CN113146604B

CN113146604B - Compact artificial muscle module with variable rigidity and passive flexibility

Info

Publication number: CN113146604B
Application number: CN202110487641.4A
Authority: CN
Inventors: 任雷; 杨皓森; 魏国武; 钱志辉
Original assignee: Jilin University
Current assignee: Beijing Daqi Yuequan Biomimetic Technology Co ltd
Priority date: 2021-05-06
Filing date: 2021-05-06
Publication date: 2022-08-26
Anticipated expiration: 2041-05-06
Also published as: CN113146604A

Abstract

A compact passive flexible artificial muscle module with variable stiffness has a motor that drives an input disc to rotate, and the input disc drives an output disc to rotate by driving a torsion spring. The wire spool fixedly connected to the output disc rotates to pull the driving rope. The driving rope rounds the pulley and outputs linear motion to realize contraction. At the passive end, the passive rope passes through two cylindrical magnets with the same poles opposite to each other and is fixed on the magnet buckle. When the muscle module is subjected to an external force. The torsion spring is deformed first, and when the external force exceeds the maximum force of the torsion spring, the distance between the two magnets begins to be reduced, so that nonlinear impedance force is generated. A non-linear passive mechanical flexibility like a muscle is achieved, the resistance increasing sharply near the moment of being destroyed.

Description

Compact artificial muscle module with variable rigidity and passive flexibility

Technical Field

The invention relates to the technical field of robot driving, in particular to a compact artificial muscle module with variable rigidity and passive flexibility.

Background

In early bionic robot designs, joints are mostly driven directly by motors through speed reducers. In some designs, a flexible drive, i.e., a safety drive, is achieved by adding a spring element, or even a variable stiffness spring system, between the reducer and the joint being driven. The design has the advantages of precise movement and reduction of design difficulty. In the development of biomimetic robots, robots are moving closer to real human bodies. Most of the existing motor-based flexible driver schemes are large in size and difficult to design into human muscle and apply to a robot based on bionic design. Therefore, designing artificial muscles with the shape and performance similar to those of human muscles is very important in designing high simulation robots nowadays.

Most human muscles can be equivalent to elongated flexible linear actuators. The passive rigidity of the muscle is nonlinear, and as the passive stretching amount is increased, the passive rigidity elastic coefficient is gradually increased from the initial lower rigidity, and exponentially increased near the tail end. This feature protects the muscles from a sharp increase in passive stiffness when subjected to high impact forces, protecting the muscles themselves and the joints. Achieving this characteristic is also critical in biomimetic muscle design.

Therefore, it is a challenge to efficiently convert the rotational output of the motor into a linear output and to realize the passive flexibility with variable stiffness without increasing the diameter of the whole device, and to simulate the form of the muscle and the passive performance of the variable stiffness.

Disclosure of Invention

In order to solve the above problems, the present invention provides a compact artificial muscle module with variable stiffness and passive flexibility, which is implemented by using a motor.

A compact type artificial muscle module with variable rigidity and passive flexibility comprises a shell, a motor, an input disc, a torsion spring, an output disc, a first pulley, a driving rope, a shell cover, a magnet box, a first magnet, a second magnet, a magnet buckle and a passive rope; the motor is inserted into the shell and is fixed on the shell by a screw; the input disc is inserted into the output shaft of the motor, and one leg of the torsion spring is fixed on the input disc and inserted into the input disc; the output disc is fixed on the input disc through a first bearing, and the other pin of the torsion spring between the input disc and the output disc is fixed on the output disc; a wire spool is arranged above the output disc, one end of a driving rope is fixed on the wire spool, and the driving rope penetrates through a first pulley hinged in the shell cover through a first screw and a second pulley hinged in the shell cover through a second screw and penetrates out of the middle of the top of the shell cover; the housing cover is fixed to the housing by screws.

