CN102198664A - Two-degree-of-freedom (two-DOF) spherical parallel robot bionic ankle joint with central spherical pair - Google Patents

Abstract

A two-degree-of-freedom spherical parallel robot bionic ankle joint with a central spherical pair, which mainly includes: a straight output rod is fixed under the supporting hemispherical socket, a ball head is arranged inside, and the upper part of the ball head is connected with a cylindrical body support push rod. The push rod is provided with a through hole with a rectangular cross-section. The outer tooth semicircle-arc fork passes through the through hole and the lower end is connected with the supporting hemispherical socket. In contact with the inner surface of the arc of the semi-arc-shaped fork, a support is provided outside the push rod of the above-mentioned body bracket. The upper composite hinge yoke is connected, and the upper composite hinge yoke is connected with the upper end of the pull rod, and the lower end of the pull rod is connected with the outer wall of the supporting hemispherical socket through the lower composite hinge yoke. The invention has a simple and compact structure, and the movement of the limbs is faster, more flexible, smooth and continuous, so that the shape, structure, movement, mechanics and function are as close as possible to the actual state of human beings.

Description

Two-DOF Spherical Parallel Robotic Bionic Ankle Joint with Central Spherical Pair

technical field

The invention relates to a humanoid robot, in particular to a bionic ankle joint of a humanoid robot.

Background technique

At present, people have developed a large number of various humanoid robots all over the world. Examining the existing humanoid robots, it is found that their body configurations are almost all serial configurations, that is, the multi-degree-of-freedom joints of the robot are composed of multiple single rotating pairs (or moving pairs) connected in series. This series configuration is relatively easy to realize in terms of control, and has a simple structure, but there are serious defects: the weight of the lower-level driver often becomes the load of the upper-level driver, thereby reducing the driving capacity; 1. Ankle joint, its movement function is only equivalent to that of human beings in a few specific directions (driver axis), and there are obvious decomposition movements in other directions, and its flexibility, accuracy and stability are far behind human beings; The series joints of the kinematic pair occupy a large space and have low stiffness; the limbs are not fully functional, and are not ideal for reasonably compensating motion, adjusting the balance of the robot, completing attitude changes, and ensuring the stability of the robot's operation.

As a part of the mechanism set, the parallel mechanism has the advantages that a series of series mechanisms do not have, such as high rigidity, high bearing capacity, high speed, and the driving motor is on the frame so that the movable components are light in weight. In recent years, with the gradual deepening of theoretical and applied research on parallel mechanisms, some people began to consider introducing parallel mechanisms into the research of humanoid robot ankle joints.

In 2009, Yu Zhiwei, Wang Liquan and others from Harbin Engineering University proposed a parallel ankle joint mechanism in the article "Optimization Design of Parallel Ankle Joints of Biped Robots" (Journal of Mechanical Engineering, Vol. 45, No. 11). The joint includes a foot, a lower leg, two guide rods and two connecting rods, and is connected by a Hooke hinge, two moving pairs, and four spherical pairs. Among them, the Hooke hinge is used as the force support body of the ankle joint, which has 2 degrees of freedom to rotate around the front x-axis and the lateral z-axis. However, the mechanism takes up a large space, has too many kinematic pairs, and has a complex structure.

The configuration of existing humanoid robots is mainly in a single series form, and some limited parallel joints are unsatisfactory in terms of complex structure, performance, and technical indicators. The gap cannot fully meet the actual needs.

