JP2001202131A - Automated guided vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automated guided vehicle(AGV) capable of executing stable autonomous traveling even on a discontinuous guide part without requiring a specific device. SOLUTION: On a part where a guide (magnetic rod) exists on a traveling route, the posture angle and lateral displacement variable of a vehicle body are calculated from the detection values of magnetic sensors 1, 2 to control a steering motor 4 and correct the posture of the vehicle body. On a part where no guide exists, the target values of the posture angle/lateral displacement variable calculated from the detection value of the magnetic sensor arranged just before the part is compared with the current values of the posture angle/ lateral displacement variable found out from the values of a gyro 3 and an encoder 7 and the motor 4 is controlled so that the current values coincide with the target values to correct the posture of the vehicle body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an automatic guided vehicle,
In particular, the present invention relates to an automatic guided vehicle that travels guided by a guide such as a magnetic bar laid on a traveling path.

[0002]

2. Description of the Related Art FIG. 6 is a view showing an example of a traveling path of such an automatic guided vehicle, wherein G is a guide made of a magnetic rod,
Reference numeral 100 denotes an automatic guided vehicle that travels on a travel path guided by the guide G. The guide G is made of a rectangular parallelepiped magnet and is buried in a groove formed on the floor. The groove is filled with a resin such as an epoxy resin, and the guide G is fixed by molding. The automatic guided vehicle 100 includes magnetic sensors (not shown) for detecting the guide G on the front and rear of the vehicle body, calculates the attitude angle and the lateral displacement amount of the vehicle body based on the detection outputs of these magnetic sensors, and performs steering. The vehicle travels on the travel path while controlling the angle to correct the posture of the vehicle body.

[0003] By the way, the guide G is ideally preferably laid continuously over the entire traveling path. However, this increases the cost and increases the proportion of the buried groove. There is a problem that the strength of the floor is reduced. For this reason, as shown in FIG. 6, the guide G is generally laid separately into a continuous portion G1 and an intermittent portion G2.

[0004]

Here, in the automatic guided vehicle on the continuous guide G1, such as the automatic guided vehicle 100 at the position A, the steering angle is determined based on the detection output obtained from the magnetic sensor of the vehicle body. , And traveling while correcting the posture and the lateral displacement of the vehicle body. However, in the automatic guided vehicle on the intermittent guide G2, such as the automatic guided vehicle 100 at the position B or the position C, a detection output is obtained from the magnetic sensor in a portion where the guide G2 is present. Since no output is obtained from the magnetic sensor in the non-existent portion, steering angle control by the magnetic sensor cannot be performed.

For this reason, conventionally, a device such as a camera for tracking the guide is provided on the vehicle body so that the vehicle can autonomously run even in a portion where the guide does not exist. However, providing such a device separately increases the cost, and requires maintenance since it is installed outside the vehicle body.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an automatic guided vehicle capable of performing stable autonomous traveling even in a portion where a guide is discontinuous without requiring a special device. It is an issue.

[0007]

In order to solve the above-mentioned problems, in an automatic guided vehicle according to the present invention, in a portion where a guide of a traveling path is present, as in the conventional case, a vehicle body obtained from a detection output of a sensor is used. The steering angle is controlled based on the attitude angle and the lateral displacement amount, while, in a portion where no guide exists, the target value of the attitude angle and the lateral displacement amount calculated based on the detection output of the immediately preceding sensor and the current attitude The steering angle is controlled such that the current value matches the target value by comparing the angle and the value of the lateral displacement amount.

In this way, when the vehicle body moves from the portion where the guide is present to the portion where the guide is not present, the virtual guide is calculated based on the target values of the attitude angle and the lateral displacement calculated from the sensor output immediately before. Since the line is set, by comparing this target value with the current position, it is possible to perform appropriate steering control even in a location where no guide exists.

