JPH0683145B2 - Optical wireless communication device for moving body - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical wireless communication device for a mobile body, and particularly to an optical wireless communication suitable for data transmission between a mobile work robot in a plant and a central control room. Regarding the device.

[Prior Art] A conventional optical wireless communication device for mobile robots was developed by Atomic Energy Society of Japan 1982 Annual Meeting, G28, (1982), Tomizawa Fumio et al. -Design of optical communication device- ", the optical beam (infrared beam) is transmitted and received between the mobile robot side and the station (fixed station where signals are transmitted to the main control room) side. Has become. In this device, the pan / tilt head equipped with the light transmitter / receiver is tracking-controlled so that the light transmitter / receiver on the robot side and the light transmitter / receiver on the station side always face each other following the traveling of the mobile robot. A two-dimensional sensor for detecting the deviation amount between the optical axes of these two transmitters / receivers is used as a sensor for pan head tracking control. In this device, the range in which the platform can be tracked in order to continue wireless transmission is such that the optical axis deviation amount of these two transmitters / receivers is up to 29 milliradians. As long as the mobile robot moves smoothly, the optical axis deviation amount is within the above range, and this device can continue optical wireless transmission.

[Problems to be solved by the invention]

However, in the above-described conventional technology, tracking control cannot be performed when the direction of the optical axis of the light transmitter / receiver suddenly changes greatly due to the mobile robot changing its position suddenly due to a step on the floor or colliding with an obstacle. , There was a problem that communication became impossible. This is for the following reason. That is, since the narrow-angle light reception is performed to receive the light beam with good S / N, the range that can be tracked is narrow, so if the optical axis direction changes significantly due to the above reasons,
This is because both the station side and the mobile robot side cannot receive the light beam of the other party and the two-dimensional sensor cannot recognize the position of the other party.

An object of the present invention is, in a tracking type optical wireless communication device, facilitating communication resumption when the optical axis of the light transmitter / receiver deviates from the optical transceiver of the partner station and the light beam from the partner station cannot be received. Especially.

[Means for solving problems]

The above-described object is to use an optical system (for example, a zoom lens) having a variable light transmission / reception angle as an optical system of the light transmission / reception device, and to change the light transmission / reception angle according to whether or not signal light from the partner station is detected. This is achieved by providing means for controlling the optics.

[Action]

When the signal light from the partner station is being detected, the tracking control similar to the conventional tracking control is performed by narrowing the transmission / reception angle range. However, when the signal light from the partner station cannot be detected due to the off-axis, the transmission / reception angle is controlled to be wide until the light beam from the partner station can be detected. Once again, if the tracking control becomes possible, the transmitting / receiving angle may be narrowed again. In this way, even if the light beam of the partner station cannot be received, communication can be easily resumed.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First, the overall configuration will be described with reference to FIG. Tracking drive mechanism (tracking platform) for both station 20 and mobile robot 21
It has a similar transmitter / receiver 13 mounted on 14, and performs optical wireless transmission by aligning the optical axes as shown by the dotted line in the figure. When the mobile robot moves, the tracking drive mechanism 14 is used to control the optical axes so that they do not shift from each other.

FIG. 1 shows an embodiment of the light transmitting / receiving device 13 and its related device of the present invention. In this figure, the conventional tracking drive mechanism 14 is not shown. The transmitter / receiver 13 has a front group of zoom lenses.
1, a zoom lens including a rear group 2 of the zoom lens, a zoom lens driving unit 3 for driving the zoom lens and changing the angle of view, a two-dimensional optical sensor 5 for detecting the incident direction of received signal light,
The half mirror 4, the light receiving unit 10, and the light emitting unit 11 are stored. The zoom lens drive unit 3 operates under the control of the zoom lens drive control unit 8. The output of the two-dimensional photosensor 5 is processed by the sensor interface 6. The light receiving unit 10 and the light emitting unit 11 are connected to the transmitting / receiving circuit 7. The CPU / memory unit 9 controls the sensor interface 6, the transmission / reception circuit 7, the zoom lens drive control unit 8 and the tracking drive mechanism control unit 12.