Contents of the invention

The object of the present invention is to provide a robot bionic ankle joint with a central spherical pair and two degrees of freedom spherical parallel connection with simple structure, small space size and bionic level close to the actual state of human beings. The present invention is mainly composed of three parts: a support center spherical auxiliary branch chain, a side swing branch chain and a pitch branch chain. The supporting center spherical secondary branch chain includes a supporting hemispherical socket, a straight output rod, a ball head and a body support push rod. Wherein, the supporting hemispherical socket is a rotary body with a concave spherical surface and the center of the ball is on the rotary axis, and its upper end surface and lower end surface are both perpendicular to the rotary axis. The lower end surface of the supporting hemispherical socket is fixedly connected with the upper end of the cylindrical straight output rod. The axis of the straight output rod passes through the center of the supporting hemispherical socket and coincides with the rotation axis of the supporting hemispherical socket. The lower end of the straight output rod can be fixedly connected with the upper surface of the foot plate. . The concave spherical surface supporting the hemispherical socket is provided with a ball head, and the centers of the two overlap to form a spherical pair, which can realize rotation in three directions. The upper part of the ball head is fixedly connected with the lower end of the push rod of the cylindrical body bracket. Passing through the center point of the ball head, its upper end can be fixedly connected with the human thigh (frame). The body bracket push rod is provided with a through hole penetrating through the two side walls and having a rectangular cross-section. The side swing branch chain includes an external tooth semi-arc fork, a support roller and two support pins on the lower side of the external tooth semi-arc fork. Among them, the semicircular arc-shaped fork with external teeth of semicircular symmetrical structure passes through the rectangular through hole of the push rod of the body support, and the middle plane of its axial width is orthogonal to the plane formed by the axis of the lead screw and the push rod of the body support. The lower end of the semicircle-arc fork with external teeth forms a rotational connection with the supporting hemispherical socket through two supporting pin shafts. The ends are parallel. The two ends of the short cylindrical support roller are rotatably supported on the front and rear walls of the rectangular through hole of the push rod of the body support. The support roller is in contact with the arc inner surface of the outer tooth semi-arc fork, and the axes of the two are parallel and located on the axis of the screw. In the plane formed by the axis of the push rod of the body support, and perpendicular to the axis of the push rod of the body support, reverse support is realized. The rotating motor drives the external tooth semi-arc fork to drive the ball socket through the meshing of the external teeth, so as to realize the lateral rolling (Roll) movement of the ball socket, the output rod and the foot plate. The pitch branch chain includes a support, a slider, a lead screw, an upper composite hinge yoke, an upper part of a pull rod, a lower part of a pull rod and a lower composite hinge yoke. A bearing is arranged outside the above-mentioned body support push rod, and the support has a strip-shaped connecting plate, which is fixed on the body support push rod, and the width midline of the strip-shaped connecting plate is parallel to the axis of the body support push rod. Two lugs are vertically fixed at both ends of the bar-shaped connecting plate, and the two ends of the lead screw are connected with the two lugs through a rotating pair, and the axis of the lead screw is parallel to the axis of the push rod of the body support and at the same time parallel to the axis of the above-mentioned support roller. in the same plane. The above-mentioned lead screw is connected with the slide block through a screw pair. The slider is connected to the upper end of the upper part of the pull rod through a T-shaped upper composite hinge yoke with two horizontal and vertical rotation axes orthogonal to each other. The vertical rotation axis of the upper composite hinge yoke passes through the center of the slider and is perpendicular to the axis of the screw. Intersecting, and located in the plane formed by the lead screw and the axis of the push rod of the body bracket; the other transverse rotation pair is symmetrical at both ends and forms a rotational connection with the upper end of the upper part of the pull rod. The pull rod is divided into upper and lower sections, and the middle is directly connected by an axial rotation pair along the length direction of the pull rod. The lower end of the lower part of the pull rod is connected to the outer wall of the supporting hemispherical socket through a lower composite hinge yoke with a T-shaped vertical axis of two rotation pairs orthogonal to each other. A vertical rotation axis of the lower composite hinge yoke passes through the center of the supporting hemispherical socket. , and is perpendicular to the common axis of the two support pin shafts at the lower end of the outer tooth semicircle-arc fork in the side swing branch chain, and is parallel to the upper end surface of the support hemispherical socket; The lower ends of the parts form a rotational connection. The slider is driven by a motor and a lead screw to achieve reciprocating motion, and drives the pull rod, ball socket and output rod to complete the pitch motion of the foot.

