 3 to deform. At this time, the bending degree of the elastic rod 3 increases, and the knee joint interface 7 rotates counterclockwise relative to the knee joint cam rod 11 due to the bending of the elastic rod 3, and the ankle joint interface 19 rotates clockwise relative to the upper end of the foot push rod 17. This process not only realizes the pre-deformation of the elastic rod 3, but also recovers the reduced gravitational potential energy of the human body and the weights it carries.

[0046] like Figure 4 As shown, when the knee joint of the supporting leg is further flexed, the knee joint cam rod 11 will roll clockwise around the inclined surface of the cam 12 under the action of the calf mechanism 4 through the roller bearing 8 and the Saida screw 10. In this process, due to the continuous increase in the radius of curvature of the contact point between the knee joint cam rod 11 and the cam 12, the lower end of the knee joint cam rod 11 will move downward relative to the calf mechanism 4. At the same time, due to the contact of the ground contact circle 23 with the ground, the spatial position of the foot push rod 17 is fixed, which will further cause the bending deformation of the elastic rod 3 to achieve the purpose of the knee joint energy storage mechanism to store energy when the knee joint of the human body's supporting leg is flexed. When the knee joint of the human body's supporting leg is subsequently extended, the radius of curvature of the contact point between the knee joint cam rod 11 and the cam 12 is continuously reduced, and the knee joint cam rod 11 gradually reduces the pressure on the elastic rod 3. The elastic rod 3 gradually returns to the initial deformation state and in this process, the potential energy stored when the knee joint is flexed is fed back to the human body, achieving the purpose of the knee joint energy storage mechanism releasing energy when the knee joint of the human body's supporting leg is extended.

[0047] like Figure 4 As shown, when the human body's supporting leg is further transformed into a swinging leg, during the process of the heel leaving the ground, the pressure of the foot push rod 17 on the elastic rod 3 gradually decreases, and the elastic rod 3 provides the human body with a power assistance compensation in the direction of leaving the ground through the foot assembly 5. This process recovers part of the reduced gravitational potential energy of the human body and the weight it carries before the leg enters the supporting period through the knee joint energy storage mechanism and feeds it back to the human body.

[0048] like Figure 4As shown, when the human knee joint flexes backward during the swing period, the ground contact circle 23 breaks away from the contact with the ground, allowing the push rod 17 to slide up and down along the linear bearing 18 and the linear bearing wrap 16. Due to factors such as gravity and the increasing radius of curvature at the contact point between the knee joint cam rod 11 and the cam 12, the downward movement of the lower end of the knee joint cam rod 11 relative to the calf mechanism 4 does not cause compression to the elastic rod 3. The downward movement of the lower end of the knee joint cam rod 11 is finally transmitted to the push rod 17 through the elastic rod 3, sliding up and down along the linear bearing 18 and the linear bearing wrap 16.

[0049] The knee joint energy storage mechanism in the present invention has a clutch function and an energy storage function. The knee joint energy storage mechanism uses the heel-touching phenomenon as a clutch control signal, and realizes energy storage by converting the displacement of the knee joint cam rod 11 in the inverted cam pair and the compression of the elastic rod 3 during the support period, and ensures that the exoskeleton does not significantly interfere with the human knee joint when the clutch is disengaged during the swing period. Specifically: the knee joint energy storage mechanism recovers the negative work of the joint during the flexion of the knee joint during the support period and transfers or compensates for the positive work of the joint during the extension of the knee joint. In addition, the knee joint energy storage mechanism recovers part of the gravitational potential energy reduced by the human body and the heavy objects it carries before entering the support period, and provides assistance compensation in the direction of the human body leaving the ground when the heel leaves the ground later.

[0050] The clutch effect of the knee joint energy storage mechanism is not affected by the error of the motion law between human bodies. The degree of freedom of the knee joint energy storage mechanism in the present invention is unique, which means that the knee joint cam pair will have a unique matching state when the human body knee joint motion input is determined (although there will be a normal separation between the cam pairs at the end of the swing period, the overall posture direction is always determined), so for a certain wearer, when the knee joint determines the flexion angle during the support period, it means that the final contact state of the knee joint cam pair is the same, and further determines that the amount of pressure on the elastic rod 3 is certain, so that the final power-assisting effect of the knee joint energy storage mechanism can be guaranteed to be constant. When facing different motion laws between human body movements, the knee joint energy storage mechanism can ensure the clutch effect between the support period and the swing period, and the flexion error when the knee joint enters the support period only determines the posture state of the cam pair when it enters the support period.

[0051] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A passive ground-contact knee exoskeleton robot, characterized in that: Includes the following components: A thigh mechanism (1), comprising a thigh rod (101); A knee joint energy storage mechanism comprises a knee joint component (2), an elastic rod (3) and a foot component (5), wherein the upper end of the elastic rod (3) is connected to the knee joint component (2), the lower end of the elastic rod (3) is connected to the foot component (5), and the knee joint component (2) is connected to the lower end of the thigh rod (101), and the knee joint energy storage mechanism is used to store and release gravitational potential energy of a human body during walking; A calf mechanism (4) comprising a calf rod (401), wherein upper and lower ends of the calf rod (401) are respectively connected to the knee joint assembly (2) and the foot assembly (5); The foot assembly (5) includes a linear bearing wrap (16), a foot push rod (17) and a linear bearing (18), wherein the upper end of the foot push rod (17) is connected to the lower end of the elastic rod (3) via an ankle joint interface (19), and the linear bearing (18) is sleeved on the lower end of the foot push rod (17) to form a cylindrical pair, the lower end of the foot push rod (17) is connected to the linear bearing wrap (16), and the lower end of the calf rod (401) is connected to the linear bearing wrap (16).

