JP2928876B2 - Autonomous vehicle position control method and autonomous vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autonomous vehicle that runs on wheels and an improved method of controlling the position of the autonomous vehicle.

[0002]

2. Description of the Related Art Conventional autonomous vehicle driving devices are roughly classified into a rack-and-pinion system and a friction drive system. Among them, the rack-and-pinion system is driven by rotating gears while meshing with each other on the rack. Therefore, the position accuracy is good. The cost is high. In addition, vibration occurs due to meshing of the teeth.

[0003] The friction drive system in which the position is controlled based on the position data calculated from the rotation speed of the motor driving the wheels and travels on the traveling path does not require a high-cost rack, so that the manufacturing cost is low and the teeth are reduced. Vibration due to meshing does not occur, but it is driven by the frictional force between the wheel and the traveling path due to the rotation of the wheel. For example, a tire is mounted on the wheel to prevent the wheel and the traveling path from slipping. Therefore, when the autonomous vehicle travels, the diameter of the wheel changes dynamically, so the position data calculated from the rotation speed of the motor that rotates the wheel at a predetermined reduction ratio and the diameter of the wheel is: It produces a cumulative error with respect to the actual position. In order to prevent this error from occurring, a high-resolution linear encoder for continuously and directly feeding back actual position data and an expensive external sensor such as a laser length measuring device are required.

[0004] On the other hand, identifiable radio waves are received from radio transmitting stations provided at a plurality of predetermined positions in a traveling range, and the relative positions with respect to the radio transmitting stations are obtained, so that the actual position of the moving object and the movement of the moving object are determined. Japanese Patent Application Laid-Open No. 51-53870 discloses a method of recognizing the direction and correcting the above-mentioned cumulative error discontinuously based on the recognized position.

[0005] Further, each time a sensor mounted on an autonomous vehicle detects a mark provided at each of a plurality of predetermined positions on a traveling route, a method of correcting the above-described cumulative error based on the position of the mark is disclosed in Japanese Patent Application Laid-Open No. H10-157,086. It is disclosed in JP-A-63-20508. For example, every time a photoelectric sensor mounted on an autonomous vehicle detects a marker provided at each of a plurality of predetermined positions on a traveling path, position data calculated by the above-described motor rotation speed and wheel diameter is used as a marker. , The above-described cumulative error can be corrected discontinuously, and an inexpensive position control method for an autonomous vehicle can be realized.

[0006]

However, in this position control method, there is a time delay from when the marker is detected until the position data is replaced with the position data of the marker. An error occurred, which reduced the accuracy of the position control. The photoelectric sensor performs a detection operation when switching from off to on and when switching from on to off.However, when switching from off to on and when switching from on to off, the relative position between the photoelectric sensor and the marker is changed. There is a difference, and a position error occurs due to the operating characteristics of the photoelectric sensor, which also reduces the accuracy of the position control.

The present invention has been made in view of the above circumstances, and in the first invention, when eliminating the accumulated error, the position calculated from the rotational speed of the motor driving the wheels from the time of detecting the marker. Position error due to response delay due to elapsed time until data is replaced with marker position data, and sensor when sensor switches from off to on and performs detection operation and switches from on to off to perform detection operation By correcting the position error caused by the operating characteristics of the sensor due to the difference between the relative positions of the wheel and the marker, the accumulated error of the position due to the dynamic change of the diameter of the wheel can be corrected with high accuracy. It is an object of the present invention to provide an autonomous vehicle position control method that can be performed with high accuracy.

In the second invention, the position error caused by the response delay is calculated from the elapsed time of the response delay determined by the control device and the sensor for controlling the position of the autonomous vehicle and the rotational speed of the motor driving the wheels. By calculating the product of the speed and the speed of the autonomous vehicle obtained by differentiating the position data, the accumulated error of the position due to the dynamic change of the wheel diameter can be corrected with high accuracy, and the positioning can be performed with high accuracy. It is an object of the present invention to provide a position control method.

