WO2022222514A1

WO2022222514A1 - Exoskeleton robot ankle joint having three flexible driving branches

Info

Publication number: WO2022222514A1
Application number: PCT/CN2021/138565
Authority: WO
Inventors: 何勇; 吴新宇; 刘静帅; 李金科; 马跃; 李锋; 孙健铨; 董遥; 王大帅; 曹武警
Original assignee: 中国科学院深圳先进技术研究院
Priority date: 2021-04-23
Filing date: 2021-12-15
Publication date: 2022-10-27
Also published as: CN113084862B; CN113084862A

Abstract

An exoskeleton robot ankle joint having three flexible driving branches, which comprises a shank fixing block (1), a constraint branch (2), a sole plate (3), a first driving branch (4), a second driving branch (5), and a third driving branch (6). The sole plate (3) is connected to the shank fixing block (1) by means of the constraint branch (2); the first driving branch (4), the second driving branch (5), and the third driving branch (6) are provided on the shank fixing block (1); the first driving branch (4) and the second driving branch (5) are linked to drive the sole plate (3) to achieve inward turning/outward turning rotation; and the first driving branch (4), the second driving branch (5), and the third driving branch (6) are linked to drive the sole plate (3) to achieve dorsiflexion/plantar flexion rotation and inward rotation/outward rotation. The exoskeleton robot ankle joint having three flexible driving branches has three rotational degrees of freedom, each degree of freedom is an active degree of freedom, and dorsiflexion/plantar flexion rotation, inward turning/outward turning rotation, and inward rotation/outward rotation of ankle joints of lower limbs of a human body can be simulated and reproduced.

Description

An exoskeleton robot ankle joint with three flexible actuation branches

technical field

The invention belongs to the technical field of robots, and relates to an exoskeleton robot ankle joint with three flexible drive branches.

Background technique

The lower extremity exoskeleton is a wearable bionic robot similar in structure to the lower extremities of the human body. It can assist the wearer to achieve lower extremity rehabilitation, assist walking, and enhance weight-bearing functions. It has broad application prospects in the fields of rehabilitation, civil and military. According to the research on the motion mechanism of human joints, the ankle joint is composed of the fork-shaped joint socket formed by the lower articular surface of the tibia, the medial ankle joint surface and the lateral ankle joint surface, and the ankle joint head of the talus. It can do dorsiflexion/plantar flexion around three rotation axes. Flexion, varus/valgus, and small internal/external rotation movements, of which dorsiflexion/plantar flexion, varus/valgus rotations are the basic prerequisites to ensure the human body performs daily movements such as balance, walking, and sitting.

The self-balancing exoskeleton is oriented to patients with quadriplegia, and needs to completely bionic reconstruct the movement ability of the lower limbs of the human body. Therefore, each joint needs to meet the requirements of human movement in terms of degrees of freedom, rotation center position, stiffness, etc., and each joint needs to be actively controllable .

The traditional exoskeleton ankle joint has defects such as few degrees of freedom, insufficient number of drives, and large end inertia.

technical problem

In order to overcome the deficiencies of the prior art, the present invention proposes an exoskeleton robot ankle joint with three flexible drive branches, which has three active degrees of freedom: dorsiflexion/plantar flexion, varus/valgus, internal rotation/external rotation , the rotation centers of the two joints dorsiflexion/plantar flexion and varus/valgus are highly coincident with the center of the human ankle joint, and are the main driving joints, while internal rotation/external rotation are mainly used to assist the robot to change the direction.

The technical solution of the present invention to solve the above problems is: an exoskeleton robot ankle joint with three flexible drive branches, the special feature of which is:

comprising a lower leg fixing block, a restraining branch, a foot sole plate, a first driving branch, a second driving branch and a third driving branch;

The foot bottom plate is connected with the calf fixing block through the restraining branch, one end of the first driving branch, the second driving branch and the third driving branch is arranged on the calf fixing block, and the other end is hinged with the foot bottom plate;

Through the linkage of the first driving branch and the second driving branch, the foot sole plate is driven to realize inversion/outversion;

Through the linkage of the first driving branch, the second driving branch and the third driving branch, the soleplate is driven to realize dorsiflexion/plantar flexion rotation and internal rotation/external rotation rotation.

