JPH0981238A - Method for controlling travelling of autonomously traveling automated guided vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an autonomously traveling automated guided vehicle capable of accurately moving its reference point to an optional destination in the case of curve traveling and obtaining a prescribed body angle after movement and having simple constitution in respect to a two-wheel driving automated guided vehicle using a battery as a power source. SOLUTION: In this method, a controller input a moving angle θand a moving distance M in the traveling direction of a vehicle body 1 as control information, finds the position of a center line of rotation of a reference point of the vehicle body based upon the control information, calculates the rotational amounts R, L of front driving wheels necessary for moving the reference point to an aimed position, and sets the wheel having a larger rotational amount as a main wheel and the wheel having a smaller rotational amount as an idler wheel. The rotational ratio of the idler wheel to the main wheel is previously calculated, the main and idler wheels are rotated at a set speed, the rotational amount of the idler wheel is detected and compared with the rotational ratio, and the idler wheel is stopped at its rotation when the rotational amount is larger than the set ratio or rotated when the amount is smaller. The processing is repeated until the main wheel reaches the set rotational amount.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autonomous guided vehicle, and more particularly to an automated guided vehicle capable of accurately moving a vehicle body to an arbitrary target position on a traveling route including a curve.

[0002]

2. Description of the Related Art Unmanned guided vehicles are widely used for transporting and handling parts and products in factories, but unmanned guided vehicles accompanying changes in the manufacturing process in response to demands for manufacturing, product diversification, etc. It is necessary to change the traveling route of the car frequently. For this, an autonomous guided vehicle that does not require a taxiway and is easy to change the travel route is suitable.

An autonomous guided vehicle has data indicating a traveling route stored in a memory in advance, and controls the vehicle so that the vehicle is on a predetermined traveling route while detecting the current position of the vehicle by various sensors. Run while doing.

When a track-type automatic guided vehicle is run, it is possible to run by detecting the deviation from the track by the left and right track detection sensors and controlling the rotation of the left and right wheels. This type of technology is disclosed in, for example, Japanese Patent Laid-Open No. 5-324057
No., published in Japanese Unexamined Patent Publication No.

[0005]

However, in the case of running without a track like a robot wagon, it is necessary to make the running accuracy extremely high because there is no track detection sensor. Further, when traveling straight, turning, turning, etc., it is necessary to calculate all how to rotate the left and right wheels and rotate them exactly.

In the case of going straight, the amount of rotation can be easily obtained by dividing the amount of movement by the circumference of the wheel. Further, in the case of turning, since the rear wheel turns in the left and right directions on the circumference having the diameter of the pitch of the rear wheel, the amount of movement of the rear wheel can be easily obtained from the turning angle.

However, in the case of curve traveling, it is difficult to easily obtain it because the left and right driving wheels of the vehicle body have different amounts of rotation.

Further, in order to faithfully reproduce the rotation amounts of the left and right drive wheels obtained by calculation, it is easy to use a servo motor or the like, but in the case of an automated guided vehicle, a battery is usually used. It is difficult to put this servo motor into practical use when considering low power consumption and cost reduction.

An object of the present invention is, in a two-wheel drive type automatic guided vehicle using a battery as a power source, accurately moving a reference point of the automatic guided vehicle to an arbitrary target position when traveling on a curve, and after moving the predetermined point. It is an object of the present invention to provide an autonomous guided vehicle having a simple configuration and capable of obtaining the vehicle body angle.

[0010]

The features of the present invention are a DC motor for driving a pair of drive wheels, which are mounted at symmetrical positions of a vehicle body, an auxiliary wheel, and a battery as a power source. -, A rotary encoder for detecting the number of rotations of the driving wheels, and a controller for outputting a rotation pulse and a rotation direction of the DC motor as command values based on control information and an output signal of the encoder. In the traveling control method for an autonomous guided vehicle, the controller obtains a movement angle θ and a movement distance M in the traveling direction of the vehicle body as the control information, and based on the control information, a reference point on the vehicle body. Of the rotation center Z of the drive wheel is calculated, and then the rotation amounts R and L of the drive wheels required to move the reference point to the target position are calculated. One is the slave wheel, the rotation ratio of the slave wheel / main wheel is calculated in advance, the main wheel and the slave wheel are rotated at the set speed, the rotation amount of the slave wheel is detected, and this is compared with the rotation ratio. When the ratio is greater than the ratio, the rotation of the slave wheels is stopped, and when the ratio is less than the ratio, the slave wheels are rotated, and this process is repeated until the main wheel reaches the preset rotation amount, and when the main wheel reaches the preset rotation amount, Stop the main wheels,
Then, the slave wheel is rotated, and when the slave wheel rotates by the set amount, the slave wheel is stopped to move the reference point to the target position.

