JPH0322108A - Mobile robot - Google Patents

Abstract

PURPOSE:To exactly reach a destination even in the case of long distance travel by searching a traveling route by referring to map information, and controlling the travel as referring to travel distance going along the traveling route, and correcting the travel distance by ultrasonic-measuring distance to a wall in the front or the rear of the traveling route. CONSTITUTION:The traveling route is searched by referring to the map information in a map memory to store the map information including the position information of the wall positioned at the front or the rear in the route in a map part 5, and the travel is controlled as referring to the travel distance measured by a travel distance measuring part. Then, the distance to the wall positioned in the front or the rear of the traveling route is measured by an ultrasonic distance measuring part 13, and the measured travel distance is corrected by a travel distance correcting means. Thus, the accumulation of an error caused according to the travel distance can be prevented, and even if the destination is distant, the mobile robot can stop exactly at a target position, and it can turn smoothly at the corner part of the traveling route.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a mobile robot that corrects a travel distance determined by ultrasonic measurement in order to accurately reach a predetermined location.

"Conventional technology" In recent years, with the development of FA (factory automation), various mobile robot systems consisting of multiple mobile robots and a control station that controls these mobile robots have been developed and put into practical use. .

FIG. 7 shows a schematic structure of this mobile robot system.
2-10) is a mobile robot that has wheels on its running section. The control station 1 instructs each mobile robot 2 wirelessly or by wire to the destination and the work to be performed at the destination. The mobile robot 2 receives instructions from the control station 1, searches for an optimal travel route from map information, and automatically travels to the designated location while checking the shape of walls along the searched optimal travel route using ultrasonic waves. The robot arrives at the location, performs the instructed work at that location, and waits for the next instruction when the task is completed.

``Problem to be Solved by the Invention'' By the way, in the above-mentioned conventional mobile robot system, the determination as to whether or not the robot has arrived at the designated location is performed using the following method and procedure.

That is, the mobile robot first calculates the distance from the starting point to the designated location (hereinafter referred to as travel route distance) based on map information.

Next, the number of rotations of the wheels during running is detected by an encoder, and the distance traveled from the starting point to the current position (hereinafter referred to as the traveling distance) is calculated based on the detected number of rotations of the wheels. It is determined that the designated location has been reached when the travel distance calculated in this way matches the travel route distance.

This method does not cause any problems if the distance to the indicated location is short, but if the indicated location is far away, measurement errors caused by the encoder will accumulate, so This caused the vehicle to stop far away from the target location, and it was no longer possible to correct the position visually.

Furthermore, when the vehicle turns a corner while traveling, there is a problem in that the vehicle cannot turn smoothly due to the cumulative effect of the measurement errors caused by the encoder.

Such a situation has been an obstacle to improving the operational efficiency of the mobile robot 2 and, furthermore, the work efficiency.

This invention was made in view of the above circumstances, and in order to improve the operation efficiency and work efficiency of mobile robot soto,
The purpose of the present invention is to provide a mobile robot that can accurately reach a destination even when traveling long distances.

``Means for Solving the Problems'' In order to solve the above problems, the present invention provides a map memory that stores map information including position information of walls in front or rear of a passage, and a a travel distance measuring unit that measures a travel distance, and searching for a travel route by referring to the map information, and referring to the travel distance measured by the travel distance measurement unit along the searched travel route; a travel control means for controlling travel; an ultrasonic distance measuring unit for ultrasonically measuring the distance to the front or rear wall of the travel route;
Based on the detection signal output from the ultrasonic ranging section,
The vehicle is characterized by comprising a travel distance correcting means for correcting the travel distance measured by the travel distance measuring section.

"Operation" According to this configuration, it is possible to prevent the accumulation of errors that occur depending on the travel distance, and even if the destination is far away, it is possible to stop at the destination position more accurately.

You can also turn corners smoothly.

Therefore, it is possible to improve the operating efficiency of the mobile robot and thus the work efficiency.

