AU678406B2 - Attitude sensor - Google Patents

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT Name of Applicant: Actual Inventors: Address for Service: zC2 TQ G Lfzop LooA EXCEL INFOTEQU PTY'LT A.C.N. 010 990 208 PAUL ANTHONY HIGGINS REYNOLD WILLIS BELL CUL',EN CO., Patent Trade Mark Attorneys, 240 Queen Street, Brisbane, Old. 4000, Australia.

ATTITUDE SENSOR Invention Title: Details of Associated Provisional Applications: NIL The following statement is a full description of this invention, including the best method of performing it known to us:- I I II IL 1k 2 THIS INVENTION relates to an attitude sensor.

In particular, the invention concerns an attitude sensor for detecting a change in position or orientation of a device from a predetermined original or desired position or orientation.

The invention will be described by way of example with reference to its use with traffic control lights or lanterns. It should be appreciated that this is by way of example only and that the attitude sensor may also be used for other purposes.

Traffic control lanterns typically have a housing and a plurality of control lights. The lights usually include a shroud or guard to ensure that the lights are only visible to traffic approaching from a particular direction. The lantern is usually mounted on a pole or the like and positioned so that only traffic approaching from a particular direction may be controlled by the lights.

In recent years there has been a trend towards employing traffic lanterns at intersections or the like which may be controlled or monitored from a central oooo remote control station. In this way the operation of traffic lanterns at a plurality of intersections or S• locations may be integrated or otherwise controlled so S 25 that their operation may be optimised to cater for varying traffic flow patterns and volumes. In this way "intelligent" operation of traffic lanterns was possible.

Traffic lanterns are sometimes displaced from their initial or predetermined desired position or S 30 orientation. This sometimes occurs if the lantern or post to which it is mounted is struck by a vehicle, S"vandalised or moved by strong winds or other forces of nature. When such displacement occurs, remote monitoring of the lantern will still indicate proper functioning.

.ee..i S 35 However the lantern may now face in an undesired direction and control signals may now be provided to unintended vehicles at an intersection with disastrous consequences.

I- mI Although traffic lanterns and control stations have become more intelligent there has been no ready means for detecting displacement of a lantern from its predetermined or desired position or orientation.

It is an object of the present invention to provide an attitude sensor which at least minimises the disadvantage referred to above.

According to one aspect of the invention there is provided an attitude sensor having a magnetic dipole on a carrier and the carrier being mounted for movement about two axes in response to positional changes of the carrier relative to the earth's magnetic field, a mount for receiving the carrier, a transmitter secured to the mount for directing signals onto the carrier, a receiver secured to the moant for receiving transmitted signals reflected from the carrier and providing an output indicative of a displacement of the mount from a predetermined original or desired position.

The transmitter preferably emits radiation and directs that radiation onto the carrier from which it may be reflected. Although any suitable radiation may be oeeo employed, it is preferred that the transmitter emit infra o "red radiation. The transmitter may comprise an infra red emitting LED. The receiver is responsive to radiation S 25 reflected from the carrier to provide an output proportional to the amount of radiation u cted by the receiver. Where the transmitter is an infra red transmitter, the receiver is also an infra red receiver.

Preferably, the receiver is a phototransistor. In one S 30 embodiment the LED and phototransistor are housed in a moulded package.

The carrier for the magnetic dipole is oe ~preferably spherical and received by the mount for movement about two axes which may be orthogonal to one go.coi S 35 another. The mount may include a gimbal mount.

Preferably the mount includes an envelope within which the carrier is housed and through which the radiation may pass. A liquid may fill the space between the envelope I I and the carrier and the carrier may act as a float free to move within the liquid. Any suitable liquid may be employed. A water/alcohol mixture is preferred.

The mount may comprise a substrate onto which the transmitter and receiver are fixed and which receives the envelope. The substrate may comprise a plate with a mounting flange.

A particular preferred embodiment of the invention will now be described with reference to the drawings in which: Figure 1 is a diagrammatic perspective view of a traffic lantern to which an attitude sensor according to the invention is secured; Figure 2 is an enlarged view of an attitude sensor according to an embodiment of the invention; and Figure 3 is a circuit diagram for the transmitter/receiver which forms part of the sensor of Figure 2.

