JPS6258313A - Steering control method for unmanned carrier - Google Patents

Abstract

PURPOSE:To attain the stable guidance of an unmanned carrier by selecting the steering gain in response to the value proportional to the weight of the body of the carrier including the loadage and also adversely proportional to the driving speed of the carrier. CONSTITUTION:The weight (m) of an unmanned carrier including the loadage is calculated from the rise time of the rotational frequency of a drive motor 27 after this rotational frequency is detected by a pulse generator 16. Then the actual driving speed V is consecutively detected for both unmanned carriers 3a and 3b by a pulse generator 16 and a speed detecting circuit 28. The detecting signal ey(=y+l1sinphi) of the deviation y137b of the carrier front end position is calculated from the drive state quantity (position deviation y and posture angle phi) of the obtained centroid position of the carrier. then the steer ing gain k1(=aXm/v) is calculated from the body weight signal (m) including the loadage and the speed V.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a steering control method for an automatic guided vehicle suitable for guiding the automatic guided vehicle stably along a planned travel route in hot weather.

[Background of the invention]

Various types of control methods are known for guiding an unmanned guided vehicle along a predetermined travel route.

For example, by pasting 11m (tape) of guidance on the road,
Some guide signs are cooled down with an optical detector and the running state of the automatic guided vehicle is calculated, and then the automatic guided vehicle is driven and steered. The automatic guided vehicle is equipped with a steering mechanism (for example, a motor, a deceleration mechanism) for driving and steering the vehicle body, and
Generally, the steering mechanism is provided with a steering control section that supplies a steering control signal.

When guiding the automated guided vehicle along a planned travel route, the steering control signal is calculated so as to eliminate the difference between the travel state (MC, e.g., position deviation) and the target position. By applying it to the steering mechanism, it controls the steering angle or the speed difference of the drive motor of Miya. In this case, it is no exaggeration to say that the quality of the driving performance of the automatic guided vehicle is determined by how the steering control signal is calculated.

In general, when the steering gain is increased, the steering angle becomes larger (
Alternatively, it is well known that the steering gain may be lowered (or the speed difference between the left and right drive motors may be different), and the steering angle may be reduced.

Therefore, if the steering gain is too high when driving at high speeds, the automatic guided vehicle will wobble left and right and become unstable.
If the steering gain is too low, the vehicle tends to be unable to follow the planned travel route.

Therefore, a system is known in which the steering gain is selectively adjusted in multiple stages in accordance with the speed command signal of the automatic guided vehicle to perform stable guided travel.

Such a technique is disclosed in, for example, Japanese Patent Laid-Open No. 53-20233. That is, by controlling the steering by switching the steering gain in multiple stages according to the speed, stable guided travel can be achieved from low speed to high speed.

However, as the use of automated guided vehicles expands, the weight of the cargo loaded on automated guided vehicles (loading load) has started to fluctuate significantly. It is no longer possible to achieve stable guided travel by simply changing the gain.

In particular, unmanned guided vehicles, etc. applied to automated warehouse systems,
In unmanned guided vehicles used for factory automation (FA) and factory manufacturing automation (FMS), it is necessary to prevent accidents such as contact with other equipment, so highly responsive and highly accurate guided driving steering is required. Control is required, and the realization of more stable guided driving is desired.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a steering control method for an automatic guided vehicle that can perform stable guided travel even when there is a significant change in the running state of the automatic guided vehicle.

[Summary of the invention]

The present invention is based on the fact that the main factors that adversely affect the stability of guided travel of automated guided vehicles are large fluctuations in vehicle weight, including speed and component load, and we have conducted a study to address these factors. As a result, new findings have been made that when a steering gain is selected that has a tendency that is inversely proportional to the speed and proportional to the vehicle body ff1fi, the automatic guided vehicle performs extremely stable yJ guided travel. This was done based on the following.

In other words, this cotton generator inputs signals related to vehicle weight including traveling speed and loaded load, calculates a steering gain using these signals, and multiplies the steering gain by a signal corresponding to the positional deviation from the traveling road. The present invention is characterized in that a steering control signal is calculated and a steering mechanism of the automatic guided vehicle is controlled based on the steering control signal.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in detail based on specific examples.

First, the configuration of an example of an operation system for an automatic guided vehicle to which the present invention is applied and an automatic guided vehicle will be explained with reference to FIGS. 2 and 3.