"Embodiments" Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(1) Configuration FIG. 1 is a block diagram showing the configuration of the mobile robot 2. As shown in FIG. Note that the general configuration of the mobile robot system of this example is the same as that of the above-mentioned conventional example (FIG. 7).

In FIG. 1, 3 is a command section, and this command section 3 is
When a destination code designated by radio from the control station 1 that supervises a plurality of mobile robots 2 is supplied via the communication device 4, a map stored in the map unit 5 (described later) is sent.
The travel command G required to search for an optimal travel route based on the , determine the nodes to pass through on the way to the destination, and travel along the travel route that sequentially connects these nodes.
(x+y+...) (described later) are sequentially created and output. Here, the term "node" refers to a running state change point provided on a running road, such as a waiting point (station), a stopping point, a branch point, an intersection, or a work point. Reference numeral 6 denotes a command receiving section that receives running commands G (x, y, . . . ) sequentially supplied from the command section 3, and is constituted by a FIFO (first-in, first-out) puffer. The command receiving unit 6 receives the sent driving command G.
(x + y +...) is supplied to the command interpretation section 7 and the trajectory correction section 15. The command interpreter 7 executes a series of travel commands G (x, y +...), ?・
Interpret and create a running pattern for mobile robot 2,
It is supplied to the servo command generator 8 as a running pattern signal VX+vll+θ. Here, the running pattern includes a speed pattern, a rotation pattern, a temporary stop pattern, and the like. The servo command generation unit 8 reads the traveling pattern signal vK+vW+θ supplied from the command interpretation unit 7 at every predetermined sampling period, and compares these signals with a feedback signal Vxf+vyf+θ, which will be described later, to generate deviation signals Δv8, ΔV■Δθ. These signals are converted into analog signals and then supplied to the servo control section 9. As a result, the servo control unit 9 receives the deviation signal Δ
The left and right motors 1 are adjusted so that vx, ΔVFIΔθ becomes zero.
Drive control of 0a and 10b to drive left and right wheels 118.1l.
Rotate b. The rotation speeds of the motors 10a, 10b are converted into electric pulses by left and right encoders 12a, 12b connected to the rotation shafts of the motors 10a, 10b, respectively, and are supplied to the trajectory correction unit l5. l3 is a mobile robot
An ultrasonic distance measurement unit that uses ultrasonic waves to measure the distance from the wall to each wall on the left, right, front, and rear? Ru. This ultrasonic sub-range section 13 drives ultrasonic transmitters 13a, 13a, . The reflected waves from each wall are received by four corresponding ultrasonic receivers 13b, 13b, . . . , and the distance to each wall is measured based on the elapsed time. This measurement result is supplied to the environment recognition section 14. The environment recognition unit 14 transfers the measurement results to the trajectory correction unit 15, and also determines the presence or absence of walls and changing points (edges).
is detected, and this detection result is also supplied to the trajectory correction section 15. The trajectory correction unit 15 includes left and right encoders 12a and 12b.
The travel distance and travel speed are determined by counting the pulse signals sent from each side, and the rotation angle is determined from the difference between the left and right pulse signals. Then, the trajectory correction unit l5
In order to travel based on the contents of the scene table SCT (i & description), the travel distance, travel speed, and rotation angle calculated from the pulse signal are compared with the output data from the environment recognition unit 14 to provide speed feedback. signal v8■vyr,
A rotation angle feedback signal θ is created.

Note that the traveling distance obtained from the pulse signal is subject to certain corrections, which will be described later. The above is the configuration of this embodiment, and the above-mentioned components 6 to 1
5 constitutes a traveling section 20, and the command section 3 and the traveling section 20 constitute the mobile robot 2.

(2) Map (information) Next, the map (information) stored in the map section 5 will be described in detail.

The map is composed of a card number table NDT, a card connection information table NWT, and a scene table SCT.

(A) Node number table NDT (FIG. 2) As shown in FIG. 2, registered node numbers are stored in the node number table NDT in the order of registration.

(B) Network information table NWT (.Figure 3)
As shown in FIG. 3, the network information table NWT stores network information of registered nodes in association with node numbers. Network information table NW
T is composed of the columns shown below.

