JPH0764206B2 - Steering mechanism for omnidirectional vehicles - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a steering mechanism for an omnidirectional vehicle that travels by turning a plurality of wheels in arbitrary directions.

BACKGROUND OF THE INVENTION Generally, there are two types of vehicles, one is a vehicle type vehicle that steers the front wheels to change the direction of the vehicle body while the other is a vehicle type vehicle that changes the direction of all the wheels. There is an omnidirectional vehicle that moves in all the front-back, left-right, and diagonal directions without changing the direction, but the above-mentioned vehicle-type vehicle has a large turning radius when changing the traveling direction. It is unsuitable as a moving vehicle that moves while changing direction even in a narrow space between desks, a moving vehicle that follows a specified complicated movement pattern, or a vehicle that requires a sharp turning direction. is there. Therefore, an omnidirectional vehicle that uses all the wheels to move in all directions without changing the direction of the vehicle body is used.

[Prior Art] As a steering mechanism for an omnidirectional vehicle as described above, there is a conventional steering mechanism configured as shown in FIGS. 5 (A) and 5 (B). That is, in this type of steering mechanism, four tubular steering shafts 2 ... Are vertically provided on a vehicle body 1 via bearings 2a. Wheels 4 made of rubber tires etc. are rotatably provided on the bearings 3 ..., and steering pulleys 5 ... Are provided above the respective steering shafts 2 ...・
By winding one belt 8 around the drive pulley 7 of the steering drive device 6 provided on the vehicle body 1 and rotating the steering shafts 2 ... With a predetermined angle by the steering drive device 6, The directions of all the wheels 4 are changed to change the traveling direction. The traveling of the omnidirectional vehicle is performed by driving the wheels 4 ... With a traveling drive device 9 provided on the vehicle body 1.
That is, a bevel gear 10 is provided on each of the axles 4a of the wheels 4, and the bevel gear 10 has a drive shaft 11 rotatably provided in the steering shaft 2 via bearings 11a and 11a. The bevel gear 11 meshes with the drive shaft 11, and the upper end of the drive shaft 11 projects upward from the steering shaft 2. Pulleys 13 are provided at the projected portions.
The belt 14 is wound around the driving pulley 15 provided on the traveling drive device 9 on the vehicle body 1. Then, when the drive pulley 9 is rotated by the drive device 9 for traveling, this rotation is transmitted to each pulley 13 ...
As a result, the drive shafts 11 ... Rotate, and this rotation is transmitted to the axles 4a ... through the bevel gears 10 and 12 that mesh with each other, and the wheels 4 ... Rotate and travel.

However, in such a steering mechanism, the steering drive device 6 and the traveling drive device 9 are required separately, and the outputs of the respective drive devices 6 and 9 are different from each other. The output (power) of the driving device 9 is large. Therefore, two types of drive devices (motors) are required, parts management becomes complicated, and not only the assembly work is troublesome but also the cost becomes high.

[Object of the Invention] The present invention has been made in consideration of the above circumstances. The object of the present invention is to eliminate the need for using a driving device having a large output (power) and to provide a small output. Moreover, it is an object of the present invention to provide a steering mechanism for an omnidirectional vehicle that can be totally controlled by one or one type of drive device without distinguishing between steering and traveling.

In order to achieve the above object, the present invention provides a vehicle body with a plurality of steering shafts rotatably, each steering shaft having at least one or more wheels, and each of the wheels can be rotated in any direction. In a steering mechanism of an omnidirectional vehicle that travels by switching to, the wheels integrally provided on the respective axles are provided at positions deviated from the center of the respective steering axles by a predetermined distance. A driven bevel gear provided,
A cylindrical first drive shaft rotatably provided around the axis of the steering shaft, a first drive bevel gear that is provided on the first drive shaft and meshes with a driven bevel gear, and a first drive shaft A second drive shaft that is rotatably provided therein and a second drive bevel gear that is provided on the second drive shaft and that meshes with a driven bevel gear are provided with respective differential devices, and the first differential is provided on the vehicle body. And a drive device that drives the first drive shaft via the transmission member and drives the second drive shaft via the second transmission member.