1 is an automatic warehouse facility, which is a storage system that moves left and right on rails using a stacker crane to handle and transport cargo on shelves. 2 is a ground computer, and automatic warehouse equipment 1
In addition, automatic guided vehicles 3a and 3b run on travel paths 4a and 4b and perform cargo handling work at loading/unloading stations 5a and 5b.
It has the function of carrying out operation management. 6a and 6b, the automatic guided vehicles 3a and 3b move from the straight running path 4a to the curved running path 4b.
This is the turning deceleration zone that leads to Conversely, 7a and 7b are turning acceleration zones extending from the curved road 4b to the straight road 4a. 8a to 8e are stopping and donating zones leading to the loading/unloading stations 5a, 5b and the automated warehouse facility 1. 93
~9C is the driving path 4a.

It is a guidance sign affixed on the automatic guided vehicle 3a,
3b is guided to run. In particular, 9a is a steering guide sign, 9b is a travel speed acceleration/deceleration guide sign, and 9C is a street address detection guide sign.

Optical detectors 10a and 10b are attached to the front and rear of the lower ends of the automatic guided vehicles 3a and 3b, respectively, and detect the guide signs 98 to 9c, respectively. Reference numeral 11 denotes a steering mechanism for steering the steering wheel in the left and right direction, and includes a servo amplifier n.
1. Consists of a speed reducer and a steering motor (not shown).

13a and 13b are running wheels, and automatic guided vehicles 3a and 3b
It rotates under the driving force of the traveling mechanism 14 for supporting and traveling the vehicle.

Reference numeral 15 denotes a control device which inputs position deviation signals from the optical detectors 10a and 10b and a speed signal from a pulse generator 16 that detects the rotation speed of the traveling motor n, and performs steering control on the traveling mechanism 14 and the steering mechanism 11, respectively. It outputs a signal. 17 is a wireless device that transmits and receives command signals from the ground computer 2;

Next, an embodiment of the present invention for controlling the steering of the automatic guided vehicle shown in FIG. 3 will be described.

Figure $1 is a diagram showing one embodiment of the present invention.

Reference numeral 18 denotes a traveling steering command section, which outputs command signals to a target position deviation setting device and a speed setting device 19 for controlling the steering of the automatic guided vehicle.

A speed setting device 19 outputs a speed setting value VO according to a speed pattern as a command signal.

The sword is a speed control section, which is a circuit that converts the speed difference value ΔV between the speed setting value vo outputted from the speed setter 19 and the actual speed V outputted from the speed detection circuit a into a frequency f.

Sae is a limiter circuit that adds saturation characteristics to the frequency f output from the speed control section and inputs the operating frequency F to the inverter circuits.

I is an inverter circuit that generates electric power according to the operating frequency F to drive the traveling motor I.

Thereby, the running wheels 13a, 13b receive rotational driving force, and the automatic guided vehicles 3a, 3b travel.

On the other hand, in the steering system, (9) is a position deviation setting device, which receives a command signal e from the travel steering command section 18. (For example, when traveling in a straight line, the set value e. (=O)) is set.

4 is a subtraction circuit, and the command signal e. A steering difference Δe is calculated between the detection signal e from the data processing unit sum and the detection signal e from the data processing unit sum, which will be described later.

(Material) is a steering control signal setting unit, which inputs the steering difference △e obtained from the subtraction circuit B, multiplies it by the steering gain〉k set by the steering gain calculation unit, and outputs the steering control signal ex. obtain.

Reference numeral 31 denotes a D/person four circuit that converts the digital steering control signal ex set by the steering control signal setting unit □□□ into an analog voltage signal ev.

11 is a steering mechanism, which includes a servo amplifier and a steering wheel 12a.
It consists of a steering motor that rotates the

n is the analog voltage signal e output from the D/human circuit 31
Although not shown, it is a servo amplifier that includes the function of a servo mechanism, and outputs the current signal i for eliminating speed deviation.

A is the steering motor, which is rotated based on the current signal it converted by the servo amplifier n, and adjusts the steering angle δ of the steering wheel.
control.

The tool is a trolley mechanism system of an automatic guided vehicle, and a driving force applied by a driving motor n or a steering motor O provides a traveling operation or a steering operation, and produces a traveling speed v36°, a position deviation y37, and an attitude angle ψa.

0 is the positional deviation y1 of the optical detector 10a attached to the lower part of the vehicle body of the automatic guided vehicle 3a, 3b.

The lead is a data processing unit, and from the binary signals obtained by the optical detectors 10a and 10b, a detection signal e of the positional deviation of the automatic guided vehicle with respect to the guidance sign 9a pasted on the driving path 4,
is calculated.

The main circuit is a speed detection circuit that counts the number of pulses from the pulse generator 16 and detects the speed V.

A is a weight calculation unit that detects the vehicle weight signal m including the live load, and has a function of calculating the vehicle weight signal m including the live load from the rising characteristic of the speed signal V output from the speed detection circuit blade. Note that the loaded weight may be directly detected by a load detector and the vehicle weight may be added thereto.

