JPH0962357A - Turning control system for automated guided vehicles - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To automatically correct a parameter at the time of program turning by measuring a deviation amount direction angle from a target position of an automatic guided vehicle at the end of the program turning. A guide installed on a road surface, a position detector for detecting the relative position of the automated guided vehicle with respect to the guide, and a direction angle detector for detecting the relative angle of the guided vehicle with respect to the guided vehicle. The automatic guided vehicle comprises a parameter storage unit that stores a turning parameter to be referred to when the vehicle turns, and a parameter correction unit that changes the turning parameter based on the output values of the position detection unit and the direction angle detection unit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turning control device for an automatic guided vehicle that automatically travels along a road surface.

[0002]

2. Description of the Related Art Conventionally, as a means for guiding an automatic guided vehicle to a target traveling path, a guide wire or magnet having an alternating current flowing through it or a derivative such as a tape for reflecting light is embedded or installed on the traveling road surface. An output method such as a magnetic field line of a dielectric or reflected light is detected by an induction detection sensor such as a pickup coil or a CCD camera mounted on a vehicle body, and a method of traveling along the traveling road surface based on the detected value is often adopted. .

However, when there is an obstacle on the road surface, or when the vehicle body changes its posture such as turning, it is not possible to travel along the guide wire or the like. Ignore the above, program the steering angle in advance from the start of non-guided traveling, or the steering angle according to that value, perform steering according to that value, and after the end of the program, guide by the program turning method that runs while detecting the derivative again. There is.

[0004]

In the conventional program turning described above, the parameters of the program for outputting the steering angle must be adjusted for each unguided point in order to match the environmental conditions such as the inclination and step of the traveling road surface. I had to do it.

In addition, wear of wheels and meshing of gears,
There is a problem that it is necessary to regularly modify the parameters of the program in order to cope with changes over time.

The present invention has been made in view of this, and automatically corrects the above parameters by measuring the deviation amount and the direction angle from the target position of the automatic guided vehicle at the end of the program turning. It is an object of the present invention to provide a turning control device for an automated guided vehicle which is capable of

[0007]

In order to solve the above-mentioned problems, a turning control device for an automatic guided vehicle according to the present invention detects a guide laid on a traveling road surface and a relative position of the guided vehicle with respect to the guide. For detecting the relative angle of the automatic guided vehicle with respect to the guide, a parameter storage section for storing the turning parameters referred to when the automatic guided vehicle makes a turn, and the position detection And a parameter correction unit that changes the turning parameter according to the output value of the direction angle detection unit.

The parameter correcting unit corrects the turning parameter by the deviation based on the outputs of the position detecting unit and the direction angle detecting unit at the end of the program turning so that the target position and the target direction angle are obtained at the end of the next program turning. It has a deviation correction function.

Further, the parameter correction section determines the increasing / decreasing direction of the turning parameter based on the outputs of the position detecting section and the direction angle detecting section at the end of the programmed turning, and the turning parameter is adjusted by its own predetermined physical quantity. It has an asymptotic correction function that corrects in the direction.

[0010]

[Operation] At the end of the program turning, the deviation amount from the target point is measured by the position detection unit and the direction angle detection unit, and the parameter correction unit appropriately modifies the parameter in the parameter storage unit by this, and the unguided point is detected. Is corrected so that the deviation amount at the end of the next guidance is reduced.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows an automatic guided vehicle A used in this embodiment. In the automatic guided vehicle A, fixed wheels 1a and 1b, one wheel each on the left and right of the front part, are driven to the central part of the rear part. One running wheel 2 which also serves as both a wheel and a steering wheel is provided. An encoder 3 is attached to the traveling wheel 2, and the distance traveled by the traveling wheel 2 is measured by the output pulse number.

One inductive detection sensor 4a, 4b is attached to each of the front and rear portions of the center of the vehicle body. Each of the inductive detection sensors 4a and 4b, as shown in FIG.
It consists of two pickup coils 5a and 5b, which are fixed at a fixed interval in the vehicle width direction.

