JP2013140083A - Self-location measuring system of mobile object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a self-location measuring system of a mobile object, which can measure the direction of the mobile object with simple structure.SOLUTION: A self-location measuring system of a mobile object comprises: a turning gear 20 arranged on a mobile object 10 which can move within a working area 70; a laser range finder 30 arranged on the turning gear 20; a mobile reflection member 40 arranged on the mobile object 10; and at least one of fixed reflection members 50a, 50b arranged at a predetermined position in the working area 70 or at a periphery of the working area. The self-location measuring system of the mobile object can accurately measure the direction of the mobile object 10 with simple structure.

Description

  The present invention relates to a mobile body self-position measurement system.

  Various self-propelled working robots are being considered, such as planting seedlings on farmland and agricultural robots for crop harvesting. In order for such a robot to work autonomously, a function for recognizing the robot's own position as to where the robot is currently working is required.

  As a method of self-position recognition, there are a method of recognizing by installing an inner world sensor in the robot, and a method of recognizing by installing an outer world sensor outside the robot. The method using the internal sensor is not suitable particularly when performing accurate guidance outdoors because the error is integrated. On the other hand, a technique using image processing, which is a typical example of an external sensor, is often difficult under outdoor conditions. On the other hand, methods using sensors from the outside of the vehicle include methods using GPS and light wave rangefinders, but these are very expensive and also cause problems related to the installation and movement of base stations.

  In addition, Patent Document 1 discloses a position control device for a self-propelled vehicle. Light reflecting means are installed at at least three reference points around the work area, and the azimuth angle of the self-propelled vehicle is measured from the angle between the self-propelled vehicle and each reference point.

JP-A-3-150609

  In Patent Document 1, it is necessary to provide at least three reference points, which cannot be said to be a simple measuring means.

  The present invention has been made in view of the above matters, and an object of the present invention is to provide a mobile body self-position measuring system capable of measuring the orientation of the mobile body with a simple configuration.

The mobile body self-position measuring system according to the present invention is:
A rotating device disposed on a movable body movable in the work area;
A laser rangefinder disposed in the rotating device;
A movable reflecting member disposed on the movable body;
And at least one fixed reflecting member installed at a predetermined position around the work area or the work area,
The laser distance meter is arranged to irradiate a laser from a rotating shaft of the rotating device,
The moving reflecting member is disposed on a straight line connecting the front surface of the moving body and the rotation axis of the rotating device,
The moving body moves to an arbitrary position in the work area, the laser rangefinder irradiates a laser while the rotating device is driven,
The laser beam reflected by the fixed reflecting member is received to measure the angle between a predetermined reference direction and the fixed reflecting member direction, and the laser beam reflected by the moving reflecting member is received to receive the reference direction and the moving reflecting member direction. Measure the angle of
Measuring the azimuth angle of the moving body from the angle between the reference direction and the fixed reflecting member direction and the angle difference between the reference direction and the moving reflecting member direction;
It is characterized by that.

Further, at least two of the fixed reflecting members are spaced apart from each other,
The moving body moves to an arbitrary position in the work area, the laser rangefinder irradiates a laser while the rotating device is driven,
It is preferable to measure the position of the moving body by receiving a laser beam reflected by each of the fixed reflecting members and measuring a distance from an arbitrary position to each of the fixed reflecting members.

Further, the mobile body is a legged robot having legs that can extend and contract in the height direction,
It is preferable that the rotating shaft of the rotating device is maintained constant and the heights of the fixed reflecting member and the laser distance meter are maintained constant.

  The legged robot is preferably an agricultural robot.

  In the mobile body self-position measurement system according to the present invention, the orientation of the mobile body can be accurately measured with a simple configuration.

