JPH01184510A - Carrying vehicle - Google Patents

Abstract

PURPOSE:To inexpensively perform positioning with high accuracy by providing a positioning means which performs positioning in two directions on a horizontal plane and three rotary directions around a vertical shaft on a load-carrying platform. CONSTITUTION:A base body 1 is supported on a pair of right and left driving wheels 2 and four front/rear and right/left auxiliary wheels 3 of a carrying vehicle, and the load-carrying platform 4 to place an article to be carried is provided on the upper part of the base body, and is mounted in such a way that it can be moved and turned freely on an equipment body 1 by the positioning means (5x...5theta) in every direction in the three directions. Also, the said positioning means (5x...5theta) are driven independent ly by driving parts (6x...6theta). Furthermore, optical sensors (7A...7B) which detect the stopping position of the equipment body are mounted at the central front and rear part of the equipment body, and a mark 8 on a floor plane is image-picked up and detected, and a positioning controller 9 which supplies a driving signal is provided. Thereby, it is possible to dissolve deviation between a relative stopping position and a regular relative stopping position by the positioning in the two directions on the horizontal plane and the three directions around the vertical rotary shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transport vehicle that automatically travels in a workplace, and more specifically to a transport vehicle that is equipped with a positioning means on a loading platform on which articles are placed.

[Prior art]

Transport vehicles, especially unmanned transport vehicles, have made great progress in recent years as core equipment in factory automation systems.

A conventional automatic guided vehicle has a loading platform on its upper surface for placing an article to be transported, and transports the article to a station provided in each process. Then, the article is automatically transferred from the automatic guided vehicle to each station by a transfer device provided at the station.

On the other hand, the stopping accuracy of an unmanned guided vehicle is about ±10m in the direction of movement and the direction crossing it, and about ±10 in the direction of rotation around the vertical axis. Since the stopping position accuracy depends on the stopping accuracy of the automatic guided vehicle, it has a value similar to the above-mentioned stopping accuracy. Due to the error in the stopping accuracy, there is a discrepancy between the relative stopping position of the transfer device and the loading platform and the normal relative stopping position. When loading, it is necessary to provide the transfer device or the transport vehicle with a structure that eliminates the deviation, or to improve the stopping accuracy of the automatic transport vehicle.

As a known means of improving stopping accuracy, a plurality of hydraulic jacks are installed on the unmanned guided vehicle, a conical screw hole is formed in the mouth of the jack, and a screw hole is provided in the regular stopping position on the floor of each station run. A plurality of positioning protrusions each having a conically shaped male portion that engages with each other are provided corresponding to the mounting positions of the hydraulic jacks, and when the automatic guided vehicle stops at a station, the hydraulic jacks are advanced and the respective positioning protrusions There is a means for external fitting and positioning. As a result, the automatic guided vehicle is lifted from the floor and positioned at its normal stopping position.

[Problem to be solved by the invention]

However, in the above means, the positioning protrusion becomes an obstacle to running, and a large number of additional equipment such as a hydraulic power source is required, which increases the price and complicates the structure. Because of the positioning, the positioning accuracy deteriorates due to wear of the screw hole and male part, and dust is generated due to abrasion powder, making it impossible to use in environments where positioning accuracy and cleanliness are specified, such as semiconductor manufacturing factories. Ta.

Further, since a transfer device is provided for each station run, if the transfer device is provided with a structure to eliminate the above-mentioned deviation, a large number of such structures will be required, leading to an increase in the price of the entire system.

The present invention has been made in view of the above circumstances, and by equipping the loading platform with means for positioning the loading platform in three directions: two directions in the horizontal plane and a rotational direction around the vertical axis,
It is an object of the present invention to provide a transport vehicle that can perform high-precision positioning of relative stop positions between a loading platform and a transfer device with a simple structure and at low cost.