2. The passive ground-contact knee exoskeleton robot according to claim 1, characterized in that: The knee joint assembly (2) comprises a knee joint outer end cover (9) and a knee joint inner end cover (14) connected thereto, wherein a cavity is formed between the two, and a deep groove ball bearing (13), a cam (12) and a knee joint cam rod (11) are installed in the cavity, wherein the deep groove ball bearing (13) and the cam (12) together form a rotating pair, wherein the cam (12) is connected to the lower end of the thigh rod (101), and the cam (12) and the knee joint cam rod (11) together form a cam pair.

3. The passive ground-contact knee exoskeleton robot according to claim 2, characterized in that: The foot assembly (5) further comprises a shoe cover (6), wherein the shoe cover (6) is connected to the calf rod (401) via a joint bearing (20), the upper end of the calf rod (401) is connected to the lower end of the knee joint outer end cover (9), and the lower end of the calf rod (401) is connected to the shoe cover (6).

4. The passive ground-contact knee exoskeleton robot according to claim 3, characterized in that: The upper end of the elastic rod (3) is connected to the knee joint cam rod (11) via a knee joint interface (7), and the knee joint interface (7) is hinged to the lower end of the knee joint cam rod (11) via a cylindrical pin.

5. The passive ground-contact knee exoskeleton robot according to claim 4, characterized in that: A roller bearing (8) is installed between the cam (12) and the knee joint cam rod (11) to prevent the knee joint cam rod (11) from moving downward due to gravity during the swinging period, causing the gap between the cam pairs to be too large.

6. The passive ground-contact knee exoskeleton robot according to claim 5, characterized in that: The knee joint cam rod (11) contacts the knee joint outer end cover (9) via two groups of roller bearings (8), each group comprising at least two roller bearings (8).

7. The passive ground-contact knee exoskeleton robot according to claim 6, characterized in that: The foot component (5) further comprises a ground contact disc (23), wherein the ground contact disc (23) is assembled on the lower end of the linear bearing wrapping piece (16).

8. The passive ground-contact knee exoskeleton robot according to claim 7, characterized in that: The thigh mechanism (1) further comprises a thigh fixing piece (102), wherein the thigh fixing piece (102) is provided with a strap hole for accommodating a strap passing therethrough so as to bind the thigh rod (101) to the thigh of a human body; The calf mechanism (4) further comprises a calf fixing member (402), and the calf fixing member (402) is also provided with a strap hole for accommodating a strap to pass through so as to bind the calf rod (401) to the calf of a human body.

9. A method for assisting the passive ground-contacting knee exoskeleton robot according to claim 8, characterized in that: The steps include: When a patient wearing the passive ground-contact knee exoskeleton robot walks, as the heel of the supporting leg of the human body gradually and completely contacts the ground, the ground contact circle (23) and the sole push rod (17) move upward relative to the human body to compress the elastic rod (3) to deform. At this time, the bending degree of the elastic rod (3) increases, and the knee joint interface (7) rotates counterclockwise relative to the knee joint cam rod (11) due to the bending of the elastic rod (3), and the ankle joint interface (19) rotates clockwise relative to the upper end of the sole push rod (17). This process not only realizes the pre-deformation of the elastic rod (3) but also recovers the part of the human body and the weight it carries that reduces the gravitational potential energy. When the knee joint of the human body's supporting leg further bends backward, the knee joint cam rod (11) rolls clockwise around the cam (12) under the action of the calf mechanism (4) through the roller bearing (8). During this process, the curvature radius of the contact point between the knee joint cam rod (11) and the cam (12) continues to increase, and the lower end of the knee joint cam rod (11) moves downward relative to the calf mechanism (4). At the same time, the spatial position of the foot push rod (17) is fixed because the ground contact circle (23) contacts the ground, which further causes the elastic rod (3) to bend and deform, so as to achieve the purpose of the knee joint energy storage mechanism storing energy when the knee joint of the human body's supporting leg is bent backward. When the knee joint of the supporting leg of the human body subsequently extends forward, the radius of curvature of the contact point between the knee joint cam rod (11) and the cam (12) continuously decreases, and the knee joint cam rod (11) gradually reduces the pressure on the elastic rod (3) at the same time, and the elastic rod (3) gradually returns to the initial deformation state and in the process feeds back the potential energy stored when the knee joint is flexed backward to the human body, thereby achieving the purpose of releasing energy of the knee joint energy storage mechanism when the knee joint of the supporting leg of the human body extends forward; When the human body's supporting leg is further transformed into a swinging leg, during the process of the heel leaving the ground, the pressure of the foot push rod (17) on the elastic rod (3) gradually decreases, and the elastic rod (3) provides the human body with a power assist compensation in the direction of leaving the ground through the foot component (5). This process partially feeds back to the human body the gravitational potential energy reduced by the human body and the weight it carries before the passive ground-contacting knee exoskeleton robot retracts its legs and enters the supporting period.

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