In the present invention, the drive device rotates the first and second drive shafts in mutually opposite directions via the first and second transmission members, and in this state, the rotational speed of the first drive shaft and the second drive shaft When the rotation speed of the drive shaft is set to be the same as the rotation speed, the steering shaft that is the differential arm does not rotate, but only the wheels rotate and the vehicle travels straight. Further, for example, when only the first drive shaft is rotated by the drive device via the first transmission member and the rotation of the second drive shaft is stopped, the steering shaft is rotated while the wheels are rolling, This changes the direction of the wheels and changes the running direction. Then, under the conditions other than the above two conditions, the composite operation is performed in which the steering shaft rotates at a certain speed to change the direction of the wheels while the wheels rotate at a certain speed to travel.

Therefore, according to the present invention, the wheels are made to travel or the direction of the wheels is changed by the differential device that utilizes the difference in the rotational speed between the first drive shaft and the second drive shaft. It is not necessary to use a drive device for the output (power), and only a small output is required.
It is possible to perform total control without distinguishing between steering type and running type with a drive device of a kind, which can simplify parts management and assembly work, and reduce cost. You can also plan.

[Structure of Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 4.

1A to 1C show an omnidirectional vehicle. Four steering shafts 21a to 21d are rotatably provided near the four corners of a vehicle body 20 of the omnidirectional vehicle via bearings 22 ... Each of the steering shafts 21a to 21d has a cylindrical shape, and wheels 23a to 23d and a differential device 24 ... Are provided below the steering shafts 21a to 21d. As shown in FIG. 1 (C), the wheels 23a to 23d rotate integrally with the axle shaft 26 rotatably attached to the axle bearings 25 of the steering shafts 21a to 21d via bearings 26a and 26a. It is provided. In this case, the wheels 23a-23d are connected to the respective steering shafts 21a-2
It is arranged at a position deviated from the axis center of 1d by a predetermined distance r. Further, the differential device 24 ... Distributes outputs of first and second drive devices 27, 28 which will be described later, and transmits the distributed output to the wheels 23a-23d so that the wheels 23a-23d are driven. The structure is the same as that of the differential device 24 shown in FIG. 1 (C). The differential device 24 is provided on the steering shaft 21a, and has a driven bevel gear 29 attached to the axle 26 and first and second drive bevel gears 30 and 31 meshing with the driven bevel gear 29. , The first drive bevel gear 30 is attached to the lower end, and the bearing 32 is provided at the shaft center in the steering shaft 21a.
a first drive shaft 32 having a tubular shape that is rotatably provided via a and 32a, and a second drive bevel gear 31 is attached to the lower end, and bearings 33a and 33a are provided in the first drive shaft 32. And a second drive shaft 33 rotatably provided. In this case, as shown in FIG. 1 (B), first driven pulleys 34a to 34d are respectively provided at the upper ends of the first drive shafts 32 ... And the second drive shafts 33. The upper end of each of the ... Drives above the first drive shaft 32 ... And the second driven pulleys 35a to 35d are provided at the protruding portions.

On the other hand, the first and second drive devices 27 and 28 are exactly the same and are composed of a motor, a speed reducer, an encoder, etc., and are provided on the vehicle body 20 as shown in FIG. 1 (A). In this case, the drive pulley 36 is attached to the output shaft 27a of the first drive device 27, and the first transmission belt 37 is wound around the drive pulley 36 and the first driven pulleys 34a to 34d. The rotation of the drive pulley 36 is controlled by the first transmission belt 37 in each first
Is transmitted to the driven pulleys 34a to 34d. Similarly, a drive pulley 38 is attached to the output shaft 28a of the second drive device 28.
A second transmission belt 39 is wound around the driving pulley 38 and the second driven pulleys 35a to 35d, and the rotation of the driving pulley 38 is rotated by each second driven pulley 35a. It is designed to be transmitted to ~ 35d.

[Operation of Embodiment] Next, the operation of the steering mechanism of the omnidirectional vehicle configured as described above will be described with reference to FIGS. 2 and 3.

In this case, the first driven pulleys 34a to 34d rotated by the first driving device 27 and the second driven pulleys 35a to 35d rotated by the second driving device 28 are as shown in FIG. In addition, the first driven pulleys 34a to 34d are rotated in the opposite directions, the rotation speed of the first driven pulleys 34a to 34d (which is the same as the rotation speed of each of the first drive shafts 32) is N ₁ , and the second driven pulley 35a is ~ 35d rpm (this is the same as the rpm of each second drive shaft 33)
N2, the steering shaft 21a- ₂ which is the differential arm of the differential 24
The rotation speed of 1d is N _S , the rotation speed of each wheel 23a to 23d is N _T , the number of teeth of the driven bevel gear 29 provided on the axle 4a is Z ₂₉ , and the number of teeth of the first driving bevel gear 30 is Z Z. _Set to ₃₀ .