In the third invention, the position error caused by the operation characteristics of the sensor is set to 0 when the autonomous vehicle is traveling in the traveling direction when the autonomous vehicle has stored the marker position data. If the vehicle is traveling in the opposite direction, each is set to a predetermined value, the traveling direction of the autonomous traveling vehicle is determined, and the error in the determined direction is selected and obtained. It is an object of the present invention to provide a position control method for an autonomous vehicle that can accurately correct a cumulative error of a position and perform positioning with high accuracy.

According to a fourth aspect of the present invention, when the sensor detects the marker, means for determining a position error due to a response delay is provided;
When the sensor detects a marker, when the sensor switches from off to on to perform the detection operation, and when the sensor switches from on to off to perform the detection operation, the operation characteristic of the sensor due to the difference between the relative positions of the sensor and the marker. With the provision of means for obtaining a position error caused by a vehicle, it is possible to highly accurately correct the cumulative error of the position due to the dynamic change of the wheel diameter, and to provide an autonomous vehicle that can perform the positioning with high accuracy. I do.

[0011]

A position control method for an autonomous vehicle according to a first aspect of the present invention is an autonomous vehicle that runs by performing position control based on position data calculated from the number of rotations of a motor driving wheels. One or a plurality of markers are provided at predetermined positions on the traveling path of the vehicle, and the position data of the markers are stored. When performing an operation and when switching from ON to OFF and performing a detection operation,
By replacing the calculated position data with the position data of the marker, in a position control method of an autonomous vehicle that eliminates a cumulative error of a position caused by a dynamic change of the wheel, when eliminating the cumulative error, A position error caused by a response delay due to an elapsed time from when the marker is detected to when the calculated position data is replaced with the position data of the marker, and the sensor and the marker when the sensor performs each of the detection operations. And a position error caused by an operation characteristic of the sensor due to a difference between the relative positions of the sensor and the sensor.

In this method of controlling the position of an autonomous vehicle, a motor for rotating and driving the wheels at a predetermined reduction ratio from the time when a marker is detected in order to eliminate a cumulative error in position caused by a dynamic change in the diameter of the wheels. Position error caused by a response delay due to elapsed time until the position data calculated from the number of rotations (rotation angle) is replaced with the position data of the marker. Also, the position caused by the operation characteristic of the sensor due to the difference between the relative positions of the sensor and the marker when the sensor switches from off to on and performs the detecting operation, and when the sensor switches from on to off and performs the detecting operation. Is corrected.

The position control method for an autonomous vehicle according to a second aspect of the present invention is a method for controlling the position error caused by the response delay, the control unit for controlling the position of the autonomous vehicle and the elapsed time determined by the sensor; The position data is calculated by differentiating the position data calculated from the rotational speed with the product of the speed of the autonomous vehicle.

In this method of controlling the position of the autonomous vehicle, the elapsed time T ₁ from the time when the marker is detected to the time when the above-mentioned position data θ _m is replaced with the position data Y _i of the marker.
Is determined by a sensor to be used and a control device for controlling the position. Therefore, the product of the elapsed time T ₁ and the speed dθ _m of the autonomous vehicle obtained by differentiating the position data θ _m when the marker is detected is obtained. T ₁ × dθ _m is a position error due to a response delay due to the elapsed time T ₁ .

According to a third aspect of the present invention, there is provided a position control method for an autonomous vehicle, wherein the position error caused by the operating characteristics of the sensor is changed in the traveling direction when the autonomous vehicle stores the position data of the marker. When the traveling vehicle is traveling, it is set to 0, and when traveling in the opposite direction, it is set to a predetermined value, the traveling direction of the autonomous traveling vehicle is determined, and the error in the determined direction is selected. It is characterized by obtaining by doing.

In this position control method for an autonomous traveling vehicle,
The traveling vehicle has a low overall travel range with one end of the travel path as the reference position.
Drive at high speed to detect markers and then drive wheels
The position data calculated from the motor rotation speed is
It is stored as correct position data. So, for example
If the autonomous vehicle described above records the correct position data of the marker,
The traveling direction when remembered is the positive direction, and the reverse direction is the negative direction.
Then, the position error f (dθ) due to the operating characteristics of the sensor
_m) Is the speed dθ of the autonomous vehicle_mIs positive, f (dθ
_m) = 0 (dθ_m≧ 0), speed dθ of the autonomous vehicle_mIs negative
When f (dθ _m) = Const. (Dθ_m<0) and
can do.

