CN107639649B - A permanent magnet variable stiffness flexible joint for robot - Google Patents

Abstract

The invention belongs to the technical field of flexible robots, and provides a permanent magnet variable stiffness flexible joint for robots, which can simulate the nonlinear variable stiffness muscle characteristics of a bionic joint. The present invention adopts the permanent magnet variable stiffness mechanism as the stiffness adjustment component, the rope as the force and motion transmission component, and its stiffness will be changed according to the change of the air gap between the permanent magnets. The decoupling of the force and position of the rope can realize the constant stiffness of the joint, only changing the joint angle, that is, to realize the adjustment of the joint position under the condition of equal stiffness; it can also realize that the joint position is unchanged, only the stiffness of the joint is changed, according to different It can work under the corresponding set stiffness conditions. The invention is a permanent magnet variable stiffness flexible robot joint structure with simple motion form, simple manufacture and simple operation.

Description

A permanent magnet variable stiffness flexible joint for robot

technical field

The invention belongs to the technical field of flexible robots, in particular to a permanent magnet variable stiffness flexible joint for robots, which is used for constructing an antagonistic flexible variable stiffness robot, and is particularly suitable for the construction of bionic robot joints.

Background technique

The flexible variable stiffness robot is a kind of flexible robot with adjustable stiffness, which is different from the traditional rigid robot. Its own stiffness can be adjusted, which can greatly improve human-machine safety and environmental adaptability, and has become an important direction for future robot development.

From the perspective of sports biomechanics, muscles are the dynamic source of the human movement system, maintaining or completing movements through muscle scaling. Skeletal muscles have two forms of scaling. During the scaling process, the muscle tension remains unchanged, and the length changes, causing joint movement, namely The stiffness does not change and the position changes; the muscle length does not change and the tension changes during the scaling process, which causes the joint stiffness to increase, that is, the position does not change the stiffness change; this nonlinear variable stiffness characteristic can buffer collision, absorb and store energy. Therefore, if we can learn from the human skeletal muscle system and design joints with bionic muscle characteristics, we can improve the shortcomings of low human-computer interaction safety and poor environmental adaptability of existing robots. The variable stiffness robot joints based on parallel rope confrontation drive are the closest to human joints in driving mode, and most of the joint stiffness is changed by connecting nonlinear elastic elements in series on the rope. In addition to realizing the flexibility of the robot, the advantage of this arrangement is that the drive unit and the variable stiffness module can be placed behind, especially when building a multi-degree-of-freedom robot, it can greatly reduce the mass and inertia of the manipulator, thus solving the traditional serial mode. , the disadvantage of insufficient joint stiffness change ability caused by the gradual increase of mass and inertia.

In recent years, the performance of permanent magnet materials has been greatly improved, especially rare earth permanent magnet materials have high magnetic energy per unit volume and excellent performance, which can be equivalent to ideal permanent magnets in simplified calculations. The permanent magnet spring using the magnetic interaction between permanent magnets can replace metal springs for fast mechanical response mechanisms due to its advantages of no mechanical contact, no wear, low power consumption, long life, low noise, no lubrication, and no heat generation.

SUMMARY OF THE INVENTION

In view of the problems existing in the prior art, the present invention provides a permanent magnet variable stiffness flexible joint assembly for robots, which can simulate joints with nonlinear variable stiffness muscle characteristics, and can effectively improve the traditional robots with low human-computer interaction safety and poor environmental adaptability. Shortcomings;

In order to achieve the above purpose, the present invention provides a permanent magnet variable stiffness flexible joint for a robot, which includes at least one degree of freedom control mechanism, an operating arm, a large arm, a large arm fixing frame, an encoder, a rotating shaft of the operating arm, and the large arm is fixed On the boom fixing frame, the operating arm is fixed on the central axis of the boom through the rotating shaft of the operating arm, and the rotating shaft of the operating arm and the encoder are fixed on the boom through the thin-walled ball bearing;

One degree of freedom control mechanism consists of two sets of position and stiffness adjustment modules symmetrically arranged along the central axis of the boom, each set of position and stiffness adjustment modules includes a rope, at least two wire pulleys, at least one permanent magnet variable stiffness module, a rope winch, harmonic reducer and servo motor; one end of the rope is fixed to the operating arm, and then passes through the wire pulley A set on the outer edge of the boom, the permanent magnet variable stiffness module and the wire pulley B fixed inside the boom, and the other rope One end is fixed on the rope winch, and the rope winch, harmonic reducer and servo motor are coaxially fixed on the boom;

The fixed pulley A of the permanent magnet variable stiffness module is parallel to the axis of the wire pulley B and the contour of the pulley is circumscribed on the same straight line; the axis of the wire pulley B is perpendicular to the axis of the rope winch, and the contour circumscribes the same straight line, this arrangement can be Effectively ensure the transmission of the rope.

