WO2022222505A1

WO2022222505A1 - Exoskeleton robot ankle joint having dual flexible drive branch

Info

Publication number: WO2022222505A1
Application number: PCT/CN2021/138028
Authority: WO
Inventors: 吴新宇; 何勇; 刘静帅; 李金科; 李锋; 马跃; 孙健铨; 连鹏晨; 曹武警; 王大帅
Original assignee: 中国科学院深圳先进技术研究院
Priority date: 2021-04-23
Filing date: 2021-12-14
Publication date: 2022-10-27
Also published as: CN113183131A; CN113183131B

Abstract

An exoskeleton robot ankle joint having a dual flexible drive branch. The exoskeleton robot ankle joint comprises a shank-fixing block (1), a restraint branch (2), a foot baseplate (3), a first drive branch (4) and a second drive branch (5), wherein the foot baseplate is connected to the shank-fixing block (1) by means of the restraint branch (2), the first drive branch (4) and the second drive branch (5) are arranged on the shank-fixing block (1), and the foot baseplate is driven by the first drive branch (4) and the second drive branch (5) to realize rotation of dorsiflexion/plantar flexion and inversion/eversion. By means of the structure, power can be flexibly and safely output.

Description

An exoskeleton robot ankle joint with dual flexible actuation branches

technical field

The invention belongs to the technical field of robots, and relates to an exoskeleton robot ankle joint with dual 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 shortcomings of the prior art, the present invention proposes an exoskeleton robot ankle joint with dual flexible drive branches, which has two active degrees of freedom of dorsiflexion/plantar flexion, varus/valgus, and the rotation center of the two joints. It is highly coincident with the center of the human ankle joint, has high structural rigidity, sufficient driving force, and a high center of gravity, and each driving unit is connected with elastic elements in series, which can realize flexible and safe power output of each joint.

The technical solution of the present invention to solve the above problem is: an exoskeleton robot ankle joint with dual 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 and a second driving branch;

The soleplate of the foot is connected with the calf fixing block through the restraining branch, the first driving branch and the second driving branch are arranged on the fixing block of the calf, and the soleplate of the foot is driven by the first driving branch and the second driving branch to realize dorsiflexion/plantar flexion and varus/inversion/ Flip out.

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, the third bearing, the fourth bearing and the rear bearing bracket form a rear rotation pair, and the axis of the rear rotation pair coincides with the axis of the inversion/valgus rotation shaft.

Further, the above-mentioned left support frame has the same structure as the right support frame. The left support frame is a tripod, the bottom edge of the tripod is fixed with the bottom plate of the foot, and the top corner of the tripod is connected with the left half shaft of the cross shaft through a bearing.

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 rear bearing bracket is provided with a second encoder, and the second encoder is used to detect the rotation angle of the varus/valgus.

Further, the structures of the first driving branch and the second 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.

Advantages of the present invention:

1) This patent designs a new type of exoskeleton robot ankle joint device, the ankle joint has two rotational degrees of freedom, and each degree of freedom is an active degree of freedom, which can bionic reproduce the dorsiflexion/plantar motion of the ankle joint of the lower limbs of the human body. Flexion, inversion/outversion;

2) The characteristic of the designed ankle joint is that the axis of the dorsiflexion/plantar flexion rotation joint meets the axis of varus/valgus rotation at a point, and this point can be adjusted to coincide with the center of the human ankle joint in practical applications. Realize the motion of human-like ankle joint without axis deviation;

3) The characteristic of the designed ankle joint is that its configuration is composed of two PSS driving branches with the same structure and one RR restraining branch with two degrees of freedom, so that the entire ankle joint forms a 2PSS-RR parallel mechanism on the mechanism, This makes this ankle joint have the advantages of high rigidity and high strength in structure;

4) The characteristic of the designed ankle joint is that 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. Since the passive degree of freedom of the driving branch is 6, each driving branch will not constrain the soleplate of the foot, and the relative motion degree of freedom between the soleplate 3 and the lower leg fixing block 1 is only determined by the restraint branch 2;

