JP2006252349A - Mobile robot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive mobile robot capable of reducing errors in position measurement, due to the fluctuations of a wheel radius or the like, and enables precise calculation of the current position. <P>SOLUTION: This mobile robot 1 moves on a travel route, comprising a plurality of sections by driving the wheels. A storage part 15 stores route information recorded with a distance between a start point and a terminal in the prescribed section, and an angle difference therebetween. When the terminal in the prescribed section is determined, a wheel information calculating part 57 calculates a wheel feature quantity, such as the wheel diameter and the wheel interval, based on a wheel rotation amount measured between the start point and the terminal in the prescribed section, and based on the route information in the storage part 15. A position calculation part 55 calculates the current position, based on the calculated wheel feature quantity and the measured wheel rotation amount. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mobile robot, and more particularly to improvement of position calculation accuracy in a mobile robot.

  In recent years, mobile robots have been provided that move along a predetermined route to carry articles and monitor abnormalities. In such a mobile robot, the amount of rotation of the wheel is measured, and the current position of the moving object is measured by calculating the moving distance and moving path based on the wheel radius and the left-right wheel interval (tread) inputted in advance. It is known to do.

In Patent Document 1, in particular, while traveling along a magnetic tape as a guide means, the address designation oscillator provided on the road surface is read to perform turning control such as right turn and left turn, and the rotation amount of the wheel is measured by an encoder. Thus, an automatic guided vehicle that calculates a current position from a travel distance is described. This automatic guided vehicle operates so as to detect existing obstacle data stored in advance according to the current position and detect obstacles other than existing ones.
Japanese Patent Laid-Open No. 9-6433 (FIG. 2)

  The conventional automatic guided vehicle described above calculates a moving distance from the rotation amount of the wheel measured by the encoder, and a wheel radius stored in advance is generally used for calculating the moving distance. The automatic guided vehicle controls turning by controlling the left and right driving motors. For such turning control, a left and right wheel interval inputted in advance is generally used.

  However, since the wheel radius varies depending on the air pressure, the road surface condition, and the weight of the vehicle body, using a fixed value may cause an error in the travel distance. In addition, since the ground contact area of the wheel is changed, there is a problem that the distance between the left and right wheels is changed, and the turning angle at the time of curve driving is changed.

  As described above, the conventional automatic guided vehicle may erroneously calculate the current position due to fluctuations in the wheel radius, and may make it difficult to accurately control the turning along the magnetic tape serving as the guide means. .

  Therefore, an object of the present invention is to realize a mobile robot capable of calculating a current position with high accuracy at a low cost by reducing an error in position measurement due to a change in wheel radius or the like.

  The present invention relates to a robot that drives a wheel and travels a traveling route composed of a plurality of sections, and the mobile robot includes a rotation amount detection unit that measures the rotation amount of the wheel and a start point and an end point of a preset predetermined section. Based on the output of the storage unit that stores the route information and the wheel feature amount, the instruction unit detection unit that detects the instruction unit disposed on the travel route, and the output of the instruction unit detection unit A section discriminating unit for detecting the start point and end point of the predetermined section, and when the section discriminating unit discriminates the end point of the predetermined section, based on the wheel rotation amount measured between the start point and end point of the predetermined section and the route information A position for calculating a current position based on a wheel information calculation unit that calculates a wheel feature amount and stores it in a storage unit, a wheel feature amount stored in the storage unit, and a wheel rotation amount measured by the rotation amount detection unit A calculation unit; It is.

  With the above configuration, the wheel feature amount such as the wheel diameter is calculated from the measured wheel rotation amount and the path information stored in advance, and the current position is calculated using the calculated wheel feature amount. Even when the amount changes, the current position can be detected with high accuracy. In addition, a predetermined section is set on the route by using the traveling route of the mobile robot including a plurality of predetermined sections, and the route information stored for the predetermined section is used for traveling in the same section. The wheel feature amount is calculated from the measured wheel rotation amount. Therefore, the wheel feature amount can be obtained by using the function of the mobile robot without adding an expensive configuration, and the current position is obtained with an inexpensive configuration. Detection accuracy can be improved.

  Further, in the present invention, the section discriminating unit discriminates the start point and the end point of the first and second predetermined sections based on the output of the instruction means detecting unit, and the wheel information calculating unit includes the section discriminating unit. When the end point of one predetermined section is determined, based on the wheel rotation amount measured between the start and end points of the first predetermined section and the distance between the start and end points of the first predetermined section recorded in the route information. The wheel diameter as the wheel feature amount may be calculated and stored in the storage unit. Furthermore, the wheel information calculation unit, when the section determination unit determines the end point of the second predetermined section, is recorded in the wheel rotation amount measured between the start point and the end point of the second predetermined section and the route information. Based on the angle difference between the start point and the end point of the second predetermined section and the wheel diameter as the wheel feature value, the driving wheel distance as the wheel feature value (left and right wheel distance) may be calculated and stored in the storage unit. Thereby, the wheel diameter and the distance between the driving wheels can be suitably calculated as the wheel feature amount. The wheel diameter may be a radius (or may be a diameter), and is used for calculating a travel distance. The distance between driving wheels is used for calculating a posture (orientation) together with the wheel diameter, and the current position can be calculated using these pieces of information.

  Further, in the present invention, the mobile robot detects an inclination of the traveling direction of the mobile robot with respect to the direction of the travel route, and the inclination detector at at least one of a start point and an end point of the first predetermined section. A section distance adjustment unit that adjusts the distance between the start point and the end point of the first predetermined section on the route information based on the slope detected by the wheel information calculation unit, the wheel information calculation unit by the section distance adjustment unit The wheel diameter may be calculated based on the adjusted distance.

  In this aspect, the section distance on the route information and the distance that the mobile robot actually travels have a deviation due to the inclination of the robot traveling direction, and the adjustment for correcting this deviation is made the distance on the route information. Has been given. As a result, the wheel diameter can be obtained more accurately by correcting the increase / decrease of the travel distance in the actual section travel, and the calculation accuracy of the current position can be improved.

