JP2001022443A - Autonomously traveling work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To considerably improve the linearity of an autonomously traveling work vehicle executing work while it travels on a floor along a wall face. SOLUTION: An autonomously traveling vehicle 1 has a distance sensor S1 measuring a distance to an obstacle at a side and a gyro sensor S2 detecting a travel direction and has a function which linearly travels while it holds a distance with a flat wall to be constant. A controller for selecting and adopting a first travel direction control system for controlling the direction so that the vehicle travels by following the wall based on the measurement value of the distance sensor S1 when a difference between travel direction change quantity calculated based on time sequential data from the distance sensor S1 and travel direction change quantity obtained from the gyro sensor S2 is within a prescribed rage, and a second travel direction control system for executing linear control based on the measurement value of the gyro sensor S2 without executing wall following travel direction controlled based on the measurement value of the distance sensor S1 when a difference between travel change quantity calculated based on time sequential data from the distance sensor S1 and travel direction change quantity obtained from the gyro sensor S2 is out of the prescribed range is installed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an autonomous traveling work vehicle, and more particularly to an autonomous traveling work vehicle that travels all over a work area and performs work such as cleaning and wax application.

[0002]

2. Description of the Related Art Various types of autonomous traveling work vehicles have already been developed. For example, JP-A-8-286747
In this publication, an autonomous vehicle that measures the distance to a side wall periodically with a distance sensor and travels in a straight line parallel to the wall, and the change in the distance from the wall exceeds a predetermined value In the case where the control based on the distance data of the ultrasonic distance sensor is temporarily stopped, the vehicle is switched to the straight running control based on the measured wheel rotation speed and the vehicle travels, and the change in the distance to the wall is within a predetermined value. Then, the control based on the distance data of the ultrasonic distance sensor is started again, and the vehicle travels in a straight line parallel to a flat wall regardless of the unevenness of the wall.

When an ultrasonic distance sensor is used as a distance sensor in this apparatus, the ultrasonic distance sensor has a relatively wide directivity, so that a step cannot be detected at an acute angle and the characteristic is measured on a curved surface. is there. Therefore, even if the actual distance is suddenly changed due to a square pillar or the like, there is a problem that the distance is a gradual change, does not reach the predetermined value, and the direction is erroneously corrected. The further away from the wall, the greater the effect.

[0004] Further, the one described in Japanese Patent Application Laid-Open No. H8-234838 has a wide directivity of an ultrasonic distance sensor.
If the distance to the wall is larger than the reference value, the travel distance may be set to a predetermined value. Until the distance is reached, distance measurement is performed multiple times, and the minimum distance data is adopted and fed back to the wall tracing control, and if the distance to the wall is smaller than the reference value, feedback is immediately applied to the wall tracing control. It is configured to be.

However, in this apparatus, since a minimum value is selected from the measured values of the distance data a plurality of times, the period for feeding back to the travel control becomes longer, during which the copying travel control is not performed, and Will occur. In addition, when columns of the same size are arranged at regular intervals, it is effective to use the minimum value of the distance. However, the size of a certain shelf on a wall is not constant, and is effective in such a case. is not.

Further, Japanese Patent Application Laid-Open No. 8-84696 has a distance sensor for measuring the distance to a wall and an azimuth sensor for detecting an azimuth. In the case where the vehicle travels such that the distance to the wall detected by the distance sensor maintains the reference distance, and when the distance to the wall is larger than a predetermined value with respect to the reference distance,
The control method is switched so that the vehicle travels straight based on the direction detected by the direction sensor.

When the vehicle travels a predetermined distance or more from the wall, the vehicle travels straight based on only the measurement value of the azimuth sensor (gyro sensor). The error in the distance from the wall due to a small angle error with the wall of the wall becomes large, and the azimuth error due to the drift of the gyro sensor cannot be ignored. There is a problem that this may cause the occurrence of.