Further, the above-mentioned permanent magnet variable stiffness module includes: a fixed pulley A, a movable pulley, an axial sliding bearing, an axially magnetized permanent magnet ring A, a movable sliding seat, a fixed seat, an axially magnetized permanent magnet ring B, and a fixed pulley B. The cross-section of the movable sliding seat is an inverted T-shaped, and the top of the center rod is provided with a movable pulley; the cross-section of the fixed seat is an H-shaped, and the fixed pulley A and the fixed pulley B are respectively set at the top, and the movable pulley and the fixed pulley A and the fixed pulley B are inverted etc. The waist triangle is arranged; the axially magnetized permanent magnet ring A is fixed on the upper side of the base of the moving carriage, and the axially magnetized permanent magnet ring B is fixed on the lower side of the center position of the moving carriage. The central axis is coaxial with the central axis of the axially magnetized permanent magnet ring B, and the magnetic poles of the same direction are arranged opposite to each other and have the same structural parameters; At the center of the permanent magnet ring B and the fixed seat provided with the axial sliding bearing, the movable sliding seat base slides along the chute at the lower part of the fixed seat; when the distance between the moving sliding seat and the fixed seat decreases, the axially magnetized permanent magnet ring A and The air gap between the axially magnetized permanent magnet rings B is reduced.

Further, the axes of the wire pulley A, the wire pulley B and the fixed pulley A and the fixed pulley B of the permanent magnet variable stiffness module are parallel and the radial symmetry centers are located in the same plane.

Further, a permanent magnet variable stiffness flexible joint comprising two or more degrees of freedom control mechanisms, wherein, in each degree of freedom direction, two sets of position and stiffness adjustment modules are symmetrically arranged along the central axis of the boom, and the operating arm of each degree of freedom control mechanism The rotation axis is perpendicular to the direction of the rope tension in the rotation direction of the degree of freedom, ensuring that the stiffness of each degree of freedom rotation direction is independent. All permanent magnet variable stiffness modules are installed at the rear, which reduces the mass and inertia of the operating arm.

The beneficial effects of the present invention are as follows: the present invention can simulate the nonlinear variable stiffness muscle characteristics of the bionic joint. The present invention adopts the permanent magnet variable stiffness mechanism as the stiffness adjustment component, the rope as the force and motion transmission component, and its stiffness will be changed according to the change of the air gap between the permanent magnets. The decoupling of the force and position of the rope can realize the constant stiffness of the joint, and only change the joint rotation angle, that is, to realize the adjustment of the joint position under the condition of equal stiffness; it can also realize that the joint position is unchanged, only the stiffness of the joint is changed, according to different It can work under the corresponding set stiffness conditions. The invention is a permanent magnet variable stiffness flexible robot joint structure with simple movement form, simple manufacture and simple operation.

Description of drawings

1 is a schematic structural diagram of a permanent magnet variable stiffness flexible joint for a robot according to the present invention;

Fig. 2 is a schematic diagram showing the internal structure of a flexible variable stiffness robot joint;

3 is a schematic cross-sectional view of the principle structure of the variable stiffness part;

4 is a schematic diagram of a multi-degree-of-freedom embodiment of the present invention;

In the figure, 1 operating arm; 2 rope A; 3 wire pulley A; 4 permanent magnet variable stiffness module A; 5 rope winch A; 6 servo motor; 7 boom fixed frame; 8 harmonic reducer; 9 boom; 10 Encoder; 11 Conductor pulley B; 12 Conductor pulley C; 13 Rope winch B; 14 Permanent magnet variable stiffness module B; 15 Conductor pulley D; Axial sliding bearing; 21 Axial magnetized permanent magnet ring A; 22 Mobile sliding seat; 23 Fixed seat; 24 Axial magnetized permanent magnet ring B; 25 Fixed pulley B.