From the perspective of structural bionics, the present invention is as close as possible to the actual state of human beings in terms of structural form. Among them, the supporting center spherical sub-branch is equivalent to the joint surface of the lower articular surface of the human tibia and the articular surface of the inner and outer malleolus. Achilles tendon between the heel and calf. From the perspective of sports bionics, it was found through comparison that: in addition to adduction and abduction around the calf, the human ankle joint can also complete the dorsiflexion with the heel as the fulcrum and the toe upwards, and the toe as the fulcrum to lift the heel upwards. Raised plantarflexion (range of motion 15 ⁰ -30 ⁰ /30 ⁰ -45 ⁰ ) and eversion and varus about the horizontal axis from heel to toe (range of motion 15 ⁰ -25 ⁰ /30 ⁰ -45 ⁰ ). And the working space of the present invention is: around the common axis of the two supporting pin shafts of the outer tooth semicircular arc type fork, and around the axis perpendicular to the plane where the common axis and the body support push rod axis are located, and passing through the center of the sphere The swings are above ±47 ⁰ ; completely covering the range of motion of the actual human ankle joint. From the perspective of functional bionics, when the motor drives the lead screw to rotate in the present invention, the slider can move up and down, pull the pull rod to move up and down, and the supporting hemispherical socket rotates around the common axis of the two supporting pins to realize the pitching motion of the sole of the foot; while another motor drives the outer When the toothed semi-arc fork swings left and right, it drives the supporting hemispherical socket, the straight output rod and the foot plate to realize the lateral swing movement, and the linkage of the two motors can realize all the functions of the human ankle joint. At the same time, when the output rod is subjected to centripetal pressure, the force load passes through the foot plate, straight output rod, supporting hemispherical socket, and ball head to reach the push rod of the body support (that is, the frame), achieving complete unloading and increasing the linear displacement stiffness; When the foot plate or the straight output rod is subjected to a pulling force away from the center of the ball, the force load is jointly borne by the side swing branch chain and the pitch branch chain respectively. So far, a highly bionic ankle joint that fully meets the requirements of humanoid robots has been invented, that is, a two-degree-of-freedom spherical parallel humanoid robot bionic ankle joint with a central spherical pair.

Compared with the prior art, the present invention has the following advantages:

The present invention is as close as possible to the actual state of human beings in terms of shape, structure, motion, mechanics and function; it has high over-constraint, large rigidity, large working space (the realizable working space is much larger than the actual range of motion of human legs) and unloading Features and other advantages; the joint structure is simple and compact, and the drivers are arranged in parallel on the body, which reduces the load on the limbs, improves the driving ability and operation ability of the limbs; makes the movement of the limbs faster, more flexible, smooth and continuous, and improves the coordination of the limbs and posture transformation. Capacity, especially high stiffness, increases the bearing capacity of the limbs and improves the stability of motion.

In short, the bionic ankle joint is of great significance and value for improving the maneuverability, operation ability, bearing capacity, motion stability, coordination ability of limb movement, attitude change, and motion control performance of humanoid robots.

Description of drawings

Fig. 1 is a three-dimensional schematic diagram of the present invention.

Detailed ways

In the three-dimensional schematic diagram of the bionic ankle joint with two degrees of freedom spherical parallel connection shown in Figure 1, the supporting hemispherical socket 1 is a rotating body with a concave spherical surface and the center of the ball is on the axis of rotation. Its upper end surface and The lower end surfaces are all perpendicular to the axis of rotation. The lower end surface of the supporting hemispherical socket is fixedly connected with the upper end of the cylindrical straight output rod 2, the axis of the straight output rod passes through the center of the supporting hemispherical socket and coincides with the rotation axis of the supporting hemispherical socket, and the lower end of the straight output rod is fixed to the upper end surface of the foot plate 3. couplet. A ball head 4 is provided in the concave spherical surface supporting the hemispherical socket, and the centers of the two overlap to form a spherical pair. The upper part of the ball head is fixedly connected with the lower end of the cylindrical body support push rod 5, and the axis of the body support push rod passes through the center point of the ball head. , the upper end of which is fixedly connected with the thigh (frame) of the human body. The body bracket push rod is provided with a through hole penetrating through the two side walls and having a rectangular cross-section. The semicircular fork 6 with outer teeth of semicircular symmetrical structure passes through the rectangular through hole of the push rod of the body support, and the middle plane of its axial width is orthogonal to the plane formed by the axis of the lead screw 7 and the push rod of the body support. , the outer tooth semi-arc-shaped fork forms a rotational connection with the supporting hemispherical socket at the lower end through two supporting pin shafts 8, the axes of the two supporting pin shafts are located on a straight line and pass through the center of the supporting hemispherical socket, and at the same time are connected with the supporting hemispherical socket The upper end faces are parallel. The two ends of the short cylindrical support roller 9 are rotatably supported on the front and rear walls of the rectangular through hole of the push rod of the body bracket. In the plane formed by the axis and the axis of the body support push rod, it is perpendicular to the axis of the body support push rod. Above-mentioned body support push rod is provided with support 10 outside, and this support has a strip connecting plate, and it is fixed on the body support push rod, and the width midline of this strip connection plate is parallel with the axis of body support push rod. Two lugs are vertically fixed at both ends of the bar-shaped connecting plate, and the two ends of the lead screw are connected with the two lugs through a rotating pair, and the axis of the lead screw is parallel to the axis of the push rod of the body support and at the same time parallel to the axis of the above-mentioned support roller. in the same plane. The above-mentioned lead screw is connected with the slide block through a screw pair. The slider is connected to the upper end of the upper part of the pull rod through a T-shaped upper composite hinge yoke 13 which is perpendicular to the axes of the two rotation pairs. The vertical rotation axis of the upper composite hinge yoke passes through the center of the slider 11 and the screw axis. It is vertical and orthogonal, and is located in the plane formed by the lead screw and the axis of the body support push rod; the other transverse rotation pair is symmetrical at both ends and forms a rotational connection with the upper end of the upper part 12' of the pull rod. The pull rod is divided into upper and lower sections, and the middle is directly connected by an axial rotation pair along the length direction of the pull rod. The lower end of the lower part 12 of the pull rod is connected to the outer wall of the supporting hemispherical socket through a lower compound hinge yoke 14 which is perpendicular to the axes of the two rotating pairs in a T shape. center, and is perpendicular to the common axis of the two support pin shafts at the lower end of the outer tooth semicircle-arc fork in the side swing branch chain, and is parallel to the upper end surface of the support hemispherical socket; the other transverse rotation pair is symmetrical at both ends and The lower end of the lower part of the pull rod forms a rotational connection.