Therefore, the autonomous traveling vehicle according to the first to third inventions
Summarizing the position control method, it is caused by the dynamic change of the wheel
Should be corrected when eliminating accumulated errors
The error err is err = θ_m-T₁× dθ_m-Y_i+ F
(Dθ_m), And the corrected position data θ_mmIs θ_mm=
θ_m-Err = T₁× dθ_m+ Y_i−f (dθ_mBy)
Can be obtained. Therefore, the position of this autonomous vehicle
The transfer function of the position control element that performs feedback is G_p,
Assuming that the data of the target position is u, the output u of the position control element
₁Is u₁= G _p× (u-θ_mm) = G_p× (u-T₁×
dθ_m-Y_i+ F (dθ_m))
You. Output u of the obtained position control element₁Drives the wheels
Autonomous driving
Position control of the traveling vehicle is performed.

According to a fourth aspect of the present invention, there is provided an autonomous traveling vehicle, wherein one or a plurality of autonomous traveling vehicles are provided at predetermined positions on a traveling path of an autonomous traveling vehicle which performs position control based on position data calculated from the number of rotations of a motor for driving wheels. A marker is provided, the position data of the marker is stored, and a sensor mounted on the autonomous vehicle is
By replacing the calculated position data with the position data of the marker when the marker is detected and the detection operation is switched from off to on and when the detection operation is switched from on to off, the movement of the wheel is performed. In an autonomous vehicle that eliminates the cumulative error of the position caused by a specific change, when the sensor detects the marker, the time from when the marker is detected to when the calculated position data is replaced with the position data of the marker Means for determining a position error due to a response delay due to time, and when the sensor detects the marker, a difference between respective relative positions of the sensor and the marker when the sensor performs the respective detection operations. Means for obtaining a position error caused by the operation characteristics of the sensor, and when eliminating the accumulated error, Characterized in that the two means are no order to correct each error found.

In this autonomous vehicle, the sensor detects the marker.
A method to find the position error due to the response delay
The column will calculate the position data since the marker was detected.
TA θ _mIs marker position data Y_iUntil replaced by
Elapsed time T₁And the position data θ_mIs obtained by differentiating
Vehicle speed dθ_mProduct T with₁× dθ_mRespond
Find the position error due to the delay.

By the way, this autonomous traveling vehicle travels at low speed in the entire traveling range with one end of the traveling road as a reference position, detects a marker, and at that time, calculates position data calculated from the rotation speed of the motor driving the wheels. It is stored as correct position data of the marker. Therefore, for example, if the traveling direction when the above-mentioned autonomous vehicle stores the correct position data of the marker is the forward direction, and the opposite direction is the negative direction, when the sensor detects the marker, it is caused by the operating characteristics of the sensor. The means for calculating the error of the position where the vehicle travels, calculates the error f (dθ _m ) when the speed dθ _m of the autonomous vehicle is positive, f (dθ _m ) = 0, and the speed dθ
_{When m} is negative, f (dθ _m ) = const. Can be obtained as

[0021] Thereby, a wheel is generated by a dynamic change of the wheel.
Error to be corrected when eliminating the accumulated error
The difference err is err = θ_m-T₁× dθ_m-Y_i+ F
(Dθ _m), And the corrected position data θ_mmIs θ_mm=
θ_m-Err = T₁× dθ_m+ Y_i−f (dθ_m)
Can be Therefore, the position of this autonomous vehicle
G is the transfer function of the position control element that performs feedback._p,Goal
Assuming that the position data is u, the output u of the position control element
₁Is u₁= G _p× (u-θ_mm) = G_p× (u-T₁×
dθ_m-Y_i+ F (dθ_m))
You. Output u of the obtained position control element₁Drives the wheels
Autonomous driving
Position control of the traveling vehicle is performed.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a position control method and a drive device of an embodiment of an autonomous vehicle according to the first to third aspects of the present invention and an autonomous vehicle according to a fourth aspect of the invention. FIG. 3 is a block diagram illustrating an example of a configuration of a unit. In the position control device and the drive device of the autonomous vehicle, a marker detection signal from the photoelectric sensor 2 is provided to the controller 1, and a control signal from the controller 1 is provided to the driver 3. Driver 3
Outputs an applied voltage for speed control to the motor 4 based on a given control signal, and the motor 4 is rotated by this. This rotation is reduced by the reduction gear 7 at a predetermined reduction ratio and transmitted to the wheels 8.

