JP3370200B2 - How to determine the steering wheel steering angle of an automatic guided vehicle - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for determining a steering wheel steering angle of an automatic guided vehicle for accurately and stably guiding a guided vehicle which is guided by a guide.

[0002]

2. Description of the Related Art An automated guided vehicle excellent in suppressing dust generation is used for transporting articles and the like in a clean room such as a semiconductor manufacturing factory. This is guided in a clean room by a guide which is previously arranged along the transfer process, and the transfer vehicle runs. This type of transport vehicle is generally of the three-wheel type, with the front wheels of the one-wheel drive type and the rear wheels of the two driven wheels, and the steering angle of the front wheels is determined by one guide sensor fixed to the front vehicle body side of the front wheels. The vehicle is guided by a guide.

[0003]

Therefore, at the front position of the transport vehicle, the position of the transport vehicle in the traveling state is detected with respect to the guide, so that the front portion of the transport vehicle travels at the normal position. However, the rear part of the guided vehicle, that is, the rear wheel side, may be largely displaced to the right or left from the guide guide. Therefore, when the guided vehicle travels, the rear wheel side sways to the left and right, which makes stable running difficult.

An object of the present invention is to accurately follow a guide guide and enable stable traveling.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and in a method of determining a steering angle of an unmanned guided vehicle of four-wheel independent steering type, the traveling is provided on the lower surface, front side, left side, and right side of a bogie, respectively. Of the wheels, two guide wheels that follow the traveling direction of the trolley are independently integrated and guided by guide sensors.
Based on the deviation amount between the guide, and determines the steering angle of each of the two running wheels, the steering angle of the other remaining two running wheels,
Operate the two traveling wheels through the determined two traveling wheels, respectively.
Align the intersection of the straight line orthogonal to the rudder angle and the other two remaining wheels.
The gist is to decide so as to be orthogonal to each straight line . In this case, the automatic guided vehicle is
The turning direction is determined based on the steering angle determined in
The steering angle of the running wheel inside the turn is used as the deviation amount of the guide sensor.
Based on the value based on the
The calculation is controlled as a function of the steering angle of the two running wheels on the side.
A switching function can be provided.

[0006]

[Operation] The lower surface of the bogie of the automatic guided vehicle is equipped with four traveling wheels that can be steered independently of each other, and is guided by the guide guides laid on the road surface. Each guide sensor has an independent guide sensor that determines the steering angle of the two front and rear wheels by following the guidance guide and determines the steering angle of the remaining running wheels without the guide sensor. It is determined by calculating as a function of, which enables stable running.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for determining a steering wheel steering angle of an automatic guided vehicle according to the present invention will be described below with reference to the embodiments shown in the drawings. In the figure, reference numeral 1 is a trolley for an automated guided vehicle, and the trolley 1 travels along a preset course in accordance with the process of transporting articles in a clean room such as a semiconductor manufacturing factory.
In this system, a magnetic, optical, or other type guide guide 2 is laid along a traveling process on a floor surface such as in a clean room, and guided by the guide guide 2 for traveling.

Although not shown, the carriage 1 is equipped with a driving device, a control circuit, a device for loading and unloading conveyed articles, a power supply (battery) for various drives, and the like. The four running wheels 31, 32, 33,
34 is provided. And all the running wheels 31, 32, 3
Each of the steering wheels 3, 34 is provided with a steering device so that the traveling direction can be arbitrarily changed. This steering device allows each traveling wheel to independently control the steering direction and the angle thereof.

The traveling of the bogie is performed by driving the traveling wheels with a motor, but all the traveling wheels can be used as the driving wheels, or two traveling wheels arranged diagonally of the bogie can be driven. The drive of the traveling wheels shall be appropriately determined so that the carriage can travel stably.