[0008]

This type of autonomous traveling work vehicle is designed to prevent a work leak from occurring on the floor.
It is necessary to travel while maintaining straightness, but none of the conventional ones can guarantee sufficient straightness.
Therefore, the present invention solves the above-described problems of the conventionally known device, and even when a wall has irregularities, an error due to a distance measurement value error in the irregularities of the wall caused by the wide directivity of the ultrasonic distance sensor. By preventing guidance and shortening the cycle of travel direction correction control, significantly improving straightness,
It is another object of the present invention to improve the straightness of the wall following running even when the size of the unevenness of the wall is not constant and includes various sizes of unevenness.

[0009]

In order to solve the above problems, the present invention employs the following configuration. That is, the autonomous traveling work vehicle according to the present invention includes a distance sensor for measuring a distance to a wall and a gyro sensor for detecting an angular velocity, and a time-series data of a distance to the wall obtained from an ultrasonic distance sensor. By comparing the data with the angular velocity and angle data obtained from the gyro sensor, the change in the distance to the wall is due to the unevenness of the wall or due to the misalignment of the angle between the wall and the running direction It is characterized in that it is determined whether or not the straightness is to be reduced, and a decrease in straightness due to unevenness of the wall is improved. Specifically, when the change value in the traveling direction calculated from the change in the distance to the wall and the angular velocity data of the gyro sensor match, the change in the distance deceases, the change in the angle between the wall and the traveling direction. Based on the distance data, it performs wall copying running control based on the distance data assuming that it is caused by deviation, and if both do not match, it is assumed that the change in distance data is due to unevenness of the wall and based on the distance data Without performing wall copying travel control,
The running control is performed only by the gyro sensor.

[0010]

FIG. 1 illustrates an embodiment of the present invention. An autonomous traveling work vehicle 1 includes a drive wheel 2a, 2b driven by a motor and a steerable driven wheel 3a. , 3b, a driving device, a sensor,
A control device and the like are mounted. At the rear of the vehicle body 5, a working unit W having a working device (not shown), for example, a nozzle for discharging a cleaning liquid, a brush for cleaning, a suction device for sucking dirty water, and the like.
Is installed. The work unit W performs cleaning, waxing, and other operations while moving on the floor, and various types of work are conventionally known. Therefore, the detailed structure and operation of the working unit W will be omitted.

Drive motors 4a and 4b are provided for the left and right drive wheels 2a and 2b, respectively, and the motors are provided with motor drivers 6a and 6b, respectively. The motor drivers 6a and 6b are connected to the control device (C
The drive motor is driven in accordance with a control signal from the PU 10. Electric power is supplied to the drive motors 4a and 4b, the working unit W, the control device 10, and the like from a battery (battery) not shown. Encoders 7a and 7b are provided on the left and right drive wheels, respectively, and the amount of rotation is detected by these encoders. The left and right drive wheels 2
a and 2b are configured to be rotationally controlled independently of each other, and curve control is performed based on the difference between the rotational speeds of the left and right wheels.

The drive motors 4a and 4b for the drive wheels are pulse control (PWM control) DC motors, and the amount of rotation is controlled by increasing or decreasing the duty ratio of energizing pulses. The amount of rotation of each motor is detected by the respective encoders 7a and 7b and input to the control device 10. The control device 10 performs the following calculation based on data input from the encoders 7a and 7b, the ultrasonic distance sensor S1, the gyro sensor S2, and the like, and outputs a control command signal to the motor drivers 6a and 6b. .

Next, the traveling control will be described. In the present invention, two types of traveling control are selectively adopted. As the control sensor, an ultrasonic distance sensor S1, a gyro sensor S2, and rotary encoders 7a and 7b are provided. Known commercial products can be used for both the ultrasonic distance sensor S1 and the gyro sensor S2. For example, as the gyro sensor, a vibration gyro sensor that detects an angular velocity when an object rotates using the Coriolis effect is used. Of the above two sensors, the ultrasonic distance sensor S1
Measures the distance to the side wall repeatedly at a predetermined cycle, and the gyro sensor S2 measures the angular velocity value of the traveling vehicle at a predetermined cycle. The traveling distance is obtained by detecting the wheel rotation speed by the encoders 7a and 7b and integrating the detected wheel rotation speed.