The operation will be described below. The control program and various data are stored in the CPU / memory unit 9, and all functions work under the control of the CPU / memory unit 9.

(1) Data Communication The data output from the transmission / reception circuit 7 becomes an optical signal in the light emitting unit 11, is reflected by the half mirror 4, passes through the rear lens group 2 of the zoom lens, and the front and rear portions 1 of the zoom lens to reach the partner station as a light beam. The received signal light passes through the front group 1 of the zoom lens and the rear group 2 of the zoom lens, is reflected by the half mirror 4, is received by the light receiving section 10, becomes an electric signal, and enters the transmitting / receiving circuit 7.

(2) Tracking control The output of the two-dimensional sensor 5 that receives the light beam that has passed through the half mirror 4 from the zoom lens is controlled so that the direction of the partner station and the optical axis direction of the own station match. That is, the two-dimensional optical sensor 5 is a semiconductor position detecting element, and by processing the output thereof by the sensor interface 6, it is possible to know at which position of the two-dimensional optical sensor 5 the signal light from the partner station was received. That is, as shown in FIGS. 3A and 3B, in the detection surface (vertical Y ₁ × horizontal X ₁ ) of the two-dimensional optical sensor 5,
For example, the position B (X, Y) of the signal light can be detected. When the position of the partner station matches the optical axis of the own station, the position B is Is detected at the position. Therefore, the CPU / memory unit 9 moves the tracking drive mechanism 14 via the tracking drive mechanism control unit 12 to control the direction of the light transmitter / receiver 13 until the state shown in FIG.

(3) Zoom view angle control FIG. 4 shows a flowchart of the zoom view angle control. Third
As shown in FIGS. (A) and (b), when the signal light of the partner station is captured on the light receiving surface of the two-dimensional optical sensor 5, the tracking control (L4 in FIG. 4) described in (2) above is performed. Work effectively. Therefore, at this time, the zoom angle control is performed by following the loop of L2 to L5 in FIG. 4, and the zoom lens is on the telephoto side and the angle of view becomes the minimum. In this case, optical wireless communication using the same light beam as in the conventional example is performed without any trouble.

If the direction of the optical axis changes significantly for some reason, for example, when the mobile robot suddenly changes its direction due to a step on the floor, or when it collides with an obstacle, the signal light of the partner station is transmitted to the light receiving surface of the two-dimensional optical sensor 5. Cannot receive light. Then, the control shifts from L2 to L1 in FIG. 4, and the CPU / memory unit 9 commands the zoom lens drive control unit 8 to make the zoom lens wide-angle. Although a control method of making the widest angle state in one stage is also conceivable, in the present embodiment, the angle of view is divided into 16 stages and is changed step by step. The operation of L1 is started at the same time on both the station side and the mobile robot side. Therefore, when the zoom lens has a wide angle, the light receiving angle increases and the emission beam also expands as shown by the alternate long and short dash line in FIG. Therefore, even if the optical axis directions are different from each other, if the position of the transmitter / receiver 13 of the partner station enters the light receiving surface of 5, it can be detected.

If the position of the partner station can be detected by L2 and L3, tracking control is performed by L4. However, at this time, since the zoom lens has a wide angle, coarse tracking control is performed. For this reason, tracking control is performed while zooming the zoom lens to the telephoto side (loop of L2 to L6) to perform accurate optical axis alignment.

The above zoom angle control is performed by both the transmitter / receiver on the mobile robot side and the transmitter / receiver on the station side.

As described above, in the tracking type optical wireless device, even when the optical axis of the light beam is deviated and the position of the partner station becomes unknown, it is possible to easily restart communication.

In this embodiment, when the zoom lens is wide-angled, the emission beam is also expanded. Therefore, unless the distance between the station and the mobile robot is extremely large, the wireless communication can be resumed before the tracking is completely stopped.