Further, one end of the above-mentioned first driving branch and the second driving branch are respectively arranged on both sides of the lower leg fixing block, and the other end is hinged with the middle of the foot soleplate;

One end of the third driving branch is arranged on the rear side of the lower leg fixing block, and the other end is hinged with the rear part of the sole plate. Further, the above-mentioned restraint branch includes a left support frame, a right support frame and a cross shaft;

The left half shaft of the cross shaft forms a left rotation pair with the left support frame and the first bearing, and the right half shaft of the cross shaft forms a right rotation pair with the right support frame and the second bearing. The axes of the left and right rotation pairs coincide at The axis of rotation of dorsiflexion/plantar flexion. The rear half shaft of the cross shaft and the third bearing intermediate bracket form a rear rotation pair, and the axis of the rear rotation pair coincides with the axis of the inversion/valgus rotation shaft. The upper half shaft of the intermediate bracket, the bearing and the upper support frame form an upper rotating pair, and the axis of the upper rotating pair coincides with the axis of the inner/outer rotation shaft.

Further, the above-mentioned left support frame has the same structure as the right support frame. The bottom edges of the left support frame and the right support frame are fixed with the foot bottom plate.

Further, the left support frame or the right support frame is provided with a first encoder, and the first encoder is used to detect the rotation angle of dorsiflexion/plantar flexion.

Further, the above-mentioned transfer bracket is provided with a second encoder, and the second encoder is used to detect the rotation angle of varus/valgus; the upper support frame is provided with a third encoder, and the third encoder is used to detect varus. /The rotation angle of the eversion.

Further, the structures of the first driving branch, the second driving branch and the third driving branch are the same.

Further, the above-mentioned first driving branch includes a driving mechanism, a moving pair, a first equivalent spherical pair and a second equivalent spherical pair;

The driving mechanism drives the moving pair to move, the first equivalent ball pair is connected with the moving pair, and the first equivalent ball pair is connected with the second equivalent ball pair through an elastic link.

Further, the above-mentioned driving mechanism is a motor with a code disc, and the moving pair includes a lead screw and a slider.

Further, the above-mentioned first equivalent spherical pair has the same structure as the second equivalent spherical pair.

Further, the above-mentioned first equivalent spherical pair includes a support frame, a cross shaft, a front mounting plate and a rear mounting plate,

The upper part of the support frame is provided with an upper half shaft, the upper half shaft is connected with the inner ring of the fifth bearing to form a Z-axis rotation pair, the outer ring of the fifth bearing is connected with the bearing frame, and the bearing frame is connected with the output flange;

The left and right shafts of the cross shaft are respectively fixed on the support frame through bearings, the axis of the left and right shafts is the Y-axis direction, the front mounting plate and the rear mounting plate are respectively connected to the front and rear shafts of the cross shaft through bearings, and the front and rear shafts of the cross shaft are the X-axis.

beneficial effect

Advantages of the present invention:

1) The present invention proposes a new type of exoskeleton robot ankle joint device, the ankle joint has three rotational degrees of freedom, and each degree of freedom is an active degree of freedom, which can bionic reproduce the dorsiflexion/plantar flexion of the ankle joint of the lower limbs of the human body Rotation, inversion/outversion, inversion/outversion;

2) In the ankle joint of the present invention, the axis of the dorsiflexion/plantar flexion rotation joint and the varus/valgus rotation axis meet at a point, and this point can be adjusted to coincide with the center of the human ankle joint in practical applications, and the inner The rotation/external rotation axis is tangent to the heel of the human body and perpendicular to the soleplate of the foot. This design can realize the motion of the human ankle joint without axis deviation;