Detailed ways

Example 1

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. In this way, the present invention can fully understand and implement the technical process of how to apply technical means to solve technical problems and achieve effects. It should be noted that, as long as no conflict is formed, the various embodiments of the present invention and the Various features can be combined with each other, and the formed technical solutions are all within the protection scope of the present invention.

1 , 2 and 3 , the present embodiment is described. A permanent magnet variable stiffness flexible joint for a robot includes: an operating arm 1 , a rope A2 , a wire pulley A3 , a permanent magnet variable stiffness module A4 , a rope winch A5 , and a servo motor 6. Boom fixing frame 7, harmonic reducer 8, boom 9, encoder 10, wire pulley B11, wire pulley C12, rope winch B13, permanent magnet variable stiffness module B14, wire pulley D15, operating arm rotating shaft 16 , rope B17, one end of the rope A2 is fixed on the operating arm 1, then passes through the wire pulley A3, the permanent magnet variable stiffness module A4, the wire pulley B11 in turn, and the other end is fixed on the rope winch A5, forming a set of position and stiffness adjustment Module, one end of the rope B17 is fixed on the operating arm 1, and then passes through the wire pulley D15, the permanent magnet variable stiffness module B14, and the wire pulley C12 in turn, and the other end is fixed on the rope winch B13 to form a group of position and stiffness adjustment modules;

The fixed pulley A18 of the permanent magnet variable stiffness module A4 is parallel to the axis of the wire pulley B11 and the contour of the pulley is circumscribed on the same straight line; the axis of the wire pulley B11 is perpendicular to the axis of the rope winch A5, and the contour circumscribes the same straight line. The arrangement can effectively ensure the transmission of the rope;

The rope A2 and the rope B17 in the present invention are ropes made of soft steel wire ropes or other soft materials that can only be bent but cannot be axially stretched;

The invention is a permanent magnet variable stiffness flexible robot joint with simple motion form, simple manufacture and simple operation;

The permanent magnet variable stiffness modules A4 and B14 include: a fixed pulley A18, a movable pulley 19, an axial sliding bearing 20, an axially magnetized permanent magnet ring A21, a movable sliding seat 22, a fixed seat 23, and an axially magnetized permanent magnet ring B24, The fixed pulley B25, the movable sliding seat 22 is slidingly matched with the axial sliding bearing 20 and the chute on the fixed seat 23, the fixed seat 23 is consolidated with the axial magnetizing permanent magnet ring B24, and the axial magnetizing permanent magnet ring B24 is fixed. The magnetic ring A21 is consolidated with the movable sliding seat 22, and the central axis of the axially magnetized permanent magnet ring A21 and the central axis of the axially magnetized permanent magnet ring B24 are arranged opposite to each other in the same direction as the magnetic poles and have the same structural parameters. When the distance between the movable sliding seat 22 and the fixed seat 23 is reduced, the air gap between the axially magnetized permanent magnet ring A21 and the axially magnetized permanent magnet ring B24 is reduced; the movable pulley 19 and the fixed pulley A18 and the fixed pulley B25 are inversely equal. waist triangle arrangement;

In the present invention, by pulling the rope, the movable pulley 10 and the movable sliding seat 13 are driven to slide upward;

The rope winch A5 is arranged coaxially with the harmonic reducer 8 and the servo motor, and the other group of rope winches is arranged coaxially with the harmonic reducer and the motor, forming two sets of drive assemblies, and the above two sets of drive assemblies are along the operating arm. 1 Symmetrically arranged and fixed on the boom 9;

The wire pulley A3, the permanent magnet variable stiffness module A4, the wire pulley B11, the wire pulley C12, the permanent magnet variable stiffness module B14, and the wire pulley D15 are fixed on the boom 9, the wire pulley A3, the wire pulley B11, the wire The pulley C12, the wire pulley D15 and the permanent magnet variable stiffness module A4, the fixed pulley of the permanent magnet variable stiffness module B14, the axes are parallel and the radial direction is located in the same plane;

In the present invention, the operating arm rotating shaft 16 and the encoder 10 are fixed on the boom 9 through thin-walled ball bearings.

