JPH0823585B2 - Self-supporting unmanned vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention relates to traveling in a factory, a warehouse, etc. while measuring a distance between a side wall surface existing along a planned traveling route using an ultrasonic sensor. About self-supporting unmanned vehicles.

"Prior Art" A self-sustaining unmanned vehicle travels along a predetermined travel route while recognizing its own position by a travel control device composed of a microcomputer. This self-supporting unmanned vehicle is provided with left and right driving wheels, a motor for rotating each of the left and right driving wheels, and a pulse encoder for detecting each rotational speed of the left and right driving wheels, and a memory in the travel control device. The information about the planned travel route, such as the distance between each passing point and the course change angle at each passing point, is stored in advance. Then, the travel control device, various information stored in the memory,
By controlling the rotational speeds of the left and right drive wheels based on the output of each pulse encoder, the vehicle travels along the planned travel route. In this case, the self-supporting unmanned vehicle travels straight by rotating the left and right drive wheels at the same number of revolutions, and makes a right turn or left turn by changing the number of revolutions of the left and right drive wheels.

By the way, the traveling control device for the self-supporting unmanned vehicle measures the traveling distance from the traveling start point by accumulating the pulse outputs of the pulse encoders, and recognizes the current position. However, if the traveling distance is measured only by the pulse output of the pulse encoder, an accurate traveling distance cannot be obtained when the drive wheels slip, etc., and as a result, it deviates from the original planned traveling route. There is a fear. Therefore, a self-supporting unmanned vehicle was developed that measures the distance between the side wall surface existing along the planned travel route using an ultrasonic sensor and corrects the route and travel distance based on this measurement result. ing.

FIG. 4 is a plan view for explaining the traveling operation of this type of self-supporting unmanned vehicle. In this figure, 1 is an autonomous unmanned vehicle, 2 is an ultrasonic sensor provided in the center of the side body of the autonomous unmanned vehicle 1, 3 is a planned traveling route of the autonomous unmanned vehicle 1, 4 is a planned traveling route 3 is a side wall surface existing along 3 and 4a is a protruding step portion of the side wall surface 4. Then, by measuring the ultrasonic wave propagation time from the ultrasonic wave sensor 2 radiating ultrasonic waves to the side wall surface 4 until the reflected wave is detected by the ultrasonic wave sensor 2, the self-supporting unmanned vehicle 1 and The distance between the side wall surfaces 4 is measured. Also,
Reference symbols P ₁ , Q ₁ , P ₂ , Q ₂ in the figure indicate respective positions described below.

P ₁ ; A point on the side wall surface 4 corresponding to the starting point of travel of the self-supporting unmanned vehicle 1.

Q ₁ ; The point where the step portion 4a of the side wall surface 4 is formed.

P ₂ ; The center position of the self-supporting unmanned vehicle 1 at the starting point.

Q ₂ ; Center position of the self-supporting unmanned vehicle 1 at the time when the step 4a is detected by the ultrasonic sensor 2.

Here, in the memory in the travel control device of the self-supporting unmanned vehicle 1, in addition to the information on the planned travel route 3 described above, the information between the self-supporting unmanned vehicle 1 and the side wall surface 4 in each part of the planned travel route 3 is stored. Distance data (for example, distances S ₁ and S ₂ ), that is, distance data for course correction, and each step 4a from the start point of travel.
Distance data to (for example, the point corresponding to the starting point
The distance L ₁ ) from P ₁ to the point Q ₁ where the step portion 4a of the side wall surface 4 is formed, that is, the distance data for correcting the traveling distance is stored in advance.

Then, the traveling control device controls the rotation speeds of the left and right drive wheels based on the distance to the side wall surface 4 obtained by the ultrasonic sensor 2 and the distance data for course correction in the memory, respectively, and the self-standing unmanned vehicle. The course is corrected so that 1 always runs on the planned route 3.