[Means to solve the problem]

A conveyance vehicle according to the present invention has a loading platform on which articles are placed and automatically travels in a workplace, and includes means for positioning the loading platform in two directions within a horizontal plane, and a vertical axis of the loading platform a. It is characterized in that the loading platform is provided with positioning means in the rotational direction.

[Effect]

In the present invention, the deviation between the relative stop position between the loading platform of the transport vehicle and the transfer device and the regular relative stopping position is determined in two directions within a horizontal plane provided on the loading platform and in a rotational direction around a vertical axis. This problem is solved by positioning means in three directions.

(Example〕 Hereinafter, the present invention will be explained in detail based on drawings showing embodiments thereof.

FIG. 1 is a left side view of a conveyance vehicle according to the present invention, and the direction of travel of the conveyance vehicle is the direction indicated by a white arrow.

In the figure, l is supported by a pair of left and right drive wheels 2 (the right drive wheel is not shown) and four auxiliary wheels 3, 3 (the right auxiliary wheel is not shown) provided on the front, rear, left and right sides of the conveyance vehicle. It is the aircraft. The drive wheels 2 are mounted on the center of the fuselage 1 at an appropriate distance from each other on the left and right sides, and each drive motor (not shown) is coaxially and directly connected to each drive motor. Move aircraft 1 forward and backward. Further, the auxiliary wheels 3.3 are rotatably attached to the front, rear, left and right sides of the fuselage 1 at suitable distances so as to be rotatable about the vertical axis of the fuselage 1.

A loading platform 4 for placing articles to be transported is provided on the upper part of the aircraft 1, with its center being the same as that of the aircraft 1, and the loading platform 4 is located at the center of the aircraft 1 in the direction of movement of the aircraft 1. , a positioning means 5 in each direction that performs positioning in three directions: a direction perpendicular to the traveling direction, and a rotational direction around the vertical axis of the aircraft body 1.
x, 5y, and 5θ, it is attached to the fuselage l so that it can move and rotate in the three directions. Further, the positioning means 5x, 5y, 5θ in each direction is a three-direction drive unit 6x,
6y and 6θ, it is possible to drive each of the three directions separately.

On the other hand, at the front and rear of the center of the fuselage l are optical sensors 7a and 7m that are made up of industrial TV cameras that detect the stopping position of the fuselage l.
are mounted downward at a distance from the center of the fuselage 1, indicating the stopping position of each process, and on the floor surface 9, at the same distance as the optical sensors 7m and 7m, a black background is placed at the center of a white square. The stopping position of the aircraft 1 is detected by the optical sensors 7a and 7g capturing images of the two circular positioning marks 8.8. The imaged positioning mark 8
．． A positioning control device 9 is provided inside the fuselage l for applying a drive signal to each of the drive units 6x, 6y, and 6θ from a position 8.

FIG. 2 is a partially cutaway side view showing each positioning means equipped with a driving part of the loading platform, and each positioning means 5x, 5y,
5θ is attached to the front and rear of the central part of the fuselage 1, and has a rectangular flat plate fixed to the center of an inverted vertical member, and its longitudinal direction is perpendicular to the traveling direction of the fuselage 1. The base 57 is fastened to the base 57.

The base 57 has a square flat plate shape with sides slightly shorter than the horizontal length of the loading platform, and has a cylindrical boss part above the center part, and a swing bearing 52θ is installed inside the boss part. stand 57
A drive motor 66θ, which is a turning stepping motor, is attached to the lower center of the rear part of the motor, with its output shaft facing upward. An eccentric shaft 62θ having a predetermined eccentricity with respect to the output shaft is connected to the tip of the drive motor 66θ via a flexible joint 61θ, and an eccentric cam is connected to the upper end of the eccentric shaft 62θ. Two ball bearings 63θ and 63θ are fitted onto the outside. Further, the base 57 has a lower mounting flange on the upper side of the rear center, and a cylindrical bearing box 64θ is mounted coaxially with the drive motor 66θ, and the eccentric shaft 62θ
are two ball bearings 6 fitted inside the upper end of the bearing box 64θ.
5θ and 65θ, and the eccentric shaft 62θ
Due to the amount of eccentricity, the rotating table 50θ, which will be described later
rotate around.