In the present invention, the guide can be constituted by a magnetic bar, and the sensor can be constituted by a magnetic sensor. It is preferable to provide the magnetic sensors before and after the vehicle body. In addition, to obtain the current attitude angle and lateral displacement in the part where the guide does not exist, a gyro and an encoder are used to determine the current attitude angle from the gyro integrated value, and the current lateral displacement is calculated using the gyro integrated value. And the output value of the encoder.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described with reference to the drawings. Since the embodiment of the traveling path is the same as that of FIG. 6, this will be referred to. FIG. 1 is a block diagram showing an electrical configuration of the automatic guided vehicle according to the present invention. In the figure, 1 is a front magnetic sensor provided at the front of the vehicle body, 2 is a rear magnetic sensor provided at the rear of the vehicle body, 3 is a gyro for detecting an attitude angle,
4 is a steering motor for changing the traveling direction of the vehicle body, 5
Is a steering angle detector for detecting a steering angle, 6 is a traveling motor for traveling the vehicle body, 7 is an encoder attached to the traveling motor 6 for counting the number of rotations of the motor, 8 is a front magnetic sensor 1, a rear magnetic sensor 2, The gyro 3, a calculation unit that calculates the attitude angle and the lateral displacement amount of the vehicle body based on the output of the encoder 7, and 9 is a control device that controls the steering angle of the steering motor 4 based on the calculation result of the calculation unit 8.

FIG. 2 is a schematic plan view of the automatic guided vehicle 100. In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals. A front magnetic sensor 1 is provided at the front of the vehicle body of the automatic guided vehicle 100, and a rear magnetic sensor 2 is provided at the rear of the vehicle body. When the vehicle travels on a traveling course as shown in FIG. The sensors 1 and 2 detect the guide G and output a detection signal. The detection output varies depending on the posture of the vehicle body, and the posture angle and the lateral displacement amount of the vehicle body can be obtained from the deviation amount. Reference numeral 10 denotes a steering tire driven by the steering motor 4, which is rotatable in the left-right direction as shown by a broken line, thereby correcting the posture of the vehicle body. 11 and 12 are front wheels of the vehicle body, and 13 is a vehicle body representative point. The vehicle body representative point 13 includes a traveling direction axis L1 passing through the center of the vehicle body and an axis L2 connecting the front wheels 11 and 12.
It is located at the intersection with.

FIG. 3 is a plan view when the posture of the vehicle body is shifted. An axis L indicated by a broken line is an axis along the guide G, and is a direction axis in which the vehicle body should originally travel. With respect to the original traveling direction axis L, the actual traveling direction axis L1 is inclined leftward by an angle θ. Θ represents the posture angle of the vehicle body. X is the distance from the vehicle body representative point 13 to the axis L, and X represents the amount of lateral displacement of the vehicle body.
The attitude angle θ and the lateral displacement X can be calculated based on the detection outputs (deviations) of the magnetic sensors 1 and 2 at the location where the guide G exists. In addition, the calculation can be performed based on the outputs of the gyro 3 and the encoder 7 in a portion where the guide G does not exist.

If the automatic guided vehicle 100 is in a posture as shown in FIG.
That is, in order to return to the posture of FIG. 2, the steering tire 10 may be steered such that the posture angle changes rightward by θ and the lateral displacement changes rightward by X. At this time, if the vehicle body is located in the place where the guide G exists, the values of θ and X can be determined from the detection values of the magnetic sensors 1 and 2 as described above. Therefore, the steering motor 4 controls the steering motor 4 so that these become zero. The steering angle of the steering tire 10 is controlled.

On the other hand, if the vehicle body is in a place where the guide G does not exist, θ and X are obtained from the detection values of the magnetic sensors 1 and 2.
Cannot be obtained, θ and X are obtained from the outputs of the gyro 3 and the encoder 7. In this case, the traveling distance per unit time obtained from the output value of the encoder 7 is Δ
Assuming that the integral value of the attitude angle obtained from the output value of the gyro 3 is θ, the lateral displacement X is calculated as follows: X = Σ (ΔS · sin θ) (1) Where Σ is a predetermined CP
This indicates that time integration is performed over a unit period of U. In addition, the gyro 3 itself has an integration function, and the output value θ is always an integrated value, which is the attitude angle at that time.