Further, the traveling control device considers that the self-supporting unmanned vehicle 1 has reached the right side of the step portion 4a when the distance to the side wall surface 4 obtained by the ultrasonic sensor 2 changes from S ₁ to S _2. , At this point, the mileage data obtained from the pulse encoder is changed to the mileage correction data in the memory.
Correct based on L ₁ . That is, assuming that the traveling distance data PD obtained by accumulating the pulse output of the pulse encoder is lq during the period from when the self-supporting unmanned vehicle 1 starts traveling to when it arrives on the right side of the step 4a. ,
What should have originally been lq = L ₁ , but in reality slips occur on the drive wheels and lq ≠ L ₁ . Therefore, the mileage data PD obtained by the pulse encoder is converted into the self-supporting unmanned vehicle 1
When it reaches the right side of the step 4a, it is corrected based on the distance data L ₁ for correcting the traveling distance in the memory, and thereafter, traveling control is performed based on the corrected traveling distance data. .

In this way, the distance from the side wall surface 4 is measured by the ultrasonic sensor 2, and the course and traveling distance are corrected based on the measurement result.

[Problems to be Solved by the Invention] However, since the ultrasonic sensor 2 has a wider directivity than an optical sensor or the like, the self-supporting unmanned vehicle 1 reaches the side of the step portion 4a of the side wall surface 4 directly on the side. Previously, the step portion 4a was detected, which causes a position detection error. For example, as shown in FIG. 5, when the ultrasonic sensor 2 has a horizontal directivity of ± θ, the distance between the ultrasonic sensor 2 and the step portion 4a measured by the ultrasonic sensor 2 is x. , When the vehicle body center position Q ₂ of the self-supporting unmanned vehicle 1 reaches a point on the front side by Δx (= x · sin θ) from the position Q ₁ where the step of the side wall surface 4 is formed, that is, (P ₁ Distance between Q and Q ₁ L ₁ )
> In the state of (distance L ₂ between P ₂ and Q _2), would be considered a free-standing unmanned vehicle 1 has already reached the positive side of the step portion 4a. As a result, the position detection error Δx is generated, and the traveling distance data PD is corrected before the self-supporting unmanned vehicle 1 actually reaches the side of the step 4a. There was a problem that the correction was not made accurately.

The present invention has been made in view of the above-mentioned circumstances, and corrects the position detection error of the step portion of the side wall surface caused by the directivity of the ultrasonic sensor, and travels measured based on the rotation speed of the drive wheel. It is an object of the present invention to provide a self-supporting unmanned vehicle in which distance data can be corrected accurately.

"Means for Solving Problems" The present invention relates to a traveling distance measuring means for measuring a traveling distance from a traveling start point based on the number of rotations of driving wheels, and an ultrasonic sensor for emitting and detecting ultrasonic waves. An ultrasonic distance measuring method for measuring a distance to a side wall surface existing on a side of a planned traveling route based on an ultrasonic wave propagation time from when the ultrasonic sensor emits an ultrasonic wave to when the reflected wave is detected. Means for storing the distance data corresponding to the distance from the travel start point to the position on the side of each step of the side wall surface in each part of the planned travel route; and the ultrasonic distance measuring device. Step detecting means for detecting a step on the side wall surface based on a change in the distance measuring data measured by the means, and the distance measuring data of the ultrasonic distance measuring means at the time when each step is detected. Horizontal orientation of the ultrasonic sensor Position detection error calculating means for calculating a position detection error, which is a distance between the position of the lateral side of the stepped portion and the position of the self-supporting unmanned vehicle at the time when the stepped portion is detected, A travel distance calculating means for adding the travel distance measured by the distance measuring means and the position detection error calculated by the position detection error calculating means to obtain a travel arrival distance at the step portion, the travel expected travel distance at the step portion, and It is characterized by comprising a correction means for correcting the traveling distance measured by the traveling distance measuring means so that the distance data stored in the storage means becomes equal.