Figure 1 shows a traffic lantern 10 having a plurality of lights surrounded by shrouds 11. The lantern 10 has a housing 12. An attitude sensor 13 is shown mounted to the housing 12.

Generally, the sensor 13 would be mounted within the housing but is shown externally of the housing 25 for ease of description. What is important is that the sensor 13 be fixed to the lantern 10 and is subject to the same forces which may cause displacement of the lantern from an original or desired orientation or attitude.

The sensor 13 is shown in greater detail in Figure 2. The transmitter/receiver are moulded into a "package 14 having a cover and infra red filter 15 to prevent the ingress of dust and eliminate the effects of ambient illumination. As shown in Figure 1, a slotted ooooo mounting hole 16 allows for adjustment of sensing distance. Leads 17 enable the output from the receiver to be determined.

The moulded package 14 is secured to a mount

I

comprising a plate 18 with a mounting flange 19.

The plate 18 has an aperture for receiving envelope 20 which receives carrier 21. A fluid may fill the space 22 between the carrier 21 and the envelope The carrier 21 is spherical and has a magnetic dipole (not visible) embedded within it. The carrier is influenced by the earth's magnetic field and assumes a predetermined position relative to that field.

Displacement of the plate 18 relative to the earth's magnetic field causes relative displacement of the carrier 21 with respect to the envelope and hence the plate.

Reflective markings may be placed on the carrier 21 and the radiation from the transmitter within package 14 is directed onto the markings. Movement of the carrier will cause a change in the signal received by the receiver within package 14 and this is indicative of movement or displacement of the lantern to which the attitude sensor is attached.

In strong wind conditions the lantern may be caused to oscillated about its desired position and in o which case the signal provided by the receiver may also be an oscillating one. By averaging the signal received under such conditions a proper indication of position of S: 25 the lantern may still be determined. If the lantern has been displaced from its desired position and is subjected to strong wind conditions an oscillating output derived from the receiver and averaged still yields an indication e~o "of misalignment of the lantern.

Figure 3 shows moulding 14 in dotted outline.

Transmitter 30 is coupled to a supply via a resistor 31.

S* Receiver 32 is connected between resistor 33 and a reference potential. Resistor 33 is coupled to a positive supply. The voltage drop developed across resistor 33 is indicative of position of the carrier 21 relative to the transmitter/receiver and provides an indication of displacement of the lantern from its desired position. This signal may be transmitted or made 6 available to a control station at a remote location and may be used to ensure a service call is made to re-align the lantern.

The carrier may be configured such that the transmitter is trained initially onto a non-reflective area and movement causes the transmitter to be trained onto a reflective area on the carrier. With such a configuration a signal maximum will indicate displacement. The reverse of this may also be employed.

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Claims (5)

1. 2. The sensor of Claim 1 wherein the transmitter is an infrared transmitter and the receiver is an infrared receiver.
2. 3. The sensor of Claim 1 or 2 wherein the carrier is contained within an envelope.
3. 4. The sensor of Claim 1 wherein a fluid fills the space between the carrier and the envelope. The sensor of Claim 4 wherein the carrier and the envelope are spherical in shape.
4. 6. The sensor of Claim 4 or 5 wherein the mount '".includes a plate with a mounting flange. The sensor of any one of Claims 1 to 6 wherein the transmitter and receiver are contained within a 25 moulded package secured to the mount.
5. 8. An attitude sensor substantially as herein described with reference to the drawings. DATED this eleventh day of January 1994 LTD. By their Patent Attorneys CULLEN CO. 0 s L ooo i e- II L ABSTRACT An attitude sensor (13) is disclosed having a transmitter and receiver (14) trained to direct onto and receive radiation from a carrier (21) is disclosed. The carrier has a magnetic dipole responsive to the earth's magnetic field. The carrier is secured relative to a mount and moves in response to positional changes. The transmitter/receiver are secured to the mount and the receiver provides an output indicative of displacement of the mount from an original or desired position. *a.g eoooo I -C -CI