(a) Node World Coordinates Column This column describes the position data of the node displayed in the XY coordinate system.

(b) Work point world coordinate column This column describes the position data of the work point displayed in the XY coordinate system. However, if no work point is connected to the node, it will not be described.

(C) Connected Node Number Column This column stores other 7 code numbers connected to the node. In this example, the maximum number of nodes connected to one node is four. Therefore, a maximum of four node numbers are stored.

(d) Scene table number column This column contains a scene table SC in which there are two series of scenes (scenes) between nodes corresponding to the connected node number.
This is a column indicating in which of T the data is stored.

(e) Scene Offset Column This column stores a scene pointer (address) indicating at which node in the scene table SCT a series of scenes between nodes corresponding to the connected node number begins.

The above-described node number table NDT and network information table NWT are referred to when the command unit 3 searches for a route and creates a travel command.

(C) Scene table SCT As shown in FIG.
A sequence of scenes from one node to the next (
This is a table that stores wall conditions) and running conditions in association with scene pointers (contents of the scene offset field).

The scene table SCT is composed of the columns shown below.

(a) Start node number field This column stores the number of the starting point node.

(b) End node number column This column stores the number of the end node. Note that the starting point node and the ending point node are simply two adjacent nodes, one of which is referred to as the starting point node and the other as the ending point node.

(c) Straight-line distance between nodes column This column stores the value of the straight-line distance from the start point node to the end point node determined from the position coordinates.

(d) Actual Measured Distance Between Nodes Column This column stores the actually measured distance from the starting point/- to the ending node. However, there is a value only if the node is not a straight line, and if it is a straight line, "0" is stored.

(e) Forward Travel Offset Column This column stores the travel offset value from the reference line when traveling from the start point node to the end point node. here,
The reference line generally refers to a straight line connecting a starting point node and an ending point node. When the above travel offset value is positive, it instructs to travel offset to the left from the reference line (with respect to the traveling direction), and when the travel offset value is negative,
Instructs the vehicle to travel offset to the right from the reference line (with respect to the direction of travel). In this manner, by arbitrarily setting the travel offset value, it is possible to specify driving on the right, driving on the left, driving on the right edge, or driving on the left edge.

(f) Reverse direction travel offset} column This column stores the travel offset value from the reference line when traveling from the end point node to the start point node. The reference line and travel offset value are as explained in the forward direction travel offset section.

(g) Speed limit column This column stores the maximum speed limit between the nodes.

(h) Left and Right Scene Command Column This column describes the status of the left and right walls. When the left or right wall is within the maximum measurement distance of the ultrasonic distance measuring unit l3, the "distance to the wall" and the length of each wall are described. The above-mentioned reference line is determined by the above-mentioned "distance to the wall".

In other words, the distance between the left (or right) wall and the left (or right) side of the mobile robot is called the "distance to the wall".
(Indicated by symbol D in FIG. 5) means that the mobile robot 2 is located on the reference line. To make the mobile robot 2 travel along the reference line, enter the travel offset column (e). The travel offset value in (f) may be set to "0". Here, if there are changing points (edges) on the left and right walls, the "distance to the wall" and the length of the wall are described for each changing point. Furthermore, when there is no wall within the maximum measurement distance of the ultrasonic distance measuring unit l3, that is, when the oven is in the oven state, the distance of the open section is described.

(i) "World coordinates of front and rear walls" column If there is a wall in front or behind this scene n, this column contains the position data of the representative points of the front and rear walls displayed in the XY coordinate system. Described. The representative point is usually a reference line S 1111 5 as shown in FIG.
The intersection of n and the front and rear walls (X a. Y m), (X
n, Yn) is selected. Note that if there is no front or rear wall within the maximum measurement distance of the ultrasonic distance measuring section 13, position data of the wall is not described.

The scene table SCT is referred to by the traveling section 20 when the mobile robot 2 travels.

(3) Travel Command Next, the travel command issued by the command unit 3 will be described in detail.

The running command consists of a GO command, a WAIT command, etc.