On the other hand, for autonomous traveling in a place where the guide G does not exist, the attitude angle is determined based on the output detected by the magnetic sensors 1 and 2 immediately before, that is, the output detected in the guide portion immediately before the guide G is interrupted. And the target value of the lateral displacement amount is calculated. As a result of reading the immediately preceding detection output, as shown in FIG. 3, if the posture angle of the vehicle body is displaced by θ in the left direction and the amount of lateral displacement is displaced by X in the left direction, the posture is returned to the normal posture. Changes the attitude angle to the right by θ as described above,
What is necessary is just to change the lateral displacement amount by X to the right. Therefore, assuming that the target values of the attitude angle and the lateral displacement are θ0 and X0, respectively, the value calculated by θ0 = θ · −1 (2) X0 = X · −1 (3) is set as the target value. Thus, a virtual guide line is set at a position where the guide G does not exist. In FIG. 3, the axis L is a virtual guide line.
And the traveling direction axis L1 of the vehicle body is the virtual guide line L
The steering angle is controlled so as to coincide with. That is, the attitude angle θ obtained from the gyro 3 and the lateral displacement X obtained by the equation (1) are set so that θ−θ0 = 0 (4) X−X0 = 0 (5), that is, the attitude angle By performing the steering control so that there is no deviation between the current value and the target value of the lateral displacement amount, the posture of the vehicle body is properly corrected.

FIG. 4 is a flowchart in the case where the attitude control of the vehicle body is performed according to the principle described above. Hereinafter, this will be described. When the automatic guided vehicle 100 starts running (step S1), the calculation unit 8 determines whether the magnetic sensors 1 and 2 detect the guide G (step S1).
2). If the guide G is detected (step S2YE
S), the detection values of the magnetic sensors 1 and 2 are read (step S3), and the posture angle θ and the lateral displacement X of the vehicle body are calculated from the deviation (step S4). Next, based on the obtained attitude angle θ and the lateral displacement amount X, the target values of the attitude angle and the lateral displacement amount are calculated in accordance with the above equations (2) and (3) (step S5). This target value is continuously calculated while the magnetic sensors 1 and 2 detect the guide G, and is constantly updated to the latest value.

When the target value is calculated, the calculation unit 8 resets the integrated value, which is the output of the gyro 3, to zero (step S6), and outputs the detected values of the magnetic sensors 1 and 2 to the control device 9. The control device 9 controls the steering motor 4 based on the deviation amount of the magnetic sensor from the calculation unit 8, and corrects the posture of the vehicle body by displacing the steering tire 10 by a predetermined steering angle (step S7).

Thereafter, the control device 9 determines whether or not a travel end command has been input (step S8). If there is no travel end command (step S8 NO), the process returns to step S2 and the guide G is detected. (Step S2YE
S), steps S2 to S7 are repeated. If there is a travel end command (step S8 YES), the control device 9
Sends a stop signal to the traveling motor 6, stops the motor 6 and stops traveling (step S9).

On the other hand, if the guide is no longer detected in step S2 (step S2 NO), the arithmetic unit 8
Reads the immediately preceding attitude angle and the target values θ0 and X0 of the lateral displacement amount obtained in step S5 (step S10). Subsequently, the output values of the gyro 3 and the encoder 7 are read (step S11), the current attitude angle θ is obtained from the output values of the gyro 3, and the current attitude angle θ is obtained from the output values of the gyro 3 and the encoder 7 according to Expression (1). The lateral displacement X is calculated (step S12).

Next, the arithmetic unit 8 converts the difference between the target values θ0, X0 read in step S10 and the current values θ, X obtained in step S12 into a deviation amount of the magnetic sensors 1 and 2 (step S13). ), And outputs this to the control device 9. The control device 9 controls the steering so that the converted deviation amount becomes zero, that is, as shown by the equations (4) and (5), so that the current values θ and X coincide with the target values θ0 and X0. By controlling the motor 4, the steering wheel 10 is displaced by a predetermined steering angle to correct the posture of the vehicle body (step S14).