[0011]

According to the present invention, a DC motor for driving a pair of driving wheels mounted symmetrically with respect to the center line in the front-rear direction of the vehicle body and an encoder for detecting the rotational speed of the driving wheels. In a vehicle having a dash, it is possible to accurately move a reference point of the vehicle body to a target position at a predetermined distance inclined by an angle θ with respect to the traveling direction of the vehicle body and control the vehicle body angle after the movement of the vehicle body. it can. In particular, it is possible to move the vehicle body to a target position at a predetermined distance inclined by a target angle θ regardless of the forward, backward, leftward or rightward direction of the vehicle body. This realizes curve traveling in the autonomous guided vehicle.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.
First, FIG. 1 is a view conceptually showing a back surface of a vehicle body 1 of an automated guided vehicle according to an embodiment of the present invention. This automated guided vehicle is
It is a rear-wheel drive type automated guided vehicle. Drive wheels 2a and 2b are attached to the rear portion of the vehicle body 1 at symmetrical positions. DC motors 3a and 3b for driving the drive wheels 2a and 2b are provided with rotary encoders 4a and 4b for detecting the rotational speed of the drive wheels. 5
Is a universal caster (auxiliary wheel), and 6 is a controller. The traveling distance and the vehicle body angle of the vehicle body 1 are determined by the encoder 4a,
It is detected by the controller 6 based on the output signal of 4b.
The vehicle body 1 is equipped with a battery as a power source for the DC motor (not shown).

The controller 6 is constructed as shown in FIG. That is, the microcomputer 61
A movement amount command and detection values of the rotary encoders 4a and 4b are received as inputs from a host (main) computer (not shown), and the position of the auxiliary wheel 5 is used as a reference point.
Is output to the spindle motor amplifier 62 as command values so as to drive the DC motors 3a and 3b so as to obtain the vehicle body angle after the vehicle body 1 is moved. . Information such as the moving course and the current position of the vehicle body 1 is held in the main computer.

Next, the control operation of the vehicle body 1 by the controller 6 will be described with reference to the vehicle body positional relationship diagram of FIG. 3 and the control flow of FIG. This control is based on the drive wheel position 2 in FIG.
When moving the reference points 5 of the triangles 5a, 2b connecting the a, 2b and the reference points 5 to the target position 5'distance M in the direction of the angle θ (front right), the drive wheels 2a, 2b are moved. It asks how much should be moved.

In the main computer, first, the vehicle body 1
It is checked whether the posture (vehicle body angle) is within a predetermined range with respect to the traveling direction, for example, within 30 ° to the left and right (step 402). If the angle of the vehicle body 1 is not within 30 ° from the left and right, the DC motors 3a and 3b are driven to turn the vehicle body 1 within 30 ° (step 40).
4).

Next, the controller 6 receives information about the traveling direction and traveling distance of the vehicle body 1 from the main computer, that is, data on the moving angle θ and the moving distance M from the current position to the traveling direction (step 406).

Next, the controller 6 calculates the position of the turning center Z of the vehicle body 1 (step 408). here,
The center Z of rotation when the reference point 5 of the triangles 5 2a 2b moves to the target position 5 ′ is the perpendicular line extending from the center point of the reference point 5 and the target position 5 ′ and the positions 2a and 2b of the drive wheels. This is the point where the extension lines intersect.

Next, the controller 6 obtains the turning amount θx of the vehicle body 1 by the following method (step 41).
0).

