JPH0218487B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of guiding an automatic guided vehicle, and particularly an object of the present invention is to provide a method of guiding an automatic guided vehicle that allows the automatic guided vehicle to autonomously and appropriately travel without providing guidance information from the outside.

The guiding method for automatic guided vehicles that automatically travel between work points, transfer points, and waiting points in a factory is to run current through wires buried under the floor and follow the resulting electromagnetic waves; A method is known in which a light-reflecting tape attached to the wire follows the wire, but the former requires extensive burying work, makes it difficult to change the running route, and also requires a constant current to be passed through the wire. The latter allows for easy route changes, but has drawbacks such as being trampled by other vehicles such as forklifts or people, resulting in dirt, and a decrease in reflectance, which impedes stable running.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a method for guiding an automatic guided vehicle that does not require ground equipment such as floor wires and can change routes by simply changing the software. shall be.

The automatic guided vehicle guidance method according to the present invention provides information on the distance between the vehicle body and an object on the side of the traveling route in association with the position in the traveling direction, and
The vehicle is characterized in that the distance is actually measured while the vehicle is running, and steering control is performed to eliminate the difference between the measured distance and distance information given in advance.

The method of the present invention will be specifically explained below based on the drawings. FIG. 1 is a drawing for explaining the principle of the method of the present invention. The dash-dotted line l ₀ indicates the reference line of the travel route, and on the left and right sides there are loads such as walls, machines, partition plates, materials, work in progress, and products (all shown with hatching). The gap between the two is used as a transport vehicle passage.

The transport vehicle is equipped with a control device 1 using a microcomputer, etc., and its memory section 11 stores distance information from the reference line _l0 to the left and right walls (hereinafter referred to as walls) in units of the traveling direction. For each distance d, L ₀ , R ₀ , L ₁ , R ₁ , L ₂ , R ₂ , ...Li, Ri...Ln- ₁ ,
Store it as Rn− ₁ , Ln, Rn.

On the other hand, the transport vehicle is provided with distance meters 2l and 2r for measuring the distance to the left and right walls, and the measured values are read into the comparator 1b in the control circuit 1 at appropriate intervals. In addition, a rotary encoder 3 for detecting travel distance is provided in the part that interlocks with the wheels of the transport vehicle (it may be provided on each of the left and right wheels, or one may be provided on the center trailing wheel, etc.), and the amount of wheel rotation. A number of pulses corresponding to the number of pulses are generated, and the pulses are input to a counter 1c in the control circuit 1. The counter 1c emits a pulse every number corresponding to the traveling distance d, and stores the pulse in the storage unit 1.
It is given to the address counter 1d of a. Control circuit 1
is stored in the storage unit 1 according to the contents of the address counter 1d.
The stored information of a is sequentially read out and applied to the comparator 1b.

The comparator 1b compares the actually measured distance on the left and right sides with the distance information on the left and right sides read out from the storage unit 1a. If the comparison data has a deviation greater than a predetermined value,
The control circuit 1 issues a steering correction signal to eliminate the deviation to drive circuits 5l and 5r for servo motors 4l and 4r provided for driving left and right wheels, respectively. The drive circuits 5l and 5r drive the servo motor 4 so as to realize the speed signal constantly given from the control circuit 1.
It is composed of a servo circuit and the like that performs rotation control of the motors 1 and 4r, and a steering correction signal is given so as to be superimposed on the speed signal. Of course, the distance information given from the storage section 1a to the comparator 1b is updated each time the vehicle travels the distance d.

In the above example, the rotary encoder 3 is used to detect the traveling distance or the position in the traveling direction, and the distance information used as a comparison standard is read and updated accordingly, but the uneven pattern on the wall surface is clear. If conditions such as the steering control system's responsiveness is good and it does not deviate significantly from the reference line _l0 , or the driving speed is slow, then the comparison standard is determined based on the actual measurement data of the range finder. It is also possible to update distance information. Figure 2 is an explanatory diagram of this, and shows Y ₁ to _{Y 2}
The road width at the part is W ₁ , and the road width at the part Y ₂ to _{Y 3} is W ₂
Therefore, it is assumed that W ₂ −W ₁ =ΔR ₁ . In this case as well, the contents given as distance information to the storage unit 1a are the distance between the reference line _l0 and the left and right wall surfaces and information on unevenness such as _ΔR1 , but in the range of _Y1 to _Y2. On the other hand, L ₁ , R ₁ ... However, L ₁ + R ₁ = W ₁ , and L ₂ , R ₂ ... However, only L ₂ + R ₂ = W ₂ for the range of Y ₂ to _{Y 3} .
The actual measured distance data of the range finders 2l and 2r is read into the comparator 1b at regular intervals, and compared with the read information from the storage section 11a, and the drive circuit 5 is operated to eliminate the deviation.
The signals are sent to 1 and 5r as before, but the difference is that the information read from the storage section 1a is updated as follows.