The boss portion of a rotating table 50θ is fitted into the inner ring of the swivel bearing 52θ, and has a flat plate shape with approximately the same external shape as the base 57, and has a cylindrical boss portion facing downward at the center. The rotary bearing 52θ allows the body l to rotate freely around the vertical axis (hereinafter referred to as the θ direction) around the rotary bearing 52θ. In addition, a cylindrical bearing box 64x having mounting flanges at the upper and lower ends is attached to the lower part of the center of the front part of the rotating table 50θ, and the lower mounting flange is attached to the front-rear direction (hereinafter referred to as the X direction). A drive motor 6 using a stepping motor for movement of
6x is installed with its output shaft facing upward. An eccentric shaft 62x having a predetermined eccentricity with respect to the drive motor output shaft is connected to the tip of the drive motor 66x via a flexible joint 61x. Two ball bearings 63x, 63x, which are cams, are fitted onto the outside. The eccentric shaft 62x is supported by two ball bearings 65x and 65χ fitted in the upper part of the bearing box 64x, and the eccentricity of the eccentric shaft 62x allows the moving table 50X, which will be described later, to move in the X direction. Move to. In addition, the rotating table 50
Four moving guides 52x, 52x in the X direction using rail parts of linear guides are spaced appropriately on the front, rear, left and right sides of θ.
is attached so that its longitudinal direction substantially coincides with the X direction of the fuselage 1.

FIG. 3 is an enlarged perspective view showing the mounting state of the eccentric cam of the driving means of the loading platform.
θ is a lower cam which has a rectangular flat plate shape and has a square bar-shaped convex portion at one end, and an oblong eccentric cam groove 59θ whose length in the longitudinal direction is in the same direction as the convex portion is formed in the center of the lower cam. The upper cam receiver 53θ is fitted inside the upper cam receiver 53θ, which has an eccentric cam groove 58θ similar to the lower cam receiver 54θ placed above the lower cam receiver 54θ.
Adjustment screws 5 are screwed together at appropriate intervals in the longitudinal direction of the convex part.
5θ and 55θ, it is possible to freely slide with respect to the lower cam receiver 54θ in a direction perpendicular to the longitudinal direction of the eccentric cam groove. The lower cam bearing 54θ and the upper cam bearing 53θ are the two ball bearings 63θ, which are eccentric cams, and the outer ring of the upper ball bearing 63θ of 63θ is the eccentric cam groove 58 of the upper cam bearing 53θ.
The outer ring of the lower ball bearing 63θ is connected to the eccentric cam groove 59θ of the lower cam receiver 54θ.
The adjustment bolt 55θ is adjusted so as to be pressed against the side surface opposite to the adjustment bolt 55θ, thereby applying a preload to each outer ring. After this adjustment is completed, the lock nut 56θ seals off the rotation of the adjustment bolt 55θ. And the lower cam receiver 54θ and the upper cam receiver 53
θ is attached to the rear center of the rotating table 50θ.

On the other hand, a moving guide 52x is attached to the rotating table 50θ.

52x..., the moving guides 52x, 52x
Four upper guides 51 x 51 This means that employees can be transferred freely in the X direction.

The moving table 50x has a flat plate shape with approximately the same external shape as the rotating table 50θ, and a cylindrical bearing box 64y having mounting flanges at the upper and lower portions is attached to the lower side of the left center of the moving table 50x. ing. In addition, a drive motor 66y using a stepping motor for moving the aircraft 1 in the direction perpendicular to the direction of travel, that is, in the left-right direction (hereinafter referred to as y-direction) is mounted on the lower mounting flange with its output shaft facing upward. ing. An eccentric shaft 62y having a predetermined eccentricity with respect to the output shaft of the drive motor 66y is connected to the tip of the drive motor 66y via a flexible bearing 61y. Two ball bearings 63y are eccentric cams.