On the lower surface of the traveling carriage 1, a carriage is guided by a guide 2
At least two guide sensors 4, 5 are provided so that the vehicle travels accordingly. The guide sensors 4 and 5 are integrally provided on the front and rear running wheels on the same side, for example, on the right and front running wheels 31 and 33 in the illustrated embodiment. That is, the guide sensor 4 is integrated with the front traveling wheel 31 and the guide sensor 5 is integrated with the rear traveling wheel 33, so that when the traveling wheel is steered, both the guide sensors 4 and 5 are displaced. To do so.

Therefore, when the guide guide 2 is curved as shown in FIG. 1, when the carriage 1 tries to travel along the guide guide 2, the guide sensor 4 integrated with the front running wheel 31 and the rear running wheel 33. With the guide sensor 5 integrated with the guide wheels ₂ , the traveling wheels 31, 33 are attached so that the amount of deviation from the guide guide 2, that is, the distances δ ₃ and δ ₂ between the guide sensors 4, 5 and the guide guide 2 become zero. The steering device controls to change the steering angles φ ₃ and φ ₂ from the straight traveling position of the traveling wheels 31 and 33. When the steering angles φ ₃ and φ _{2 of the} traveling wheels 31 and 33 are determined, the other two on the inner circumference side of the curve are
The steering angles φ ₁ , φ _{4 of the} two running wheels 32, 34 are also determined.
In this case, letting C be the intersection of the turning radii ρ ₃ and ρ ₂ orthogonal to the steering angles φ ₃ and φ _{2 of the} traveling wheels 31 and 33, the traveling wheels 32 and 3
The steering angles φ ₁ and φ ₄ of _{No. 4} are determined so as to be orthogonal to the turning radii ρ ₁ and ρ ₄ .

In this way, all the traveling wheels 31, 32, 33, 3
By making four turning radii orthogonal to an arbitrary steering angle of 4 gather at one point C, the traveling direction of each running wheel is V
_{1 to} V ₄ are in the direction orthogonal to each turning radius, and the sideslip (slip in each turning radius direction) can be minimized with respect to the ground on which the vehicle travels.

Next, the relationship between φ ₃ , φ ₂ and φ ₁ , φ ₄ will be described with reference to FIG. The relationship between the steering angles φ ₄ and φ ₂ is as follows.

[0014]

[Formula 1]

Similarly, the relationship between the steering angles φ ₃ , φ ₂ and φ ₁ is as follows.

[0016]

[Formula 2]

From equations (9) and (10), it is shown that φ ₁ is determined when φ ₂ and φ ₃ are determined. By determining the steering angle of each traveling wheel in this way, (1) the guide angle of which the guiding guide should follow within the four traveling wheel steering angles
The one steering wheel can be steered independently of the other wheels and independently of the other wheels. (2) The steering angle can be controlled freely and independently so that the amount of deviation of the traveling wheel for each steering with respect to the guide by the guide sensor is always zero, and therefore the control calculation for control can be simplified.

FIG. 3 is a block diagram of a steering system control circuit mounted on the trolley 1, and FIG. 4 shows the essential parts thereof in more detail.

Next, FIG. 5 shows a configuration in which a turning direction discrimination switching circuit is provided in the steering system control circuit, and FIG. 6 shows a main part thereof. FIG. 7 shows a cart 1 for a guide 2 on a straight road.
FIG. 8 is an explanatory diagram when turning right when the vehicle tilts to the left for some reason, and when the carriage 1 turns right as shown in FIG. 7, the deviation of the front guide sensor with respect to the center of the guide guide is as shown in FIG. dr, and the steering angle control output at this time is φ ₃ ,
If the outside wheel steering angle command value is φ ₁ , turn right (φ ₃ ≧
0) Therefore, the right front wheel is steered to φ ₃ and the left front wheel is steered to φ ₁ by the operation of the switching determination circuit shown in FIGS. 5 and 6.

[0020]

[Formula 3]

When the vehicle 1 turns to the left when the vehicle 1 leans to the right for some reason as shown in FIG. 9, the deviation of the front guide sensor is set to dr '(= -dr), and the steering angle control output at this time is set. phi ₃ When '(= -φ _3), the outer wheel steering angle command value phi _1' and, left turn (φ ₃ '<0) thus, ₁ right front wheel by the action of the switching determination circuit phi', the left front wheel Steer to φ ₃ ′.