That is, the CPU of the control circuit 1 reads data m, m read from the rangefinders 2l and 2r as shown in
Calculate the difference Δ=m−m ₋₁ , Δ=m−m ₋₁ between and the read data m ₋₁ , m ₋₁ one cycle before, and if the absolute value is within the tolerance range α,
Storage section 1a assuming that there is no change in the travel path width or wall surface.
Do not change the read address of . On the other hand, if one exceeds α, further judgment processing is performed based on the level difference information in the storage unit 1a (that there is a level difference of ΔR ₁ on the right side). That is, in this case, the magnitudes of Δ and α, Δ and ΔR ₁ ±α are compared, and |Δ
If |≦α, ΔR ₁ −α≦|Δ|≦ΔR ₁ +α, the read address is updated assuming that the step has been passed, and from the comparison with L ₁ and R ₁ up to that point, L ₂ ,
Change to compare with R ₂ . If the above conditions are not met, the read address is retained as it is.

By using such a method, the self-propelled vehicle can update the distance information to the wall surface on which the vehicle is traveling.

Note that this type of automated guided vehicle may be equipped with a function to recognize its own position, but it is possible to have the recognized position corrected when a step is detected as described above. , the accumulation of errors can be avoided.

Now, in steering control, it is necessary to consider the positional deviation from the reference line l ₀ and the deviation in the traveling direction. The former is Li, Ri in the storage section, and the actual measured value i,
Of course, it can be easily obtained as the difference from i. On the other hand, the latter can be found as follows. In other words, as shown in Figure 4, the tread of the transport vehicle is
Tr, the actual measured values by the range finders 2l and 2r are i,
i, the distance information in the storage unit 1a in this part
Let Li and Ri. Then, the deviation θi in the traveling direction with respect to the reference line l ₀ is based on the triangle ABC in the figure. is determined, and steering control is performed based on this.

Note that when θi becomes larger than a certain level, the comparison between the actual measurement value and the stored distance information becomes meaningless. This is because the former is larger than the latter on both the left and right sides. Therefore, if θi becomes larger than a predetermined value, the stored distance information Li, Ri is corrected to Licosecθi, Ricosecθi, and then compared with the actual measured values i, i to detect the deviation from the reference line _l0 . etc. corrections are necessary.

In the case of the present invention as described above, no special ground equipment is required, and the conveyance vehicle can be run as is on a general path defined by a wall. The route can be changed by simply rewriting the distance information in the software, that is, the storage unit. Furthermore, since the distance to the wall is measured and this is used as guidance information, the narrower the passage, the higher the accuracy. Further, the more uneven the wall surface of the passage, the more information about the traveling direction is obtained, and the accuracy of position detection in that direction increases accordingly.The present invention has excellent effects.

[Brief explanation of drawings]

1 and 2 are drawings together showing a principle explanatory diagram of the method of the present invention and a block diagram showing an apparatus for carrying out the method, FIG. 3 is a flowchart for the read address update process, and FIG. The figure is an explanatory diagram of an algorithm for calculating a shift in the traveling direction. 1...Control circuit, 1a...Storage unit, 2l, 2r
...Distance meter, 3...Rotary encoder, 4l, 4r
...Servo motor, 5l, 5r...drive circuit.

Claims (1)

[Claims] 1 Information on the distance between the vehicle body and an object existing on the side of the driving route is given in advance in relation to the position in the driving direction, while the distance is actually measured while driving, and the measured distance is combined with the distance information given in advance. A method for guiding an automated guided vehicle, characterized in that steering control is performed to eliminate the difference between the two.