First, if either of the front and rear directions of the drive wheels 2a and 2b and the reference point 5 is set to H, the moving turning radius (SZ) of the center point of the drive wheels 2a and 2b is the side 5B of the triangle 5AB in FIG. And the side CZ of the triangle BCZ. The side 5B = M / 2 * cosec θ. It is calculated by the side ZC = H * cotθ. Side SZ = side 5B + side CZ = M / 2 * cosec θ + H * cot θ = M * cosec θ / 2 + H * cos θ / sin θ = (M + 2H * cos θ) / (2 * sin θ)

Therefore, the radius of gyration of movement of the drive wheel 2a is the side 2
aZ = side SZ + side 2a2b / 2, and the moving radius of rotation of the drive wheel 2b is obtained by side 2bZ = side SZ−side 2a2b / 2.

Further, the movement angle and the vehicle body angle after the movement are θX.
= ΘY = θZ Here, θY = ARCTAN ((H + Mcosθ) / (side SZ-Msinθ)) = ARCTAN ((H + Mcosθ) / (((M + 2Hcosθ) / (2sinθ))-Msinθ)) = ARCTAN ((H + Mcosθ) / ((M + 2Hcosθ-2Msinθ * sinθ) / 2sinθ)) = ARCTAN ((2sinθ (H + Mcosθ) / ((M + 2Hcosθ-2M (1-cosθ * cosθ))) = ARCTAN ((2sinθ (H + Mcosθ)) / (2cosθ (H + Mcosθ) -M)) In addition, θZ = ARCTAN (H / side SZ) = ARCTAN (H / ((M + 2Hcosθ) / 2sinθ)) = ARCTAN (2Hsinθ / ( M + 2cos θ)) Next, the rotation amounts R and L of the left and right rear wheels are obtained (step 4
12). The moving distance (R) of the right wheel when moving the reference point 5 to the target position 5 ′ moves by θX on the circumference having the radius of the side 2b2, so R = 2 * side 2bZ * π * θX / Required by 360.

Further, the moving distance (L) of the left wheel moves by θX on the circumference having the radius of the side 2aZ, so that L = 2 * side
It is calculated by 2aZ * π * θX / 360.

Next, the one with the larger amount of rotation is the main wheel and the one with the smaller amount of rotation is the slave wheel (step 414), and the main wheel and the slave wheel are rotated at the set speed (step 416).

Further, the rotation amount of the slave wheel is detected and compared with the calculated value. When the slave wheel is large, the slave wheel is stopped, and when it is small, the slave wheel is rotated, and this process is repeated until the master wheel rotates by the set amount. When the wheel has rotated by the set amount, the main wheel is stopped (steps 418 to 422).

Then, the driven wheel is rotated, and when the rear wheel has rotated by the set amount, the driven wheel is stopped (steps 424 to 42).
8).

If the vehicle moves to the front right, it moves without any problem in the calculation of R and L in step 412, but if it moves in any other direction, it moves, but it is unnatural for an automated guided vehicle. It will be in motion. That is, the operation is similar to turning.

Therefore, in such a case, if the traveling direction is smaller than 90 °, the calculation is performed as it is. When the traveling direction is 90 ° <θ <180 °, (180 °
-Θ) is replaced with θ, and the left and right rear wheels are reversed.

When the traveling direction is 270 ° <θ <360 °, (360 ° -θ) is replaced with θ for calculation, and the rotation amount of the left rear wheel and the rotation amount of the right rear wheel are exchanged for normal rotation. .

When the traveling direction is 180 ° <θ <270 °, (θ-180 °) is replaced with θ, and the left rear wheel rotation amount and the right rear wheel rotation amount are replaced and both are reversed.

That is, when moving to the rear right, (18
(0 ° -running direction) is replaced with the running direction, the same calculation is performed, and when the left and right wheels are rotated and moved in reverse, the reference point 5
Can be moved to the target position 5'by retreating.

When moving to the left front, (360 °
-When the traveling angle) is replaced with the traveling angle, the calculation is performed, and the left and right wheels are moved in the opposite amounts, the reference point 5 can be moved to the target position 5 '.

When moving to the left rear, (running direction -180 °) is replaced with the running direction, the same calculation is performed,
It is possible to move the reference point 5 to the target position 5'by reversing the movement amount of the left and right wheels, rotating the wheels in the opposite direction, and backward turning left.