The pickup coils 5a and 5b
In the vicinity of the front and rear induction detection sensors 4a and 4b, for example, on the traveling road surface B, when an induction wire 6 through which an alternating current flows exists, an induction magnetic field generated by the induction wire 6 induces an electromotive force in the coil. ing.

The inductive detection sensors 4a and 4b output the differential voltage of the electromotive force of each of the pair of pickup coils 5a and 5b constituting the inductive detection sensors 4a and 4b, and the amount of deviation from the inductive wire 6 (deviation in the vehicle width direction). The output voltage Vdef as shown in FIG. 3 is obtained for the quantity X.

A mark detection sensor 7 is attached to the right side of the vehicle body of the automatic guided vehicle A, and a trigger mark (not shown) set on the traveling road surface B is read by this sensor 7.

In FIG. 8, the position detecting section C is composed of inductive detection sensors 4a and 4b and an operation section which receives the output voltage Vdef of the inductive detection sensors 4a and 4b and outputs the deviation amount X from the inductive wire (derivative) 6. When the inductive detection sensors 4a and 4b are configured as described above, the relationship between the output voltage Vdef and the deviation amount X is approximately represented by the equation (1). However, a ₁ is a constant. X = a ₁ Vdef (1)

Since the guide detection sensors 4a and 4b are installed separately in the front-rear direction of the vehicle body, there are two kinds of deviations _Xf by the front guide detection sensor 4a and a deviation amount Xr by the rear guide detection sensor 4b. The output is obtained, but in this embodiment, the deviation amount X output from the rear-side guidance detection sensor 4b
_The deviation amount X representing the position detection unit C is set as _r , and this is output to the parameter correction unit D.

The direction angle detecting section E is provided with deviation amounts X _f and X which are outputs from the front and rear induction detecting sensors 4a and 4b.
_{It is composed} of an arithmetic unit that receives _r as an input and outputs the angle formed by the guide wire 6 and the center axis of the vehicle body, that is, the direction angle θ. If the distance between the front and rear guidance detection sensors 4a and 4b is L, (2)
The above-mentioned direction angle θ can be obtained by a formula. θ = Sin ⁻¹ (X _f −X _r ) / L (2)

The parameter storage unit F is composed of a memory for storing each parameter for calculating the target steering angle during the programmed turning. For example, the pre-turning count number N _p in FIG.
The maximum rudder angle count number N _o , the maximum rudder angle φ _max , the rising count number N ₁ , and the falling count number N ₂ are recorded.

When a program turning start command is input, the parameters are read from the parameter storage unit F,
The target steering angle with respect to the number of pulses of the encoder 3 as shown in FIG. 4 is determined.

The parameter correction unit D expresses the relational expression of the increase / decrease amount of the parameter value recorded in the parameter storage unit F, the deviation amount X of the automatic guided vehicle A from the target point at the end of the program turning, and the direction angle θ. Given a deviation amount X and a direction angle θ, the calculation unit that outputs the correction amount of each parameter, and the parameter storage unit F based on this result.
And a processing unit for rewriting the parameters recorded in.

As an example, the parameters N _p (pre-turn count number) and N _o in the automatic guided vehicle A having the above-described configuration are set.
Increase / decrease amount of (maximum rudder angle count), deviation amount X, direction angle θ
The relationship is shown in (a) and (b) of FIG. In this example,
When the parameter N _p is increased, the deviation amount X increases proportionally, and the direction angle θ does not change. When the parameter N _o is increased, both the deviation amount X and the direction angle θ increase proportionally. That is, the deviation amount X and the direction angle θ are represented by the following relational expressions. However, a ₂ , b ₂ and b ₃ are constants.