3) The configuration of the ankle joint in the present invention is composed of three PSS driving branches with the same structure and one RRR restraining branch with three degrees of freedom, so that the entire ankle joint forms a 3PSS-RRR parallel mechanism on the mechanism. The ankle joint has the advantages of high rigidity and high strength in structure;

4) In the ankle joint of the present invention, each drive branch has one moving pair and two 3-DOF equivalent ball pairs, wherein the moving pair is the active pair driven by the motor, and the two equivalent ball pairs are passive pairs. The passive degree of freedom of the driving branch is 6, so each driving branch will not constrain the soleplate of the foot, and the relative motion degree of freedom between the soleplate 3 and the calf fixing block 1 is only determined by the restraint branch 2;

5) In the ankle joint of the present invention, the moving pair of each driving branch contains a driving motor, so its weight is higher than that of the passive equivalent ball pair. The center of gravity of the ankle joint is on the upper side, and its main moving part, the sole plate, can become light and low inertia, which makes the whole ankle joint have high dynamic characteristics;

6) In the ankle joint of the present invention, the two equivalent ball pairs of each driving branch are connected to each other by an elastic link, and the elastic coefficient of the elastic link can be adjusted according to the requirements. The drive branch becomes an elastic drive branch, which can improve the control compliance, wearing safety and comfort of the ankle joint;

7) In the ankle joint of the present invention, the constraining branch 2 has three rotational degrees of freedom, namely the above-mentioned dorsiflexion/plantar flexion rotation, varus/valgus rotation, and internal rotation/external rotation rotation. These three rotational degrees of freedom are passive degrees of freedom, and the rotational angle of each axis can be measured in real time by the encoder, and the measured three direction angle values are fed back to the three drive branches to achieve closed-loop control, which can solve the problem of flexibility The problem of low control precision of the drive branch.

Description of drawings

Figure 1 is an overall structural diagram of the ankle joint;

Figure 2 is an exploded view of the overall structure of the ankle joint;

Fig. 3 is an exploded view of two rotationally constrained branch structures;

Fig. 4 is an exploded diagram of the drive branch structure;

Fig. 5 is the exploded view of the equivalent spherical pair structure of the drive branch;

Figure 6 is an ankle dorsiflexion diagram;

Figure 7 is a plantar flexion diagram of the ankle joint;

Figure 8 is an ankle joint varus diagram;

Figure 9 is an ankle valgus diagram;

Figure 10 is an ankle joint inversion diagram;

Figure 11 is a valgus view of the ankle joint.

in:

1. Calf fixing block;

2. Constrain branch;

21, cross shaft; 22, left support frame; 23, first bearing; 24, right support frame; 25, second bearing; 26, first encoder; 27, third bearing; 28, transfer bracket; 29, first Second encoder; 210, lower bearing; 211, upper bearing; 212, upper support frame; 213, third encoder;

3. Foot sole;

4. The first drive branch;

41, motor; 42, lead screw; 43, slider; 44, adapter plate; 45, first equivalent ball pair; 46, elastic connecting rod; 47, second equivalent ball pair;

451, support frame; 452, output flange; 453, bearing frame; 454, fifth bearing; 455, front baffle, 456, sixth bearing, 457, front mounting plate; 458, rear baffle; 459, seventh Bearing; 4510, rear mounting plate; 4511, left baffle; 4512, eighth bearing; 4513, right baffle; 4514, ninth bearing; 4515, cross shaft;

5. The second driving branch; 6. The third driving branch.

Embodiments of the present invention

In order to make the purposes, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments These are some embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. Accordingly, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention.

