JPH0753005B2 - Automated guided vehicle - Google Patents

Description

TECHNICAL FIELD The present invention relates to an automated guided vehicle for transporting articles in a factory or the like.

[Conventional technology]

As a conventional automatic guided vehicle of this type, for example, an alternating current is applied to an electric wire (induction wire) laid on the ground side to generate magnetic force lines, and the magnetic force lines are detected by an induction coil arranged on the vehicle side, There is an electromagnetic induction type unmanned vehicle in which the electromotive force induced in the induction coil is used as a positional deviation feedback amount to give a speed difference to the two left and right driving wheels to control the direction and to travel on the guide wire.

FIG. 3 is a block diagram showing a configuration of a main part of an automatic guided vehicle of this type. In this figure, 1a is a right driving wheel and 1b is a left driving wheel, and these are rotationally driven separately by motors 2a and 2b. The motors 2a, 2b are proportionally / integrally controlled by the PI control circuits 3a, 3b, and are feedback-controlled so that their rotation speeds match the input command values Ca, Cb to the PI control circuits 3a, 3b. The command values Ca and Cb are supplied from the addition points 4a and 4b, and are obtained from the right and left speed commands Va and Vb and the positional deviation feedback amount F by the following equation.

Ca = Va + F (1a) Cb = Vb-F (1b) Here, the speed commands Va and Vb are supplied from a control circuit (not shown) to determine the speed of the vehicle, and the positional deviation feedback amount F is calculated. The positional deviation obtained from the induction coil described above is corrected.
That is, when the vehicle shifts to the right, the feedback amount F becomes positive and Ca> Cb, the speed of the right driving wheel 1a becomes faster than the speed of the left driving wheel 1b, and the vehicle advances to the left. Reverse the operation to move the vehicle to the right and correct the displacement.

[Problems to be solved by the invention]

By the way, in the above-mentioned conventional automated guided vehicle, the output of the induction coil is amplified by a constant amplification factor and this is used as the positional deviation feedback amount F. Therefore, the vehicle speed changes as long as the positional deviation is constant. However, the feedback amount F was constant. Therefore, when the speed commands Va and Vb are small, the positional deviation feedback amount F becomes relatively large,
While the positional deviation correction becomes excessive with respect to the speed and the running becomes unstable, when the speed commands Va and Vb are large, the positional deviation feedback amount F becomes relatively small and the running curve of the vehicle becomes a gentle curve. However, there is a problem that the positional deviation cannot be corrected sufficiently.

[Means for solving problems]

In order to solve the above problems, the present invention provides a speed difference to the left and right driving wheels based on a speed command given separately to each of the left and right driving wheels and a position deviation feedback amount corresponding to a position deviation of the vehicle, thereby In the automatic guided vehicle for controlling the direction of the vehicle, each of the left and right moving wheels is provided with a feedback amount adjusting means for adjusting a positional deviation feedback amount to the moving wheel in proportion to an absolute value of the speed command. It is characterized by

[Action]

According to the above configuration, the positional deviation feedback amount to the driving wheel is increased or decreased in proportion to the absolute value of the speed command. For example, when the speed command for the right driving wheel is small, the amount of positional deviation feedback to the right driving wheel decreases. As a result, the ratio between the speed command of each moving wheel and the positional deviation feedback amount to the moving wheel is always kept substantially constant regardless of the magnitude of each speed command.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a main part of an embodiment of the present invention, and parts corresponding to respective parts in FIG. 3 are designated by the same reference numerals.

In this figure, 11 is an absolute value circuit that takes the absolute value | Va | of the right speed command Va, 12 is a triangular wave oscillator that generates the triangular wave TW shown in Fig. 2 (a), and 13 is an absolute value | Va | and the triangular wave. Compared with TW (Fig. 2 (b)), when | Va | TW, it is "H" level, | Va | <
A pulse-shaped control signal Sg (second
It is a comparator that outputs the figure (c)). As can be easily understood from this figure, the pulse width (“H” level width) of the control signal Sg becomes wider as the absolute value | Va | becomes larger, and becomes narrower as it becomes smaller.