It is a schematic block diagram of the self-position measurement system of a moving body. It is a top view of a moving body. It is a figure explaining the measurement of the position and direction of a moving body. It is a figure explaining the measurement of the direction of a moving body. It is a side view which shows the mode of the movement of the mobile body in the ground which has an unevenness | corrugation. It is a figure explaining the experimental condition in an Example. It is a figure which shows the measurement result of the position of the moving body in an Example.

  The mobile body self-position measurement system according to the present embodiment will be described with reference to the drawings. The moving body self-position measuring system includes a rotating device 20 installed in a moving body 10 movable in a work area 70, a laser distance meter 30, a moving reflecting member 40, fixed reflecting members 50a and 50b, and an arithmetic unit. 60. In this description, the work area 70 will be described as XY plane coordinates.

  The moving body 10 is a so-called legged robot provided with a base 11 and a plurality of legs 12, and automatically moves the work area 70 based on an instruction from a control device (not shown). The moving body 10 is not particularly limited as long as it is a robot capable of performing various tasks in various work areas that can be defined by XY plane coordinates.

  The rotating device 20 is installed on the base 11. As described above, since the base 11 can maintain a parallel state with respect to the XY plane, the rotating device 20 is also configured to be rotatable in parallel with the XY plane. Thereby, the rotating shaft of the rotating device 20 is maintained substantially perpendicular to the XY plane. The rotation device 20 may have any configuration as long as it can rotate on the base 11. For example, the rotation device 20 is a combination of a driving source such as a high-precision rotary head, a stepping motor, a servo motor, and the rotation table. A configuration is mentioned.

  A laser distance meter 30 is disposed on the rotating device 20. As shown in FIG. 2, the laser distance meter 30 rotates following the rotation of the rotating device 20. Installation of the laser rangefinder 30 on the rotating device 20 may be direct or indirect. The laser distance meter 30 can irradiate and receive a laser, irradiates the object with the laser, receives the laser reflected by the object, and measures the distance from the laser distance meter 30 to the object. The laser rangefinder 30 may be any device as long as it can measure the distance to an object based on various information such as time, frequency, and phase.

  The laser distance meter 30 is arranged so that the laser irradiation / light receiving unit is positioned on the rotation axis of the rotating device 20. It arrange | positions so that a laser may be irradiated to the direction perpendicular | vertical to a rotating shaft from the rotating shaft of the rotating apparatus 20. FIG. That is, since the rotating device 20 can rotate in parallel with the XY plane as described above, the laser distance meter 30 also irradiates and receives laser in parallel with the XY plane.

  The moving reflecting member 40 is installed on the moving body 10. As shown in FIG. 2, the movable reflecting member 40 is installed between the rotating body 20 and the rotating shaft in the front direction of the moving body 10. The movable reflecting member 40 may be made of any material as long as it can reflect the laser.

The fixed reflecting members 50a and 50b are arranged at predetermined positions in the XY plane coordinates. That is, the coordinates of the fixed reflecting members 50a and 50b in the XY plane are both known and are represented by A (x _a , y _a ) and B (x _b , y _b ). The fixed reflecting members 50a and 50b may be made of any material as long as the material can reflect the laser. The fixed reflecting members 50a and 50b are disposed at a height at which the laser irradiated from the laser distance meter 30 is irradiated.

  The calculation device 60 stores a reference vector and coordinate information of the fixed reflecting members 50a and 50b, which will be described later, and a calculation unit that calculates the position and orientation of the moving body 10 from the obtained distance data and direction vector. have.

  Next, measurement of the position and orientation of the moving body 10 will be described.

First, measurement of the position of the moving body 10 will be described. As shown in FIG. 3, consider a case where the moving body 10 has moved to a point P (x _p , y _p ) on the XY plane coordinates. The point P is a rotation axis coordinate of the rotation device 20. At the point P, the rotating device 20 is driven. Further, the laser distance meter 30 is irradiated with the laser while being rotated by driving the rotating device 20.

When the laser beam is reflected by the reflecting member 50a installed at the point A (x _a , y _a ), the laser distance meter 30 receives the laser beam reflected by the reflecting member 50a. Thus, the distance L ₁ between the points A and P are measured.