On the other hand, the rotation of the motor 4 is converted into a predetermined number of pulses per rotation by an encoder 5 attached to the motor shaft, and this pulse train signal is given to the controller 1. The pulse train signal is differentiated by the differentiating means 6 to become a speed signal, which is provided to the driver 3 and the controller 1. The driver 3 performs the above-described speed control based on the speed signal, and the controller 1 performs an error correction of the position control using the speed signal.

FIG. 2 is a perspective view showing an example of a configuration of a main part of the autonomous vehicle described above. This autonomous vehicle is a box-shaped cart 10
A plurality of pairs of wheels 8 attached to the lower part of the vehicle are moved by rotationally driving on two parallel running paths 9. A transmission type photoelectric sensor 2 is attached to a lower portion of the carriage 10 so as to detect a marker 11 attached to a side surface of the traveling path 9.

FIG. 3 shows an example of the arrangement of the markers 11.
FIG. In FIG. 3, four markers 11 are autonomous.
It is installed discretely in the moving range of the traveling vehicle,
X ₁X_Two, X_ThreeX_Four, X_FiveX₆, X₇X₈In each
Is displayed. In the transmission type photoelectric sensor 2,
When the camera 11 is approaching and the marker 11
The output signal of the photoelectric sensor 2 switches when
Instead, the photoelectric sensor 2 performs a detection operation at that time. Photoelectric cell
When the marker 11 enters the sensor 2 and the photoelectric sensor 2
When the force signal switches and when the marker 11
When the output signal of the photoelectric sensor 2 switches due to the
, There is a difference in the relative position between the photoelectric sensor 2 and the marker 11.
Therefore, a position error due to the operation characteristics of the photoelectric sensor 2 is reduced.
Occurs.

Position X ₁ X ₂ , Position X ₃ X ₄ , Position X
_{Between 5} X _{6 and} between positions X ₇ X ₈ , for example, photoelectric sensor 2
Is on and the other sections are off. The autonomous vehicle travels at low speed over the entire travel range with one end of the travel path 9 as a reference position to detect the marker 11, and at that time the wheels 8
Storing the position data calculated from the rotational speed of the motor 4 that drives as the correct position data X _i of the marker 11. Correct position data X _i of the markers 11, (1) as the pulse conversion value Y _i of the encoder 5 from equation stored in the memory of a microcomputer constituting the controller 1.

Y _i = X _i × N × E / (π × D) (1) i = 1, 2,..., 8 Y _i ; number of pulses N; reduction ratio of reduction gear E: encoder pulse per motor rotation Number D; Wheel diameter

FIG. 4 shows the position control of an autonomous vehicle according to the present invention.
It is a block diagram which shows an example of a control method. This block
The diagram shows the motor 4 (the controlled object 17) that drives the wheels 8.
The pulse-converted rotational angular velocity is integrated by an integrating element 18.
And the current position data θ_mOutput as This current
Position data θ_mAnd marker position detected by photoelectric sensor 2
X_iPulse conversion value Y_iIs given to the correction element 19,
In the correction element 19, the position data θ_mAnd marker position X_i
Pulse conversion value Y_iAnd the position data θ _mComplement
Correct the position data θ after correction._mmIs output to the subtraction point 13.
I do. At the subtraction point 13, the pulse conversion data u of the target position
From the corrected position data θ_mmAnd subtract the difference
Output to the position control element 14. The position control element 14 receives an input
Transfer function G_pMultiplied by
Target speed u₁Is output to the subtraction point 15.