5) The characteristic of the designed ankle joint is that the moving pair of each drive branch contains a drive motor, so its weight is higher than that of the passive equivalent ball pair, and the heavy moving pair is fixed at the upper end of the calf fixing block. The center of gravity of the ankle joint is on the upper side, and the sole plate of its main moving part can become light and low inertia, so that the whole ankle joint has high dynamic characteristics;

6) The characteristic of the designed ankle joint is that the two equivalent ball pairs of each drive branch are connected to each other by an elastic link, and the elastic coefficient of the elastic link can be adjusted according to the needs. This design The driving branch becomes an elastic driving branch, which can improve the control flexibility, wearing safety and comfort of the ankle joint;

7) The designed ankle joint is characterized in that the restraint branch 2 has two rotational degrees of freedom, namely the above-mentioned dorsiflexion/plantar flexion rotation and varus/valgus rotation. These two 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 two directional angle values are fed back to the two 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 a varus view of the ankle joint.

Figure 9 is an ankle valgus diagram.

in:

1. Calf fixing block;

2. Constrain branch;

21, cross shaft; 22, first bearing; 23, left support frame; 24, right support frame; 25, second bearing; 26, first encoder; 27, third bearing; 28, fourth bearing; 29, rear bearing bracket; 210, the second 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 drive 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 two rotational degrees of freedom, wherein the two rotational degrees of freedom of the ankle joint are active drive degrees of freedom. As shown in Figure 1, the designed exoskeleton ankle joint can realize two rotational degrees of freedom (R pair) of varus/valgus, dorsiflexion/plantar flexion, and is characterized by the rotational axis of varus/valgus and dorsiflexion The axis of rotation of the plantar flexion/plantar flexion intersects at the center of the ankle joint of the lower extremity of the human body. This design can highly restore the motion of the human ankle joint, solve the problems of insufficient driving freedom of the existing exoskeleton ankle joint and the deviation of the rotation center, and then realize human-machine compatible rehabilitation. Mobility aid.

As shown in Figure 2, an exoskeleton robot ankle joint with dual flexible drive branches includes a calf fixing block 1, a restraint branch 2, a foot base 3, a first drive branch 4 and a second drive branch 5; the foot base 3 passes through The restraint branch 2 is connected with the calf fixing block 1, the first driving branch 4 and the second driving branch 5 are arranged on the calf fixing block 1, and the foot sole plate 3 is driven by the first driving branch 4 and the second driving branch 5 to realize dorsiflexion/plantar flexion Flexion and inversion/outversion.

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, and the first driving branch 4 and the second driving branch 5 include A driving moving pair, two passive equivalent ball 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 produce two directions relative to the calf fixing block 1 rotational degrees of freedom. The movable sub-bases of the first driving branches 4 and 5 are respectively fixed to the mounting holes of the left rear and right rear outer mounting surfaces of the lower leg fixing block 1 , and the ends of the first driving branches 4 and 5 are equivalent to spherical pairs. It is fixedly connected with the left rear and right rear mounting holes of the foot bottom 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 sole plate 3 and the lower leg fixing block 1, but it can drive the two 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 the binding and fixing of the lower limbs of the human body, and it has three installation planes of left rear, right rear and right rear, which is convenient for the fixing of the driving branch and the restraining branch connect. Mounting holes with different heights are designed on the three mounting surfaces of the left rear, right rear and right rear of the calf fixing block 1, which can be used to adjust the mounting height of each driving branch and restraining 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 two rotational degrees of freedom, and the axes of each rotational degree of freedom are perpendicular to each other. It intersects with the axis of dorsiflexion/plantar flexion at point P, which can be adjusted to coincide with the center of the ankle joint of the lower limb of the wearing human body in practical applications. 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 23 and the first bearing 22, 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 left support frame 23 and the right support frame 24 are both tripod structures. The bottom edge of the tripod is fixed to the foot bottom plate 3 , and the top corner of the tripod is connected to the left half shaft of the cross shaft 21 through a bearing. The rear half shaft of the cross shaft 21, the third bearing 27, the fourth bearing 28, and the rear bearing bracket 29 form a rear rotation pair, and the axis of the rear rotation pair coincides with the axis of the inversion/valgus rotation shaft.