The driving control method is specifically described as follows. First, variables are set as follows. i: Number of measurements Do: Reference distance to wall D (i): Measured distance to wall. As (i): Angular velocity calculated from the measured distance to the wall. A (i): Angular velocity measurement value. V: Travel speed T: Measurement cycle L: Travel distance that advances during the measurement cycle. θ (i): The angle between the wall and the traveling direction. M (i): the corrected traveling direction amount _{C 1, C 2, C 3} : constant

Here, L = V · T (1) θ (i) = sin ⁻¹ ((D (i) −D (i−1)) / L) (2) As ( i) = (θ (i) −θ (i−1)) / T (3)

The correction amount of the traveling direction is based on the following equation (4), and M (i) = C ₁ (D (i) -Do) + C ₂ · θ (i) + C ₃ · A (i ) (4) One of the following two calculation methods is selected according to the comparison result between As (i) and A (i).

The absolute value of the difference between As (i) and A (i) is a predetermined value N
If it exceeds (the value may be set in advance according to the working conditions, etc., but is usually set to almost 0), C ₁ = C ₂ = OC ₃
In the following equation (5) with ≠ O, the traveling direction correction amount based on the distance measurement value is set to zero, and the direction correction is performed based only on the angular velocity measurement value. M (i) = C ₃ · A (i) (5)

When the absolute value of the difference between As (i) and A (i) is within a predetermined value, C ₁ ≠ OC ₂ ≠ 0 C ₃ ≠ O, and the distance measurement value is calculated based on the equation (4). The traveling direction may be corrected based on the measured value of the angular velocity and the traveling direction may be modified based on the measured value of the angular velocity, or the traveling direction may be corrected based on only the distance measurement value with C ₁ ≠ OC ₂ ≠ OC ₃ = 0.

In the condition (1), the reference distance Do that determines how far away from the wall the vehicle travels in parallel is determined at the start of travel by using the measured distance D (0) of the start of travel as the reference distance. Substituting ₀ into Do = D (0) Thereafter, the distance measurement value D (i) immediately after the transition from the state to the state is substituted into Do as the reference distance. Do = D (i)

FIG. 2 shows an example in which there is no unevenness on the wall, and the traveling direction is gradually inclined due to the influence of the unevenness of the slip or floor, the difference between the left and right wheel diameters, and the like. In this case, (1)
(2) Since the value of the angular velocity value As (i) calculated by the equation (3) is substantially equal to the measurement value A (i) of the gyro sensor, it corresponds to the above case, and the wall based on the distance measurement value Copying control is performed.

FIG. 3 shows a case where the wall has no irregularities.
This is an example of a case where the vehicle is traveling straight, but the direction at the start of traveling is not parallel to the wall, so that the vehicle gradually moves away from the wall. In this case, the value of the angular velocity value As (i) calculated by the equations (1), (2), and (3) and the measured value of the angular velocity A (i) by the gyro sensor are almost zero and almost coincide with each other. This also corresponds to the above-described case, and wall tracing control based on the distance measurement value is performed, and control is performed so that the parallelism with the wall and the distance to the wall are maintained. In the apparatus described in JP-A-8-84696, the wall profiling control is not performed when the apparatus is separated from the wall by a predetermined distance or more, and the control is performed only by the gyro sensor. There is a risk of disappearing.

FIG. 4 shows an example in which the wall has irregularities.
In this case, the wall tracing control is executed until the measurement of D (i), and the vehicle goes straight in parallel with the wall.However, since the wall has a step, the distance measurement value changes after D (i). I have. At this time, the wall changes steeply as shown in the figure, but because the directivity of the ultrasonic distance sensor is relatively wide, the measured value becomes a curve shown by a broken line in the figure, and is gentle as shown by D (i) in the figure. In some cases. If this change is fed back to the wall copying travel control as it is, the straightness is impaired. At this time, the angular velocity measured value A (i) by the gyro sensor is almost zero, but the angular velocity value As (i) calculated by the equations (1), (2), and (3).
Does not become zero, which corresponds to the case described above, in which the wall tracking control based on the distance measurement value is stopped, and the control is switched to control in which only the gyro sensor is used, thereby preventing a decrease in straightness.

After measuring D (i + 3), As (i + 3) is measured again.
+3) and A (i + 3) fall within a predetermined range, so the distance measurement D (i + 3) at that time is used as the reference distance to the wall, and thereafter, the distance to the wall is used as the reference. Wall copy running control is performed to maintain the distance.