Example 2

As shown in FIG. 4 , it is a schematic diagram of the joint mechanism of a two-degree-of-freedom parallel variable-stiffness robot of the present invention, and two permanent-magnet variable-stiffness modules are symmetrically arranged in each rotation degree of freedom direction. The rotation axis of each operating arm is perpendicular to the direction of the rope tension in the rotation direction, thus ensuring that the rigidity of the two rotation directions is independent. All permanent magnet variable stiffness modules are installed at the rear, which reduces the mass and inertia of the operating arm.

Claims (2)

1. a permanent magnet variable rigidity flexible joint for a robot is characterized in that, comprising more than two degrees of freedom control mechanisms, wherein each degree of freedom direction, two groups of positions and rigidity adjustment modules are symmetrically arranged along the central axis of the large arm, each The rotation axis of the operating arm of the degree of freedom control mechanism is perpendicular to the direction of the rope pulling force in the rotation direction of the degree of freedom, ensuring that the rigidity of the rotation direction of each degree of freedom is independent; it also includes the operating arm (1), the boom (9), and the boom fixing frame (7), encoder (10), operating arm rotating shaft (16), the big arm (9) is fixed on the big arm fixing frame (7), and the operating arm (1) is fixed on the large arm through the operating arm rotating shaft (16). On the central axis of the arm (9), the rotating shaft (16) of the operating arm and the encoder (10) are fixed on the boom (9) through a thin-walled ball bearing; Wherein, the degree of freedom control mechanism is composed of two groups of position and stiffness adjustment modules symmetrically arranged along the central axis of the boom, and each group of position and stiffness adjustment modules includes a rope (2), at least two wire pulleys, at least one permanent magnet Variable stiffness module (4), rope winch (5), harmonic reducer (8) and servo motor (6); one end of the rope (2) is fixed to the operating arm (1), and then passes through the outer edge of the boom in sequence The set wire pulley A (3), the permanent magnet variable stiffness module (4) fixed inside the boom, and the wire pulley B (11), the other end of the rope is fixed on the rope winch (5), the rope winch (5), harmonic The reducer (8) and the servo motor are coaxially fixed on the boom (9); The fixed pulley A (18) of the permanent magnet variable stiffness module (4) is parallel to the axis of the wire pulley B (11) and the contour of the pulley is circumscribed on the same straight line; the axis of the wire pulley B (11) is perpendicular to the rope winch (5) The axis of , and the contour circumscribes the same straight line; the permanent magnet variable stiffness module includes: a fixed pulley A (18), a movable pulley (19), an axial sliding bearing (20), an axially magnetized permanent magnet ring A (21) ), a movable slide (22), a fixed base (23), an axially magnetized permanent magnet ring B (24), and a fixed pulley B (25); A movable pulley is arranged at the top of the rod; the cross-section of the fixed seat is H-shaped, and a fixed pulley A and a fixed pulley B are respectively arranged at the top, and the movable pulley, the fixed pulley A and the fixed pulley B are arranged in an inverted isosceles triangle; the axially magnetized permanent magnet ring A ( 21) It is fixed on the upper side of the base of the movable slide, and the axially magnetized permanent magnet ring B (24) is fixed on the lower side of the center of the movable slide. The central axis of the axially magnetized permanent magnet ring A is connected to the axial magnetized The central axis of the permanent magnet ring B is coaxial, and the magnetic poles of the same direction are arranged oppositely and have the same structural parameters; At the center position of the fixed seat of the axial sliding bearing (20), the base of the mobile sliding seat slides along the chute at the lower part of the fixed seat; two permanent magnet variable stiffness modules are symmetrically arranged in each rotational degree of freedom direction; the rotation axis of each operating arm is vertical The direction of the rope tension in the rotation direction ensures that the stiffness of the two rotation directions is independent; all permanent magnet variable stiffness modules are installed at the rear, which reduces the mass and inertia of the operating arm. 2. The permanent magnet variable stiffness flexible joint for a robot according to claim 1, wherein the axes of the wire pulley A, the wire pulley B and the fixed pulley A and the fixed pulley B of the permanent magnet variable stiffness module are parallel to each other And the center of radial symmetry lies in the same plane.

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