"Operation" At the time when each step portion of the side wall surface is detected based on the change in the distance measurement data measured by the ultrasonic distance measuring means, the distance measuring data of the ultrasonic distance measuring means and the horizontal direction of the ultrasonic sensor are detected. Based on the directivity, a position detection error, which is the distance between the position of the lateral side of each step on the side wall surface and the position of the self-supporting unmanned vehicle at the time when the step is detected, is calculated. And
The travel distance measured by the travel distance measuring means and the position detection error calculated by the position detection error calculating means are added to obtain the expected travel distance of the step portion. Furthermore, in order to make the expected traveling distance at the step portion equal to the distance data stored in the storage means,
The mileage measured by the mileage measuring means is corrected. As a result, the position detection error of each step of the side wall surface caused by the directivity of the ultrasonic sensor is corrected, and the traveling distance data measured based on the rotation speed of the drive wheel is corrected accurately.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In this figure, 10a and 10b are left and right drive wheels, and 11a and 11b.
Is a motor for rotating the left and right drive wheels 10a, 10b respectively, 12a, 1
Reference numeral 2b is a pulse encoder that detects the rotational speeds of the left and right drive wheels 10a and 10b, respectively. Further, 14 is a traveling control device, which is a CPU
(Central processing unit) 15, ROM (read only memory) 16 in which programs used in this CPU 15 are stored, and RAM (random access memory) 17 in which various data are stored
And I / O interface (input / output interface) 1
8 and drivers 19a and 19b.

In addition to the conventional travel control program, the ROM 16 stores the detection error correction processing subroutine shown in FIG. 2, which is an essential part of this embodiment. Also, in RAM17,
As in the conventional case, in addition to the information about the planned traveling route 3, the self-supporting unmanned vehicle 1 and the side wall surface 4 in each part of the planned traveling route 3 are also included.
Distance data (for example, distances S ₁ and S ₂ ) between them, that is, distance data for course correction, and each step from the start point of travel.
Distance data up to 4a (for example, distance L ₁ from point P ₁ to point Q ₁ where step portion 4a of side wall surface 4 is formed), that is, distance data for travel distance correction, is stored in advance. In addition, drivers 19a and 19b connect the CPU 15 to the I / O interface 18
Based on the drive command supplied via
Rotate b respectively. The pulse signals output from the pulse encoders 12a and 12b are I / O interface 18
Is supplied to the CPU 15 via the and is counted, and the count value is sequentially written in the traveling distance storage area in the RAM 17 as traveling distance data PD.

On the other hand, 20 is an ultrasonic sensor 2 for transmitting ultrasonic waves to the side wall surface 4
Ultrasonic ranging for measuring the distance between the self-supporting unmanned vehicle 1 and the side wall surface 4 by measuring the ultrasonic wave propagation time from the radiation of the reflected wave to the detection by the ultrasonic sensor 2 The distance measurement data XD output from the ultrasonic distance measurement circuit 20 is a circuit via the I / O interface 18 to the CPU 15
Is supplied to. In this case, the ultrasonic sensor 2 has a directivity of ± θ in the horizontal direction.

Next, the operation of the self-supporting unmanned vehicle 21 having the above-described configuration will be described with reference to FIGS. 2 and 3. However,
The description will be made on the assumption that the height of the side wall surface 4 is higher than the height of the ultrasonic sensor 2 provided in the self-supporting unmanned vehicle 21.

First, the traveling control device 14 determines the distance to the side wall surface 4 obtained by the ultrasonic sensor 2, that is, the ultrasonic distance measuring circuit 20.
Based on the distance measurement data XD output from the vehicle and the route correction distance data stored in advance in the RAM 17, that is, the distance data between the self-supporting unmanned vehicle 1 and the side wall surface 4 in each part of the planned traveling route 3. By controlling the rotational speeds of the drive wheels 10a and 10b respectively, the course is corrected so that the self-supporting unmanned vehicle 21 always travels on the planned travel route 3. The above operation is similar to the conventional one.

Next, the self-supporting unmanned vehicle 21 detects the stepped portion 4a of the side wall surface 4, corrects the position detection error caused by the directivity ± θ of the ultrasonic sensor 2 at this time, and corrects the drive wheels 10a and 10b. The operation of correcting the traveled distance data PD measured based on the rotation speed will be described.