Two cylindrical magnets, namely a first magnet and a second magnet, are arranged in the magnet box in a homopolar opposite mode. The initial distance between the two magnets is calculated, and the repulsive force of the distance between the two magnets is just equal to the force required by pulling the driving rope to enable the torsion spring to be completely deformed when the motor does not rotate. The middle of the magnet is provided with a hole, and one end of the passive rope penetrates through the magnet and is fixed on the magnet buckle. The other end of the passive rope passes through the magnet box cover. The magnet box cover is fixed on the magnet box through screws, and the magnet box is fixed on the shell through screws.

The working process of the invention is as follows:

1. the driving rope and the driven rope of the muscle module are respectively connected with two ends of the joint to be driven.

2. When the muscle module receives a contraction instruction, the motor rotates to drive the input disc to rotate, and the input disc drives the output disc to rotate through the driving torsion spring. The wire spool fixedly connected to the output disc rotates to pull the driving rope. The driving rope winds the first pulley and the second pulley, linear motion is output from the top end of the muscle module, contraction is achieved, and then joint motion is achieved.

3. When the contraction of the muscle module is limited, the initial distance between the two magnets is calculated, so that the repulsive force of the distance between the two magnets is just equal to the force required by the complete deformation of the torsion spring due to the pulling of the driving rope when the motor does not rotate, and the torsion spring can generate the deformation firstly. When the external force applied to the muscle module is increased to exceed the maximum torque force which can be borne by the torsion spring, the torsion spring is limited and cannot continuously generate deformation, the passive rope pulls the magnet buckle, and the distance between the two magnets is reduced.

The invention has the beneficial effects that:

1. compact linear output: the design of the muscle module converts the rotary output of the motor into linear output, and the pulley is adopted in a limited space to reduce friction, so that the diameter of the whole module is ensured to the maximum extent. Thereby facilitating subsequent application of the muscle module to a robot driven by an elongated artificial muscle.

2. Mechanical flexibility: the muscle module achieves flexible passive performance. When the contraction of the drive rope is restricted, the torsion spring is deformed, or the magnet distance is then decreased. Damage to the motor and the driven device is prevented. Meanwhile, the operation safety of personnel is realized.

3. Nonlinear passive mechanical compliance: due to the adoption of the mode of combining the spring and the magnet, the muscle module can realize nonlinear passive mechanical flexibility. The repulsive force between two magnets opposing the same stage will sharply rise as the distance between the magnets decreases. The repulsive force of the magnets can be used to simulate the characteristic of a muscle that has a steep rise in resistance near the stage of failure. And the early stage torsion spring is contracted to generate deformation, so that the passive characteristic that the muscle is gentle in the stage of receiving a small external force can be simulated.

4. Compact implementation of nonlinear passive mechanical flexibility: compared with other schemes for realizing nonlinear passive mechanical flexibility, the diameter of the muscle module cannot be enlarged due to the adoption of the cylindrical magnet close to the diameter of the motor. This characteristic allows the muscle module to mimic a human muscle of elongate shape while achieving a non-linear passive characteristic similar to a human muscle. In subsequent application, great advantages are exerted.

Drawings

Fig. 1 is a front view of the present invention.

Fig. 2 is a side view of the present invention.

Fig. 3 is a sectional view a-a in fig. 1.

Fig. 4 is an exploded view of the present invention.

Detailed Description

As shown in fig. 1, 2, 3 and 4, a compact artificial muscle module with variable stiffness and passive flexibility comprises a housing 1, a motor 2 input disc 3, a torsion spring 4, an output disc 5, a first pulley 7, a driving rope 11, a housing cover 12, a magnet box 14, a first magnet 15, a second magnet 16, a magnet buckle 17 and a passive rope 19; the motor 2 is inserted into the housing 1, and the motor 2 is fixed to the housing 1 by screws. An input disc 3 is inserted into an output shaft of the motor 2, and one leg of a torsion spring 4 is fixed to the input disc 3 and inserted into the input disc 3. The output disc 5 is fixed to the input disc 3 by a first bearing 13, and the other leg of the torsion spring 4 between the input disc 3 and the output disc 5 is fixed to the output disc 5. A spool part is provided above the output disc 5, on which one end of a drive cord 11 is fixed. The drive rope 11 passes through the second pulley 9 hinged in the housing cover 12 by the first screw 8 and hinged in the housing cover 12 by the second screw 10, and passes out from the middle of the top of the housing cover 12. The housing cover 12 is fixed to the housing 1 by screws.