The invention relates to an exoskeleton robot ankle joint device with three rotational degrees of freedom, wherein the three rotational degrees of freedom of the ankle joint are all active drive degrees of freedom. As shown in Figure 1, the designed exoskeleton ankle joint can realize three rotational degrees of freedom (R pair) of varus/valgus, dorsiflexion/plantar flexion, internal rotation/external rotation, and is characterized by varus/valgus The rotation axis of the dorsiflexion/plantar flexion and the rotation axis of the dorsiflexion/plantar flexion intersect at the center of the ankle joint of the lower limb of the human body, and the rotation axis of the internal rotation/external rotation is upward along the tangent of the heel of the human lower limb. This design can highly restore the motion of the human ankle joint and solve the existing external There are problems such as insufficient driving freedom of the skeletal ankle joint and deviation of the rotation center, so as to realize the human-machine compatible rehabilitation walking motion.

As shown in Figure 2, an exoskeleton robot ankle joint with three flexible drive branches includes a lower leg fixing block 1, a restraint branch 2, a foot sole plate 3, a first drive branch 4, a second drive branch 5 and a third drive branch 6;

The foot bottom plate 3 is connected with the calf fixing block 1 through the restraining branch 2, and the first driving branch 4, the second driving branch 5 and the third driving branch 6 are arranged on the calf fixing block 1; through the first driving branch 4 and the second driving branch 5. The linkage drives the sole plate 3 to realize inversion/outversion;

Through the linkage of the first driving branch 4 , the second driving branch 5 and the third driving branch 6 , the soleplate 3 is driven to achieve dorsiflexion/plantar flexion rotation and internal rotation/external rotation rotation.

Specifically, the lower leg fixing block 1 is a structure with a concave cross-section, the restraining branch 2 has two rotational degrees of freedom, the sole plate 3 is a light-weight and high-strength plate, the first driving branch 4, the second driving branch 5, Each of the third driving branches 6 includes a driving moving pair, two passive equivalent spherical pairs and a flexible connecting rod.

The upper end of the restraining branch 2 is fixedly connected with the lower end mounting hole of the inner concave surface of the calf fixing block 1, and the lower end of the restraining branch 2 is fixedly connected with the mounting hole on the upper surface of the foot bottom plate 3, so that the foot bottom plate 3 can generate three directions relative to the calf fixing block 1 rotational degrees of freedom. The movable sub-bases of the first drive branch 4 , the second drive branch 5 and the third drive branch 6 are respectively fixed to the mounting holes of the left, right and rear three azimuth outer mounting surfaces of the lower leg fixing block 1 , while the first drive Equivalent ball pairs at the ends of the branch 4 , the second driving branch 5 and the third driving branch 6 are fixedly connected to the left, right and rear mounting holes of the foot sole plate 3 . Since each driving branch has 6 passive degrees of freedom and 1 active degree of freedom, the driving branch will not produce motion constraints between the foot sole plate 3 and the lower leg fixing block 1, but it can drive the three generated by the restraining branch 2. rotational degrees of freedom.

Preferably, the lower leg fixing block 1 has a concave cross section along the horizontal direction, and the structure has the characteristics of light weight and high strength, which can reduce the overall weight of the ankle joint while ensuring the strength requirements. The concave structure can form a semi-closed cavity in space, which is convenient for binding and fixing the lower limbs of the human body, and has three mounting planes in left, right and rear directions, which is convenient for the fixed connection of the driving branch and the restraining branch. Mounting holes with different heights are designed on the left, right and rear mounting surfaces of the calf fixing block 1, which can be used to adjust the mounting heights of each drive branch and restraint branch, thereby adapting to different sizes of human lower limbs.