When the step 4a is protruding In this case, as shown in Fig. 3 (a), the self-supporting unmanned vehicle
The stepped portion 4a is detected when it reaches the side just before the point R ₁ on the front side of the position Q ₁ where the stepped portion 4a protruding from 21 is formed. That is, the distance measurement data XD output from the ultrasonic distance measurement circuit 20 corresponds to the approximate distance S ₂ that is smaller than the distance S ₁ when the self-supporting unmanned vehicle 21 arrives just beside the point R _1. It becomes the value x. The CPU 15 detects the step portion 4a based on the change in the distance measurement data XD supplied from the ultrasonic distance measurement circuit 20 through the I / O interface 18, and thereafter executes the position detection error correction subroutine shown in FIG. Run.

First, in step SP ₁ shown in FIG.
When the stepped portion 4a of the is detected, the process proceeds to step SP _2, whether protruding step 4a is determined. Here, the distance measurement data XD
If a is changed in a direction to be small, it is determined that it has detected a step 4a protruding, the process advances to step SP _3. In this step SP ₃ , the currently obtained distance measurement data XD = x,
The position detection error Δx is calculated based on the directivity ± θ of the ultrasonic sensor 2. That is, the position detection error Δx is obtained by Δx = x · sin θ, as is apparent from FIG. Next, at step SP ₄ , the traveling distance data PD temporarily stored in the traveling distance data storage area of the RAM 17 is corrected based on the position detection error Δx obtained at the previous step SP ₃ . That is, the mileage data PDD at the time when the self-supporting unmanned vehicle 21 arrives just beside the point R ₁ and the step 4a is detected is lr.
(See FIG. 3 (a)) (however, it is not always lr = L ₂ ), when the self-supporting unmanned vehicle 21 actually arrives at the right side of the position Q ₁ where the step portion 4a is formed. The expected travel distance data PD is obtained by lq = lr + Δx (however, it is not always lq = L ₁ ).

Next, the value lq of the mileage data PD that is expected to be obtained when the vehicle reaches the right side of the step 4a, which is calculated in step SP ₄ , and the mileage correction value previously stored in the RAM 17 for correction. The travel distance data PD is corrected based on the distance data L ₁ . That is, what should be the main body lq = L ₁ is actually slipped on the drive wheels 10a, 10b, so that ld
≠ L ₁ . Therefore, the pulse encoders 11a and 11b
The mileage data PD obtained based on the pulse output of is corrected. After that, the traveling control is performed on the basis of the corrected traveling distance data PD.

When the step 4a is dented In this case, as shown in Fig. 3 (b), the self-supporting unmanned vehicle
The stepped portion 4a is detected when it reaches the position just beside the point F ₁ which passes through the position Q ₁ where the stepped portion 4a having the depression 21 is formed. That is, the distance measurement data XD output from the ultrasonic distance measurement circuit 20 becomes larger than the distance S ₂ at the time when the self-supporting unmanned vehicle 21 arrives just beside the point F ₁ . The CPU 15 detects the step portion 4a based on the change in the distance measurement data XD supplied from the ultrasonic distance measurement circuit 20 via the I / O interface 18,
After that, the position detection error correction subroutine shown in FIG. 2 is executed.

First, in step SP ₁ shown in FIG.
When the stepped portion 4a of the is detected, the process proceeds to step SP _2, whether protruding step 4a is determined. Here, the distance measurement data XD
When it changes to a larger value, it is determined that the recessed step 4a is detected, and the process proceeds to the next step SP ₅ . This step S
At P ₅ , the position detection error Δx is calculated based on the distance measurement data XD = x obtained previously and the directivity ± θ of the ultrasonic sensor 2. That is, the position detection error Δx is obtained by Δx = x · (−sin θ), as is clear from FIG. Then, in step SP _6, based on the position detection error Δx obtained in the previous step SP _5, the correction of traveling distance data PD stored temporarily in the travel distance data storage area of the RAM17 are performed. That is, the mileage data PD at the time when the self-supporting unmanned vehicle 21 arrives just beside the point F ₁ and the step portion 4a is detected is lf.
(See FIG. 3 (b)) (however, not necessarily lf = L ₂ ), the self-supporting unmanned vehicle 21 is at the position where the step portion 4a is formed.
The travel distance data PD expected to be obtained when the vehicle arrives on the right side of Q ₁ is obtained by lq = lf−Δx (however, lq = L ₁ is not always satisfied).