Further, when reflected by the reflecting member 50b which lasers are disposed point B (x _{b, y b),} the laser rangefinder 30 receives the laser reflected by the reflecting member 50b. Thus, the distance L ₂ between the point B and the point P is measured.

Then, from the measured L ₁ and L ₂ of the distance data, the arithmetic unit 60 obtains the coordinates of a point P on the X-Y plane coordinates. Specifically, the point of intersection of the circle of radius L ₁ centered on point A and the circle of radius L ₂ centered on point B is the coordinates of point P. In this way, the coordinates of the point P, that is, the position of the moving body 10 is measured.

  Next, measurement of the orientation of the moving body 10 on the XY plane coordinates will be described. Here, the direction θ of the moving body 10 is an amount of change from a reference direction (hereinafter also referred to as a reference vector) of the moving body 10 and an azimuth angle with respect to the reference vector. In this description, a vector in the X-axis direction will be described as a reference vector.

First, as shown in FIG. 3, a state is considered in which the moving body 10 moves to a point P (x _p , y _p ) and faces an arbitrary direction. Then, the rotating device 20 is driven at the point P as described above. While the rotating device 20 is driven, the laser distance meter 30 irradiates the laser.

When the laser beam is reflected by the reflecting member 50a, the laser distance meter 30 receives the laser beam reflected by the reflecting member 50a. Thereby, a vector (hereinafter also referred to as vector A) connecting the point P and the point A is obtained. Then, as shown in FIG. 4, a difference angle θ _A between the reference vector and the vector _A is obtained.

Further, when the laser is reflected by the reflecting member 40 installed in the front direction of the moving body 10, the laser distance meter 30 receives the laser reflected by the reflecting member 40. Thereby, a vector connecting the point P and the reflecting member 40 (hereinafter also referred to as a vector F) is obtained. Then, a difference angle θ _F between the reference vector and the vector _F is obtained.

Then, the direction θ of the moving body 10 is obtained from the difference angle between θ _A and θ _F. Thus, if the arithmetic unit 60 stores the reference vector in advance, θ _A and θ _F can be obtained, and thereby the azimuth angle θ of the moving body 10 can be obtained.

  Alternatively, a vector connecting the point P and the point B and a vector connecting the point P and the reflecting member 40 may be obtained, and the direction θ of the moving body 10 may be obtained from the difference angle between them. The reference vector may be a vector in the Y-axis direction or a vector in an arbitrary direction.

  Note that the moving method of the moving body 10 is not limited to the leg type, but may be moved by wheels or the like. However, the self-position measuring system according to the present embodiment is used for seedlings and seeds on farmland such as fields. It is particularly useful for legged agricultural robots that perform farming operations such as planting and harvesting crops. In the case of farmland or the like, since the surface has many irregularities and the ground is soft, posture change is likely to occur when the robot moves. Even in such a situation, if the leg type is used, as shown by the arrow in FIG. 5, when the moving body 10 moves, each leg 12 expands and contracts independently. Can be controlled to remain substantially constant. Thereby, the height relationship between the laser distance meter 30 and the fixed reflecting members 50a and 50b and the irradiation angle of the laser with respect to the horizontal plane can be maintained. Similarly, the inclination of the rotating shaft of the rotating device 20 can be maintained substantially constant. Therefore, the position and azimuth angle of the moving body 10 can be measured with high accuracy.

  The fixed reflecting members 50a and 50b can reflect the laser irradiated by the laser distance meter 30, and can be located at any position around the work area 70 or the work area 70 as long as the coordinates of the position can be recognized. It may be installed.