Claims (1)

1. robot bionic ankle-joint with two-freedom sphere parallel connection of center spherical pair, it is characterized in that: supporting the hemisphere nest is interior concave spherical surface and the revolving body of the centre of sphere on axis of rotation, its upper surface is all vertical with axis of rotation with the lower surface, this support hemisphere nest lower surface and cylindrical straight take-off lever upper end connect firmly, the axis of this straight take-off lever passes the center of support hemisphere nest and overlaps with the gyroaxis that supports the hemisphere nest, be provided with bulb in the interior concave spherical surface of support hemisphere nest, both centers overlap and constitute spherical pair, this bulb top and cylindricality body rack push rod lower end connect firmly, the axis of this body rack push rod is crossed the bulb central point, this body rack push rod is provided with and runs through the two side, the through hole that the cross section is rectangular, the rectangular through-hole that the external tooth semicircle camber fork of semicircle symmetrical structure passes the body rack push rod, the mid-plane of its axial width with by leading screw, the planar quadrature that axis constituted of body rack push rod, external tooth semicircle camber fork supports bearing pins formation with support hemisphere nest by two in the lower end and is rotationally connected, this two axis that supports bearing pin is positioned on the straight line and crosses the centre of sphere that supports the hemisphere nest, parallel with the upper surface of supporting the hemisphere nest simultaneously, short cylindrical shape backing roll two ends rotational support is on the front and rear wall of body rack push rod rectangular through-hole, this backing roll contacts with the circular arc inner surface of external tooth semicircle camber fork, both axis are parallel and be positioned at the axis of leading screw and the plane that body rack push rod axis is constituted, simultaneously with the axis normal of body rack push rod, outside above-mentioned body rack push rod, be provided with bearing, this bearing has a bar shaped connecting plate, it is fixed on the body rack push rod, and the width center line of this bar shaped connecting plate is parallel with the axis of body rack push rod, in this bar shaped connecting plate two ends vertical fixing two journal stirrups are arranged, the two ends of leading screw link to each other with two journal stirrups by revolute pair, and leading screw axis and body rack push rod shaft line parallel simultaneously again with the axis of above-mentioned backing roll in same plane, on above-mentioned leading screw, link to each other with slide block by screw pair, the upper end on this slide block and pull bar top by a T font anyhow the last compound hinges crotch of two revolute pair axis quadratures be connected, the vertical revolute pair axis that should go up the compound hinges crotch passes through slide block center and leading screw axis perpendicular quadrature, and is positioned at leading screw, in the plane that body rack push rod axis is constituted; The secondary upper end for two ends symmetry and pull bar top of another lateral rotation forms and is rotationally connected, this pull bar is two sections, middle by directly connecting along the axial rotation of pull bar length direction is secondary, the lower end of this pull bar lower part is connected with the following compound hinges crotch of support hemisphere nest outer wall by the perpendicular two revolute pair axis quadratures of a T font Guang, a vertical revolute pair axis of this time compound hinges crotch is by supporting the center of hemisphere nest, and with the side-sway side chain in two of external tooth semicircle camber fork lower end to support the bearing pin common axis perpendicular, and parallel with the upper surface of supporting the hemisphere nest; The secondary lower end for two ends symmetry and pull bar lower part of another lateral rotation forms and is rotationally connected.

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