[0022]

[Formula 4]

If the bias with respect to the guide is the same,
Since the vehicle turns with the same turning radius, the running trajectories of the vehicle body on the right and left sides of the guide are the same, and the followability and the meandering characteristics are improved.

[0024]

The method for determining the steering wheel steering angle of an unmanned guided vehicle according to the present invention is a four-wheel independent steering type unmanned guided vehicle, in which the traveling direction of the bogie is one of the traveling wheels provided on the front, rear, left and right of the bogie. The steering angle of each traveling wheel is determined based on the deviation amount of the guide sensor provided independently for each of the two traveling wheels.
In order to calculate and determine the steering angle of the other two remaining running wheels as a function of the steering angle, the front and rear steering wheels follow the guiding guide by the action of the steering wheel that follows the guiding guide among the four running wheels. Therefore, compared to the case of only the front wheels, the running stability is excellent and the tracking accuracy is greatly improved, and the calculation of the steering angle of the other two wheels can be simplified as a function of the steering angle of the above two wheels. It has advantages such as simplification. That
The direction of travel of each running wheel is perpendicular to each radius of gyration
And skid against the ground on which the vehicle travels (in each turning radius direction)
Slip) can be minimized.

[Brief description of drawings]

FIG. 1 is a bottom view of a bogie showing an embodiment of a method for determining a traveling wheel steering angle of an automatic guided vehicle according to the present invention.

FIG. 2 is a relationship diagram of respective steering angles of traveling wheels.

FIG. 3 is a block diagram of a steering system control circuit.

FIG. 4 is a detailed circuit diagram of the same.

FIG. 5 is a block diagram of a steering system control circuit provided with a turning direction determination switching circuit.

FIG. 6 is a detailed circuit diagram of the same.

FIG. 7 is an explanatory diagram when the cart turns right.

FIG. 8 is an explanatory diagram of the deviation of the guide sensor.

FIG. 9 is an explanatory diagram when turning to the left.

[Explanation of symbols]

1 dolly 2 guide 31, 32, 33, 34 Running wheels 4,5 guide sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Harumasa Yamamoto 3-11-1 Shimosaka, Amagasaki City, Hyogo Pref., Inside Nitate Kiden Kogyo Co., Ltd. (72) Hiroshi Jinbe 3-chome, Shimosaka, Amagasaki, Hyogo Prefecture No. 11-1 Nitate Kiden Kogyo Co., Ltd. (72) Inventor Kunihiko Nishibe 3-11-11 Shimozakabe, Amagasaki-shi, Hyogo Nikko Ritsudenki Kogyo Co., Ltd. (56) Reference JP-A-7-334236 (JP , A) JP-A-5-189042 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G05D 1/00-1/12

Claims (2)

(57) [Claims] 1. A method for determining a steering angle of an unmanned guided vehicle of a four-wheel independent steering type, wherein among two traveling wheels provided on the front, rear, left, and right of a bogie, two traveling wheels that are along the traveling direction of the bogie are independently provided. The steering angle of each of the two traveling wheels is determined based on the deviation amount of the guide sensor provided integrally with the guide guide, and the steering angles of the other two traveling wheels are determined.
Each of the two traveling wheels is orthogonal to the steering angle of the two traveling wheels.
Pass the intersection of the straight line and the other two running wheels
A method for determining a steering wheel steering angle of an automated guided vehicle, characterized by determining so as to be orthogonal to a straight line . 2. The automatic guided vehicle discriminates the turning direction based on the steering angle determined by the calculation method, and always controls the steering angle of the traveling wheel on the inside of the turning with a value based on the deviation amount of the guide sensor. 2. The method for determining a steering wheel steering angle of an automatic guided vehicle according to claim 1, wherein a switching function is provided so that the steering wheel angle on the outside of the turning is controlled as a function of the steering angle of the two traveling wheels on the inside of the turning. .