Although a photodiode is used for the light receiving unit 10 in this embodiment, a phototransistor, a photomultiplier tube, or the like can also be used. Although a light emitting diode is used for the light emitting unit 11, a semiconductor laser can be used. The two-dimensional optical sensor 5 uses a semiconductor position detecting element in this embodiment, but an image pickup tube or a semiconductor image pickup element (CCD or the like) can also be used. In this case, it goes without saying that a circuit such as an image memory is required. Image processing is required for position detection, but human monitoring is also possible.

Further, as another embodiment, it is possible to add a light emitting unit for tracking to the light transmitter / receiver 13 in addition to the light emitting unit 11 for data transmission. For example, add a high-brightness LED or miniature bulb. With this configuration, the emission intensity for tracking is higher than that of the infrared LED for data transmission, and thus the detection by image processing is easy.

Further, in the above-mentioned embodiment, the light transmission and the light reception are performed through the same optical system, but two optical systems for light transmission and light reception, which are arranged close to each other with their optical axes in parallel, are provided. It is also possible to provide each of these optical systems as an optical system such as a zoom lens capable of changing the light transmitting and receiving angles as described above, and change the light transmitting and receiving angles in the same manner as described above. Therefore, in the present invention, the term "transmitter / receiver" is provided with the same optical system that is used for both light transmission and light reception as described above, or for light transmission respectively arranged with their optical axes parallel to each other. Also, it is used as a term that means any of those having two optical systems for receiving light.

Further, in the above-mentioned embodiments, the glass lens is used as the zoom lens and the transmitting and receiving angles are changed by moving the front lens group and the rear lens group, but a lens made of a material capable of directly controlling the change of the refractive index by an electric signal. If a material is used, it is possible to realize a zoom lens that can change the transmission / reception angle at high speed without moving the lens, and if this is used, tracking control at higher speed becomes possible.

It is also possible to change the transmission / reception angle by inserting and removing the attachment lens instead of the zoom lens.

Furthermore, it goes without saying that the present invention is applicable not only to optical wireless communication between a mobile unit and a fixed station, but also to optical wireless communication between mobile units.

〔The invention's effect〕

According to the present invention, since the position detection range of the partner station for tracking can be varied, when the optical axis of the optical transceiver deviates from the optical axis of the optical transceiver of the partner station and tracking becomes impossible, Expanded to find the other station and made it possible to track again,
Communication can be resumed easily, and during normal tracking, narrow-angle transmission and reception can be performed to maintain a good S / N ratio.

[Brief description of drawings]

FIG. 1 is a block diagram of an optical transmitter / receiver and its related apparatus in one embodiment of the present invention, FIG. 2 is an overall schematic view of an optical wireless communication system for a mobile robot according to one embodiment of the present invention, and FIG. ) And (b) are explanatory views of tracking control by the two-dimensional optical sensor, and FIG. 4 is a flowchart of communication restart control of the same embodiment. 1 ... Zoom lens front group, 2 ... Zoom lens rear group 3 ... Zoom lens drive unit 4 ... Half mirror, 5 ... Two-dimensional optical sensor 6 ... Sensor interface 7 ... Sending / receiving circuit 8 ... Zoom Lens drive control unit 9 …… CPU / memory unit, 10 …… Light receiving unit 11 …… Light emitting unit 12 …… Tracking drive mechanism control unit 13 …… Transmitter / receiver, 14 …… Tracking drive mechanism 20 …… Station, 21… … Mobile robot.

Continuation of the front page (56) Reference JP-A 61-98033 (JP, A) JP-A 60-80332 (JP, A) JP-A 55-93336 (JP, A) JP-B 49-7168 (JP , B1) JP-B-56-45541 (JP, B2) JP-B-54-15365 (JP, B2)

Claims (1)

[Claims] 1. A light beam is transmitted and received for communication while automatically tracking the direction of the light transmitter and receiver so that the optical axes of the light transmitter and receiver on the moving body and the light transmitter and receiver of the partner station coincide with each other. In a suitable optical wireless communication device, the optical system in the light transmitter / receiver that can change the light transmitter / receiver angle and the optical system described above to widen the light transmitter / receiver angle when the light beam from the transmitter / receiver of the partner station cannot be received. An optical wireless communication device for a mobile body, comprising: a control unit for automatically controlling.