JPH04274502A - Method for controlling running of unmanned carrier - Google Patents

Abstract

PURPOSE:To improve the running performance of an unmanned carrier when the carrier runs along a straight and curved courses at the time of controlling the running of the carrier by repeatedly detecting the deviation of the carrier from a guide line under a non-contact state while the carrier runs and controlling the speeds of both left and right driving wheels of the carrier based on controlled variable computed results, and then, automatically correcting the deviation at any time by causing a speed difference between both driving wheels. CONSTITUTION:Three pieces of linear guide line sensors 17, 18, and 19 which detect a guide line 1 in non-contact states are fitted to the lower surface section of an unmanned carrier 15 at intervals in the direction perpendicular to the advancing direction of the carrier 15 and the degree of the curved state of the guide line 1 is measured from the detected positions of the guide line 1 of the sensors 17-19 and intervals d1 and d2 between each sensor 17-19. Then, on the basis of the measured results, the gain constant of the controlled variable computation is changed from the value obtained when the carrier runs along a straight course in accordance with the degree of curved state of the line 1.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention detects, in a non-contact manner, deviation from the guideline laid down on the driving route while driving, and based on this detection, calculates the speed difference between the left and right driving wheels. The present invention relates to a travel control method for an unmanned guided vehicle that automatically steers the unmanned guided vehicle according to guidelines.

0002

2. Description of the Related Art Conventionally, in factories, hospitals, etc., unmanned guided vehicles with robot configurations have been used to transport equipment, luggage, etc. in order to improve work efficiency.

[0003] This type of unmanned guided vehicle uses guide lines 1 laid out on the traveling route as shown in FIG. Some automatic guided vehicles 2 travel by repeatedly detecting deviations in their running in a non-contact manner using magnetism, light, sound waves, radio waves, etc. as media, and correcting the deviations as needed through automatic steering based on this detection.

In this case, as shown in FIG. 7, the conveyance vehicle 2 is provided with driving wheels 4 and 5 on each of the left and right sides of the main body 3, and for example, the conveyance vehicle 2 is provided with driving wheels 4 and 5 on both sides of the left and right sides of the main body 3. Conventionally, one guideline sensor 7, 8 in which a plurality of sensor elements 6 sensitive to a magnetic material are linearly arranged is installed on the front and rear of the lower surface of the main body 3 for detection.
is installed perpendicular to the direction of travel.

In FIGS. 6 and 7, 9 and 10 are direction indicators that notify left and right turns, 11 is a melody alarm output device that generates a melody sound while moving, and 12 is a unit that exchanges information with a work station, etc. antenna for
13 and 14 are rotatable casters attached to the front and rear of the lower surface of the main body 3.

The main body 3 has a built-in microcomputer (hereinafter referred to as CPU) that performs travel control, communication processing, etc. Conventionally, the driving wheels 4 and 5 are driven by the travel control of this CPU as described below. do.

[0007] First, a point marked with a * mark at the center of the lower surface of the main body 3 shown in FIG. 7 is set as a representative point P of the travel control reference.

[0008] While the vehicle is running, the outputs of the sensors 7 and 8 are repeatedly read at a sampling period of approximately several tens of milliseconds.

At this time, the outputs of both sensors 7 and 8 are formed using the output of each element 6 as 1 bit, and the output of both sensors 7 and 8 is formed by increasing or decreasing the output of the bit of element 6 facing guideline 1. The position facing guideline 1 (line passing position) is determined.

Then, as shown in FIG.
The line segment connecting the line passing positions is defined as the X axis, and the axis perpendicular to this axis is defined as the Y axis, and the distances df and dr are determined based on the running deviation between the reference line of a dashed line passing through the representative point P and the X axis.

Furthermore, based on the tread width 2·T and the distances wf and wr between the representative point P and the sensors 7 and 8, respectively, and the distances df and dr in FIG. The amount of deviation y in the lateral direction and the amount θ of deviation in the posture (running direction) of the figure with respect to the guideline 1 are determined.

Then, based on the deviation amounts y and θ, forward speed data V and data ω for adding a speed difference to the left and right are obtained from the following equations 1 and 2.

[0013]

[Math 1]

[0014]

[Math 2]

Furthermore, based on the data V and ω, the speed control amount Vl of each of the driving wheels 4 and 5 is calculated from the following equations 3 and 4.
, Vr are determined.

[0016]

[Math 3]

[0017]

[Math 4]

[0018] In each of the above formulas, G1, G2
, G3 are preset control gain constants, and V
ref is reference speed data given to both driving wheels 4 and 5.

Then, the driving wheels 4 and 5 are driven independently according to the speed control amounts Vl and Vr, and a speed difference is given to both the driving wheels 4 and 5 according to the running deviation, and this speed difference causes bending of the guideline 1, etc. The transport vehicle 2 is controlled to travel by correcting the posture according to the situation and automatically correcting the travel deviation as needed.