Thereafter, it is determined whether or not the traveling is completed (step S8), and if the traveling is not completed (step S8 NO).
Returning to step S2, steps S10 to S14 are repeated until the guide G is detected, and the posture is corrected. When the guide G is detected (Step S2YE)
S), steering control based on the detection values of the magnetic sensors 1 and 2 is performed again (steps S3 to S7).

As described above, in the place where the guide G exists, the steering control is performed based on the deviation amount detected by the magnetic sensors 1 and 2 as in the related art, and in the place where the guide G does not exist, The gyro 3 and the encoder 7 determine the current attitude angle θ and the lateral displacement X, and the steering is performed so that these current values θ, X match the target values θ0, X0 calculated from the immediately preceding detection value of the magnetic sensor. Control is performed. For this reason, even if a special device such as a camera is not provided, the posture of the vehicle body is appropriately corrected in a place where the guide G does not exist, whereby the automatic guided vehicle 100 can perform stable autonomous traveling. it can.

It should be noted that the present invention is not limited to the above-described embodiment, but may adopt various other forms. For example, in FIG. 1, the arithmetic unit 8 is provided separately from the control device 9. However, as shown in FIG. 5, only the control device 9 may be provided, and the function of the arithmetic unit 8 may be included in the control device 9. .

In FIG. 4, the target value is calculated continuously while the guide G is detected (step S5). However, only the detected value of the magnetic sensor is updated and stored. , When the guide G is no longer detected,
The target value may be calculated by reading the immediately preceding detection value.

Further, in the above-described embodiment, an example is shown in which the guide is constituted by a magnetic bar and this is detected by a magnetic sensor. And an electromagnetic induction type in which current is detected by a pickup coil provided on the vehicle body, or an optical system in which an optically readable mark is used as a guide and detected by a mark sensor on the vehicle body Can also be applied to

[0026]

According to the present invention, even in a place where there is no guide on the traveling road, the posture angle and the lateral displacement of the vehicle body are compared with the target values calculated based on the immediately preceding detection value of the sensor. Thus, since the steering angle can be controlled, the posture of the vehicle body can be appropriately corrected without providing a special device, and stable autonomous traveling can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an electrical configuration of an automatic guided vehicle according to the present invention.

FIG. 2 is a schematic plan view of the automatic guided vehicle.

FIG. 3 is a schematic plan view when a posture of a vehicle body is shifted.

FIG. 4 is a flowchart of attitude control.

FIG. 5 is a block diagram according to another embodiment of the present invention.

FIG. 6 is a diagram illustrating a traveling path of the automatic guided vehicle.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Front magnetic sensor 2 Rear magnetic sensor 3 Gyro 4 Steering motor 7 Encoder 8 Operation part 9 Control device 10 Steering tire 100 Automatic guided vehicle G Guide X Lateral displacement θ Attitude angle

Claims (4)

[Claims] 1. An automatic guided vehicle which travels along a guide along a guide while controlling a steering angle based on a detection output of the sensor, the sensor being provided on a vehicle body and detecting a guide intermittently laid on the travel path. In a portion where the guide is present, a steering angle is controlled based on a posture angle and a lateral displacement amount of a vehicle body obtained from a detection output of the sensor, and in a portion where the guide is not present, a steering angle is controlled based on a detection output of a previous sensor. By comparing the calculated values of the attitude angle and the lateral displacement amount with the current values of the attitude angle and the lateral displacement amount,
An automatic guided vehicle characterized by controlling a steering angle such that a current value matches a target value. 2. The automatic guided vehicle according to claim 1, wherein the guide comprises a magnetic bar, and the sensor is a magnetic sensor. 3. The automatic guided vehicle according to claim 2, wherein the magnetic sensors are respectively provided before and after the vehicle body. 4. A gyro for detecting an attitude angle of a vehicle body, and an encoder for detecting a traveling distance, a current attitude angle is obtained from an integrated value of the gyro in a portion where no guide exists, and a current lateral displacement is obtained. 4. The method according to claim 1, wherein the quantity is calculated from an integrated value of the gyro and an output value of the encoder.
Automatic guided vehicle described in.