Then, first, a traveling mode for traveling the omnidirectional vehicle will be described. In this case, the first and second drive devices 27 and 28 equipped with encoders are driven at the same time, and the rotation speed N _{1 of} the first driven pulleys 34a to 34d and the second driven pulleys 35a to 35d are increased. The number of revolutions N ₂ is the same as the number of revolutions N ₂ (N = N ₁ = N ₂ ).
Servo control so that Then, as shown in FIG. 2 (B), the rotational speed N _S of the steering shafts 21a to 21d, which are the differential arms, becomes zero (N _S = 0), and the steering shafts 21a to 21d.
Does not rotate, but the rotation speed N _T of the wheels 23a to 23d is N ・ Z ₃₀ / Z
_{Since the} wheels 23a to 23d rotate at ₂₉ , the omnidirectional vehicle goes straight.

Further, a steering switching mode for changing the direction of the omnidirectional vehicle will be described. In this case, only the first drive device 27 is driven to rotate the first driven pulleys 34a to 34d at the rotation speed N (N = N ₁ ), and the second drive device 28 is stopped (N ₂ = 0). Then, the rotation speed N _S of the steering shafts 21a to 21d, which are the differential arms, and the rotation speed N _{T of the} wheels 23a to 23d are at a certain ratio (N _T / N _S = 2 · r / d, provided that d is the diameter of the wheel), and the steering shafts 21a to 21d also rotate while the wheels 23a to 23d roll. Therefore, the steering shafts 21a to 21d do not move, and the wheels 23a
Only ~ 23d rolls around the steering shafts 21a-21d,
Since the rolling direction (wheel direction) changes, the traveling direction of the omnidirectional vehicle is changed.

In addition, under the conditions other than the above-mentioned two conditions, the omnidirectional vehicle performs a composite operation of traveling at a certain speed while changing the traveling direction by rotating the steering shafts 21a to 21d at a certain speed.

Now, the above-mentioned differential device 24 will be described in more detail with reference to Table 1 below.

However, Za in Table 1 is the number of teeth Z ₃₀ of the first driving bevel gear ₃₀ , and Zb is the number of teeth Z ₂₉ of the driven bevel gear 29.

In such a differential device 24, the rotation speed N ₁ of the first driven pulley 34a and the second driven pulley 35a are determined by the "pasting method".
Speed N ₂ , differential 24, steering shaft, which is a differential arm
When the relationship between the rotational speed N _{S of} 21a and the rotational speed N _T of each wheel 23a to 23d is calculated, N ₁ = N _S + k (1) N ₂ = −N _S + k (2) N _T = K · Z ₃₀ / Z ₂₉ (3), and if k is eliminated from the equations (1) and (2), N _S = (1/2) · (N ₁ −N ₂ ) and N _S After erasing, N _T = (1/2) ・ (N ₁ −N ₂ ) ・ (Z ₃₀ / Z ₂₉ ).

Therefore, when the omnidirectional vehicle changes direction (rotates the steering shaft), N _S = N / 2 N _T = (N / 2) · (Z ₃₀ / Z ₂₉ ). Then, the ratio between the number of teeth Z _{30 of} the first driving bevel gear 30 and the number of teeth Z 29 of the driven bevel gear ₂₉ and the ratio of the wheel radius (d / 2) and the wheel eccentricity r are set to be equal. If you do,
Substitute (Z ₃₀ / Z ₂₉ ) = (d / 2) / r into the above two equations. Then, (N _T / N _S ) = 2 · r / d.

By the way, as described above, when the wheel having the diameter d is provided so as to be deviated from the axial center of the steering shaft by the distance r, when the steering shaft rotates by θ _S , the wheel has to roll by r θ _S. . As a result, when the rotation angle θ _T of the wheel is obtained, θ _T = rθ _S / (d / 2) θ _T = θ _S = 2 · r / d. Therefore, it is proved that (N _T / N _S = 2 · r / d) is a necessary condition, and the steering switching mode for changing the direction of the omnidirectional vehicle as described above satisfies this condition.