With this traveling control, the transport vehicle 2 travels according to the guideline 1.

[0021]

[Problems to be Solved by the Invention] In the case of the conventional driving control method, the gain constants G1, G2, and G3 in the control amount calculation formulas of Equations 1 to 4, which greatly affect the driving performance, are written in the ROM, for example. The problem is that no matter how they are set, it is not possible to improve driving performance both when driving straight and when driving around curves.

For example, if the gain constants G2 and G3 are increased, the ability to follow the guideline 1 when driving on a curve improves, but when driving in a straight line, overcontrol occurs, causing the vehicle 2 to sway to the left or right, making driving unstable. Become.

Furthermore, if the gain constants G2 and G3 are made small, straight-line traveling becomes stable, but control becomes insufficient when traveling on a curve, and the ability to follow the guideline 1 deteriorates.

On the other hand, in a control method for teaching an unmanned guided vehicle a traveling route, for example, a marker is installed just before each curve, and the gain constant for travel control is changed from the value when traveling straight by detecting the marker for each curve. It is conceivable that the driving performance can be improved both when driving straight and when driving on curves.

However, this method requires complicated teaching work in advance, which is extremely disadvantageous in terms of labor saving.

The present invention provides a driving control method for an automatic guided vehicle that detects a deviation from a guideline while driving and applies a speed difference to the left and right driving wheels to automatically correct the deviation as needed. The purpose is to improve driving performance both when driving and when driving around curves.

[0027]

[Means for Solving the Problems] In order to achieve the above-mentioned object, in the travel control method for an unmanned guided vehicle of the present invention, three linear guide lines are installed on the lower surface of the vehicle to detect guide lines in a non-contact manner. guideline sensors are installed at intervals in a direction perpendicular to the traveling direction of the vehicle,

0028
] measuring the degree of bending of the guideline from the detection position of the guideline of each of the sensors and the interval between the sensors;

Based on the result of the measurement, the gain constant for calculating the travel control amount is varied from the value when traveling straight, depending on the degree of curvature of the guideline.

[0030]

[Operation] In the case of the control method of the present invention configured as described above, the degree of bending of the guideline is determined by the position of the guideline passing through the three guideline sensors provided on the lower surface of the vehicle and the spacing between each sensor. be measured.

[0031] Since the gain constant for calculating the travel control amount is varied according to the degree of the curve, the gain constant is automatically varied when traveling straight and when traveling on a curve. Gain constant changes.

[0032] Therefore, the running performance during both straight running and curved running is improved without complicated teaching in advance.

[0033]

Embodiment One embodiment will be described with reference to FIGS. 1 to 5. In those drawings, the same reference numerals as in FIGS. 6 to 8 indicate the same or equivalent parts.

[0034] Then, the unmanned guided vehicle 15 is replaced by the conventional vehicle 2.
The difference in appearance is that, as shown in FIG. 1, three guideline sensors 17, 18, and 19 are attached to the lower surface of the main body 16 at intervals perpendicular to the traveling direction.

[0035] In order to detect the guideline 1 magnetically, the sensors 17 to 19 are similar to the conventional sensors 7 and 8.
It is formed by arranging a plurality of sensor elements 6 in a straight line.

The control block of the main body 16 is configured as shown in FIG. 2 using a CPU that performs travel control, communication processing, etc.

In the figure, 20 is a CPU, 21 is an A/D converter that digitally converts the detected values of sensors 17 to 19 and transmitted to the CPU 20, 22 and 23 are motor drivers,
24 and 25 are motors for driving the driving wheels 4 and 5, respectively;
6 and 27 are speed detection encoders attached to the motors 24 and 25, respectively; 28 is the CPU 20 and the antenna 1;
A communication interface 29 is an input/output interface between the CPU 20 and the direction indicators 9, 10, melody alarm 11, etc.

While driving, the CPU 20 controls the motors 24 and 24 via the motor drivers 22 and 23.
25 are driven separately, and the driving wheels 4 and 5 are driven independently.

Further, the CPU 20 reads the values of the encoders 26 and 27 that are proportional to the rotation of the driving wheels 4 and 5, and
monitor the speed of

Furthermore, for example, based on the timing pulses shown in FIG.
The A/D converted detection values of the sensors 17 to 19 are read repeatedly.

At this time, the detected values of the sensors 17 to 19 are:
The bits of the elements 6 at the line passing positions facing the guideline 1 are inverted.

[0042]The CPU 20 then uses, for example, the sensor 17,
19 are the detection values of the conventional sensors 7 and 8, and calculate the speed control amounts Vl and Vr of the driving wheels 4 and 5 from the control amount calculation formulas of Equations 1 to 4 above, and calculate the speed control amounts Vl and Vr of the driving wheels 4 and 5 respectively, Gain constants G1, G2,
Vary G3.

