JP2006231477A - Calibration method for distance detection means in mobile element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a calibration method for a distance detection means in a mobile element such as an autonomous mobile robot, in which calibration work to a distance detection means (distance sensor) installed on the mobile element can be easily performed to achieve correct results of calibration. <P>SOLUTION: This calibration method is for a distance detection means in a mobile element provided with a plurality of drive wheels to travel, a light receiving part to receive reflection light of radiation light projected from a light emitting part to a travel surface in a travel zone, and the distance detection means for detecting distance to the travel surface in the travel zone. The distance detection means is calibrated using a target surface vertically provided on the travel surface at the farthest part in a possible detection range of the distance detection means in the travel zone of the mobile element. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a calibration method of a distance detecting means that is provided with a light emitting unit and a light receiving unit on a moving body and detects an obstacle or the like in front of the moving body, and more particularly in a moving body such as an autonomous mobile robot. The present invention relates to a method for calibrating distance detection means in a moving body, which is suitable for application to distance detection means for detecting an obstacle.

  Industrial robots such as articulated arm robots and transfer robots have been known for a long time and are often used in factories and the like. However, these industrial robots are limited in their purpose of use such as welding, painting, transportation, etc., and are fixed in one place such as an arm robot or a route determined like a transport robot. Most of them moved in a predetermined order.

  However, in recent years, autonomous mobile robots have been announced. This autonomous mobile robot is configured to be able to move freely within a predetermined space, coexists with humans in a human living environment, and performs simple, dangerous, and difficult tasks in industrial and production activities. It is intended to help and act as a substitute. Examples of such work include maintenance work in nuclear power plants and thermal power plants, cleaning work in high-rise buildings, rescue activities at disaster sites such as fire sites, and the like.

  In addition, the range of use of autonomous mobile robots is, for example, installed in the homes of elderly people living alone, such as cleaning the room, managing the physical condition of the resident, or checking indoor safety when the resident is away from the house. A robot designed to support daily life and to support life has also been announced. Such life-supporting robots are positioned as robots that can be applied to general households.

  In these robots, if there is an obstacle in the movement range, it will hinder the work, so always monitor the surroundings to see if there is an obstacle or whether a person enters the movement range and poses a danger. Need to be monitored.

  However, monitoring of obstacles in a fixed robot such as the arm robot described above and a robot that moves along a predetermined route such as a transfer robot can be performed only within the arm movement range and the predetermined route. For example, it is only necessary to image the entire action range and determine whether there is an obstacle, but in an autonomous mobile robot, first of all, there is a problem whether there is a running surface such as the floor or the ground ahead of the future, Next, it is necessary to determine whether there is an obstacle in the driving area, and if there is an obstacle in the destination or there is no driving surface, it is necessary to take action such as detouring or getting over the obstacle in some cases .

  For this reason, technology for detecting the presence of a running surface and obstacles is indispensable for autonomous mobile robots. Distance detection using a light emitting unit and a light receiving unit using infrared rays or the like for a mobile object such as an autonomous mobile robot. It has been proposed to provide a means to check the floor or the ground where such a moving body travels and to check an obstacle.

  Such distance detection means for confirming floors and grounds and obstacles acquire information not only in a single direction but also in the entire travel area of the moving object, thereby braking or detouring the moving object. It is preferable that the search can be performed.

  With regard to such technology, for example, in Patent Document 1 and Patent Document 2, distance detection means that measures a distance from a front obstacle to a moving body by a plurality of distance detection means arranged in the width direction of the moving body, and detects the obstacle. A method of avoiding an obstacle by calculating a turning direction and a turning radius for the moving body to avoid an obstacle based on the position in each width direction of the means and the detection distance is shown. At this time, the moving body moves along the obstacle avoidance trajectory based on the calculated turning direction and turning radius, but until the moving body reaches the side of the obstacle even if the distance detecting unit does not detect the obstacle. Continue turning.

  However, when a plurality of distance detecting means are arranged in the width direction of the moving body in this way, variation in the mounting angle of the light emitting part in each distance detecting means, mounting error of the light receiving optical system in the light receiving part, light emission intensity of the light emitting part As shown in FIG. 5, the output of the light receiving element constituting the light receiving unit varies depending on the individual distance detecting means due to the variation of the distance. In FIG. 5, the horizontal axis is the distance from the distance detecting means to the measurement point, the unit is mm, the vertical axis is the output voltage (V) of the light receiving element constituting the light receiving unit, and the curves 51 and 52 are a certain one. The maximum output voltage (51 curve) with respect to the distance between two light receiving elements and the minimum output voltage (52 curve) with respect to the distance between the light receiving elements, and other light receiving element output voltages fall within the hatched range. It shows that.

  That is, the graph of FIG. 5 shows that the relationship between the output voltage and the distance differs for each individual distance detection means even if measured under the same conditions. A calibration work is required to clarify the relationship between the distances and thereby obtain a calculation formula for calculating the relationship between the output voltage from the light receiving unit and the distance.

  However, it is good if there are few moving bodies that use such distance detection means, but it takes a lot of time to perform such calibration work for each of many distance detection means, such as when mass-producing moving bodies. Not practical.

  Furthermore, since such a distance detection means is generally provided with a certain height from the traveling surface of the moving body and projects the irradiation light at an angle on the traveling surface, Variations in the amount of reflected light may occur due to the shape and dirt, and accurate distance detection may not be possible.

  Regarding the calibration of such a distance detection means (distance sensor), Patent Document 3 relates to the calibration of a distance sensor that measures the degree of wear of a pantograph of a train, but a suspended wire arranged above the overhead wire of the train. A calibration plate is placed on the wear plate, and the wear detection device equipped with a distance sensor group can be moved in the direction of the sleepers, the wear detection device is moved on the calibration plate, and each distance sensor measures the distance to the calibration plate. An apparatus is shown in which measurement distance data with a calibration plate of each distance sensor is compared to calibrate a variation error of the distance data.

Japanese Patent No. 2608509 Japanese Patent No. 2627472 JP 2004-56901 A

  However, although the apparatus shown in Patent Document 3 uses a plurality of distance detection means (distance sensors), it measures a distance that is known in advance before measuring the wear level of the pantograph, and thereby measures it. This is to calibrate the output of the distance sensor where the error occurred. This calibration work is different from the calibration work of the distance detection means (distance sensor) attached to the moving body such as the autonomous mobile robot described above. In order to correct an error that has occurred after calibrating output voltage variations in a plurality of distance sensors, the present invention is applied to an operation for calibrating output voltage variations in individual distance detection means as shown in FIG. It is not possible.

  Further, as described above, the distance detecting means provided on the moving body is attached to a position having a certain height from the traveling surface of the moving body so that the irradiation light to be projected has an angle with respect to the traveling surface. Therefore, the amount of reflected light varies due to the shape of the traveling surface, dirt, and the like. However, the apparatus described in Patent Document 3 cannot cope with such variations.

  Therefore, in the present invention, the distance detecting means (distance sensor) attached to the moving body such as the autonomous mobile robot can be easily calibrated, and the calibration result of the distance detecting means in the moving body is accurate. It is a problem to provide.

In order to solve the above problems, the calibration method of the distance detection means in the moving body according to the present invention is:
A distance detection unit that travels with a plurality of drive wheels and has a light receiving unit that receives reflected light of the irradiation light projected from the light emitting unit onto the traveling surface of the traveling region, and detects the distance to the traveling surface in the traveling region A method for calibrating a distance detecting means in a moving body comprising:
The distance detecting means is calibrated by providing a calibration point at the farthest part of the detectable area of the distance detecting means in the traveling area of the moving body.
Further, in order to solve the above problem, the calibration method of the distance detection means in the moving body according to the present invention is:
A distance detection unit that travels with a plurality of drive wheels and has a light receiving unit that receives reflected light of the irradiation light projected from the light emitting unit onto the traveling surface of the traveling region, and detects the distance to the traveling surface in the traveling region A method for calibrating a distance detecting means in a moving body comprising:
The distance detecting means calibrates using a target surface erected on the farthest traveling surface in the detectable region of the distance detecting means in the traveling region of the moving body.

  In distance detection means that projects infrared light or the like on the traveling surface, detects reflected light at the light receiving unit, and detects the distance based on the output voltage, the reflected light from the traveling surface is the square of the distance from the light emitting unit. Therefore, as the distance increases, the output of the light receiving unit decreases rapidly, and the change in voltage decreases as the distance increases. Therefore, for example, a calculation formula is created by a plurality of distance-voltage characteristics as shown in FIG. 5 measured in advance by a plurality of distance detection means, and the distance detection means light receiving unit output at a specific distance is set to a predetermined specific voltage. If the distance between the distance detection means and the calibration point is short, the voltage difference is large and the error in the short distance is reduced. End up. However, in this way, if a calibration point is provided at the farthest part of the detectable area of the distance detecting means in the traveling area of the moving body, the distance in the vicinity can be accurately calculated, and distance detection in the moving body that can perform accurate calibration A calibration method of the means can be provided.

  In addition, by setting the calibration point as a target surface erected on the farthest traveling surface in the detectable region of the distance detecting means, when the traveling surface is used as the calibration point, as described above, the shape of the traveling surface, dirt, etc. However, these problems can be solved.

  In a preferred embodiment of the present invention, the calibration is performed by obtaining a difference between an output voltage of the light receiving unit that receives reflected light from the calibration point and a voltage obtained in advance.

Furthermore, in order to solve the above-mentioned problem, the calibration method of the distance detection means in the moving body according to the present invention is:
Traveling with a plurality of drive wheels, the reflected light of the irradiation light projected from the plurality of light emitting units to the traveling surface of the traveling region is received by a light receiving unit provided corresponding to each of the plurality of light emitting units, A method for calibrating a distance detecting means in a moving body comprising a distance detecting means for detecting a distance to a running surface in a running area,
The distance detecting means calibrates using a target surface erected corresponding to each of the plurality of light emitting parts at the farthest part of the detectable area of the distance detecting means in the traveling area of the moving body. And

  And, in addition to the effect of the present invention described above, the calibration is performed by obtaining the difference between the output voltage at each of the plurality of light receiving units that have received the reflected light from the calibration point and a predetermined voltage, It can be performed by a simple method of taking the difference between the output voltage of the calibration point and a predetermined voltage in each of the plurality of distance detection means, and a large amount of distance detection means can be calibrated very easily. It is possible to provide a calibration method for distance detection means in a moving object.

  Further, the detectable region of the distance detection means is determined depending on the braking ability of the moving body, so that when the moving body detects an obstacle, the moving body can perform an avoiding operation without colliding with the obstacle. Can provide a calibration method of the distance detecting means.

  As described above, according to the present invention, it is possible to calibrate distance detection means (distance sensor) attached to a moving body such as an autonomous mobile robot very easily, and the calibration result is also accurate. It is possible to provide a calibration method of distance detection means in a moving object.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.

  FIG. 1 is a side view (A) and a top view (B) showing a configuration for carrying out a calibration method for distance detection means in a moving body according to the present invention, and FIG. (A) showing the relationship between the angle of the irradiation light projected onto the traveling surface, (B) showing the irradiation range of each irradiation light, and FIG. 3 are calibrations of the distance detecting means in the moving body of the present invention. FIG. 4 is a graph showing the light receiving unit output of the distance detecting means calibrated by the calibration method of the present invention. In the figure, the same components are given the same numbers. Further, in the following description, the case where the moving body in the present invention is an autonomous mobile robot will be described as an example, but it is clear that the present invention can be applied not only to such a robot but also to various moving bodies that move autonomously. It is.

The moving body 1 that performs the calibration method of the distance detecting means in the moving body according to the present invention has a substantially human shape and a plurality of drives for traveling on the traveling surface 2 as schematically shown in FIG. A light emitting unit having a wheel 3 and an auxiliary wheel 4 and outputting five light beams from a traveling sensor 2 at a predetermined height, for example, as shown in FIG. A plurality of wide angle sensors 5 (hereinafter abbreviated as WAS), which are distance detecting means including a light receiving portion for receiving light separately, are provided as 5 ₁ , 5 ₂ , 5 ₃ , and the WAS 5 ₁ , 5 ₂ , 5 _3. By irradiating the traveling surface 2 and receiving reflected light, the presence of the traveling surface 2 and the distance to the obstacle can be detected.

In the present invention, from the WAS 5 to the target 6 standing at a substantially right angle (90 °) to the traveling surface 2 at a predetermined distance from the WAS 5 ₁ , 5 ₂ , 5 ₃ provided on the moving body 1. The reflected light is received by the light receiving part by irradiating the light beam, the output voltage is compared with a predetermined voltage, and the difference voltage is used as a calibration voltage, thereby enabling easy calibration. For example, when the reference output voltage for calibration is set to 1.2V, if a voltage larger than that is output from WAS5, the difference from 1.2V is subtracted, and if a small voltage is output, the difference is output. And the difference is used as a calibration value. Then, a common calibration equation is obtained in advance from the measurement results as shown in FIG. 5 using a plurality of WASs 5, and the calibration voltage obtained by measurement is added to the light receiving unit output voltage, so that a substantially correct distance is obtained. Can be calculated.

Here, the irradiation light beam 8 from the WAS 5 irradiates the traveling surface 2 and is directed at an angle in the direction of the traveling surface 2 as shown in FIG. prepared and uphill section _71, and the stop plate 7 ₃ of the moving body 1 in consideration measurement platform 7 ₂ serving as a predetermined height relative to the running surface 2 and its measurement table 7 _2, moving the moving body 1 barrel autonomous type robot to climb to the measuring table ₇₁ on their own, it is to allow the measurement stopped at the stop plate 7 _3.

Then, from each of the WASs 5, 5 ₁ , 5 ₂ , 5 ₃ , as shown in FIG. 1B, for example, five irradiation light beams 8 ₁₁ , 8 ₁₂ , 8 ₁₃ , 8 ₁₄ , 8 ₁₅ , 8 ₂₁ , 8 ₂₂ , 8 ₂₃ , 8 ₂₄ , 8 ₂₅ , 8 ₃₁ , 8 ₃₂ , 8 ₃₃ , 8 ₃₄ , 8 ₃₅ , are output and provided corresponding to the respective WAS 5, 5 ₁ , 5 ₂ , 5 _3. Measurement is performed by irradiating the targets 6 ₁ , 6 ₂ , and 6 ₃ .

As shown in FIG. 2A, the relationship between the WAS 5 and the traveling surface 2 and the target 6 is, for example, that the installation height Z _w0 from the traveling surface 2 of the WAS 5 is 347.45 mm, and the emitted light from the WAS 5 Assuming that the angle θ _w formed with the traveling surface 2 is 30 °, the horizontal distance L _w0 to the point where the light emitted from the WAS 5 reaches the traveling surface 2 is 585.26 mm, and the linear distance X _w0 from the WAS 5 to the traveling surface 2 is When the distance L _w1 between the WAS 5 and the target 6 is 519.6 mm, the linear distance X _w1 between the WAS 5 and the target 6 is 600 mm.

If the spread angle θ _bw of the light emitted from the WAS 5 is 5 ° on one side and 10 ° on both sides, the lateral spread B _ww of each light on the target 6 is 105 mm as shown in FIG. The direction spread _Bwh is 148 mm. Further, a 150mm as the height _{Z 0} is an example of the measuring table _{7 2,} the target 6 is a height _{T wL} 300 mm, a width _{T ww} as 360 mm, when the irradiation range of the five light beams and _{B w5,} the light beam Since they overlap each other, this _Bw5 is about 200 mm. When the width _{Bww of the} light beam is added to this, a width of 305 mm is irradiated. Further, the surface shape of the target is white matte and has a few irregularities.

The reason was 600mm linear distance X _w1 between WAS5 and target 6 as an example, a small proportion of the output voltage change of the light receiving portion with respect to the increase in the distance, performs calibration farthest portion of the detection area of WAS5 This is to reduce errors at a long distance. In other words, the light emitted from the WAS 5 decreases in proportion to the square of the distance from the light emitting unit, and as the distance increases, the rate of change in the output voltage of the light receiving unit decreases. When the distance changes, the voltage changes greatly. When calibration is performed at a short distance, the error at a long distance increases. For this reason, the vicinity of 600 mm, which is the farthest part of the detectable area of the WAS 5, is selected as the calibration point, and this is a value that also takes into account the braking distance of the moving body 1 such as a robot. It is obvious that this distance depends on the braking distance of the moving body 1 and the ability of the WAS 5, and is not limited to the above distance.

The actual calibration work is performed according to the flowchart shown in FIG. That is, first in step S1, as shown as 1 _1, 1 ₂ in Figure 1, it is moved to stop at the position of the stop plate 7 ₃ mobile 1 from the uphill section ₇₁ to the measuring table 7 _2. In the next step S2, the light beams 8 ₁₁ , 8 ₁₂ , 8 ₁₃ , 8 ₁₄ , 8 ₁₅ , 8 ₂₁ , 8 ₂₂ , 8 ₂₃ , 8 ₂₄ , 8 ₂₅ , 8 ₃₁ , 8 ₃₂ , 8 ₃₃ , 8 ₃₄ , ₈₃₅ is irradiated toward the target 6, the reflected light is detected, the output voltage is compared with the reference voltage 1.2V (which is an example) set in advance as described above, and the difference is taken as the calibration voltage. Remember me.

  When all the calibration voltages have been captured, the calibration voltage is reflected in each WAS 5 as an offset value in the next step S3, and as shown in FIG. 5 using a plurality of WASs 5 as described above in the last step S4. In other words, the output voltage of the WAS 5 is converted into a distance by applying to a common calibration formula obtained in advance from such measurement results.

  FIG. 4 is a graph showing the light receiving unit output of the WAS 5 calibrated by the calibration method of the present invention described above. As in FIG. 5, the horizontal axis is the distance from the WAS 5 to the measurement point (unit: mm), and the vertical axis. The axis is the output voltage (V) of the light receiving element constituting the light receiving unit, and the curves 41 and 42 are the maximum value of the output voltage with respect to the distance of the light receiving element (the curve of 41) and the minimum value of the output voltage with respect to the distance. (42 curves). In the graph shown in FIG. 5, the WAS 5 has a variation in the output of the light receiving element constituting the light receiving unit for each light emitting unit due to variations in the mounting angle of the light emitting unit and the mounting error of the light receiving optical system in the light receiving unit. However, after calibrating according to the present invention, the most accurate value is obtained in the most necessary region of about 300 mm to 800 mm, and the calibration method can obtain an accurate value very easily. I understand.

  As described above, according to the present invention, the distance of the necessary region is substantially reduced by performing the calibration by standing the target 6 at the farthest part of the detectable region of the WAS 5 in the traveling region of the moving body 1. It is possible to provide a calibration method for distance detection means in a moving object that can be accurately calculated and can be accurately calibrated.

  The calibration is performed by calculating the difference between the output voltage at each of the light receiving units that have received the reflected light from the target 6 and a predetermined voltage, thereby determining the output voltage at the calibration point in each of the plurality of WASs 5 in advance. It is possible to provide a method for calibrating the distance detecting means in the moving body, which can be performed by a simple method of taking a difference from the measured voltage, and can calibrate a large number of distance detecting means very easily.

  According to the present invention, a necessary calibration value can be easily obtained even if a large number of distance detecting means having large variations are used, so that a movable body having the distance detecting means can be provided at low cost.

It is the side view (A) and top view (B) which showed the structure which implements the calibration method of the distance detection means in the moving body which becomes this invention. It is the figure which showed the relationship between the position on the moving body of the light emission part in a distance detection means, and the angle of the irradiation light projected on a driving | running | working surface, and the figure (B) which showed the irradiation range of each irradiation light. It is a flowchart of the calibration method of the distance detection means in the moving body of this invention. It is the graph which showed the light-receiving part output of the distance detection means calibrated by the calibration method of this invention. Using a plurality of distance detection means, the reflected light from the traveling surface of the moving object irradiated by each light emitting unit is received by the light receiving unit provided corresponding to each light emitting unit, and the distance from the light emitting unit to the reflection point and the output voltage It is the graph which plotted the relationship of.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mobile body 2 Running surface 3 Drive wheel 4 Auxiliary wheel 5, 5 ₁ , 5 ₂ , 5 ₃ Wide angle sensor (WAS)
6 Target 7 ₁ Climbing section 7 ₂ Measuring stand 7 ₃ Stop plate 8 WAS irradiation light beam

Claims (6)

A distance detection unit that travels with a plurality of drive wheels and has a light receiving unit that receives reflected light of the irradiation light projected from the light emitting unit onto the traveling surface of the traveling region, and detects the distance to the traveling surface in the traveling region A method for calibrating a distance detecting means in a moving body comprising:
The distance detecting means calibrates by providing a calibration point at the farthest part of the detectable area of the distance detecting means in the traveling area of the moving body. A distance detection unit that travels with a plurality of drive wheels and has a light receiving unit that receives reflected light of the irradiation light projected from the light emitting unit onto the traveling surface of the traveling region, and detects the distance to the traveling surface in the traveling region A method for calibrating a distance detecting means in a moving body comprising:
The distance detecting means calibrates using a target surface erected on the farthest traveling surface in the detectable region of the distance detecting means in the traveling area of the moving body. Calibration method.   The distance in the moving body according to claim 1 or 2, wherein the calibration is performed by obtaining a difference between an output voltage of the light receiving unit that receives reflected light from the calibration point and a voltage obtained in advance. Calibration method for detection means. Traveling with a plurality of drive wheels, the reflected light of the irradiation light projected from the plurality of light emitting units to the traveling surface of the traveling region is received by a light receiving unit provided corresponding to each of the plurality of light emitting units, A method for calibrating a distance detecting means in a moving body comprising a distance detecting means for detecting a distance to a running surface in a running area,
The distance detecting means calibrates using a target surface erected on the traveling surface corresponding to each of the plurality of light emitting units at the farthest part of the detectable region of the distance detecting means in the traveling region of the moving body. A method for calibrating a distance detecting means in a moving body.   5. The moving body according to claim 4, wherein the calibration is performed by calculating a difference between an output voltage at each of the plurality of light receiving units that receive reflected light from the calibration point and a predetermined voltage. Calibration method of distance detection means in   6. The method of calibrating a distance detecting means in a moving body according to claim 1, wherein the detectable region of the distance detecting means is determined depending on a braking ability of the moving body.

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