As a preferred embodiment of the present invention, the restraining branch 2 is shown in FIG. 3 , the branch has three rotational degrees of freedom, and the axes of each rotational degree of freedom are perpendicular to each other, wherein the rotation axis of the varus/valgus is The axis of dorsiflexion/plantar flexion intersects at point P, which can be adjusted to coincide with the center of the ankle joint of the lower limb of the wearer in practical applications, while the axis of internal rotation/external rotation will be tangent to the heel of the human body in practical applications and perpendicular to the sole of the foot. The cross axis 21 of the restraining branch 2 is designed in a concave shape, in order to form a semi-closed loop cavity to wrap the heel of the human body. The left half shaft of the cross shaft 21 forms a left rotation pair with the left support frame 22 and the first bearing 23, while the right half shaft of the cross shaft 21 forms a right rotation pair with the right support frame 24 and the second bearing 25, and the left and right rotations The axis of the pair coincides with the axis of the axis of dorsiflexion/plantar flexion. The rear half-shaft of the cross shaft 21, the third bearing 27 and the intermediate support frame 28 form a rear rotation pair, and the axis of the rear rotation pair coincides with the axis of the inversion/valgus rotation shaft. The upper half shaft of the intermediate bracket 28, the lower bearing 210, the upper bearing 211, and the upper support frame 212 form an upper rotation pair, and the axis of the upper rotation pair coincides with the axis of the inner/outer rotation shaft.

Preferably, an encoder 26 is fixed on the right support frame 24 for detecting the rotational angle of dorsiflexion/plantar flexion. The encoder 29 is fixed on the intermediate bracket 28 for detecting the rotation angle of varus/valgus. The encoder 213 is fixed on the upper support frame 212, and is used for detecting the rotation angle of pronation/external rotation. Since the three drive branches 4, 5, and 6 all contain elastic elements, it is impossible to ensure accurate driving of the three rotary joints of the ankle joint under open-loop control. Therefore, the angle values fed back by the encoders 26, 29, and 213 are used for the three The three drive branches are closed-loop controlled, thereby ensuring precise control of the three rotary joints. The left support frame 22 and the right support frame 24 are fixed on the corresponding installation holes of the foot bottom plate 3, and the upper support frame 212 is fixed on the calf fixing block 1, so that the foot bottom plate 3 can only produce three freedoms relative to the calf fixing block 1. degrees of rotation without relative movement.

As a preferred embodiment of the present invention, the first driving branch 4 , the second driving branch 5 , and the third driving branch 6 have the same structure.

The first driving branch 4 includes a driving mechanism, a moving pair, a first equivalent ball pair 45 and a second equivalent ball pair 47; the driving mechanism drives the moving pair to move, the first equivalent ball pair 45 is connected to the moving pair, and the first equivalent ball pair 45 is connected to the moving pair. The effective ball pair 45 is connected with the second equivalent ball pair 47 through the elastic link 46 .

Specifically, take the first driving branch 4 as an example, as shown in FIG. 4 . The driving branch contains a moving pair and two 3-DOF equivalent spherical pairs, which constitute a PSS branch. The moving pair is composed of a lead screw 42 and a slider 43, and is driven by a motor 41 with a code disc. The first equivalent ball pairs 45 and 47 with 3 degrees of freedom are connected end to end through an elastic link 46, wherein the first equivalent ball pair 45 is fixedly connected to the slider 43 through the adapter plate 44, and the second equivalent ball pair is 47 is fixed on the corresponding mounting hole of the foot bottom plate 3.

