A new transmission structure for omnidirectional movement of Mecanum wheels

Abstract

A novel transmission structure for omnidirectional movement of Mecanum wheels, comprising a main transmission structure, two differential structures and four speed superposition structures. The two differential structures are respectively a front-wheel differential structure and a rear-wheel differential structure; the four speed superposition structures are respectively a front-left speed superposition structure, a front-right speed superposition structure, a rear-left speed superposition structure and a rear-right speed superposition structure; the main transmission structure is respectively connected to the four speed superposition structures, the front-wheel differential structure is respectively connected to the front-left speed superposition structure and the front-right speed superposition structure, and the rear-wheel differential structure is respectively connected to the rear-left speed superposition structure and the rear-right speed superposition structure. The present invention effectively avoids the occurrence of the situation that when controlling the omnidirectional movement of Mecanum wheels, the movement component of [1 1 -1 -1]T causes abnormal movement and the structure self-blocks and rotates, resulting in damage, and at the same time, only three power sources are required to complete the omnidirectional movement of the chassis on the plane.

Description

Technical Field

[0001] The present invention relates to the field of machinery and automation control, and is a novel transmission structure for omnidirectional movement of Mecanum wheels. Background Art

[0002] The Mecanum wheel is a patent of the Swedish company Mecanum. This omnidirectional movement method is based on the principle of a central wheel with many wheel axles located around the periphery of the wheel. These angled peripheral wheel axles convert a part of the wheel's turning force into a wheel normal force.

[0003] Depending on the direction and speed of each wheel, the final synthesis of these forces generates a resultant force vector in any required direction, thus ensuring that the platform can move freely in the direction of the final resultant force vector without changing the direction of the wheels themselves. Many small rollers are obliquely distributed on its rim, so the wheel can slide laterally. The generatrix of the small roller is very special. When the wheel rotates around the fixed wheel center axis, the envelope of each small roller is a cylindrical surface, so the wheel can roll forward continuously. The Mecanum wheel has a compact structure and flexible movement, and is a very successful omnidirectional wheel. By combining 4 such new wheels, the omnidirectional movement function can be realized more flexibly and conveniently.

[0004] The existing transmission structures for realizing the omnidirectional movement of Mecanum wheels are mainly as Figure 1 shown. Four motors respectively control the rotation direction and speed of the corresponding Mecanum wheel, and omnidirectional movement is achieved according to the linear superposition of the rotation directions and speeds of the four Mecanum wheels.

[0005] The specific movement principle is as follows. The omnidirectional movement of the Mecanum wheel is a pure linear system, and the rigid body movement can be linearly decomposed into three components, namely translation along the X-axis, translation along the Y-axis, and self-rotation around the geometric center. In actual debugging, as long as the rotation speeds and directions of the four wheels corresponding to the translation of the Mecanum wheel chassis along the X-axis, translation along the Y-axis, and self-rotation around the geometric center are calculated, the rotation speeds of the four wheels required for the omnidirectional movement synthesized by these three simple movements can be calculated through simple addition. Finally, controlling the motors to rotate accordingly can realize the omnidirectional movement of the Mecanum wheel chassis.

[0006] Its omnidirectional movement diagram is as Figure 2 shown. It can be found that when the movement directions of the No. 1 and No. 2 Mecanum wheels are opposite to those of the No. 3 and No. 4 Mecanum wheels, the chassis cannot move. In this case, the motors will be stuck and damaged.

[0007] Represent several simple movement situations of the Mecanum wheel in vector form, and normalize the rotation speed of the Mecanum wheel, where 1 represents unit positive rotation and -1 represents unit reverse rotation.