FIG. 5 illustrates a flowchart of a direction correction amount calculation subroutine flowchart.

A direction correction amount calculation subroutine is executed by a timer interrupt at a fixed period. First, the distance D (i) to the wall and the angular velocity A (i) were measured in # 1 and # 2, and then in # 3 (1) (2)
The calculated angular velocity value As (i) is calculated by using the equation (3), and it is determined at # 4 whether the case is the above case. If it is the case, proceed to # 8 and use the formula (5) to calculate the traveling direction correction amount M
Calculate (i) and proceed to # 9. If the determination result of # 4 is, the process proceeds to # 5, and it is determined whether or not the direction correction amount was calculated by the formula (4) last time.If the determination is affirmative, the process directly proceeds to # 7,
If not, the current distance measurement D (i) is substituted for the reference distance _Do , and the process proceeds to # 7. In # 7, the distance to the wall is calculated based on equation (4).
The direction correction amount for maintaining _Do is calculated, and the process proceeds to # 9. # 9
Then, the rotational speeds of the left and right wheels are changed based on the calculated M (i), and the subroutine ends.

The autonomous traveling work vehicle 1 travels straight along the wall under the above-described control. When it reaches the end of the work range, it makes a U-turn and travels straight again in the reverse direction (if necessary, it also travels backward). Is possible). In this way, the work is performed without omission on the entire floor surface to be worked. In the above-described embodiment, the traveling vehicle of the left and right two-wheel independent control is exemplified. However, a traveling vehicle having steering wheels separately from the driving wheels may be used. In that case, in step # 9 of the flowchart, the angle of the steered wheel may be corrected instead of correcting the rotational speeds of the left and right wheels.

[0027]

As described above, the autonomous traveling work vehicle according to the present invention has both an ultrasonic distance sensor and a gyro sensor and travels straight in parallel with a flat wall so that the distance from the wall is constant. Having a function to perform, and time-series data of the distance to the wall obtained from the ultrasonic distance sensor,
By comparing angular velocity data and angle data obtained from the gyro sensor to determine whether the change in the distance to the wall is due to unevenness of the wall or an azimuth error, and maintain straightness Thereby, it is possible to improve a decrease in straightness due to a step on a wall or the like.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating a configuration of an autonomous traveling work vehicle.

FIG. 2 is an explanatory diagram of a traveling control method.

FIG. 3 is an explanatory diagram of a traveling control method.

FIG. 4 is an explanatory diagram of a traveling control method.

FIG. 5 is a flowchart illustrating a direction correction amount calculation subroutine program.

[Explanation of symbols]

 Reference Signs List 1 autonomous traveling work vehicle 2 (a, b) driving wheel 3 (a, b) driven wheel 4 (a, b) driving motor 5 body 6 (a, b) motor driver 7 (a, b) encoder 10 control device S1 Ultrasonic distance sensor S2 Gyro sensor W Working device

Claims (2)

[Claims] 1. An autonomous device having a distance sensor for measuring a distance to a side obstacle and a gyro sensor for detecting a traveling direction, and having a function of traveling straight while keeping a constant distance from a flat wall. In the traveling work vehicle, if the difference between the traveling direction change amount calculated based on the time series data from the distance sensor and the traveling direction change amount obtained from the gyro sensor is within a predetermined range, the distance sensor A first traveling direction control method that performs direction control so as to follow the wall based on the measured value, a traveling direction change amount calculated based on time series data from a distance sensor, and a gyro sensor. When the difference from the traveling direction change amount is out of the predetermined range, the second traveling direction control method that does not perform the wall following traveling direction control based on the measurement value of the distance sensor but performs the straight traveling control based on the measurement value of the gyro sensor; Select adopt An autonomous traveling work vehicle provided with a control device that performs operation. 2. The method according to claim 1, wherein the first traveling direction control method switches from the second traveling direction control method to a first traveling direction control method as a distance reference value for determining how far away from the wall the vehicle travels. The autonomous traveling work vehicle according to claim 1, wherein control is performed using a measured distance to a wall immediately after the operation.