As shown in fig. 3 and 4, two cylindrical magnets, namely a first magnet 15 and a second magnet 16, are arranged in the magnet box 14 in a manner that the same poles are opposite; the initial distance between the two magnets is calculated, so that the repulsive force of the distance is just equal to the force required by the torsion spring 4 to be completely deformed by passively pulling the driving rope 11 when the motor 2 does not rotate; the middle of the first magnet 15 and the second magnet 16 is provided with a hole, one end of the passive rope 19 passes through the first magnet 15 and the second magnet 16 and is fixed on the magnet buckle 17, and the magnet buckle 17 is clamped on the first magnet 15. The other end of the passive rope 19 passes through the magnet box cover 18; the magnet case cover 18 is fixed to the magnet case 14 by screws, and the magnet case 14 is fixed to the housing 1 by screws.

Claims

1. A compact artificial muscle module with variable stiffness passive flexibility, characterized in that: the device comprises a shell (1), a motor (2), an input disc (3), a torsion spring (4), an output disc (5), a first pulley (7), a driving rope (11), a shell cover (12), a magnet box (14), a first magnet (15), a second magnet (16), a magnet buckle (17) and a driven rope (19); the motor (2) is inserted into the shell (1), and the motor (2) is fixed on the shell (1) by screws; the input disc (3) is inserted into an output shaft of the motor (2), one leg of the torsion spring (4) is fixed on the input disc (3) and is inserted into the input disc (3); the output disc (5) is fixed on the input disc (3) through a first bearing (13), and the other pin of the torsion spring (4) between the input disc (3) and the output disc (5) is fixed on the output disc (5); a wire spool is arranged above the output disc (5), one end of a driving rope (11) is fixed on the wire spool, the driving rope (11) penetrates through a first pulley (7) which is hinged in a shell cover (12) through a first screw (8) and a second pulley (9) which is hinged in the shell cover (12) through a second screw (10) and penetrates out of the middle of the top of the shell cover (12), and the shell cover (12) is fixed on the shell (1) through screws; two cylindrical magnets are placed in the magnet box (14) according to a homopolar opposite mode, the two cylindrical magnets are respectively a first magnet (15) and a second magnet (16), holes are formed in the middles of the first magnet (15) and the second magnet (16), one end of a driven rope (19) penetrates through the first magnet (15) and the second magnet (16) and is fixed on a magnet buckle (17), the magnet buckle (17) is clamped on the first magnet (15), the other end of the driven rope (19) penetrates through a magnet box cover (18), the magnet box cover (18) is fixed on the magnet box (14) through a fourth screw, and the magnet box (14) is fixed on the shell (1) through screws;

the driving rope and the driven rope of the muscle module are respectively connected with two ends of a joint to be driven;

when the muscle module receives a contraction instruction, the motor rotates to drive the input disc to rotate, the input disc drives the output disc to rotate through the driving torsion spring, the wire spool fixedly connected to the output disc rotates to pull the driving rope, the driving rope winds the first pulley and the second pulley, linear motion is output from the top end of the muscle module, contraction is achieved, and joint motion is achieved;

when the contraction of the muscle module is limited, the initial distance between the two magnets is calculated, so that the repulsive force of the distance where the muscle module is located is just equal to the force required by the complete deformation of the torsion spring when the motor does not rotate, the driving rope is pulled, the torsion spring can deform firstly, when the external force applied to the muscle module is increased to exceed the maximum torsion force which can be borne by the torsion spring, the torsion spring is limited and cannot continuously deform, the driven rope pulls the magnet buckle, and the distance between the two magnets is reduced.