(a) Go command The Go command is a command that provides information for traveling on a continuous route.

The Go command is written in the following format.

<Go>=GO(x, y, v, θ+ p+ n) Here, X is a variable that specifies the traveling distance (mm) in the X-axis direction shown in Figure 5, and when robot 2
The forward distance is specified, and when X is negative, the backward distance is specified. y is the traveling distance in the Y-axis direction shown in Figure 5! ! It
(mm); when y is positive, the leftward movement distance of the mobile robot 2 is specified, and when it is negative, the rightward movement distance is specified. Further, V is a variable indicating the composite speed of the X-axis (forward/reverse) speed component and the Y-axis (left/right) speed component.

θ is a variable indicating the rotation angle (rad) of the mobile robot 2 at the time of command execution (when θ is counterclockwise, it is assumed to be in the positive direction). p is the scene pointer mentioned above. Further, n specifies the node number reached after the command is executed.

(b) WAIT Command This command is a command that instructs the temporary stop of the running operation, the stopping method, the brake state after stopping, the servo power state after stopping, and also provides information such as the reason for stopping.

The WAIT command is written in the following format.

〈W^IT〉=11AIT(f, b, s, r
) Here, f is a parameter specifying the stopping method, and when f is "0", it means a slow deceleration stop, and when f is "1", it means a sudden stop. b is a parameter that specifies the brake state after stopping; when b is rOJ, it means the brake is not applied, and when it is rlJ, it means the brake is applied. S is a parameter that specifies the servo power state after stopping; when S is "0", it means the servo power is off, and when it is "1", it means the servo power is on. r is a parameter indicating the reason for stopping, and when r is "0", the normal pause state is changed to "1".
'' specifies the stopped state after work positioning, "2" specifies the stopped state after returning to the station, and "3" specifies the stopped state after job completion.

(4) Principle of correction of mileage distance Next, with reference to FIG. 5, the principle of correction of mileage distance applied to this example will be explained.

The mobile robot 2 first searches for a travel route from the starting position to the destination by referring to a map, then calculates the travel route distance, and then starts traveling along the searched travel route. While traveling, the trajectory correction unit l5 receives the command receiving unit 6.
The vehicle moves while correcting its trajectory while referring to the scene n (in the scene table SCT) specified by the scene pointer p (which is part of the GO command) supplied from the GO command.
At this time, also refer to the "world coordinates of front and rear walls" column.

If it is determined that there is a wall in front or behind from the "world coordinates of front and rear walls" column, the position coordinates of the wall and the position coordinates of the starting position are read out, a predetermined calculation is performed, and the wall is moved from the starting position to the wall. Calculate the distance M to. This distance wlM is hereinafter referred to as the distance M to the wall on the map. On the other hand, the ultrasonic ranging unit 13 emits ultrasonic waves toward the wall from an ultrasonic transmitter 13a attached to the front or rear side of the mobile robot 2, and transmits the reflected waves to an ultrasonic receiver l3.
By receiving the signal from b, the actual measured value L from the wall to the mobile robot 2 is obtained. The trajectory correction unit 15 uses the encoders 12a, 12 on the actual measurement value L obtained in this way.
The travel distance S up to the present time obtained based on the detection signal from b is added. The added value (L+S) obtained in this way is calculated below as the distance to the wall on the encoder (L+S).
). Next, the trajectory correction unit l5 calculates the distance to the wall on the map! ! Distance from lIM to the wall above the encoder (L + S
) is subtracted. The subtraction result ΔM thus obtained indicates the cumulative distance measurement error by the encoders 12a and 12b. Next, the trajectory correction unit l5 encodes the encoders 12a, 1
ΔM (including positive and negative) is added to the traveling distance S obtained from 2b. The addition result thus obtained indicates the corrected travel distance M(S+ΔM). The trajectory correction unit 15 converts the numerical content of the distance traveled up to the present time from S (S + ΔM).
After that, the distance measurement data obtained from the encoders 12a and 12b are sequentially added to the corrected distance (S+ΔM) as the vehicle travels to measure the distance traveled. When the travel distance updated in accordance with the rotation of the wheels 11a, llb matches the travel route distance, it is determined that the destination has been reached.