At the subtraction point 15, the speed of the control target 17 (motor 4) is subtracted from the target speed u ₁ , and the difference is output to the speed control element 16. Speed control element 16, by multiplying the transfer function G _v on the input difference, and outputs to the controlled object 17 as a manipulated variable (the applied voltage). The control target 17 is
Rotates in accordance with the operation amount, the rotational angular velocity, the operation amount and the moment of inertia J _m is represented by the product of the transfer function 1 / (J _m s) including, a subtraction point 15 as a velocity which is converted pulse integrating element 18 Is output to In the integral element 18, then up to the photoelectric sensor 2 detects the marker, by integrating the speed which has been input, and outputs as the next position data theta _m.

Hereinafter, a position control method for an autonomous vehicle having such a configuration will be described with reference to the flowchart of FIG. When the photoelectric sensor 2 detects the marker 11 and the output signal switches (S
1), reads the current position data theta _m obtained by integrating the rotational angular speed of the motor 4 which is converted pulse encoder 5 (S3). Next, the marker 11 detected by the photoelectric sensor 2
Of the position X _i of the pulse conversion value Y _i stored in the memory
Is read (S5). At this time, the pulse conversion value Y _i is
For example, it is possible to choose by selecting the closest to the position data theta _m, those photoelectric sensor 2 corresponding to the marker 11 has been detected.

Next, the controller 1 reads the velocity dθ _m obtained by differentiating the position data θ _m by the differentiating means 6 (S
7) determining the direction of the velocity d [theta] _m (S9). The controller 1 determines the position error f (dθ _m ) due to the operation characteristics of the photoelectric sensor 2 based on the determination result (S1).
1). For example, autonomous vehicles are correct positional data Y _i traveling direction when storing the positive direction of the marker 11, if the opposite direction and the negative direction, the position due to operating characteristics of the sensor error f (d [theta] _m) when speed d [theta] _m of the autonomous vehicle is _{positive, f (dθ m) = 0} , when the speed d [theta] _m is negative, f (d
θ _m ) = const. Can be obtained as

Next, the controller 1, -T ₁ × error err = theta _m to be corrected upon to eliminate the accumulated error position caused by dynamic changes in the wheel dθ _m -Y _i + f a (d [theta] _m) The calculation is performed (S13). Here, the elapsed time T ₁ from when the marker 11 is detected to when the current position data θ _m is replaced with the position data Y _i of the marker 11 is determined by the photoelectric sensor 2 and the controller 1. and T _1, the product T ₁ × d [theta] _m the speed d [theta] _m of the autonomous vehicle when the marker 11 is detected, the elapsed time T ₁
Position error due to the response delay caused by the

Next, the controller 1 calculates the corrected position data θ _mm = θ _m -err = T ₁ × dθ _m + Y _i -f (d
theta _m) computing a (S15). Next, the controller 1 outputs the output u ₁ = G _p × (u−θ _mm ) = G _p × (u−) of the position control means (subtraction point 13, position control element 14) for performing position feedback of the autonomous vehicle. _{T 1 × dθ m -Y i +} f (dθ m)) calculates the (S17), and outputs to the driver 3 (net point 15, the speed control element 16) (S19). Here, G _p is a transfer function of the position control means, and u is data of the target position.

[0034]

According to the position control method of the autonomous vehicle according to the first to third aspects of the present invention, the accumulated error of the position due to the dynamic change of the diameter of the wheel can be accurately corrected, and the positioning can be performed with high accuracy. . In addition, since a high-precision external sensor is not required, high-precision positioning can be performed at low cost. Also,
For example, a wheel having a large dynamic change in the diameter of the wheel, such as a tire, can be used, so that the occurrence of slip between the wheel and the traveling path can be suppressed. In addition, since a position error due to a response delay can be corrected, a low-cost microcomputer with a low operating speed and a low-cost sensor with a low response can be used, and an inexpensive autonomous vehicle can be realized.