Preferably, a first encoder 26 is fixed on the right support frame 24 for detecting the rotation angle of dorsiflexion/plantar flexion. A second encoder 210 is fixed on the rear bearing bracket 29 for detecting the rotation angle of varus/valgus. Since the two first driving branches 4 and the second driving branch 5 both contain elastic elements, it is impossible to ensure accurate driving of the two rotating joints of the ankle joint under the condition of open-loop control. Therefore, the angle fed back by the first encoders 26 and 210 cannot be guaranteed. The values are used for closed-loop control of the two drive branches, which in turn ensures precise control of the two revolute joints. The left support frame 23 and the right support frame 24 are fixed on the corresponding installation holes of the foot bottom plate 3, and the rear bearing bracket 29 is fixed on the calf fixing block 1, so that the foot bottom plate 3 can only produce two 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 branches 4 and 5 have the same structure, and 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 .

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:

When the motors of the first drive branch 4 and the drive branch 5 are started at the same time, the lead screw 42 drives the slider 43 to move downward or upward at the same time. The exoskeleton robot ankle joint can realize dorsiflexion/plantar flexion rotational motion, as shown in Figure 6 and Figure 7.

When the motors of the first drive branch 4 and the drive branch 5 are activated at the same time, and the two drive branches move in opposite directions, the slider 43 drives the foot sole plate 3 to rotate left and right through the equivalent ball pair and the elastic link 46, so that the exoskeleton robot ankle joint Realize the inversion/outversion movement, as shown in Figure 8 and Figure 9.

In order to improve the stiffness of the ankle joint and reduce the moment of inertia of the moving parts, the present invention uses two driving branches with the same structure to drive the two 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 2PSS-RR parallel mechanism in mechanism, wherein 2PSS represents two moving pairs-ball pair-ball pair drive distributed in the left and right rear positions of the ankle soleplate branch, RR represents a two-rotation pair constraint branch. Since the three 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 dual 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) and a second driving branch (5);

The foot bottom plate (3) is connected to the lower leg fixing block (1) through the restraining branch (2), and the first driving branch (4) and the second driving branch (5) are arranged on the lower leg fixing block (1), and the first driving branch (5) is connected to the lower leg fixing block (1) through the first driving branch (4) and the second driving branch (5) drive the sole plate (3) to realize dorsiflexion/plantar flexion and varus/valgus rotation.
An exoskeleton robot ankle joint with dual flexible drive branches according to claim 1, characterized in that:

The restraint branch (2) includes a left support frame (23), 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 (23) 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 rear bearing bracket (29) through a bearing to form a rear rotating pair.
An exoskeleton robot ankle joint with dual flexible drive branches according to claim 2, characterized in that:

The left support frame (23) has the same structure as the right support frame (24). The left support frame (23) is a tripod, the bottom edge of the tripod is fixed with the foot bottom plate (3), and the top corner of the tripod is connected with the left half shaft of the cross shaft (21) through a bearing.
An exoskeleton robot ankle joint with dual flexible drive branches according to claim 3, characterized in that:

The left support frame (23) 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 dual flexible drive branches according to claim 4, characterized in that:

A second encoder (210) is provided on the rear bearing bracket (29), and the second encoder (210) is used to detect the rotation angle of varus/valgus.
An exoskeleton robot ankle joint with dual flexible drive branches according to any one of claims 1-5, characterized in that:

The first driving branch (4) and the second driving branch (5) have the same structure.
An exoskeleton robot ankle joint with dual flexible drive branches according to claim 6, 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 dual flexible drive branches according to claim 7, 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 dual flexible drive branches according to any one of claims 1-5, 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 dual flexible drive branches according to claim 9, 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. The axis of the left and right shafts is the Y-axis direction. The front mounting plate (457) and the rear mounting plate (4510) pass through the bearings and the cross shaft (4515) ) is connected to the front and rear axles, and the front and rear axles of the cross shaft (4515) are the X-axis.