Reference numeral 4 denotes a steering gain calculating section for adjusting the steering gain k (=aXm-) according to the speed signal V and the vehicle weight signal m outputted from the speed detection circuit.

The characteristic part of this embodiment is the steering gain calculation unit, which calculates the steering control signal in response to a large change in the traveling speed signal V and the vehicle weight signal m including the loaded load.
It is possible to drive the steering wheels 2 and obtain stable guided running performance.

Here, the equation of motion between the positional deviation y 37 a and the attitude angle ψ for the steering control signal 1 of the automatic guided vehicles 3a and 3b is (
1) to (3) are approximated. (Abe: Vehicle Movement and Control, P39-42, Kyoritsu Shuppan KK, October 2, 1979
First edition published on 0th) d2δ dδ i = −2cω. π-ωI, △e to 2δ+...
・・・・・・・・・ (11 However, m: Vehicle weight including loaded weight I: Yaw moment of inertia (=ml!2) ψ Two vehicle body attitude angles: Cornering force of steered wheels and running wheels l: Steering wheels and the distance between the wheels and the running wheels. The transfer function (h(sl
.

The transfer function 03(s) of the actual traveling speed V to G2(s) and the speed command vo is expressed by the following equation. However, it is expressed in Laplace transformed form.

・・・・・・・・・・・・・・・ (4)(4)～(6
) is shown in a block diagram as shown in FIG. In the figure, elements that are the same as those in Figure 1 are marked with a ``'.

4' is a system of a steering gain calculation unit that calculates the steering gain k;
Nod' is the proportional system of the steering control signal setting section, 11' is the secondary delay system of the steering mechanism 11, A' is the detection system of the weight calculation section, and X'
is the detection system of the data processing unit Xun. n' is a proportional system of the speed control section B, 14' is an integral system of the traveling mechanism 14, and 14' is a detection system of the speed detection circuit Z. Also, 41a, 41b
is the position deviation constant of the control system A' of the bogie mechanism system U - 2 the attitude angle constant ゝ.

mml! In this block diagram, the variable parameters are the traveling speed V and the vehicle weight m including the loaded load, and as shown in the figure,
The attitude angle ψ or the positional deviation y37a is significantly affected by the change in the -2- term, which is the V2 proportionality constant.
m to be heard. In particular, eo=0. Steering gain = constant and initial position deviation y. Then, automatic guided vehicles 3a and 3b
moves its posture while traveling so as to eliminate the initial positional deviation yo, but if - is small, the steering control signal e of the feed pack is small, so the coordination between the automatic guided vehicles 3a and 3b deteriorates, and the scheduled travel is delayed. Unable to follow the road.

When the reverse heat is large, the feedback steering control signal e becomes large, and the coordination between the automatic guided vehicles 3a and 3b improves, but there is a tendency for small vibrations to occur and unstable running. .

Therefore, as shown in Figure @5, by selecting the steering gain k to be 1, which is proportional to the vehicle weight m including the live load and inversely proportional to the traveling speed V, the above-mentioned phenomenon can be solved. This makes it possible to implement stable guided driving.

FIG. 6 shows an operational flowchart of the above embodiment.

First, when the power is turned on, the initial setting of step (a) is performed, and the operations of steps (b) to (1) shown below are performed.

Step (b)... Guidance sign 9 while driving
8 to 9C are detected by the optical detectors 10a and 10b, the number of marks is counted, and the actual number of traveling stops x39 is calculated.Then, a comparison calculation is made with the set number of traveling stops x6, and a stop positioning operation is performed. Ru. Therefore, the number x0 of running stops is set by a running command signal from the outside (for example, a running command manually issued by an operator is automatically issued via the communication device 17).

Step (c): By detecting the rotational speed of the traveling motor n with the pulse generator 16, the vehicle weight m of the loaded load is calculated from the rise time of the rotational speed. Instead of this calculation, a weight value obtained in advance via the communication device 17 may be used.

Step (d)...Actual traveling speed V when the automatic guided vehicles 3a, 3b are traveling is sequentially detected from the pulse generator 16 and the speed detection circuit Z.

Step (e)... After detecting the guidance signs 93 to 9C with the two optical detectors 10a and 10b provided before and after and converting them into binary signals of ON and OFF. , the automatic guided vehicle 3 for the guide signs 9a to 9C accurately pasted on the travel routes 4a and 4b by the data processing unit ω.
Positional deviation Y1 of a and 3b + attitude angle ψ and number of running stops X
Calculate.