63y is fitted on the outside. The eccentric shaft 62y has two ball bearings 65y, 65 fitted inside the upper part of the bearing box 64y.
The moving table 50y, which will be described later, moves in the y direction depending on the amount of eccentricity of the eccentric shaft 62y.

Also, above the center of the front part of the moving table 50x, there is a rotating table 50θ.
Upper cam receiver 53θ and lower cam receiver 54θ installed on
An upper cam receiver 53x and a lower cam receiver 54x having a similar structure are attached with the longitudinal direction of the eccentric cam grooves 58x and 59x as the y direction. Furthermore, moving platform 50×
Four y-direction moving guides 52y* using rail portions of linear guides spaced appropriately on the upper front, rear, left and right sides.
52y... is installed. Then, four upper guides 51 y + are formed using the transfer parts of the linear guides.
51 y... are attached to the lower part of the rectangular plate-shaped moving table 50y so as to engage with the moving guides s2y, szy..., making the moving table 50y freely transferable in the y direction. In addition, at the lower center of the left side of the moving table 5Qy, an upper cam receiver 53y and a lower cam receiver 54y, which are engaged with the ball bearings 63y and 63y and have the same structure as the upper cam receiver 53θ and the lower cam receiver 54θ, are located on the eccentric side. The longitudinal direction of the cam grooves 58y and 59y is the X direction, and the upper and lower cam receivers 53
θ and the lower cam receiver 54θ are installed in reverse.

A loading section 41 for loading articles constituting the loading platform 4 is attached to the upper part of the moving platform 50y.

FIG. 4 is a block diagram showing the configuration of a positioning control device for a conveyance vehicle related to daylight and brightness, and the positioning control device 9 includes a positioning mark 8 imaged by optical sensors 7a and 1m.
．． 8, a position detection unit 91 detects the position of the positioning mark 8, which detects the center position pA, pm of the field of view of the optical sensor.
．． Positioning correction values ΔX in the X direction, y direction, and θ direction for calculating the deviation from the center of gravity position PAZPI' of the transport vehicle 8 and positioning the loading platform 4 of the conveyance vehicle in a direction that eliminates the deviation amount based on the deviation, Positioning correction value calculation unit 92 that calculates Δy and Δθ and each calculated positioning correction value ΔX
.

The relationship between Δy, Δθ and the number of pulses applied to each drive motor 66x, 66y, 66θ is stored, and based on the memory, a predetermined number of pulses Lχ is applied to each drive motor 66x, 66y, 66θ.
, L.V.

It includes a motor drive section 93 that provides Lθ.

Next, a method of controlling a conveyance vehicle and calculating a positioning correction value at a stop position according to the present invention will be explained.

The positioning correction values ΔX, Δy, and Δθ are the center position G of the loading platform 4 and its X direction, and the intermediate position G' of the positioning mark 8.8.
and the drive unit 5 of the loading platform in order to match the installation direction.
x, 6y, and 6θ, thereby eliminating the above-mentioned deviation.

FIG. 5 is a flowchart showing the flow of control;
The figure is a diagram explaining the method of calculating the positioning correction value.
The conveyance vehicle is automatically driven by a predetermined guidance device toward the station run provided at each process, and the positioning mark 8
．． The black circle in the center of 8 is stopped at a position where the optical sensor has a field of view of 7m and 1m. When the transport vehicle stops,
The positioning marks 8, 8 are imaged by the optical sensor 7A, 1 m, and based on the imaging result, the position detection unit 91 determines that the intermediate position G' of the positioning marks 8.8 is the origin, the installation direction is the X' axis, and it is orthogonal thereto. The center positions PA and PB of the field of view and the positioning mark P in a coordinate system with the Y' axis in the direction of
Distance to AtPl M dXAI dVA* d Xl+
Find d%'1. The positioning correction value calculation unit 92 calculates each distance d)IA determined by the position detection unit 91.
+dXI+dYA+d□, each positioning correction value ΔX, Δy, Δθ is calculated by the calculation method described later. Then, each positioning correction value Δ is determined by the motor drive unit 93.
X, Δy9Δθ are the required pulses Lx, Ly of each drive motor
, Lθ, the required number of pulses x y, and Lθ for each drive motor 66x.