Next, 14 is an analog switch which is turned on / off by a control signal Sg and outputs a pulse signal S (FIG. 2 (d)) having an amplitude equal to the amplitude of the positional deviation feedback amount F when turned on. This pulse signal S is integrated and smoothed by the integrating circuit 15 at the next stage, and is output as the position deviation feedback amount Fa after speed adjustment (hereinafter referred to as correction amount Fa) (Fig. 2 (e)), and the addition point 4a. Is supplied to.

Here, the magnitude of the correction amount Fa increases / decreases according to the increase / decrease in the speed command Va. That is, as the speed command Va increases, as is apparent from FIGS. 2B and 2C, the ON period of the control signal Sg is extended and the ON period of the pulse signal S is also extended.
Therefore, the correction amount Fa obtained by integrating the pulse signal S also increases.

The components 11 to 15 constitute the feedback amount adjusting means 16a on the right side. A similar feedback amount adjusting means 16b is also provided on the left side and outputs the correction amount Fb. However, when the outputs of the speed commands Va and Vb are equal, the left feedback amount adjusting means 16b may be omitted and the correction amount Fa may be added instead of the correction amount Fb and added to the combining point 4b.

In such a configuration, if the vehicle is at the correct position on the guide line, the positional deviation feedback amount F becomes zero and the correction amounts Fa and Fb also become zero. Therefore, the speeds of the right and left driving wheels 1a, 1b are controlled so as to match the speed commands Va, Vb.

Next, when the vehicle shifts to the right, the positional shift feedback amount F becomes a positive value, and the correction amounts Fa and Fb also become positive. As a result, the rotation command value Ca (= Va + Fa) of the right driving wheel 1a becomes the left driving wheel.
It becomes larger than the rotation command value Cb (= Vb-Fb) of 1b, the vehicle moves to the left, and the positional deviation is corrected. On the contrary, when the vehicle shifts to the left, the positional shift feedback amount F becomes negative, and the positional shift is corrected by the operation reverse to the above.

In the above case, the correction amounts Fa and Fb are larger as the speed commands Va and Vb are larger and smaller as the speed commands Va and Vb are smaller, so that the ratios of Va and Fa and Vb and Fb are substantially constant. Therefore, regardless of the magnitude of the speed commands Va and Vb, the vehicle will be corrected for position deviation with a substantially constant curve, and as in the conventional case, the vehicle will be corrected with a sharp curve when the speed is slow and with a gentle curve when the speed is fast. The drawbacks of unstable driving are eliminated. Fine adjustment of the feedback gain depending on the speed can be performed by the absolute value circuit 11. Further, the deterioration of the steering ability at an extremely low speed can be dealt with by giving an offset to the absolute value circuit 11.

〔The invention's effect〕

According to the present invention described above, since the positional deviation feedback amount to the driving wheel is increased or decreased in proportion to the absolute value of the speed command, it is possible to obtain a very smooth running property on a curve.

At this time, since the ratio between the speed command of each driving wheel and the positional deviation feedback amount to the driving wheel is always kept substantially constant, a substantially constant traveling curve is drawn regardless of speed when traveling on a curve. As described above, the positional deviation correction can be performed.

Further, when the speed is low, the positional deviation correction is appropriately performed without being excessive. On the other hand, when the speed is high, the positional deviation correction can be sufficiently performed, so that stable traveling and accurate positional deviation control can be performed. Can be realized. As a result, there is an advantage that stable traveling and accurate position shift control can be realized.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a main part of an embodiment of the present invention, FIG. 2 is a waveform diagram showing a waveform of each part of the embodiment, and FIG.
FIG. 1 is a block diagram showing a configuration of a main part of a conventional automated guided vehicle. 1a …… Right driving wheel, 1b …… Left driving wheel, 16a, 16b …… Feedback amount adjusting means, F …… Position deviation feedback amount, V
a, Vb ... Speed command.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-55-156183 (JP, A) JP-A-60-194701 (JP, A) Actual development 61-308 (JP, U) JP-B 53- 32948 (JP, B2)

Claims (1)

[Claims] 1. A speed difference is given to the left and right driving wheels based on a speed command given separately to each of the left and right driving wheels and a positional deviation feedback amount corresponding to a positional deviation of the vehicle, thereby controlling the direction of the vehicle. In the unmanned guided vehicle, the unmanned guided vehicle is provided with feedback amount adjusting means for adjusting the positional deviation feedback amount to the driving wheels in proportion to the absolute value of the speed command. car.