  Further, in the present invention, the mobile robot detects an inclination of the traveling direction of the mobile robot with respect to the direction of the travel route, and the inclination detector at at least one of a start point and an end point of the second predetermined section. A section angle difference adjustment unit that adjusts an angle difference between the start point and end point of the second predetermined section on the route information based on the inclination detected by the wheel information, and the wheel information calculation unit adjusts the adjusted angle. The distance between the drive wheels may be calculated based on the difference.

  In this aspect, the angle difference between the two ends of the section on the route information and the angle difference actually generated in the mobile robot are caused by a deviation due to the inclination of the robot traveling direction, and adjustment for correcting this deviation is performed on the route information. The angle difference is given. Thereby, the increase / decrease of the angle difference in the actual section traveling can be adjusted and the distance between the drive wheels can be obtained more accurately, and the calculation accuracy of the current position can be improved.

  In addition, the present invention is not limited to the above-described mobile robot. The invention may be expressed and specified in the form of another apparatus, method, program or system. For example, another aspect of the present invention is a current position detection device or a wheel feature amount calculation device provided in the above-described mobile robot or other moving body. Another aspect of the present invention is a current position detection method or a wheel feature amount detection method that performs the operation of the above configuration. Another aspect of the present invention is a method for controlling a mobile robot. Another aspect of the present invention is a program that causes a computer to execute such a method. Another aspect of the present invention is a system in which a mobile robot and a monitoring center are connected by communication.

  As described above, according to the present invention, a mobile robot capable of calculating a current position with high accuracy by reducing an error in position measurement due to a change in wheel radius and the like can be realized at low cost.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The mobile robot according to the present embodiment travels along a predetermined route in a predetermined environment serving as a monitoring area, detects an object that appears or disappears in the monitoring area, and detects an abnormality. When the mobile robot detects an abnormality, it sends an abnormality signal to a remote monitoring center. When the monitoring center receives the abnormality signal, the monitoring center checks the image by the imaging means mounted on the mobile robot, or remotely operates the mobile robot to deal with the abnormality.

  The configuration of the mobile robot is shown in FIG. The mobile robot 1 includes a moving means 3, a movement control unit 5, a guide detection unit 7, a self-position detection unit 9, an obstacle detection unit 11, an obstacle determination unit 13, a storage unit 15, a communication unit 17, an imaging unit 19, and the like. It is comprised from the control part 21 which controls each part, and the power supply part 23 which supplies electric power to each part. Each part will be described below.

  The moving means 3 includes motors 35 and 37 that independently drive the right wheel 31, the left wheel 33, and the left and right wheels. As shown in FIG. 2B, the mobile robot 1 has four wheels, two of which are drive wheels, and correspond to the right wheel 31 and the left wheel 33 in FIG. These driving wheels rotate and the mobile robot 1 travels. The straight traveling speed and the turning traveling speed are controlled by the rotational speeds of the left and right wheels, and the turning direction is also controlled. The rotational speeds of the left and right wheels are independently controlled by the movement control unit 5. Instead of wheel driving, a method of independently controlling the left and right crawlers may be employed.

  The guide detection unit 7 detects guide means on the movement path. The guide means is shown in FIG. As shown in the figure, a white line tape 101 as a guide means is fixedly provided over the entire length of the path on the movement path that the preset mobile robot circulates. In addition to the white line tape 101, an indication marker 103 as a point indication means is fixedly provided at a predetermined point in the route. The indication marker 103 is a pair of white and square marks, and is provided at the boundary of the section set on the movement route. In the present embodiment, for example, a point moving from a straight line to a curve and a point opposite thereto are set as the boundary of the section, and an instruction marker 103 is provided. In addition to the change point between the straight line and the curve, the boundary of the section may be set and the indication marker 103 may be provided within the scope of the present invention. For example, one straight line may be divided into a plurality of sections, and the indication marker 103 may be provided at the boundary of the sections.

  The guide detection unit 7 includes a white line detection camera 41 and an image processing unit 43. The white line detection camera 41 is installed on the bottom surface of the mobile robot 1 so that the road surface can be photographed. The image processing unit 43 is realized by a computer of the mobile robot 1 and has a white line tape 101 to be used to guide the path of the mobile robot 1 from a photographed image of the white line detection camera 41 by processing such as edge extraction and Hough conversion, and an indication marker. 103 is detected and output to the control unit 21. The control unit 21 detects the start point and end point of each section of the travel route based on the detection information of the instruction marker 103 input from the image processing unit 43. That is, the number of detections of the indication marker 103 is counted, and the current section is determined based on the number of detections and the route information. In the present embodiment, the instruction marker 103 corresponds to an instruction unit that indicates a boundary of a section, the guide detection unit 7 corresponds to an instruction unit detection unit, and the control unit 21 functions as a section determination unit.

  In addition, the guide detection part 7 is not limited to said structure. The guide detection unit 7 may be configured by a magnetic sensor, an electromagnetic induction sensor, or the like. In this case, the guide detection unit 7 may be configured to detect a magnetic guide or an electromagnetic induction guide as guide means installed in the movement path. It is preferable that the guide means and the guide detection unit can be selected depending on the installation environment.

  The movement control unit 5 is a means for controlling the drive motors 35 and 37. The movement control unit 5 controls the drive motors 35 and 37 to move along the white line tape 101 by, for example, well-known PID control according to the detection output of the white line tape 101 by the guide detection unit 7. Further, the movement control unit 5 controls the movement speed based on the route information set in advance in response to the detection of the travel section by the self-position detection unit 9. The moving speed is preset for each section and stored as part of the route information.

  The self-position detection unit 9 includes resolvers 51 and 53 and a position calculation unit 55 and functions as a position recognition unit. The self-position detection unit 9 further includes a wheel information calculation unit 57.

  The resolvers 51 and 53 are installed in the motors 35 and 37, respectively, and detect the absolute positions of the motor rotation shafts of the motors 35 and 37, respectively. The resolvers 51 and 53 are one form of the rotation amount detection unit.

  The position calculation unit 55 is realized by a computer of the mobile robot 1 and calculates the rotation amounts of the left and right wheels 31 and 33 from the rotation amount of the motor rotation shaft obtained from the resolver output. The position (X, Y) and posture (θ) are calculated. In this process, the travel distance and the angle change are obtained from the wheel rotation amount, and the position and posture at each time point are captured from these pieces of information. The angle change is calculated from the difference in the wheel rotation amount and the wheel interval (right and left wheel interval, driving wheel distance or tread meaning, the same applies hereinafter). Such position detection is a technique generally known as dead reckoning (autonomous navigation).

  In addition, the position calculation unit 55 recognizes the start point and end point of the movement route, corrects the self-position, and the like according to the detection output of the instruction marker 103 by the guide detection unit 7 and the section determination by the control unit 21.

  The wheel information calculation unit 57 calculates a wheel feature amount from the rotation amounts of the left and right wheels and the route information in the storage unit 15. In the present embodiment, the wheel feature amounts are a wheel radius and a wheel interval. The calculated wheel radius and wheel interval are stored in the storage unit 15 and used for position and orientation calculation in the position calculation unit 55.

  The wheel information calculation unit 57 performs the above calculation process from the wheel rotation amount measured between the start point and end point of the section in response to the section determination by the control unit 21 which is the section determination unit. In the travel route, a wheel diameter update section Tn and a wheel interval update section Tw are set (FIG. 2A), the wheel radius is calculated from the wheel rotation amount in the wheel diameter update section Tn, and the wheel interval update is performed. The wheel interval is calculated from the wheel rotation amount in the section Tw. As the wheel diameter update section Tn, a section that is a straight line and the road surface is approximated horizontally is set. Further, as the wheel interval update section Tw, a section that is a curve and the road surface is approximated horizontally is set.

  The obstacle detection unit 11 is means for detecting an object in front of the mobile robot 1. The obstacle detection unit 11 includes a laser sensor 61 installed toward the front of the mobile robot 1 and receives reflected light when the laser light emitted from the laser oscillator is reflected by an object on the optical path. The obstacle detection unit 11 controls the irradiation direction of the laser light emitted from the laser oscillator by the scanning mirror and the means for rotationally driving the scanning mirror, so that a predetermined range including the front of the mobile robot 1 is set to, for example, 30 msec. Spatial scanning is performed at a period of.

  The obstacle detection unit 11 then scans the distance between the obstacle detection unit 11 calculated from the time from laser light irradiation to reflected light detection and the object (measurement point) reflecting the laser light, and rotationally driven scanning. Based on the angle of the mirror, the relative position of the object reflecting the laser beam, that is, the measurement point reflecting the laser beam is calculated. The relative position is the position of the measurement point with respect to the mobile robot 1.

  The obstacle detection unit 11 may be configured with a sensor other than the laser sensor. For example, the obstacle detection unit 11 may be configured by an infrared type sensor or a millimeter wave radar type sensor.

  The storage unit 15 stores information used for various processes in the mobile robot 1. The information stored in the storage unit 15 includes route information 71 indicating information on the moving route, an environment map 73 indicating the monitoring area in a two-dimensional coordinate system, and the position of the mobile robot 1 calculated by the position calculating unit 55. And position information 75 including the wheel position and wheel information 77 indicating wheel feature information.

  As the route information 71, corresponding to the number of each section (section from one indication marker to the next indication marker) in the movement route, the traveling speed of each section, the section distance measured in advance, the direction between the start point and end point of the section The angle difference (angle difference) is stored. In the route information, the section number is associated with the number of markers (number of detections) to be detected by the corresponding section. In the traveling control, the section number is specified from the number of marker detections, and the traveling speed of each section is specified from the section number.

  In addition to the boundary of the section, the indication marker may be set at other locations (for example, the indication marker is used as a mark of a check point that the mobile robot 1 captures and transmits an image of a predetermined location). In this case, the section is identified by associating the section number with the number of marker detections as described above.

  Further, the route information 71 includes information on a section in which the wheel feature amount is updated. In the present embodiment, a wheel diameter update section Tn (first predetermined section) for updating the wheel radius and a wheel interval update section Tw (second predetermined section) for updating the wheel interval are set (FIG. 2). (A)). More specifically, update identification data is assigned in correspondence with the section number. The update identification data is data indicating whether the corresponding section is the wheel diameter update section Tn, the wheel interval update section Tw, or neither. For these sections, the section distance and the angular difference before and after the section are accurately measured and recorded in order to use them as reference values for calculating the wheel feature amount.

  The environmental map 73 is map information of a monitoring area, and is partitioned by a grid for each predetermined distance, and an identification number is given to each grid. In this embodiment, an example in which an environmental map is partitioned by a 5 cm × 5 cm grid will be described. For example, when dividing every 5 cm × 5 cm, the environmental map of the 500 m square monitoring area is divided into 100 million grids. Along with the environment map 73, existing object information that is position information of existing objects on the environment map is stored. The existing object information includes attribute information of each grid of the environment map 73, and the presence / absence of an existing object is registered as attribute information of each grid, whereby the position of the existing object is specified. The existing object information may be acquired by actually running the mobile robot 1. For example, a mode for generating existing object information is set at times other than patrol, the mobile robot 1 is run along the travel route, and an object detected by the obstacle detection unit 11 at this time is obtained as an existing object. The position of the existing object may be registered in the storage unit 15.

  FIG. 3 is a schematic diagram showing the environment map 73. In FIG. 3, only the peripheral part of the mobile robot 1 is shown. The hatched grid in the figure is a grid in which the position of an object is indicated by existing object information, that is, an existing object grid.

  The position information 75 is the position and posture of the mobile robot calculated by the position calculation unit 55. The position and orientation are calculated from the wheel rotation amount using the following wheel information 77.

  As the wheel information 77, preset radius reference values and wheel interval reference values for the left and right wheels, and the current left and right wheel radiuses and wheel intervals calculated by the wheel information calculation unit 57 are stored. The radius reference value and the wheel interval reference value are fixed values. On the other hand, the wheel radius and the wheel interval calculated by the wheel information calculation unit 57 reflect changes due to wheel air pressure, wear, and the like, and are more accurate values.

  The communication unit 17 is a wireless communication unit that transmits and receives signals to and from a remote monitoring center. When the obstacle determination unit 13 detects an abnormality, the communication unit 17 outputs an abnormality signal wirelessly to a remote monitoring center. The communication unit 17 transmits an image captured by the imaging unit 19 to a remote monitoring center, and inputs a control command received from the monitoring center to the control unit 21.

  The imaging unit 19 is an imaging unit that is mounted on the mobile robot 1 and images the surroundings of the robot. For example, as shown in FIG. 2B, the imaging unit 19 is housed in a hexagonal prism housing at the top of the robot. In the housing, six image pickup units are accommodated in six directions, so that the entire visual field in the horizontal direction is covered. The image captured by the imaging unit 19 is buffered in the storage unit 15 and transmitted from the communication unit 17 to the monitoring center.

  The obstacle determination unit 13 includes an abnormality determination unit 81, and determines whether there is an abnormality based on the output of the obstacle detection unit 11. When an abnormality is determined, an abnormality signal is output from the communication unit 17, and the movement control unit 5 performs predetermined processes such as movement stop and deceleration, obstacle avoidance and tracking.

  The abnormality determination unit 81 determines an abnormality using the environment map and existing object information. When the obstacle detection unit 11 detects an object at a position where there is no existing object, the abnormality determination unit 81 determines that an intruder exists and an abnormality has occurred. In addition, when the existing object is not detected by the obstacle detection unit 11, the abnormality determination unit 81 determines that an abnormality has occurred in which the existing object disappears.

  The obstacle determination unit 13 may determine the presence or absence of an object by the following voting process. In this case, the obstacle determination unit 13 is provided with a voting unit. When the obstacle detection unit 11 measures the relative position of the measurement points, the measurement points measured based on the position and orientation of the mobile robot 1 are measured. The grid corresponding to is determined from the environment map 73, and the vote value is added to the corresponding grid. For this process, the storage unit 15 stores a voting table for recording the voting value of each grid, and the voting value is written into this voting table. And an object determination part is provided, This object determination part determines the presence or absence of the object of each grid based on the vote value for every grid in a voting table. The object determination unit determines that an object exists in the grid whose vote value is equal to or greater than a predetermined threshold value. By performing the voting process as described above, even if an erroneous measurement point is measured when the orientation of the mobile robot 1 is instantaneously blurred, the voting value of such a measurement point does not increase. False detection can be prevented.

  The voting value may be weighted. The weight is preferably inversely proportional to the distance to the measurement point. Furthermore, a weight that is inversely proportional to the distance between adjacent measurement points is attached. A weighted vote value is calculated, and this vote value is added to the corresponding grid of the vote table.

  The control unit 21 is a means for controlling the configuration of each part of the mobile robot 1 described above, and is configured by a computer including a CPU and the like. What can be computer-processed by each part structure of FIG. 1 may be implement | achieved by the same computer. For example, the image processing unit 43 of the guide detection unit 7, the position calculation unit 55 and the wheel information calculation unit 57 of the self-position detection unit 9 are realized by the above-described computer, and a part of the obstacle detection unit 11 and the obstacle determination unit Thirteen functions may also be realized by the same computer. The same applies to the movement control unit 5. For example, an upper command value related to motor control may be calculated and transmitted to the motor drive circuit. Furthermore, the storage unit 15 may be realized by a memory of the computer and an external storage device.

  Next, the operation of the mobile robot 1 according to the present embodiment will be described. Here, the outline of the overall operation of the mobile robot 1 will be described first, and then the operation for obtaining the wheel feature amount will be described.

  The mobile robot 1 is set to the patrol mode when it detects the arrival of a preset patrol start time by a timing means (not shown), or receives an input from the operation unit or a command from the monitoring center, and detects the guide. With the signal from the unit 7 as an input, the movement control unit 5 controls the moving unit 3 to start moving along the white line tape 101 (FIG. 2A) which is a guide unit. The white line tape 101 is detected from the image, and the movement control unit 5 independently controls the rotations of the motors 35 and 37 so that the white line tape 101 always faces a predetermined angle at a predetermined position of the image. In the present embodiment, the movement control unit 5 operates so that the white line tape 101 is directed in the vertical direction at the center of the image. Further, based on the instruction marker 103, the current moving section and the traveling speed are obtained by referring to the route information 71 in the storage unit 15, and the motor rotation is controlled according to the traveling speed.

  When the mobile robot 1 starts to move, the obstacle detection unit 11 is operated to spatially scan the front. When detecting the reflected light, the obstacle detection unit 11 outputs the distance measurement data S (Φm) of the measurement point. Here, Φm is an angle indicating the irradiation direction of the laser beam. For example, the obstacle detection unit 11 scans a range of −90 ° <Φm <90 °, and the front of the mobile robot is 0 °. The obstacle detection unit 11 outputs measurement data at a predetermined short time interval.

When the obstacle determination unit 13 receives an input from the obstacle detection unit 11, the abnormality determination unit 81 determines whether there is an abnormality. At this time, the obstacle determination unit 13 acquires the position (X, Y) and posture θ of the mobile robot 1 on the environment map from the self-position detection unit 9. In the self-position detection unit 9, the position and posture of the mobile robot 1 are calculated from the detection values of the resolvers 51 and 53, the wheel radii, the wheel interval, and the like by a method generally called dead reckoning. The obstacle determination unit 13 projects the output result of the measurement point by the obstacle detection unit 11 on the coordinates on the environment map based on the following formula. That is, the position of the measurement point obtained as a relative position with respect to the mobile robot 1 is converted into coordinates (Xs, Ys) on the environment map.
Xs = X + S (Φm) cos (Φm + θ)
Ys = Y + S (Φm) sin (Φm + θ)

  The abnormality determination unit 81 of the obstacle determination unit 13 determines whether or not there is an abnormality based on the measurement result. At this time, the voting process as described above is performed, and the vote value is added to the grid of the measurement points, and whether or not there is an abnormality may be determined for the grid in which the vote value is equal to or greater than a predetermined threshold value.

  In the abnormality determination, existing object information stored in the storage unit 15 together with the environment map is referred to. If the position of the existing object corresponding to the measurement point is not registered in the storage unit 15, it is determined that there is an object other than the existing object and there is an abnormality (there is an intruder). Moreover, the abnormality determination part 81 determines whether the information of the other existing object which should be located between a measurement point and a self position is registered. If another existing object is registered, the existing object has disappeared, so the abnormality determination unit 81 determines that there is an abnormality. If the abnormality determination unit 81 determines that there is an abnormality, the control unit 21 stops the traveling of the mobile robot 1 and further outputs an abnormality signal from the communication unit 17 to the monitoring center.

  While performing obstacle detection and abnormality determination as described above, the mobile robot 1 travels to the end point of the movement route.

  Next, an outline of the operation of the mobile robot 1 for obtaining the wheel feature amount will be described. The mobile robot 1 detects the instruction marker 103 while traveling along the travel route, determines the section in progress, and determines whether the current section is the wheel diameter update section Tn or the wheel interval update section Tw. .

  The mobile robot 1 calculates the wheel radius in the wheel diameter update section Tn, and updates the wheel radius in the wheel information in the storage unit 15. At this time, the wheel information calculation unit 57 acquires the rotation amount of the left and right wheels from the output of the resolvers 51 and 53 until it passes through the marker at the start point of the section Tn and passes through the marker at the end point. Then, the wheel radius of each of the left and right wheels is calculated from the rotation amount using the section distance in the route information.

  Further, the mobile robot 1 calculates the wheel interval in the wheel interval update section Tw, and updates the wheel interval in the wheel information in the storage unit 15. At this time, the wheel information calculation unit 57 obtains the rotation amounts of the left and right wheels from the output of the resolvers 51 and 53 until it passes through the marker at the start point of the section Tw and passes through the marker at the end point. Then, the wheel interval is calculated using the angle difference in the route information (the angle difference between the start point and the end point, which is expressed by the difference between the route tangent angles).

  The wheel radius is also used for calculating the wheel interval. Therefore, it is desirable to set the wheel interval update section Tw in the subsequent stage rather than the wheel diameter update section Tn on the route. Thereby, since the wheel interval can be calculated using the updated wheel diameter, the calculation accuracy of the wheel interval is improved.

  Next, the details of the wheel feature amount calculation processing will be described with reference to the flowcharts of FIGS. These drawings show the calculation operation of the current position and the detection operation of the wheel radius and the wheel interval, and are mainly performed by the position calculation unit 55 and the wheel information calculation unit 57 of the self-position detection unit 9.

As shown in FIG. 4, when traveling starts, an initial state of a carriage (mobile robot) as described below is set (S1).
Current position: (X0, Y0)
Current posture: θ0
Current section n: n0

Then, measurement of the wheel rotation speed by the resolvers 51 and 53 is started (S3), and the wheel rotation speed is stored as follows (S5). In the following, for example, wheel A is the right drive wheel and wheel B is the left drive wheel.
Wheel A rotation speed: La1
Wheel B rotation speed: Lb1
Further, the wheel rotational speed measured in the next cycle is also stored as follows (S7).
Wheel A rotation speed: La2
Wheel B rotation speed: Lb2

Then, the position and orientation of the carriage are calculated from the above rotational speed information according to the following formula (S9). Here, according to the following expression, the left and right wheel rotation amounts between the measurement points represented by subscripts 1 and 2 twice (two cycles) are obtained, and the change amount of the position and orientation is obtained.
Wheel A rotation amount: θa (= La2-La1)
Wheel B rotation amount: θb (= Lb2-Lb1)
Wheel A travel distance: Da (= Ra × θa)
Wheel B travel distance: Db (= Rb × θb)
Dolly turning angle: θ (= (Da−Db) / W)
Translation distance: Ds (= (Da + Db) / 2)

Here, Ra is the radius of the wheel A, Rb is the radius of the wheel B, W is the wheel interval, and are acquired from the storage unit 15. Further, the current position (Xt + 1, Yt + 1) and the current posture (θt + 1) are obtained from the stored current position (Xt, Yt) and posture (θt) one cycle before by the following equations. . In the first measurement after the start of traveling, the value (X0, Y0) (θ0) in the initial state is used as the value one cycle before.
θt + 1 = θt + θ
Xt + 1 = Xt + Ds × cosθt + 1
Yt + 1 = Yt + Ds × sinθt + 1

Subsequent to step S9, the wheel rotational speed is changed as follows (S11).
Wheel A rotation speed: La1 = La2
Wheel B rotation speed: Lb1 = Lb2

  Subsequently, it is determined whether or not an instruction marker at the section boundary has been detected (S13). The instruction marker is detected by the guide detection unit 7, and the detection of the marker is transmitted from the control unit 21 to the self-position detection unit 9. If the instruction marker is not detected, the process returns to step S5. As a result, the calculation of the current position and orientation described above is repeated by the position calculation unit 55.

When the instruction marker is detected in step S13, the process proceeds to FIG. 5, and the wheel rotational speeds Ma1 and Mb1 at the time of detection of the instruction marker are stored as follows (S15). Whereas La1 and Lb1 described above are used for calculating the current position, Ma1 and Mb1 are parameters stored for use in calculating the wheel feature amount.
Wheel A rotation speed: Ma1
Wheel B rotation speed: Mb1

  Next, the section number is determined in step S17 (S17). Here, since it moves to the next section by marker detection, the path information is referred to and it is determined what section the next section number is. Then, it is determined whether or not the movement route has ended (S19). Whether or not the route is completed can be determined by referring to the route information based on the section n. If the section number is already the number of the last section, the path is ended by detecting the pointing marker, the measurement of the wheel rotation speed is ended (S21), and the traveling of the mobile robot 1 is ended.

  If the route is not completed in step S19, it is determined from the route information whether or not the next section is the wheel diameter update section Tn (S23). If the determination of step S23 is Yes, it will progress to FIG. 6 and will calculate a wheel radius in the next area. If the determination in step S23 is No, it is determined from the route information whether the next section is the wheel interval update section Tw (S25). If the determination in step S25 is Yes, the process proceeds to FIG. The wheel spacing is calculated in the next section. If the determination in step S25 is No, the next section is neither the wheel diameter update section Tn nor the wheel interval update section Tw, so the process returns to step S5 to perform normal position detection.

  Referring to FIG. 6, in the wheel diameter update section Tn, the same position detection as described above is performed, and the wheel rotation speed is measured to calculate the wheel radius. In FIG. 6, the processes of steps S31, S33, S35, and S37 are the same as steps S7, S9, S11, and S13 of FIG. That is, the wheel rotation speed obtained sequentially is recorded, the position change amount and the posture change amount are obtained, and the current position and posture are updated. This process is continued until the indication marker is detected.

When the next instruction marker is detected (S37, Yes), this instruction marker is an end point marker of the wheel diameter update section Tn. Therefore, the wheel rotation speed at the time of detection of the instruction marker is stored as follows (S39).
Wheel A rotation speed: Ma2
Wheel B rotation speed: Mb2

And the wheel diameter update process which calculates a wheel radius is performed (S41). This process is illustrated in FIG. In FIG. 8, the section distance D (distance from the section start point marker to the section end point marker) of the wheel diameter update section Tn that has traveled is read from the storage unit 15 (S71). Then, the wheel diameters of the left and right wheels are calculated from the wheel rotation amount in the wheel diameter update section Tn and the section distance D as follows (S73). Here, the left and right wheel rotation amounts are obtained, and the wheel radius is calculated from the wheel rotation amount and the section distance for each wheel.
Wheel A rotation amount: θa (= Ma2-Ma1)
Wheel B rotation amount: θb (= Mb2-Mb1)
Section distance: D (obtained from storage)
Wheel A radius: Ra (= D / θa)
Wheel B radius: Rb (= D / θb)

  Here, Ma1 and Mb1 are the rotation speeds of the wheels A and B stored at the time of detecting the marker at the start point of the wheel diameter update section Tn in the above-described step, and Ma2 and Mb2 are the end points of the section Tn in the above step. The number of rotations of the wheels A and B stored when the marker is detected.

  When the wheel radius is calculated as described above, the wheel radius of the storage unit 15 is updated (S75). Here, the wheel radius in the wheel information stored in the storage unit 15 is replaced with the calculated value.

Returning to FIG. 6, when the wheel diameter update process in step S41 is completed, the wheel rotation speed for calculating the wheel information is replaced as follows (S43). After step 43, the process proceeds to step S17 in FIG. 5, and processing corresponding to the next section is performed.
Wheel A rotation speed: Ma1 = Ma2
Wheel B rotation speed: Mb1 = Mb2

  FIG. 7 shows processing when it is determined in step S25 of FIG. 4 that the next section is the wheel interval update section Tw. In the wheel interval update section Tw, the same position detection as that in the normal section is performed, and the wheel rotation is measured to calculate the wheel interval. In FIG. 7, the processes of steps S51, S53, S55, and S57 are the same as steps S7, S9, S11, and S13 of FIG. That is, the wheel rotation speed obtained sequentially is recorded, the position change amount and the posture change amount are obtained, and the current position and posture are updated. This process is continued until the indication marker is detected.

When the next instruction marker is detected (S57, Yes), this instruction marker is an end point marker of the wheel interval update section Tw. Therefore, the wheel rotation speed at the time of detection of the instruction marker is stored as follows (S59).
Wheel A rotation speed: Ma2
Wheel B rotation speed: Mb2

And the wheel space | interval update process which calculates a wheel space | interval is performed (S61). This process is illustrated in FIG. In FIG. 9, the angle difference φ between the start and end points of the wheel interval update section Tw that has traveled and the wheel radii Ra and Rb are read from the storage unit 15 (S81). Then, the wheel interval is calculated as follows from the wheel rotation amount in the wheel interval update section Tw, the angle difference φ and the wheel radii Ra, Rb (S83). Here, the left and right wheel rotation amounts are obtained, and the wheel interval W is calculated from the wheel rotation amount, the angle difference, and the wheel radius.
Wheel A rotation amount: θa (= Ma2-Ma1)
Wheel B rotation amount: θb (= Mb2-Mb1)
Angle difference between section start and end points: φ (obtained from storage)
Wheel A radius: Ra (obtained from storage)
Wheel B radius: Rb (obtained from storage)
Wheel spacing: W (= (Ra × θa−Rb × θb) / φ)
Here, Ma1 and Mb1 are the rotational speeds of the wheels A and B stored at the time of detecting the marker at the start point of the wheel interval update section Tw in the above-described step, and Ma2 and Mb2 are the end points of the section Tw in the above step. The number of rotations of the wheels A and B stored when the marker is detected.

  When the wheel interval is calculated as described above, the wheel interval in the storage unit 15 is updated (S85). Here, the wheel interval in the wheel information stored in the storage unit 15 is replaced with the calculated value.

Returning to FIG. 7, when the wheel interval updating process in step S61 is completed, the wheel rotation speed for calculating the wheel information is replaced as follows (S63). After step 63, the process proceeds to step S17 in FIG. 5, and processing corresponding to the next section is performed.
Wheel A rotation speed: Ma1 = Ma2
Wheel B rotation speed: Mb1 = Mb2

  The operation of the mobile robot 1 related to the calculation of the wheel feature amount has been described above. Next, processing for further improving the calculation accuracy of the wheel feature amount will be described. Here, in consideration of the inclination of the traveling direction of the mobile robot 1 with respect to the direction of the traveling route, the angle difference between the section start point and the end point, which is information on the path side that is the calculation reference of the wheel feature amount, is adjusted. .

  FIG. 10 schematically shows the mobile robot 1 that travels from the straight section to the next straight section through the curved section. On the mobile robot 1, images of white line detection cameras are shown superimposed. FIG. 10A shows an ideal state, in which the traveling direction of the mobile robot 1 always coincides with the direction of the travel route (the direction of the white line tape 101 as the guide means), and the inclination of both is zero.

  On the other hand, FIG. 10B shows the actual posture of the mobile robot 1, and as shown in the figure, in the actual travel, the traveling direction of the mobile robot 1 may be tilted with respect to the route direction. The vehicle is running while being corrected by controlling both drive wheels. In particular, the posture tends to become unstable at the exit of the curve, and the traveling direction tends to be inclined with respect to the path direction (both are not parallel). Such an inclination in the traveling direction causes an error in the calculation of the vehicle feature amount. That is, in the present embodiment, the wheel radius and the wheel interval are calculated from the wheel rotation amount based on the section distance of the route information and the angle difference between both ends of the section, but the traveling direction of the vehicle at the start point and end point of the section is calculated. If the vehicle is tilted, the actual travel distance and the angle difference produced by the travel will deviate from the value of the route information. Therefore, if the route information is used as it is, an error occurs in the calculated value of the wheel feature amount.

  Therefore, in the present embodiment, as described below, the inclination of the traveling direction of the mobile robot 1 is detected, the route information is adjusted according to the inclination, and the wheel feature amount is calculated therefrom. .

  FIG. 11 shows a curve section that is the wheel interval update section Tw. In the present embodiment, when the start point (point 1) and end point (point 2) markers of the section Tw are detected, the angular deviation amounts Δφ1 and Δφ2 are detected, respectively. These are the inclination angles of the traveling direction and the path direction described above.

  The angle deviation amounts Δφ 1 and Δφ 2 are detected by the guide detection unit 7. In the guide detection unit 7, the image processing unit 43 detects the white line tape 101 from the image of the white line detection camera 43 and obtains the direction of the white line tape 101. The direction of the white line tape 101 is the path direction. Therefore, the angle deviation amount of the mobile robot 1 is obtained from the inclination of the white line tape 101 in the image. This angle deviation amount may be always used in traveling control.

  Thus, the guide detection unit 7 functions as an inclination detection unit, and when the pointing marker 103 is detected, the angle deviation amount is passed to the self-position detection unit 9 and stored in the storage unit 15. The angle shift amount Δφ1 at the start point of the section is stored together with the wheels A and B rotation speeds Ma1 and Mb1 at the same point, and the angle shift amount Δφ2 at the end point of the section is stored at the wheel A and B rotation speeds Ma2 at the same point. Will be stored together with Mb2.

Then, the wheel information calculation unit 57 of the self-position detection unit 9 functions as a section angle difference adjustment unit, reads the angle deviation amounts Δφ1 and Δφ2, and calculates the angle difference φ between the start point and end point of the wheel interval update section Tw, Adjust (correct) according to the following formula.
φ = φ− (Δφ1−Δφ2)

Thereby, the angle difference actually generated in the mobile robot 1 between the start point and the end point of the wheel interval update section Tw is obtained. The wheel interval is calculated using this angle difference φ. Therefore, after all, the wheel interval is calculated by the following equation.
Wheel spacing: W (= (Ra × θa−Rb × θB) / (φ− (Δφ1−Δφ2)))

  Next, FIG. 12 shows a straight section that is the wheel diameter update section Tn. Here, in the same manner as described above, when the marker at the start point (point 1) of the section Tn is detected, the angle deviation amount Δφ1 is detected by the guide detection unit 7, and the wheels A and B rotation speed Ma1 at the same point are detected. And stored together with Mb1. Similarly, when a marker at the end point (point 2) of the section Tn is detected, the angle deviation amount Δφ2 is detected by the guide detection unit 7 and stored together with the wheels A, B rotation speeds Ma2 and Mb2 at the same point. .

  And the wheel information calculation part 57 of the self-position detection part 9 functions as a section distance adjustment part, and adjusts a section distance using said angle deviation | shift amount. As described below, the distance deviation amount is obtained from the angle deviation amount, and the section distance is adjusted using the distance deviation amount. Here, the angle deviation amount is the inclination angle between the traveling direction and the route direction described above, and the distance deviation amount is a deviation amount between the section distance on the route information and the actual travel distance.

FIG. 13 shows processing for obtaining distance deviation amounts ΔDa1 and ΔDb1 for each wheel at the same point from the angle deviation amount Δφ1 of the section start point. In the figure, d is the distance in the path direction (the direction of the white line tape 101) from the midpoint of the left and right wheels to the center position of the pointing marker. A detection signal of the pointing marker 103 is output. The distance deviation amounts ΔDa1 and ΔDb1 are obtained from the angle deviation amount Δφ1 by the following equation.
ΔDa1 = d− (W × sinΔφ1) / 2
ΔDb1 = d + (W × sinΔφ1) / 2
Similarly, distance deviation amounts ΔDa2 and ΔDb2 at the end point of the section are also obtained from the angle deviation amount Δφ2 by the following equation.
ΔDa2 = d− (W × sinΔφ2) / 2
ΔDb2 = d + (W × sinΔφ2) / 2

Then, the wheel information calculation unit 57 of the self-position detection unit 9 adjusts the distance D between the start point and the end point of the wheel diameter update section Tn using the distance deviation amounts ΔDa1, ΔDb1, ΔDa2, and ΔDb2 according to the following formula ( to correct. The section distance D is adjusted individually for the wheels A and B, and section distances DA and DB for the wheels A and B are obtained.
DA = D− (ΔDa1−ΔDa2)
DB = D− (ΔDb1−ΔDb2)

Thereby, the distance actually traveled of each of the wheels A and B in the wheel diameter update section Tn is obtained. Then, using these DA and DB, the wheel radii Ra and Rb of the wheels A and B are calculated according to the following equation.
θa = (Ma2−Ma1)
θb = (Mb2-Mb1)
Ra = (DA / θa)
Rb = (DB / θa)

  The above processing is applied to the operation flow of the present embodiment shown in FIGS. 4 to 9 as follows. That is, when the wheels A and B rotation speeds Ma1 and Mb1 are stored in step S15, the angle deviation amount Δφ1 is stored together. In steps S39 and S59, the wheels A and B rotation speeds Ma2 and Mb2 are stored. The angle deviation amount Δφ2 is stored together. In addition, when the rotation speeds of the wheels A and B are switched in steps S43 and S63 (Ma1 = Ma2, Mb1 = Mb2), the angle deviation amount is also switched (Δφ1 = Δφ2). Then, before calculating the wheel radius in step S73, the section distance D is adjusted to the section distances DA and DB for the wheels A and B as described above, and this adjustment value is used in step S73. Further, before calculating the wheel interval in step S83, the angle difference φ between the two ends of the section is adjusted as described above, and this adjustment value is used in step S83.

  Through the processing as described above, the calculation accuracy of the wheel feature amount can be improved. In the present embodiment, slopes detected at both the start point and end point of the section are used in order to improve calculation accuracy. However, only the slope at the start or end point may be used within the scope of the present invention. Since the inclination at the end point of the curve tends to increase, it is preferable to use the inclination of the end point of the section when updating the wheel interval, and it is preferable to use the inclination of the start point of the section when updating the wheel radius. is there.

  The preferred embodiments of the present invention have been described above. According to the present embodiment, even when the wheel feature value changes, the changed wheel feature value can be obtained, and the current position can be detected with high accuracy. In addition, a predetermined section is set on the route by using the traveling route of the mobile robot including a plurality of predetermined sections, and the route information stored for the predetermined section is used for traveling in the same section. The wheel feature amount is calculated from the measured wheel rotation amount. Therefore, the wheel feature amount can be obtained by using the function of the mobile robot without adding an expensive configuration, and the current position is obtained with an inexpensive configuration. Detection accuracy can be improved.

  Further, according to the present embodiment, the wheel diameter update interval and the wheel interval update interval can be appropriately set, and the wheel diameter and the driving wheel distance used for autonomous navigation in the left and right wheel independent drive can be calculated. .

  Further, according to the present embodiment, the inclination of the route direction and the traveling direction at the end of the section is detected, and the section distance on the path information is adjusted to the distance actually traveled for each wheel, and the adjusted section The wheel diameter is calculated using the distance. In this way, the increase / decrease of the travel distance in the actual section travel can be corrected for each wheel, so that each wheel diameter can be obtained more accurately, and the calculation accuracy of the current position can be improved.

  Further, according to the present embodiment, the inclination of the route direction and the traveling direction at the end of the section is detected, and the angle difference between the two ends of the section on the route information is adjusted to the angle difference actually generated by the mobile robot. The wheel spacing is calculated using the adjusted angle difference. In this way, the increment or decrement of the angle difference in actual section travel can be corrected to determine the wheel interval more accurately, and the current position calculation accuracy can be improved.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and it goes without saying that those skilled in the art can modify the above-described embodiments within the scope of the present invention.

  The present invention is useful as a mobile robot that detects surrounding objects while moving.

It is a functional block diagram of the mobile robot which concerns on embodiment of this invention. It is a figure which shows the environment where a mobile robot is used, and the external appearance of a mobile robot. It is a figure which shows the environmental map and existing property information which are memorize | stored in the memory | storage part. It is a flowchart which shows the process of present position calculation and wheel feature-value calculation. It is a flowchart which shows the process of present position calculation and wheel feature-value calculation. It is a flowchart which shows the process of present position calculation and wheel feature-value calculation. It is a flowchart which shows the process of present position calculation and wheel feature-value calculation. It is a flowchart which shows the update process of a wheel diameter. It is a flowchart which shows the update process of a wheel space | interval. It is a figure explaining the influence by the advancing direction of a mobile robot tilting. It is a figure explaining the wheel space | interval update process based on the inclination of the advancing direction. It is a figure explaining the wheel diameter update process based on the inclination of the advancing direction. It is a figure explaining the wheel diameter update process based on the inclination of the advancing direction.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mobile robot 3 Moving means 5 Movement control part 7 Guide detection part 9 Self-position detection part 11 Obstacle detection part 13 Obstacle determination part 15 Storage part 17 Communication part 19 Imaging unit 21 Control part 31 Right wheel 33 Left wheel 35, 37 Motor 41 White Line Detection Camera 43 Image Processing Unit 51, 53 Resolver 55 Position Calculation Unit 57 Wheel Information Calculation Unit 61 Laser Sensor 71 Route Information 73 Environmental Map 75 Position Information 77 Wheel Information 81 Abnormality Determination Unit

Claims (4)

A robot that drives a wheel and moves along a travel route composed of a plurality of sections,
A rotation amount detector for measuring the rotation amount of the wheel;
A storage unit for storing the route information and the wheel feature amount, which records the distance and angle difference between the start point and the end point of the predetermined section set in advance;
An instruction means detector for detecting an instruction means disposed on the travel route;
A section discriminating section for detecting a start point and an end point of the predetermined section based on an output of the instruction means detection section;
When the section discriminating unit discriminates the end point of the predetermined section, the wheel information calculation that calculates the wheel feature amount based on the wheel rotation amount measured between the start point and the end point of the predetermined section and the route information and stores it in the storage unit And
A position calculation unit that calculates a current position based on the wheel feature amount stored in the storage unit and the rotation amount of the wheel measured by the rotation amount detection unit;
A mobile robot characterized by comprising: The section discriminating unit discriminates the start point and the end point of the first and second predetermined sections based on the output of the instruction means detection unit,
The wheel information calculation unit
When the section determining unit determines the end point of the first predetermined section, the wheel rotation amount measured between the start point and end point of the first predetermined section and the start point end point of the first predetermined section recorded in the route information The wheel diameter as the wheel feature amount is calculated based on the distance between and stored in the storage unit,
When the section discriminating unit determines the end point of the second predetermined section, the wheel rotation amount measured between the start point and the end point of the second predetermined section and the start point end point of the second predetermined section recorded in the route information 2. The mobile robot according to claim 1, wherein a distance between driving wheels as a wheel feature amount is calculated based on an angle difference between the two and a wheel diameter as a wheel feature amount and stored in a storage unit. An inclination detector that detects an inclination of the traveling direction of the mobile robot with respect to the direction of the travel route;
A section distance adjustment unit that adjusts the distance between the start point and the end point of the first predetermined section on the route information based on the inclination detected by the inclination detection unit at at least one of the start point and the end point of the first predetermined section And comprising
The mobile robot according to claim 2, wherein the wheel information calculation unit calculates the wheel diameter based on the distance adjusted by the section distance adjustment unit. An inclination detector that detects an inclination of the traveling direction of the mobile robot with respect to the direction of the travel route;
Angle difference adjustment for adjusting the angle difference between the start point and end point of the second predetermined section on the route information based on the tilt detected by the tilt detecting unit at at least one of the start point and end point of the second predetermined section And comprising
The mobile wheel according to claim 2, wherein the wheel information calculation unit calculates the distance between the driving wheels based on the angle difference adjusted by the angle difference adjustment unit.