According to the autonomous vehicle according to the fourth aspect of the invention, the accumulated error of the position due to the dynamic change of the diameter of the wheel can be corrected with high accuracy, and the positioning can be performed with high accuracy. In addition, since a high-precision external sensor is not required, high-precision positioning can be performed at low cost. In addition, for example, a wheel having a large dynamic change in the diameter of the wheel, such as a tire, can be used, so that occurrence of slip between the wheel and the traveling path can be suppressed.
In addition, since a position error due to a response delay can be corrected, a low-cost microcomputer with a low operating speed and a low-cost sensor with a low response can be used, and an inexpensive autonomous vehicle can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an example of a main configuration of a position control device and a drive device of an embodiment of an autonomous vehicle according to first to third inventions and an autonomous vehicle according to a fourth invention.

FIG. 2 is a perspective view showing a configuration example of a main part of an embodiment of a position control method of an autonomous vehicle according to first to third inventions and an autonomous vehicle according to a fourth invention.

FIG. 3 is an arrangement diagram showing an example of marker arrangement.

FIG. 4 is a block diagram showing a method for controlling the position of an autonomous vehicle according to the present invention.

FIG. 5 is a flowchart illustrating a position control method for an autonomous vehicle according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Controller 2 Photoelectric sensor 3 Driver 4 Motor 5 Encoder 6 Differentiating means 8 Wheel 9 Travel path 10 Truck 11 Marker 13, 15 Subtraction point 14 Position control element 16 Speed control element 19 Correction element

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G05D 1/02

Claims (4)

(57) [Claims] 1. An autonomous vehicle traveling by performing position control based on position data calculated from the number of revolutions of a motor driving a wheel is provided with one or a plurality of markers at predetermined positions on a traveling path. The data is stored, and when the sensor mounted on the autonomous vehicle detects the marker and performs a detection operation by switching from off to on and performs a detection operation by switching from on to off, the calculation is performed. In a position control method for an autonomous vehicle that replaces position data with position data of the marker to eliminate a cumulative error of a position caused by a dynamic change of the wheel, the marker is detected when the cumulative error is removed. Error in the position caused by the response delay due to the elapsed time from the time when the calculated position data is replaced with the position data of the marker, and Position control of an autonomous vehicle, wherein a position error caused by an operation characteristic of the sensor due to a difference between respective relative positions of the sensor and the marker when the sensor performs each of the detection operations is corrected. Method. 2. A position error caused by the response delay,
The autonomous vehicle is obtained by multiplying the elapsed time determined by the control device and the sensor that controls the position of the autonomous vehicle and the speed of the autonomous vehicle obtained by differentiating the position data calculated from the rotation speed. Autonomous vehicle position control method. 3. The position error caused by the operation characteristic of the sensor is set to 0 when the autonomous vehicle is traveling in the traveling direction when the autonomous vehicle has stored the marker position data. The vehicle according to claim 1, wherein when the vehicle is traveling in the opposite direction, the vehicle is set to a predetermined value, the traveling direction of the autonomous vehicle is determined, and the error in the determined direction is selected. An autonomous vehicle position control method. 4. One or a plurality of markers are provided at predetermined positions on a traveling path of an autonomous vehicle that travels by performing position control based on position data calculated from the number of rotations of a motor that drives wheels, and the positions of the markers are provided. The data is stored, and when the sensor mounted on the autonomous vehicle detects the marker and performs a detection operation by switching from off to on and performs a detection operation by switching from on to off, the calculation is performed. In an autonomous vehicle that replaces the position data with the position data of the marker to eliminate the accumulated error of the position caused by the dynamic change of the wheel, when the sensor detects the marker, Means for calculating a position error caused by a response delay due to an elapsed time until the calculated position data is replaced with the marker position data. Means for determining a position error caused by an operation characteristic of the sensor due to a difference between respective relative positions of the sensor and the marker when the sensor performs the respective detection operations when the sensor detects the marker; and An autonomous traveling vehicle, characterized in that when eliminating the accumulated error, the respective errors obtained by the two means are corrected.