Output to 66y and 66θ.

The loading platform 4 is thereby positioned.

On the other hand, each positioning correction value ΔX, Δy, Δθ is calculated by the sixth
When the optical sensor 7a shown by the two-dot chain line in the figure captures the center of gravity of the positioning marks 8, 8 within a field of view of 1 m, the distance dXA+ dVan dXl+ dYIS is determined. Using the determined distances, positioning correction values ΔX, Δy, and Δθ are determined using the following equations.

dy=dyad□ However, 2L: Installation distance of positioning sign 8.8 Above (1)
- Each positioning correction value ΔX, Δy according to equation (3).

Δθ is calculated, a predetermined number of pulses corresponding to each positioning correction value ΔX, Δy, Δθ is outputted by the motor drive unit 93, and the motor drive unit 93 outputs the pulses corresponding to each positioning correction value ΔX, Δy, Δθ.
By driving θ, the loading platform 4 is positioned at the normal stop position. The amount of movement and rotation in the three directions due to the amount of eccentricity is a sufficiently large value relative to the amount of deviation (in this example, ±15M in the X direction, ±20 in the Y direction, and ±2° in the θ direction). Even if the stopping precision of the vehicle is not sufficient, the relative positional precision between the loading platform and the transfer device will be within ± in the X and Y directions.
It became possible to suppress the lam and θ directions within the permissible values.

Furthermore, in this embodiment, an eccentric cam using a ball bearing is used, and a preload is applied to its outer ring, so the structure of the positioning means is simplified and play between the eccentric cam and the eccentric cam groove can be suppressed. This enabled smooth positioning.

In this embodiment, a t-eccentric cam mechanism is used as the positioning means, but the present invention is not limited to this, and positioning means in the three directions of the X direction, y direction, and θ direction such as a rack pinion, a ball screw, etc. Any mechanism that makes it possible may be used.

Further, in this embodiment, a stepping motor is used as the drive motor, but the present invention is not limited to this, and any motor capable of position control, such as a servo motor with an encoder, may be used.

〔effect〕

As detailed above, in the conveyance vehicle according to the present invention, the loading platform on which the article is placed is equipped with a positioning means that can position the article with high precision in two directions in the horizontal plane and in three directions in the rotational direction around the vertical axis. Therefore, it is possible to provide an equivalent effect of providing a transport vehicle that can accurately position the stop position of the loading platform at low cost with a simple structure.

[BRIEF DESCRIPTION OF THE DRAWINGS] The drawings show one embodiment of the present invention, and FIG. 1 is a left side view of a conveyance vehicle according to the present invention, and FIG. 2 is a partially cutaway view showing positioning means for a loading platform. 3 is an enlarged perspective view showing the mounting state of the eccentric cam, FIG. 4 is a block diagram showing the configuration of the positioning control device of the present invention, FIG. 5 is a flow chart showing the flow of control, and FIG. 6 2 is a diagram showing a method of calculating a positioning value. FIG. 1... Airframe 5x... X direction positioning means 5y.
...Y direction positioning means 5θ...θ direction positioning means

Claims (1)

[Scope of Claims] 1. A transport vehicle that has a loading platform on which articles are placed and that automatically travels in a workplace, comprising means for positioning the loading platform in two directions within a horizontal plane, and a vertical axis of the loading platform. A conveyance vehicle characterized in that a loading platform is provided with positioning means in a rotational direction.