The first equivalent ball pairs 45 and 47 in the driving branch have the same structure, and the first equivalent ball pair 45 is taken as an example, as shown in FIG. 5 . The three rotation axes X, Y, and Z of the first equivalent spherical pair 45 are perpendicular to each other, and the three intersect at one point. The upper half shaft of the support frame 451 is connected with the inner ring of the fifth bearing 454 to form a Z-axis rotation pair, the outer ring of the fifth bearing 454 is connected with the bearing frame 453, and the output flange 452 is fixed on the mounting hole of , used to connect the elastic link 46 . The bearing 4512 is installed on the hole of the left mounting plate of the support frame 451, its outer ring is fixed by the left baffle 4511, and its inner ring is sleeved with the left half shaft of the cross shaft 4515 to form a left rotation pair. The ninth bearing 4514 is installed on the hole of the right mounting plate of the support frame 451, its outer ring is fixed by the right baffle 4513, and its inner ring is sleeved with the right half shaft of the cross shaft 4515 to form a right rotating pair. The axes of the left and right rotating pairs coincide with each other on the Y axis. The sixth bearing 456 is sleeved in the hole of the front mounting plate 457, the outer ring is fixed by the front baffle 455, and the inner ring of the sixth bearing 456 is sleeved with the front half shaft of the cross shaft to form the front rotating pair. The seventh bearing 459 is sleeved in the hole of the rear mounting plate 4510, and its outer ring is fixed by the rear baffle 458. The inner ring of the seventh bearing 459 is sleeved with the rear half shaft of the cross shaft to form a rear rotating pair. The axes of the front and rear rotating pairs coincide with each other on the X axis. The bottom surfaces of the front mounting plate 457 and the rear mounting plate 4510 are parallel to each other and are used to be fixed in the corresponding holes of the foot bottom plate 3 .

The working principle of the present invention:

The motors 41 that control the first drive branch 4, the second drive branch 5, and the third drive branch 6 rotate according to the set rule, and the rotation of the three motors 41 drives the slider 43 through the lead screw 42 of each drive branch to meet The up and down movement of the set motion law is set, and the sliders 43 of the three branches drive the sole plate 3 to perform different regular rotational movements through the equivalent ball pair 45 and the elastic link 46, thereby enabling the exoskeleton robot ankle joint to achieve dorsiflexion/plantar flexion Rotational motion (as shown in Fig. 6, Fig. 7), varus/valgus rotational motion (as shown in Fig. 8, Fig. 9), varus/valgus rotational motion (as shown in Fig. 10, Fig. 11), and also A compound motion of these three rotational motions can be realized.

In order to improve the stiffness of the ankle joint and reduce the moment of inertia of the moving parts, the present invention adopts three driving branches with the same structure to drive the three rotational degrees of freedom of the ankle joint. Each driving branch consists of a moving pair (P pair) and two three-degree-of-freedom equivalent spherical pairs (S pair) connected end to end, wherein the moving pair is the driving pair, and the equivalent spherical pair is the passive pair. By arranging the moving pair with larger mass on the upper end of the ankle joint, the position of the center of gravity of the ankle joint can be increased, thereby reducing the motion inertia of the main moving parts (the sole plate) and improving the dynamic characteristics of the system. In addition, the two three-degree-of-freedom equivalent ball pairs are connected by an elastic rod, so that the driving branch forms a flexible driving branch, which can not only absorb the impact force from the sole of the foot, but also improve the wearing flexibility of the ankle joint, thereby improving the The wearing safety and comfort of the exoskeleton robot are improved.

The exoskeleton ankle joint designed by the present invention can be equivalent to a 3PSS-RRR parallel mechanism in terms of mechanism, wherein 3PSS represents three moving pairs-ball pair-ball pair driving distributed in the left, right and rear positions of the ankle joint soleplate branch, RRR represents a three-rotation pair constraint branch. Since the four branches can bear the external force/moment exerted on the ankle joint, the ankle joint has the advantages of high stiffness and high strength.

The above descriptions are only the embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the description and drawings of the present invention, or directly or indirectly applied to other related The system field is similarly included in the protection scope of the present invention.

Claims

An exoskeleton robot ankle joint with three flexible drive branches, characterized by:

comprising a lower leg fixing block (1), a restraining branch (2), a foot sole plate (3), a first driving branch (4), a second driving branch (5) and a third driving branch (6);

The foot bottom plate (3) is connected with the calf fixing block (1) through the restraining branch (2), and the first driving branch (4), the second driving branch (5) and the third driving branch (6) are arranged on the calf fixing block (1) )superior;

Through the linkage between the first driving branch (4) and the second driving branch (5), the foot sole plate (3) is driven to realize inversion/outversion;