Then, calculated in step SP _6, the value lq mileage data PD that is expected to obtain the time it reaches the positive side of the stepped portion 4a, for mileage modified previously stored in the RAM17 The travel distance data PD is corrected based on the distance data L ₁ . After that, the traveling control is performed on the basis of the corrected traveling distance data PD.

As described above, the position detection error of the step portion 4a of the side wall 4 caused by the directivity of the ultrasonic sensor 2 is corrected, and the traveling distance data measured based on the rotation speeds of the drive wheels 10a and 10b. The PD is corrected correctly.

In addition, in the above-described embodiment, the ultrasonic sensor 2
The case where the self-supporting unmanned vehicle 21 is provided on only one side surface has been described as an example. However, a pair of ultrasonic sensors 2 are provided on both side surfaces, and the distance between the left and right side wall surfaces of the planned travel route 3 is present. Of course, it may be configured such that the traveling control is performed while detecting each of the above.

[Advantages of the Invention] As described above, according to the present invention, the position detection error of the step of the side wall surface caused by the directivity of the ultrasonic sensor is corrected and measured based on the rotational speed of the drive wheel. It is possible to obtain an effect that the traveled distance data is corrected accurately.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention,
FIG. 2 is a flow chart for explaining a position detection error correction subroutine which is a main part of the embodiment, and FIG. 3 (a).
And (b) is a plan view for explaining the operation of the embodiment, and FIG. 4 is a view for explaining the traveling operation of the self-supporting unmanned vehicle traveling while correcting the course and the traveling distance using the conventional ultrasonic sensor. FIG. 5 is a plan view for doing so, and FIG. 5 is a diagram for explaining a position detection error Δx caused by the directivity of the ultrasonic sensor 2 in the conventional self-supporting unmanned vehicle. 2 ... Ultrasonic sensor, 3 ... Expected travel route, 4 ... Side wall surface, 4a ... Step portion, 10a, 10b ... Driving wheel, 11a, 11b ... Motor, 12a, 12b ... Pulse encoder, 14 ...... Running control device, 15 …… CPU, 16 …… ROM, 17 …… RAM, 18 …… I / O interface, 19a, 19b …… Driver, 20 …… Ultrasonic ranging circuit, 21 …… Unmanned vehicle , ± θ ... Horizontal directivity of the ultrasonic sensor 2, Δx ... Position detection error.

Claims (1)

[Claims] 1. A travel distance measuring means for measuring a travel distance from a travel start point based on the number of rotations of driving wheels, an ultrasonic sensor for emitting and detecting an ultrasonic wave, and the ultrasonic sensor detects an ultrasonic wave. Ultrasonic distance measuring means for measuring the distance to the side wall surface existing on the side of the planned traveling route based on the ultrasonic wave propagation time from the emission to the detection of the reflected wave, and each part of the planned traveling route Of the distance measuring data measured by the ultrasonic distance measuring means, the memory means storing distance data corresponding to a distance from the traveling start point to a position on the side of each step of the side wall surface. Step detecting means for detecting a step on the side wall surface based on the change, and distance measurement data of the ultrasonic distance measuring means and horizontal direction of the ultrasonic sensor at the time when each step is detected. Based on the Position detection error calculating means for calculating a position detection error which is a distance between the position of the lateral side and the position of the self-supporting unmanned vehicle at the time when the step portion is detected, and the traveling distance measured by the traveling distance measuring means. A travel distance calculating unit that adds the position detection error calculated by the position detection error calculating unit to an estimated travel distance of the step portion, the estimated travel distance of the step portion, and the distance data stored in the storage unit. And a correction unit that corrects the traveling distance measured by the traveling distance measuring unit so that the two become equal to each other.