(5) Operation Next, the traveling operation of the mobile robot described above will be explained with reference to FIG.

First, it is assumed that the mobile robot 2 is waiting at the position of node n0. Here, when the control station 1 instructs the node n4 as the destination, the command unit 3 that received this instruction determines the shortest travel route from the node n0 to 04 based on the map (information) of the map unit 5. search, no-+nI-+n
, →n3→n4 is determined. The search methods applied here include the well-known vertical search method and horizontal search method.

When the travel route is thus determined, the command section 3 creates the following series of travel commands as commands to be transferred to the travel section 20.

<G○+>1G O (X OI+ o, vQl+
'+pOI+n+)<c o ,)1c o (
x I1+01 v +t+-1.5708+ p I
I n 2) <GOz>=GO(Xts+O, V**,
+1.5708, pt3+n*)<c O 4>= G
O (X 34+0+ V 34, -1.57081
p341 n 4) <WAIT>= IIIAIT (
0,1,0.0) The first run command <CO,> is the current node n.

Without changing direction, the speed is V. 1 means that moving forward by XOI will reach node n. Furthermore, the scene (scene of the surrounding walls) that may be seen while traveling from node n0 to node n1 is p of the scene table SCT.

This shows that it is stored at address 1. Second
The th running command <G0,> is from node n, to θ+
t=-1. X. in the direction of rotation of 5708 rad, that is, in the direction of 90 degrees clockwise, at a speed of v1. This means that if you move forward, you will reach 7th grade. Further, it is shown that the scene of the surrounding wall that may be seen while traveling from node n1 to node n is stored at the address I)+t. The third running command <G03> is from node n, θxs= +l, 5
708 rad rotation direction, i.e. 9 counterclockwise
This means that if the vehicle moves forward by Xt3 at a speed of Vt3 in the direction in which the direction has changed by 0 degrees, it will reach node n3. Also,
This shows that the scene (scene of the surrounding walls) that may be seen while traveling from node n to node n is stored at the address pts in the scene table SCT.

4th running command <GO. > is node n,
θs* - 1.5708 rad rotated direction, that is, 90 degrees clockwise, speed V3
This means that if you move forward by X34 at 4, you will reach 7th node n4. Also, while traveling from node n to node n4, the scene of the surrounding walls that may be seen is p! This shows that it is stored at address 4. Further, the fifth running command <WAIT> instructs a temporary stop of the operation (slow deceleration and stop). Then, after stopping, apply the brakes,
Instructs to turn off the servo power supply. When such a running command is received by the command receiving unit 6, as described above, the command receiving unit 6 transfers the received running command to the command interpreting unit 7, and also converts the scene pointer which is a component of the Go command. p is transferred to the trajectory correction unit l5. The command interpreter 7 interprets the supplied travel command, creates a travel pattern (speed pattern, rotation pattern), and sends it to the servo command creator 8. When the trajectory correction unit 15 receives the scene pointer p, it reads out the scene n specified by the scene pointer p from the scene table SCT of the map unit 5, and reads it from the environment recognition unit l4 in order to follow the instructions and contents of the scene n. Compare the output data of and the output pulses from encoders 12a and 12b,
Create speed and rotation angle feedback signals. Furthermore, upon receiving each scene pointer p, the trajectory correction unit l5 reads the contents (position data of the front and rear walls) written in the "world coordinates of front and rear walls" column of the scene specified by the scene pointer p. The distance traveled to the current position is corrected using the same procedure as described in the above-mentioned "Distance Correction Principle". In this way, the vehicle travels toward the destination while constantly repeating corrections to the travel distance. Then, the traveling distance is the traveling route distance (xot1X,,+Xx3
+X When 3a) is matched, destination n. is determined to have been reached.

In this way, in the case of the running example shown in FIG. 6, even if the inter-node distance x01+ Failure to bend can be prevented.