[0008] Unit vector for lateral movement (translation along the x-axis): [1 -1 -1 1] T

[0009] Unit vector for longitudinal movement (translation along the y-axis): [1 1 1 1] T

[0010] Unit vector for rotational movement (rotation about the geometric center): [1 -1 1 -1] T

[0011] Unit vector for immovable movement: [1 1 -1 -1] T

[0012] After calculation, each vector is linearly independent. Therefore, the vectors for the omnidirectional movement of the Mecanum wheel can be regarded as a simple linear superposition of the above several simple movement vectors. Summary of the Invention

[0013] In order to overcome the deficiencies that when using the existing 4 power sources to control the omnidirectional movement of the Mecanum wheel, the movement components of [1 1 -1 -1] T may lead to abnormal movement and the structure may be damaged due to self-blocking rotation, the present invention provides a new transmission structure for the omnidirectional movement of the Mecanum wheel. Through the design and combination of various parts, the present invention effectively avoids the occurrence of abnormal movement caused by the movement components of [1 1 -1 -1] T during the control of the omnidirectional movement of the Mecanum wheel and the damage caused by self-blocking rotation of the structure. At the same time, only three power sources are required to complete the omnidirectional movement of the chassis on the plane.

[0014] The technical solution adopted by the present invention to solve its technical problems is as follows:

[0015] A new transmission structure for the omnidirectional movement of the Mecanum wheel, including a main transmission structure, two differential structures and four speed superposition structures. The two differential structures are respectively a front-wheel differential structure and a rear-wheel differential structure; the four speed superposition structures are respectively a front-left speed superposition structure, a front-right speed superposition structure, a rear-left speed superposition structure and a rear-right speed superposition structure;

[0016] The main transmission structure is respectively connected to the four speed superposition structures, the front-wheel differential structure is respectively connected to the front-left speed superposition structure and the front-right speed superposition structure, and the rear-wheel differential structure is respectively connected to the rear-left speed superposition structure and the rear-right speed superposition structure.

[0017] Further, the main transmission structure includes a power source and a mechanical transmission structure. The rotational speed output by the power source is scaled by the mechanical transmission structure and then divided into four rotational speeds with the same magnitude and the same direction, which are synchronously output to the four speed superposition structures respectively. The characteristic motion vector of the rotational speed finally output by the main transmission structure to the four Mecanum wheels is: [1 1 1 1] T .

[0018] Furthermore, the front-wheel differential structure includes a power source and a mechanical transmission structure. The rotational speed output by the power source is scaled by the mechanical transmission structure and then output to the front left speed superposition structure and the front right speed superposition structure respectively as two rotational speeds with the same magnitude and opposite directions. The characteristic motion vector of the rotational speed finally output by the front-wheel differential structure to the four Mecanum wheels is: [1 -1 0 0] T .

[0019] Even further, the rear-wheel differential structure includes a power source and a mechanical transmission structure. The rotational speed output by the power source is scaled by the mechanical transmission structure and then output to the rear left speed superposition structure and the rear right speed superposition structure respectively as two rotational speeds with the same magnitude and opposite directions. The characteristic motion vector of the rotational speed finally output by the rear-wheel differential structure to the four Mecanum wheels is: [0 0 1 -1] T .

[0020] The main body of the speed superposition structure consists of a differential. Using the differential principle, the rotational speeds of the differential main body and the input side of the differential (any side of the differential) are linearly superposed into the rotational speed of the outer side of the differential (the other side of the differential). According to the differential principle formula: v l is the rotational speed of the inner side of the differential, v r is the rotational speed of the outer side of the differential, ν C is the rotational speed of the differential main body. The rotational speed of the outer half shaft of the differential is deduced as: v r = 2v c - v l , where the rotational speeds output by the main transmission structure and the differential structure to the speed superposition structure are v C and v l respectively. Thus, the linear superposition output of the rotational speeds output by the main transmission structure and the differential structure is realized, and the synchronous rotation of the Mecanum wheels connected thereto is driven by the outer side of the differential, thereby realizing the linear superposition of the three characteristic motion vectors of [1 1 1 1] T , [1 -1 0 0] T , [0 0 1 -1] T . Also, because of [1 1 1 1] T , [1 -1 0 0] T , [0 0 1 -1] TThree characteristic motion vectors and [1 1 1 1] T 、[1 -1 -1 1] T 、[1 -1 1 -1] T The three omnidirectional motion unit vectors of the Mecanum wheels are linearly equivalent, and the non-movable unit vector is [1 1 -1 -1] T which is linearly independent, thus finally effectively avoiding the occurrence of the situation where the motion component of [1 1 -1 -1] T causes abnormal motion and the structure self-blocks and rotates, resulting in damage, and at the same time, only three power sources are required to complete the omnidirectional motion of the chassis on the plane.