According to the steering mechanism for an omnidirectional vehicle as described above, it is possible to drive and change the direction of the omnidirectional vehicle with one type of drive device 27, 28, which simplifies parts management and assembly work. Can be realized. In particular, since the outputs of the two driving devices 27 and 28 are controlled by the differential device 24, it is not necessary to use a device having a large output as in the conventional case, and a device having a small output can be used, and the cost can be reduced. You can also

The present invention is not limited to the above-described embodiment, but may be the fourth embodiment, for example.
As shown, one drive device 41 with a clutch 40
The wheels 23a to 23d and the steering shafts 21a to 21d may be driven by. That is, the drive device 41 includes a motor, a speed reducer, and an encoder, and is provided on the lower surface of the vehicle body 20. A bevel gear 42 is provided on one output shaft 41a of the drive device 41, and the first drive pulley 36 is provided on the bevel gear 42.
Bevel gears 43 provided on the support shaft 36a of the gear mesh with each other.
The clutch 40 is connected to the other output shaft 44 of the drive device 41. An output shaft 40a of the clutch 40 is provided with a bevel gear 45, and a bevel gear 46 provided on a support shaft 38a of the second drive pulley 38 meshes with the bevel gear 45. Then, as the drive device 41 operates,
When the clutch 40 is engaged, each bevel gear 42, 43, and 4
Since the first and second drive pulleys 36, 38 are rotated by 5, 46, the same operation as in the traveling mode of the above-described embodiment is performed and the omnidirectional vehicle is moved straight. Also drive
Although 41 operates, when the clutch 40 is disengaged, it operates in exactly the same manner as in the steering switching mode of the above-described embodiment, and changes the traveling direction of the omnidirectional vehicle.

Further, in the above-described embodiment, the rotation of the drive devices 27 and 28 is transmitted by the transmission belts 37 and 39, but the present invention is not limited to this, and may be performed by a gear mechanism, a link mechanism, a chain, or the like. Needless to say.

[Effects of the Invention] As described above, according to the steering mechanism of the omnidirectional vehicle according to the present invention, the differential device that utilizes the difference in the rotational speed between the first drive shaft and the second drive shaft is used. Since the wheels are run or the direction of the wheels is changed, it is not necessary to use a drive device having a large output (power) as in the conventional case, and a small output is sufficient, and one or one type of drive device is used. Therefore, it is possible to perform total control without making a distinction between steering and traveling, so that it is possible to simplify parts management and assembly work, and also to reduce costs. .

[Brief description of drawings]

1 to 3 show one embodiment of the present invention, FIG. 1 (A) is a plan view of the omnidirectional vehicle, and FIG. 1 (B) is a sectional view taken along line AA of FIG. (C) is an enlarged cross-sectional view of the steering shaft 21a, FIG. 2 (A) is a view showing a basic configuration of a differential device, and FIG. 2 (B) is a view showing its traveling mode state.
FIG. 3C is a diagram showing a direction change mode state, FIG. 3 is a diagram showing a movement example of an omnidirectional vehicle, and FIG. 4 is a diagram showing a modification example.
FIG. 5 shows a conventional example, FIG. 5 (A) is a plan view thereof, and FIG. 5 (B) is a BB sectional view thereof. 20 …… Body, 21a-21d …… Steering shaft, 23a-23d…
… Wheels, 24 …… Differential gear, 26 …… Axle, 27 …… First drive, 28 …… Second drive, 29 …… Driven bevel gear, 30
...... First drive bevel gear, 31 …… First drive bevel gear, 32…
... first drive shaft, 33 ... second drive shaft, 34a-34d ... first driven pulley, 35a-35d ... second driven pulley, 37 ...
… First transmission belt, 39 …… Second transmission belt, 41 ……
Drive.

Claims (1)

[Claims] 1. An omnidirectional vehicle in which a plurality of steering shafts are rotatably provided on a vehicle body and each steering shaft is provided with at least one wheel, and these wheels are converted into an arbitrary direction for traveling. In the steering mechanism, each wheel provided integrally with each axle is provided at a position deviated from the center of each steering shaft by a predetermined distance, and each steering shaft is provided on the axle. A driven bevel gear, a cylindrical first drive shaft rotatably provided about the axis of the steering shaft, and a first drive bevel gear provided on the first drive shaft and meshing with the driven bevel gear. And a second drive shaft rotatably provided in the first drive shaft, and a second drive bevel gear provided on the second drive shaft and meshing with the driven bevel gear. Moving device The vehicle body is provided with a drive device that drives the first drive shaft via the first transmission member and drives the second drive shaft via the second transmission member. The steering mechanism of an omnidirectional vehicle that is characterized by: