JPH0714819Y2 - Device for detecting the angle between signs for autonomous vehicles - Google Patents

Description

[Detailed description of the device] [Industrial applications]

The present invention relates to a device for detecting an angle between signs when an autonomous vehicle is autonomously driven by a sign installed outside.

[Prior art]

Conventionally, using a plurality of wide markers made of a corner cube prism type reflector, it consists of a light projecting unit that projects a broad light beam and a light receiving unit that detects the reflected light from the markers. An autonomous traveling vehicle is known that includes an optical sensor having an on-sensitivity curve that differs from an on-sensitivity curve that has different characteristics, and an angle sensor that detects a rotation angle of an optical sensor such as an encoder.

[Problems to be solved by the device]

Regarding the detection characteristics of the marker (reflection plate) of the optical sensor, the detection angle width becomes narrower as the distance to the marker increases. Therefore, there is a problem that an error becomes large when an angle between two markers at different distances is detected by an angle difference at the moment when the optical sensor detects the reflector, that is, at a rising time of the trigger pulse. The present invention has been made to solve the above problems, and an object of the present invention is to provide a device for detecting an angle between signs of an autonomous vehicle that measures an angle between signs with a small error.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the present invention uses a plurality of wide markers composed of a corner cube prism type reflector, and detects a reflected light from the projector, which projects a spread light beam. And an angle sensor that detects a rotation angle of an optical sensor such as an encoder, and the like. At, the opening angle θ around the optical sensor between two signs A and B at different distances is defined as an angle Aon at which the optical sensor starts detecting the sign A and turns on, and an angle Aoff at which the optical sensor completes detection and turns off.
And the angle Bon that turns on when the marker B starts to be detected, and the angle Boff that turns off after detecting the marker B, the detection is performed by the formula: θ = (Aon + Aoff) / 2− (Bon + Boff) / 2 And

[Action]

With the above configuration, the device for detecting an angle between signs of an autonomous vehicle according to the present invention can accurately measure an angle between signs A and B having two different distances.

【Example】

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 is a rotary encoder (photoelectric sensor) mounted on a vehicle such as an agricultural tractor (not shown) that has an autonomous traveling function, and the encoder 1 rotates about a vertical axis. It is equipped with a light projecting section 2 and a light receiving section 3 which are capable. A wide marker 4 made of a corner cube prism type reflecting plate corresponding to the rotary encoder 1 is provided at three places, for example, corners A, B, C of a field in a certain section, which is not shown. The light beam emitted from the light projecting unit 2 is a relatively thick (spread) light beam, and it is possible to allow the vehicle to shake for detecting a sign. The detection characteristics of the mark (reflecting plate) 4 of the photoelectric sensor 1 are as shown in FIGS. 2 (a), (b) and FIGS. 3 (a), (b), as the distance to the mark 4 increases. The photoelectric sensor 1 detects the angle between the marks A and B at different distances when the trigger pulse rises (Aon point and Bon point in FIG. 3).
The error becomes large when detected by the angle difference of (point). Therefore,
In order to reduce the error, paying attention to the fact that the equisensitivity curve in which the photoelectric sensor 1 is on and the isosensitivity curve in which it is off are almost parallel over the entire detection distance, and the inter-marker angle is approximated by the following formula. . θ = (Aon + Aoff) / 2− (Bon + Boff) / 2 The measurement data by the rotary encoder 1 is
It is input to a microcomputer mounted on the vehicle and read in, and the self-position is calculated based on the principle of triangulation. In the device for detecting the inter-marker angle having such a configuration, the light-projecting and light-receiving units 2 and 3 of the rotary encoder 1 have a light beam solid angle of about 5 degrees, and apply the light beam to the marker (reflecting plate) 4 while rotating together. , Emits a signal when it receives the reflected light.
With this trigger signal, angle data between a plurality of markers (for example, between A and B) is read from the rotary encoder 1 into the microcomputer, and the self-position is detected by the above calculation formula. Regarding the accuracy of the angle data, the intensity of the light beam decays with the detection distance. Therefore, if the angle between markers A and B at different distances is measured at the rising edge (on) of the trigger pulse, the error as described above will occur. Therefore, in order to minimize this, the accurate self-position is detected by the above calculation formula.

[Effect of device]

As described above, according to the device for detecting an angle between signs of an autonomous vehicle of the present invention, two signs A, which are located at different distances,
The opening angle θ between the B and the optical sensor is the angle Aon at which the optical sensor starts detecting the sign A and turns on, the angle Aoff at which the optical sensor ends detecting the sign A, and the angle at which the sign B starts to detect and turn on. Bon, and the angle Boff that turns off after detection, are detected by the formula: θ = (Aon + Aoff) / 2- (Bon + Boff) / 2, so an accurate position with few errors can be detected and autonomous It works effectively as a control device for traveling vehicles.

[Brief description of drawings]

FIG. 1 is a perspective view showing a detection state of an external marker by a photoelectric sensor, FIGS. 2 (a) and 2 (b) and FIG. 3 (a),
(B) is a graph showing the label detection characteristics of the photoelectric sensor. DESCRIPTION OF SYMBOLS 1 ... Rotary encoder, 2 ... Emitter, 3 ... Light receiver, 4
… Sign, θ… Correct angle between signs A and B.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akira Hirata 1-40-2 Nisshin-cho, Omiya-shi, Saitama Prefecture Inside the dormitory of the Biological Special Industrial Technology Research Promotion Organization (72) Yosuke Matsuo 1 Nisshin-cho, Omiya-shi, Saitama -40-2 Inside the dormitory of the Biotechnology Research Institute for Industrial Technology (56) Reference JP 59-67476 (JP, A) JP 62-211506 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A plurality of markers each having a width formed of a corner cube prism type reflecting plate are used, and a light projecting section for projecting a light beam having a spread and a light receiving section for detecting reflected light from the markers are used. , An autonomous traveling vehicle equipped with an optical sensor having an isosensitivity curve that is turned on by light reception and an isosensitivity curve that is turned off by light reception, and an angle sensor that detects the rotation angle of the optical sensor such as an encoder are at different distances The angle (θ) between the two markers (A, B) centered on the optical sensor is the angle (Aon) at which the optical sensor starts detecting the marker (A) and turns on, and the angle at which the optical sensor turns off after detecting. (Aoff), the angle (Bon) at which the marker (B) starts to detect and turns on, and the angle (Bon) at which it stops after detecting (B).
off) from the equation: θ = (Aon + Aoff) / 2− (Bon + Boff) / 2.