[0021] The beneficial effects of the present invention are: a novel transmission structure for the omnidirectional movement of Mecanum wheels, which can replace the existing transmission structure for the omnidirectional movement of Mecanum wheels. The present invention effectively avoids the occurrence of the situation where the motion component of [1 1 -1 -1] T causes abnormal motion and the structure self-blocks and rotates, resulting in damage, and at the same time, the number of required power sources is reduced to three to complete the omnidirectional motion of the chassis on the plane. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 are the three-view drawings of the existing transmission structure for the omnidirectional movement of Mecanum wheels.

[0023] Figure 2 is the omnidirectional motion diagram of the Mecanum wheel.

[0024] Figure 3 is the structural block diagram of the present invention.

[0025] Figure 4 are the overall three-view drawings of the present invention.

[0026] Figure 5 are the three-view drawings of the main transmission structure.

[0027] Figure 6 are the three-view drawings of the differential structure.

[0028] Figure 7 are the three-view drawings of the speed superposition structure. DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention will be further described below with reference to the accompanying drawings:

[0030] Refer to Figures 3 to 7, a novel transmission structure for omnidirectional movement of Mecanum wheels, including a main power structure, two differential structures, and four speed superposition structures. Among them, the two differential structures are respectively a front-wheel differential structure and a rear-wheel differential structure; the four speed superposition structures are respectively a front-left speed superposition structure, a front-right speed superposition structure, a rear-left speed superposition structure, and a rear-right speed superposition structure. The main transmission structure is respectively connected to the four speed superposition structures, the front-wheel differential structure is respectively connected to the front-left speed superposition structure and the front-right speed superposition structure, and the rear-wheel differential structure is respectively connected to the rear-left speed superposition structure and the rear-right speed superposition structure.

[0031] As Figure 4 shown: The specific structure of the present invention mechanically consists of 4 Mecanum wheels (1, 2, 3, 4), differential gears (5), bevel gears (6), differentials (7), transmission gears (8), 3 power sources (9, 10, 12), and transmission shafts (11).

[0032] As Figure 5 shown: The main transmission structure includes a power source and a mechanical transmission structure. The power source uses a reduction motor; the mechanical transmission structure consists of a transmission gear, a transmission shaft, and a bevel gear. Among them, the rotational speed output by the power source is scaled through the mechanical transmission structure and divided into four rotational speeds with the same magnitude and the same direction, and is synchronously output to the four speed superposition structures respectively.

[0033] As Figure 6 shown: The front (rear) wheel differential structure includes a power source and a mechanical transmission structure. The power source uses a reduction motor; the mechanical transmission structure consists of a transmission shaft and a bevel gear. Among them, the rotational speed output by the power source is scaled through the mechanical transmission structure and output to the front (rear) left speed superposition structure and the front (rear) right speed superposition structure respectively with two rotational speeds of the same magnitude and opposite directions synchronously.

[0034] As Figure 7 shown: The main body of the speed superposition structure consists of a differential. Using the differential principle, the rotational speeds of the differential main body and the input side of the differential (any side of the differential) are linearly superposed into the rotational speed of the outer side of the differential (the other side of the differential). According to the differential principle formula: v l is the rotational speed of the inner side of the differential, v r is the rotational speed of the outer side of the differential, v C is the rotational speed of the differential main body. The rotational speed of the outer half shaft of the differential is deduced as: v r = 2v c - v l , where the rotational speeds output from the main transmission structure and the differential structure to the speed superposition structure are v C and v l, thus achieving the linear superposition output of the rotational speeds output by the main transmission structure and the differential structure, and driving the synchronous rotation of the Mecanum wheels connected thereto by the outside of the differential, thereby realizing the linear superposition of the three characteristic motion vectors of [1 1 1 1] T , [1 -1 0 0] T , [0 0 1 -1] T . Also, because the three characteristic motion vectors of [1 1 1 1] T , [1 -10 0] T , [0 0 1 -1] T are linearly equivalent to the three omnidirectional motion unit vectors of the Mecanum wheels of [1 1 1 1] T , [1 -1 -1 1] T , [1 -1 1 -1] T , and are linearly independent of the non-movable unit vector of [1 1 -1 -1] T , thus finally realizing that the present invention effectively avoids the occurrence of the situation where the motion component of [1 1 -1 -1] T causes abnormal motion and the structure self-blocks and rotates, resulting in damage, and at the same time, only three power sources are required to complete the omnidirectional motion of the chassis on the plane.