  Moreover, although the above demonstrated the example in which the two fixed reflection members were installed, three or more may be installed. For example, in the case of the rectangular work area 70, fixed reflecting members may be installed at the four corners of the work area 70. In this case, four pieces of distance data from the position of the moving body 10 to each fixed reflecting member are obtained, and the intersection coordinates of the circles of the respective distances using the respective fixed reflecting members as fulcrums become the position of the moving body 10. If an arbitrary reference vector is set, the azimuth angle of the moving body 10 is measured in the same manner as described above using any fixed reflecting member.

  The rotating device 20, the laser distance meter 30, and the moving reflection member 40 are installed in the vehicle 80. Then, as shown in FIG. 6, the vehicle 80 was moved indoors in a 10 m × 4 m area while repeating stop and go. When the vehicle 80 stopped, an attempt was made to measure the position and azimuth on the XY plane coordinates of the vehicle 80 at each stop position. What was performed with the said apparatus is described as LDS.

  Further, for evaluation, the position and azimuth angle of the vehicle 80 on the XY plane coordinates were measured at a total station (accuracy 5 mm) as a comparative example. Hereinafter, TS performed at the total station will be described.

  Table 1 shows the X coordinate, Y coordinate, azimuth angle of the vehicle 80 determined by the LDS and TS, and the difference between the LDS and TS. Table 2 shows the average and standard deviation of the norm at the position of the vehicle 80 and the average and standard deviation of the error absolute value of the angle at the azimuth angle of the vehicle 80.

  When the difference between TS and LDS was examined, the mean (standard) and standard deviation (SD) of the norm (RMS (m)) were each about 10 mm. In addition, the average (mean) and standard deviation (SD) of the absolute error value (abs_θ (°)) were about 0.2 °, respectively. Thus, it was confirmed that the position and azimuth angle of the moving body can be accurately measured even with a simple configuration.

  As described above, the mobile body self-position measuring system can accurately measure the position and orientation of the mobile body in the work area with a simple configuration. Therefore, it is expected to be used for various self-propelled working robots, including agricultural robots for planting seedlings and harvesting crops on farmland.

1 Self-positioning system 10 Mobile body (robot)
11 Base 12 Leg 13 Wheel 20 Rotating Device 30 Laser Distance Meter 40 Moving Reflective Member 50a Fixed Reflective Member 50b Fixed Reflective Member 60 Arithmetic Unit 70 Work Area 80 Vehicle

Claims (4)

A rotating device disposed on a movable body movable in the work area;
A laser rangefinder disposed in the rotating device;
A movable reflecting member disposed on the movable body;
And at least one fixed reflecting member installed at a predetermined position around the work area or the work area,
The laser distance meter is arranged to irradiate a laser from a rotating shaft of the rotating device,
The moving reflecting member is disposed on a straight line connecting the front surface of the moving body and the rotation axis of the rotating device,
The moving body moves to an arbitrary position in the work area, the laser rangefinder irradiates a laser while the rotating device is driven,
The laser beam reflected by the fixed reflecting member is received to measure the angle between a predetermined reference direction and the fixed reflecting member direction, and the laser beam reflected by the moving reflecting member is received to receive the reference direction and the moving reflecting member direction. Measure the angle of
Measuring the azimuth angle of the moving body from the angle between the reference direction and the fixed reflecting member direction and the angle difference between the reference direction and the moving reflecting member direction;
A self-positioning system for a moving object. At least two fixed reflecting members are spaced apart from each other;
The moving body moves to an arbitrary position in the work area, the laser rangefinder irradiates a laser while the rotating device is driven,
Receiving the laser beam reflected by each of the fixed reflecting members, measuring the position of the movable body by measuring the distance from any position to each of the fixed reflecting members,
The self-position measuring system for a moving body according to claim 1. The mobile body is a legged robot having legs that can expand and contract in the height direction,
The rotational axis of the rotating device is maintained constant, and the height of the fixed reflecting member and the laser distance meter is maintained constant.
The mobile body self-position measuring system according to claim 1 or 2, The legged robot is an agricultural robot;
The self-position measuring system for a moving body according to claim 3.

Images