[0023]

[Equation 1]

As an example of performing the program turning, consider an operation of turning left from the guide line 6a at the intersection G and transferring to another guide line 6b as shown in FIG.

[0025] The program turning start trigger mark M ₁ that is installed at a point P ₁ in the AGV A which has been advanced along the one guide line 6a from below in FIG. 6 is detected by the mark detection sensor 7, the program Start turning.

In accordance with the target steering angle obtained from the parameters recorded in the parameter storage section F, the vehicle travels while operating the steered wheels in accordance with the number of output pulses of the encoder 3, and makes a left turn. At this time, the pre-turn count number N _{p is set} to N _pn , and the maximum steering angle (steering angle maintenance) count number N _{o is set} to N _on .

When the point P ₂ at which the program turning ends is reached, the automatic guided vehicle detects the position detecting section C and the direction angle detecting section E.
As shown in FIG. 7, the deviation amount X _n from the other guide line 6b, which is the guide line on the transfer side, and the direction angle θ _n are measured.
The output Xn of the position detecting unit C and the direction angle detecting unit E,
θ _n is input to the parameter correction unit.

In the calculation unit in the parameter correction unit D, the deviation amount X _{n + 1} from the lane at the end of the next program turning from the input deviation amount X _n and the direction angle θ _n , and the direction angle θ _{n + 1.} The pre-turn count number N _{pn + 1} and the maximum steering angle count N _{on + 1 for} setting the target values X = X _d and θ = θ _d given in advance are calculated.

For example, the guide line 6b on the transfer side of the target value
If the deviation amount from is 0 and the direction angle is 0, X _d = 0, θ
_{Since d} = 0, N _{pn + 1} and N _{on + 1} are obtained from the above equations (3) to (4).

[0030]

[Equation 2]

The processing section in the parameter correction section D is (4)
The parameters N _{pn + 1} and N _{on + 1} obtained by the equation are rewritten to the parameters N _p and N _o recorded in the parameter storage unit F. By using this modified parameter, the deviation from the transfer line at the end of the program turning at the next guidance point can be set to the target value. The above operation is shown in FIG.

In this embodiment, the deviation correction function using the parameter correction value for eliminating the deviation as the output of the parameter correction section D is shown.

Next, an example of the parameter correction unit D having an asymptotic correction function will be shown. The configuration and the program turning operation are the same as those in the above embodiment.

When the automated guided vehicle A reaches the turning end point P ₂ , the position detecting section C, the direction angle detecting section E to the parameter correcting section D are detected.
X _n and θ _n are input to. Instead of the equation (3), the calculation section in the parameter correction section D is provided with a conditional judgment equation such as the following equation (5). However, a _4, b ₄ are predetermined constants.

[0035]

(Equation 3)

N _padd and N _{oadd in} the above equation (5) are correction amounts of the parameters N _p and N _o , and if the deviation amount is within the allowable error (| a ₄ |, | b ₄ | or less), it is corrected. If it is not within the error, the parameter is changed by one count in the direction of reducing the error.

Based on the above equation (5), N _{pn + 1} and N _{on + 1} are obtained by the following equation (6).

[0038]

(Equation 4)

N _{pn + 1} , N obtained by the processing unit by the equation (6)
By rewriting _{on + 1} with the parameter of the parameter storage unit F, the deviation amount at the end of turning asymptotically approaches the target value, and the asymptotic correction function is realized.

This method is effective even when only a qualitative relationship is known without obtaining a quantitative relational expression of the parameter increase / decrease amount and the deviation amount at the end of the program turning as in the equation (3). . Further, for example, the parameter is prevented from being excessively corrected by a temporary and large deviation amount that is measured when an obstacle such as a plate temporarily placed on the traveling road surface is overcome.

Further, as means for absorbing measurement errors of the position detection section C and the direction angle detection section E, encoder output count errors, etc., the outputs of the parameter correction section D are recorded several times in the past for each unguided point. It is possible to envisage a method of determining a parameter correction value based on the average value, and a method of providing a dead zone in the parameter correction unit D and correcting the parameter only when the correction amount exceeds a certain amount.