Claims

1. A novel transmission structure for omnidirectional movement of Mecanum wheels, characterized in that, The novel transmission structure includes a main transmission structure, two differential structures and four speed superposition structures. The two differential structures are a front-wheel differential structure and a rear-wheel differential structure respectively; the four speed superposition structures are a front-left speed superposition structure, a front-right speed superposition structure, a rear-left speed superposition structure and a rear-right speed superposition structure respectively; The main transmission structure is respectively connected to the four speed superposition structures. The front-wheel differential structure is respectively connected to the front-left speed superposition structure and the front-right speed superposition structure. The rear-wheel differential structure is respectively connected to the rear-left speed superposition structure and the rear-right speed superposition structure; The front-wheel differential structure includes a power source and a mechanical transmission structure. The rotational speed output by the power source is scaled by the mechanical transmission structure and then output in two paths with the same magnitude and opposite directions to the front-left speed superposition structure and the front-right speed superposition structure respectively. The characteristic motion vector of the rotational speed finally output by the front-wheel differential structure to the four Mecanum wheels is: [1 -1 0 0] T ; The main body of the speed superposition structure consists of a differential. Using the differential principle, the rotational speeds of the differential main body and the input side of the differential are linearly superimposed to obtain the rotational speed on the outer side of the differential. According to the differential principle formula: v l is the rotational speed on the inner side of the differential, v r is the rotational speed on the outer side of the differential, v C is the rotational speed of the differential main body. By derivation, the rotational speed of the outer half shaft of the differential is: v r = 2v c - v l , where the rotational speeds output from the main transmission structure and the differential structure to the speed superposition structure are v c and v l , thus realizing the linear superposition output of the rotational speeds output from the main transmission structure and the differential structure, and driving the synchronous rotation of the Mecanum wheels connected thereto by the outer side of the differential, and further realizing the linear superposition of the three characteristic motion vectors of [1 1 1 1] T , [1 -1 0 0] T , [0 0 1 -1] T . Also, because [1 1 1 1] T , [1 -1 0 0] T , [0 0 1 -1] T are linearly equivalent to the three omnidirectional motion unit vectors of the Mecanum wheels [1 1 11] T , [1 -1 -1 1] T , [1 -1 1 -1] T , and are linearly independent of the non-movable unit vector [1 1 -1 -1] T , thus finally effectively avoiding the occurrence of the situation where the motion component of [1 1 -1 -1] T causes abnormal motion and the structure rotates and stops automatically, resulting in damage, and only three power sources are required to complete the omnidirectional motion of the chassis on the plane.

2. The novel transmission structure for omnidirectional movement of Mecanum wheels according to claim 1, characterized in that, The main drive structure includes a power source and a mechanical drive structure. The rotational speed output by the power source is scaled by the mechanical drive structure and then divided into four rotational speeds with the same magnitude and the same direction, which are synchronously output to the four speed superposition structures respectively. The characteristic motion vector of the rotational speed finally output by the main drive structure to the four Mecanum wheels is: [1 1 1 1] T .

3. A novel transmission structure for omnidirectional movement of Mecanum wheels according to claim 1 or 2, characterized in that, The rear-wheel differential structure includes a power source and a mechanical transmission structure. The rotational speed output by the power source is scaled by the mechanical transmission structure and then output in two paths with the same magnitude but opposite directions to the rear left speed superposition structure and the rear right speed superposition structure respectively. The characteristic motion vector of the rotational speed finally output by the rear-wheel differential structure to the four Mecanum wheels is: [0 0 1 -1] T .

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