In this way, the reference point 5 is moved to the target position 5'by rotating the drive wheels 2a, 2b by the moving distances R and L in the above manner. However, at this time, the drive wheel 2a (2b) must rotate at a constant rate with respect to 2b (2a).

Normally, in such a case, the driving motor-3
It is a general method to construct a servo system in a and 3b and rotate them at a constant speed by a speed control.

In the case of the present invention, since the battery is used as the drive source, the power consumption is suppressed and the drive wheel 2 is used.
In order to keep the rotation ratios of a and 2b more accurate, the processing flow is as shown in the above step 414 and thereafter.

That is, of the drive wheels 2a, 2b, the one with the longer travel distance is the main wheel and the one with the smaller travel distance is the slave wheel, and the ratio of the travel distance of the slave wheel / main wheel is calculated in advance and used for the master wheel and the slave wheel. The drive motors 3a and 3b are rotated at a designated speed. At this time, the rotation speed of the main wheel is set to the encoder 4a (4
b), read the value, multiply the value by the ratio (subordinate wheel / main wheel), and compare the encoder 4b (4a) of the secondary wheel with
When the amount of rotation of the driven wheel is large, the driven motor for the driven wheel-3a (3
By turning off the rotation of b) and turning it on at high speed when it is small, it is possible to always keep the rotation ratio of the main wheel and the sub-wheel close to the ideal state.

In the case of straight traveling, the drive motors 3a and 3b are rotated at a designated speed, and the number of rotations is set to the encoder 4a,
It is possible to make the rotation amounts of the left and right drive wheels 2a and 2b always the same by reading at 4b and turning off the rotation of the drive motor having the larger rotation amount at high speed.

In the case of this system, the minimum electric power required to move the automatic guided vehicle can be used, and the consumption of the battery can be suppressed.

There is no problem if the traveling direction is forward only or backward only in the above step 414, but when switching from forward to backward / backward to forward, the universal caster 5 rotates midway, so that the body 1 of the vehicle body 1 rotates. The position shifts. This is a phenomenon that occurs when the rotation of the caster is not known by the control system, and it is impossible to correct the deviation.

Therefore, it is desirable to carry out this correction before the processing of step 414 and thereafter. This correction is shown in FIG.
This will be described with reference to FIG. Although the example of the drawing has two left and right casters 5a and 5b, there is no difference from the case of one caster. In the correction, in order to forcibly rotate the caster 5 by changing the direction of the vehicle body 1 from the state of FIG. 6 (A), as shown in FIG. 6 (B), the drive wheel 2a, 2b on either the left or right side is moved first. Then, rotate the caster 5 until it faces straight. As a result, the vehicle body moves to the 1'position. Then, as shown in FIG. 6C, the other drive wheel is rotated by the same amount to rotate the caster first. As a result, the car body moves to the 1 "position.

In FIG. 5, the distance between the drive wheels 2a and 2b is PW (mm) The distance between the center of the drive wheels and the axis of the caster 5 is H (mm) The distance between the center of the caster 5 axis and the center of the mounting axis is e (mm ) The turning angle of the vehicle body due to turning is θa. The deviation of the vehicle body to the front is x (mm), and the deviation of the vehicle body to the left (right) is y (mm). Θa = arccos (H / (he)) x = PW-PW cos θa y = PW sin θa Thus, the displacements x and y of the vehicle body 1 at the time of changing the direction are calculated, and corrective control can be performed by correcting the displacements when traveling thereafter.

When this method is applied to a relatively simple moving device such as a bed and a wagon, front wheel control is not required, so that the cost can be reduced and the power consumption can be reduced. Therefore, this method can be used in various applications. It is possible.

Needless to say, the present invention can also be applied to a front wheel drive type automatic guided vehicle.

[0044]

According to the present invention, in an automatic guided vehicle using a battery as a drive source, a reference point of the guided vehicle can be moved to an arbitrary target position and a predetermined vehicle body angle can be obtained after the movement. Especially, it is possible to always keep the rotation ratio of the main wheel and the slave wheel close to the ideal state.

In the case of this system, the minimum electric power required for moving the automatic guided vehicle can be used, and the consumption of the battery can be suppressed.