That is, based on the line passing positions of the sensors 17 to 19, distances l1, l2, l3 from the reference line l0 shown in FIG. 4 to each line passing position are determined as detection positions.

Then, based on the distances l1, l2, l3 and the intervals d1, d2 between the sensors 17 to 19, the degree of curvature of the guideline 1 is determined by the following equations 5, 6, and 7. It is measured as the angle θc.

[0045]

[Math 5]

[0046]

[Math 6]

[0047]

[Math 7]

[0048] Note that the closer the guideline 1 is to a straight line, the more
θc approaches 180°.

Furthermore, the CPU 20 sets gain constants G1, G2, G3 according to the degree of bending of the guideline 1.
A combination of optimal values of is stored in a gain table made of ROM or RAM, for example, and each time the degree of bending is measured,
A combination of optimum values at that time is selected and read from the table, and each gain constant G1, G2, G3 is changed.

With this change, each gain constant G1, G2
, G3 are automatically varied depending on the degree of curvature of the guideline 1. For example, when driving on a curve, G1 becomes smaller than when driving straight, G2 and G3 become larger, and 9
The conveyance vehicle 15 travels without deviating from the guideline 1 even at a bend close to 0°.

In order to prevent overcontrol, in this embodiment, upper limits are set for each gain constant G1, G2, G3, and even when the measurement result of the degree of bending becomes excessive, each gain constant Keep G1, G2, and G3 below the upper limit.

[0052]The process shown in FIG. 5 is executed every period T to change each gain constant G1, G2, G3 to the optimum value according to the degree of bending at that time. The running performance of the transportation vehicle 15 has improved.
The conveyor always runs smoothly according to the guideline 1, and there is almost no possibility that the conveyed objects will be dislocated or deviate from the guideline 1.

[0053] In the above embodiment, the running deviation is detected magnetically, but it may also be detected using light, sound waves, radio waves, or the like as a medium.

The degree of curvature may also be measured by triangular approximation or by finding the locus of the center of curvature using formulas different from Equations 5 to 7.

[0055]

[Effects of the Invention] Since the present invention is configured as described above, it produces the effects described below. Three guideline sensors 17 and 18 are installed on the bottom of the unmanned guided vehicle 15.
, 19 at an interval d1 in the direction perpendicular to the traveling direction of the vehicle 15.
, d2, and the degree of curvature of the guideline 1 is measured based on the position of the guideline 1 passing each sensor 17 to 19 as the vehicle 15 travels and the spacing d1, d2 between each sensor 17 to 19. Since the gain constants G1, G2, and G3 for calculating the travel control amount were varied according to the degree of travel control, the gain constant G is different when traveling straight and when traveling on a curve.
1, G2, and G3 are automatically varied, and when driving on a curve, the gain constant G can be changed depending on the degree of the curve.
1, G2, and G3 are changed, and the optimum speed control is given to each of the driving wheels 4 and 5 according to the running deviation from guideline 1, without the need for complicated work such as prior teaching, and the stability and stability during straight running are improved. The traveling of the vehicle 15 can be controlled using a method that provides high followability when traveling on a curve.

[Brief explanation of the drawing]

FIG. 1 is a perspective view from below of a vehicle according to an embodiment of the method for controlling travel of an automatic guided vehicle according to the present invention.

FIG. 2 is a circuit diagram of a control block provided in the main body of FIG. 1;

FIG. 3 is a waveform diagram of timing pulses in FIG. 2;

FIG. 4 is an explanatory diagram for measuring the degree of bending in FIG. 2;

FIG. 5 is a flowchart for explaining the operation of FIG. 2;

FIG. 6 is a perspective view of a conventional automatic guided vehicle seen from above.

FIG. 7 is a perspective view seen from below in FIG. 6;

FIG. 8 is an explanatory diagram of conventional measurement of the degree of bending.

[Explanation of symbols]

1 Guidelines 4,5 Driving wheel

Claims (1)

[Claims] [Claim 1] An unmanned guided vehicle equipped with one driving wheel on each of the left and right sides repeatedly detects deviations from the guideline laid down on the travel route, and based on the detection results, a guideline is set. In the driving control method for an automatic guided vehicle, the speed control amount of each of the two driving wheels is calculated from the control amount calculation of a gain constant, and a speed difference is given to the two driving wheels to correct a driving deviation. Three linear guideline sensors for non-contact detection are installed at intervals in a direction perpendicular to the traveling direction of the vehicle, and from the detection position of the guideline of each sensor and the interval between the sensors A travel control method for an automatic guided vehicle, characterized in that the degree of curvature of a guideline is measured, and the gain constant is varied from a value when traveling straight in accordance with the degree of curvature of the guideline based on the measurement result.