Steps (f) to (h)... Set scheduled number of travel stops X. Then, it is determined whether the automatic guided vehicles 3a, 3b have actually reached that position, and if not, the process jumps to step (i). If so, a deceleration command to the traveling mechanism 14 is output in the form of a pattern. As a result, the automatic guided vehicles 3a and 3b move to the planned position and stop.

Step (i)...A detection signal e of the positional deviation y137b of the front end position of the cart from the running state quantity (positional deviation y, attitude angle ψ) of the center of gravity position of the automatic guided vehicle obtained in step (e), (= Y +l!tainψ) is calculated.

Step (j)...The vehicle weight signal m including the live load calculated in step (C) and step (d) is changed from the actual running speed signal V to the steering gain shown in Fig. 5 by 1. (=aX-) is calculated.

Step (k)...The difference between the deviation signal eO set by the position deviation setting device λ and the position deviation signal ey of the front end of the bogie calculated by the data processing unit The steering control signal txt (
= kt X (eo-e, )).

Step (1) By supplying the steering control signal exi calculated in step (k) to the steering motor via the servo amplifier support, the steering wheel section is actuated, and the automatic guided vehicle is guided to the guide mark 9a. The vehicle is guided stably along 9c.

As a result, stable guided travel can be performed even if the automatic guided vehicle is subject to significant changes in the traveling conditions due to changes in travel speed and changes in vehicle weight including payload.

FIGS. 7 and 8 show other embodiments of the present invention. The difference from the previous embodiment in FIGS. 5 and 6 is that 2 is calculated as the steering gain.

This is to calculate a steering gain of 2, which is inversely proportional to the square of the running speed and proportional to the vehicle weight m including the live load. Therefore, in the flowchart of FIG.
A steering control signal ex2 is obtained by multiplying the steering gain calculated in step j)' by the difference between 2 (= a

According to this embodiment, since the responsiveness to positional deviations in a straight-ahead running situation is improved, more stable guided running can be performed.

Further, FIGS. 9 and 10 show still other embodiments of the present invention. The difference from the above embodiment is that the steering gain is calculated as 1+2, which is based on the driving conditions (high speed driving, low speed driving 2 positioning and turning driving), and the steering gain kl(=aX=)r k2 ＜=a x
, 2).

Therefore, in Figure 79 and Figure 1θ, step (j)'
Using 1+2 for the steering gain calculated in step (
Depending on the running conditions of m) and (n), step (k)
'.

Select steps (0) to (q) and send the rolling control signal exl
+eYo2 is obtained, and the automatic guided vehicles 3a and 3b can be stably guided.

According to this embodiment, since the steering gain can be adjusted depending on the driving condition, stable guided driving can be performed over a wide range.

〔Effect of the invention〕

According to the present invention, stable guided travel can be performed even when there is a significant change in the traveling conditions of the automatic guided vehicle.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing the operational system configuration of the automatic guided vehicle, Fig. 3 is a diagram showing the configuration of the automated guided vehicle, and Fig. 4 is the overall travel steering control system. FIG. 5 is a diagram showing the configuration for adjusting the steering gain with respect to changes in vehicle weight including traveling speed and live load. FIG. 6 is a flowchart showing the operating procedure in the embodiment of FIG. 1.
FIG. 8 is a gain adjustment explanatory diagram regarding another embodiment of the present invention, FIG. 8 is a flowchart diagram according to another embodiment of the present invention,
FIG. 9 is an explanatory diagram of gain adjustment regarding another embodiment of the present invention, and FIG. 10 is a flow chart diagram of another embodiment of the present invention. Automatic guided vehicles for 3a, 3b..., 9a-9c...
・Guiding intelligence, 10a, 10b... optical detector,
11... Steering mechanism, twist... Steering wheel, 1
3a, 13b...four running wheels, 14...travel mechanism, 15...control device, 16...curve PLG (pulse generator), 18...curve steering command unit, 19・
...Speed setter, acceleration...Position deviation setter, column...Speed detection circuit, 4.Turn/steering gain calculation section,
(9)...1 Steering control signal setting unit, A...Truck mechanism system, A...Turn weight calculation unit, Off...Data processing unit
, z-Th agent and patent attorney Masaru Ogawa
Figure 1') Figure 3 Figure 4 Off view

Claims (1)

[Claims] 1. In a steering control method of an automatic guided vehicle for driving the automatic guided vehicle along a traveling route, information regarding the traveling speed and vehicle weight including the loaded load of the automatic guided vehicle is input, and the steering is performed using the signals. calculating a gain, multiplying a signal corresponding to the positional deviation from the traveling path by the steering gain to calculate a steering control signal, and controlling a steering mechanism of the automatic guided vehicle based on the steering control signal. Features: Steering control method for automated guided vehicles.