[Brief description of drawings]

FIG. 1 is a view conceptually showing a back surface of a vehicle body 1 of an automated guided vehicle according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a controller shown in FIG.

3 is a vehicle body positional relationship diagram for explaining a vehicle body control operation by the controller of FIG. 1. FIG.

FIG. 4 is a control flow showing a control operation of a vehicle body by the controller of FIG.

FIG. 5 is an explanatory diagram of vehicle body position deviation correction when switching the traveling direction to either forward or backward.

FIG. 6 is an explanatory diagram of an operation for correcting the displacement of the vehicle body position in FIG.

[Explanation of symbols]

1 ... vehicle body, 2a, 2b ... drive wheels, 3a, 3b ... direct current mode
4a, 4b ... Rotary encoder, 5 ... Flexible casters (auxiliary wheels), 6 ... Controller

Claims (5)

[Claims] 1. A pair of drive wheels mounted at symmetrical positions on a vehicle body, an auxiliary wheel, a DC motor for driving the drive wheels using a battery as a power source, and the rotational speeds of the drive wheels. Travel control in an autonomous guided vehicle that includes a rotary encoder for detection and a controller that outputs a rotation pulse and a rotation direction of the DC motor as command values based on control information and an output signal of the encoder. In the method, the controller obtains, as the control information, a movement angle θ and a movement distance M of a vehicle body in a traveling direction, obtains a position of a turning center Z of a reference point on the vehicle body based on the control information, In addition, the rotation amounts R and L of the drive wheels required to move the reference point to the target position are calculated, and the one with the larger rotation amount is the main wheel and the one with the smaller rotation amount is the slave wheel. Times The ratio is obtained by calculation in advance, the main wheel and the slave wheel are rotated at a set speed, the rotation amount of the slave wheel is detected, and this is compared with the rotation ratio. Stop, rotate when the amount is small, repeat this process until the main wheel reaches the set rotation amount, when the main wheel reaches the set rotation amount, stop the main wheel, then, A traveling control method in a self-propelled automatic guided vehicle, comprising rotating the driven wheel by the set amount and stopping the driven wheel to move the reference point to the target position. 2. The traveling control method for a self-propelled automatic guided vehicle according to claim 1, wherein the moving angle of the vehicle body in the front right direction is θ, the deviation between the drive wheel and the reference point in the front-rear direction is H, and the right side is Letting the moving radius of rotation of the drive wheel be side aZ and the radius of rotation of the left drive wheel be side bZ, the moving angle of the vehicle body and the vehicle body angle after the movement are θX =
When ARCTAN (2Hsinθ / (M + 2cosθ)), the moving distance R of the right driving wheel when moving the reference point to the target position in the front right is R = 2 * side 2bZ * π * θX / 360, a traveling control method in a self-propelled automatic guided vehicle, characterized in that the moving distance L of the left driving wheel is obtained by L = 2 * side 2aZ * π * θX / 360. 3. The traveling control method for a self-propelled automatic guided vehicle according to claim 2, wherein the moving angle θ in the traveling direction of the vehicle body is 90 ° <θ <18.
When 0 °, (180 ° −θ) is replaced with θ to perform the calculation, the left and right driving wheels are both reversed, and the reference point is moved backward to the target position on the right rear. A traveling control method for a self-propelled automated guided vehicle. 4. The traveling control method for a self-propelled automatic guided vehicle according to claim 2, wherein the moving angle θ in the traveling direction of the vehicle body is 270 ° <θ <3.
When the angle is 60 °, (360 ° −θ) is replaced with θ to perform the calculation, and the rotation amounts of the left and right drive wheels are replaced with each other so that the left and right drive wheels move in reverse. And moving the reference point to the target position on the left front side of the vehicle. 5. The traveling control method for a self-propelled automatic guided vehicle according to claim 2, wherein a moving angle θ in the traveling direction of the vehicle body is 180 ° <θ <2.
When the angle is 70 °, (θ-180 °) is replaced with θ, the above calculation is performed, the rotation amounts of the left and right drive wheels are exchanged, and both are reversed to reverse the movement amounts of the left and right drive wheels. A traveling control method in a self-propelled automatic guided vehicle, wherein the reference point is moved to a target position on the left rear by rotating the drive wheel in the opposite direction.