Further, even if the inter-node distance 1'tI X34 is sufficiently large, it is possible to accurately stop at the node n4 (with an accuracy within the range that allows visual position correction).

Furthermore, even in the case of long-distance travel that includes many straight sections, the above structure allows the vehicle to reach the destination accurately.

Therefore, it is possible to improve the operation efficiency of the mobile robot, and thus the work efficiency.

In the above embodiment, the distance traveled from the starting point to the final destination is accumulated, and when the accumulated driving distance matches the driving route distance from the starting point to the final destination, the distance traveled from the starting point to the final destination is reached. We have described the case where it is determined that the target has been reached, but as a modification of this invention, by the method shown below,
You can also adjust the mileage.

In other words, the distance traveled up to a specific 7th node, which is the waypoint, is accumulated, the accumulated distance is compared with the distance on the map up to the node, and if there is an error, the stopping position is determined. is corrected and stopped at the relevant node. After stopping at the corrected position, the accumulated mileage is cleared and a new mileage measurement is started from the node. This modification is particularly effective when the travel route includes many turns (FIG. 6).

In addition, in the case of the above modification, if the node does not stop at the above node, the distance to the next 7th node may be added or subtracted, and if this is done, it is especially possible to increase the number of straight sections on the travel route. It is effective when it includes.

"Effects of the Invention" As explained above, the present invention provides a map memory that stores map information including position information of walls in front or behind a passageway, and a map memory that stores map information including position information of walls in front or behind a passage, and a distance measuring section, and a traveling control that searches for a traveling route by referring to the map information and controls traveling along the searched traveling route and with reference to the traveling distance measured by the traveling distance measuring section. means, an ultrasonic distance measuring section that ultrasonically measures a distance to a wall in front or behind the traveling route, and measurement by the traveling distance measuring section based on a detection signal output from the ultrasonic distance measuring section. Since it is equipped with a travel distance correction means that corrects the travel distance, it is possible to prevent the accumulation of errors that occur depending on the travel distance, and even when the destination is far away, it is possible to more accurately reach the destination location. Can be stopped.

Additionally, corners of the travel route can be turned smoothly.

Therefore, it is possible to improve the operation efficiency of the mobile robot, and thus the work efficiency.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the electrical configuration of a mobile robot according to an embodiment of the present invention, Fig. 2 is a conceptual diagram showing the structure of a maid number table stored in the map section of the mobile robot, and Fig. 3 4 is a conceptual diagram showing the structure of a network information table stored in the map section, and FIG. 4 is a conceptual diagram showing the structure of a scene table stored in the map section.
Fig. 5 is an explanatory diagram for explaining the principle of compensation for the traveling distance applied to the mobile robot, Fig. 6 is an explanatory diagram for explaining the operation of the mobile robot Noto, and Fig. 7 is an explanatory diagram for explaining the movement of the mobile robot Noto. 1 is a diagram showing the structure of a mobile robot soto system to which this is applied. 1...Control station, 2.2~1~2-10...
...Mobile robot, 3...Command section, 5...
...Map section, NDT...Node number table,
NwT・・・Network information table, sCT
......Scene table, 6...◆Command receiving section, 7...Command interpretation section, 8...
・Servo command generation section, 9... Servo control section, 1
2a, 12b... Encoder, 13...
・Ultrasonic ranging section, 14...Environment recognition section, l5.
・・・・・・Track correction department, 2o・゜゜゜゜゜travel department, no
+n++nt+ns+n++ns+nsnt"... ・
・●／One do.

Claims (1)

[Scope of Claims] A map memory that stores map information including position information of walls in front or behind a passage; a travel distance measuring section that measures travel distance from the number of rotations of traveling wheels; a travel control means that searches for a travel route by referring to the travel route and controls travel along the searched travel route while referring to the travel distance measured by the travel distance measuring section; an ultrasonic distance measuring unit that ultrasonically measures the distance to the rear wall; and a detection signal output from the ultrasonic ranging unit,
A mobile robot comprising: a travel distance correcting means for correcting the travel distance measured by the travel distance measuring section.