The soleplate (3) is driven by the linkage of the first driving branch (4), the second driving branch (5) and the third driving branch (6) to realize dorsiflexion/plantar flexion rotation and internal rotation/external rotation.
An exoskeleton robot ankle joint with three flexible drive branches according to claim 1, characterized in that:

One end of the first driving branch (4) and the second driving branch (5) are respectively arranged on both sides of the lower leg fixing block (1), and the other end is hinged with the middle of the foot sole plate (3);

One end of the third driving branch (6) is arranged on the rear side of the lower leg fixing block (1), and the other end is hinged to the rear of the foot sole plate (3).
An exoskeleton robot ankle joint with three flexible drive branches according to claim 2, characterized in that:

The restraint branch (2) includes a left support frame (22), a right support frame (24) and a cross shaft (21);

The left half shaft of the cross shaft (21) is installed on the left support frame (22) with the bearing to form a left rotation pair, and the right half shaft of the cross shaft (21) is installed on the right support frame (24) with the bearing to form a right Rotating pair; the rear half shaft of the cross shaft (21) is mounted on the transfer bracket (28) through a bearing to form a rear rotating pair; the upper half shaft of the transfer bracket (28) forms an upper rotating pair with the upper support frame (212) through the bearing .
An exoskeleton robot ankle joint with three flexible drive branches according to claim 3, characterized in that:

The left support frame (22) and the right support frame (24) have the same structure, and the bottom of the left support frame (22) and the right support frame (24) are fixedly connected with the foot bottom plate (3).
An exoskeleton robot ankle joint with three flexible drive branches according to claim 4, characterized in that:

The left support frame (22) or the right support frame (24) is provided with a first encoder (26), and the first encoder (26) is used to detect the rotation angle of dorsiflexion/plantar flexion;
An exoskeleton robot ankle joint with three flexible drive branches according to claim 5, characterized in that:

The transfer bracket (28) is provided with a second encoder (29), and the second encoder (29) is used to detect the rotation angle of varus/valgus.
An exoskeleton robot ankle joint with three flexible drive branches according to claim 6, characterized in that:

The upper support frame (212) is provided with a third encoder (213), and the third encoder (213) is used for detecting the rotation angle of varus/valgus.
An exoskeleton robot ankle joint with three flexible drive branches according to any one of claims 1-7, characterized in that:

The first driving branch (4), the second driving branch (5) and the third driving branch (6) have the same structure.
An exoskeleton robot ankle joint with three flexible drive branches according to claim 8, characterized in that:

The first driving branch (4) includes a driving mechanism, a moving pair, a first equivalent ball pair (45) and a second equivalent ball pair (47);

The driving mechanism drives the moving pair to move, the first equivalent ball pair (45) is connected with the moving pair, and the first equivalent ball pair (45) is connected with the second equivalent ball pair (47) through the elastic link (46).
An exoskeleton robot ankle joint with three flexible drive branches according to claim 9, characterized in that:

The driving mechanism is a motor (41) with a code disc, and the moving pair includes a lead screw (42) and a slider (43).
An exoskeleton robot ankle joint with three flexible drive branches according to claim 10, characterized in that:

The first equivalent ball pair (45) has the same structure as the second equivalent ball pair (47).
An exoskeleton robot ankle joint with three flexible drive branches according to claim 11, characterized in that:

The first equivalent ball pair (45) includes a support frame (451), a cross shaft (4515), a front mounting plate (457) and a rear mounting plate (4510),

The upper part of the support frame (451) is provided with an upper half shaft, the upper half shaft is connected with the inner ring of the fifth bearing (454) to form a Z-axis rotation pair, and the outer ring of the fifth bearing (454) is connected with the bearing frame (453) , the bearing frame (453) is connected with the output flange (452);

The left and right shafts of the cross shaft (4515) are respectively fixed on the support frame (451) through bearings, and the axis of the left and right shafts is the Y-axis direction. ) is connected to the front and rear axles, and the front and rear axles of the cross shaft (4515) are the X-axis.