Further, by adding a parameter monitoring function for outputting an error signal when an abnormally large correction amount is generated in the parameter correction section D or when a parameter out of the set range is calculated, there is no need for a carrier vehicle. At the guidance point, it is possible to prevent the vehicle from deviating significantly from the road.

In the above-described embodiment, an example in which the induction wire 6 and the pickup coils 5a and 5b in which an alternating current is applied is used as the position detecting means and the direction angle detecting means has been shown, but the present invention is not limited to this method. , For example, instead of using an optical sensor such as a CCD array including a reflection tape and a light emitting device, a magnet is used instead of the guide wire, and a magnetic sensor for detecting this on the vehicle body side is used as the position detecting means. Alternatively, the direction and angle are detected by integrating the output of the angular velocity sensor, and the direction and angle are not limited to the above.

[0044]

According to the present invention, the automatic guided vehicle can automatically correct the turning parameter according to the deviation amount from the target point.

Therefore, it is not necessary to manually adjust the turning parameter for each non-guide point or to regularly check the deviation amount and make a correction as in the conventional case. Further, since the turning parameter according to the deviation amount is obtained, even an unskilled worker can appropriately determine the turning parameter, which simplifies the parameter correction work of the program turning,
It is expected that the time will be shortened.

[Brief description of drawings]

FIG. 1 is a schematic configuration explanatory diagram of an automated guided vehicle used in an embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a configuration of a guidance detection sensor.

FIG. 3 is a diagram showing a relationship of an output voltage of an induction detection sensor with respect to a deviation amount from an induction wire.

FIG. 4 is a diagram showing a relationship between a target steering angle and a pulse number of an encoder.

5 (a) and 5 (b) are diagrams showing the relationship between the increase / decrease amount of the parameters N _p and N _o , the deviation amount X, and the direction angle θ.

FIG. 6 is an explanatory diagram showing an example of performing a program turning of an automatic guided vehicle.

FIG. 7 is an explanatory diagram showing an end state of program turning.

FIG. 8 is a block diagram showing an operation of the exemplary embodiment of the present invention.

[Explanation of symbols]

 A ... Automated guided vehicle B ... Traveling road surface C ... Position detection unit D ... Parameter correction unit E ... Direction angle detection unit F ... Parameter storage unit G ... Intersection points 1a, 1b ... Fixed wheel 2 ... Traveling wheel 3 ... Encoders 4a, 4b ... Induction detection sensor 5a, 5b ... Pickup coil 6, 6a, 6b ... Induction wire 7 ... Mark detection sensor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hidehiro Kawamata 142 Yuuki, Yuki City, Ibaraki Prefecture

Claims (3)

[Claims] 1. A guide installed on a road surface, a position detector for detecting a relative position of the automatic guided vehicle to the guide, and a direction angle detector for detecting a relative angle of the automatic guided vehicle to the guide. A parameter storage unit that stores a turning parameter to be referred to when the automatic guided vehicle turns, and a parameter correction unit that changes the turning parameter based on the output values of the position detection unit and the direction angle detection unit. Turning control device for automated guided vehicles. 2. The parameter correcting unit according to claim 1, based on the outputs of the position detecting unit and the direction angle detecting unit at the end of the program turning, turning so that the target position and the target direction angle are reached at the end of the next program turning. A turning control device for an automated guided vehicle, which has a deviation correction function capable of correcting a parameter by a deviation. 3. The parameter correction unit according to claim 1, based on the outputs of the position detection unit and the direction angle detection unit at the end of the programmed turning, determines the increasing / decreasing direction of the turning parameter, and determines each turning parameter by a predetermined value. A turning control device for an automated guided vehicle, which has an asymptotic correction function that corrects the physical quantity of the vehicle in that direction.