GB2209835A

GB2209835A - A miniaturized dead reckoning automatic position sensor and recorder for attachment to animals

Info

Publication number: GB2209835A
Application number: GB8721726A
Authority: GB
Inventors: Rory Paul Wilson; Marie-Pierre Wilson
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-09-15
Filing date: 1987-09-15
Publication date: 1989-05-24
Also published as: GB8721726D0

Abstract

An automatic dead reckoner for determining the movements of animals consists of a magnet G attached to a spring- mounted arm E, orientated so as to react to differential pressure caused by the medium through which the animal moves, and a miniature fluid-filled compass B surrounded by Hall generators A. The position of the arm, and hence (by derivation) the animal's travelling speed, is sensed by an adjacent linear Hall generator H. The direction faced by the animal is sensed by the Hall generators around the compass. Information on the heading and speed of the animal wearing the device is stored against a time base, eg by an array of LEDs I and photographic film J. <IMAGE>

Description

- A XIN;ATTJRIZED DEAD RECKONING AUTOMATIC POSITION SENSOR AND REG..:^* FOR ATTACoMEET TO YIXALS This invention relates to a dead reckoning automatic position sensor and recorder.

There are a number of systems available for monitoring the spatial position cf vehicules whilst being insensitive to attitude. However, these systems are expensive and/or bulky and/or generally have high power requirements and may involve the additional total system cost of telemetry. The only system currently available for monitoring animal position is telemetric.

According to the present invention the spatial position of a free-living animal during a given time period is recorded automatically by a 'dead reckoning automatic sensor and recorder' which is fixed to some part of the animal. The device senses and stores information on two parameters simultaneously, each as a function of time: (1) the animal's heading (direction) (2) the animal's speed.

The information is recovered when the animal is recaptured.

A specific embodiment of the invention will now be described by way of example with reference to the accompanying drawing in which: Figure 1 (upper) shows a schematic dorsal view of the device incorporating the film recording mechanism (see text) Figure 1 (lower) shows a longitudinal cross section of the device.

(1) Xethod of sensing the animal's heading.

The direction that an animas faces is sensed by Hall generators (A) n associaticn with a a f'uia-~s112d (3) miniature ship's compass. The float (C) in the compass always orientates itself accoraing to the earth's magnetic fiei: jut the position of the container in which the bat is housed is dependen on the direction that the animal faces. The relative position of the float with respect to the container is sensed by the Hall generators which are located around the equator of the container. When a specific pole of the magnet (D) in the float comes within a critical distance of any of the Hall generators the relevant generator becomes active and produces a voltage.

(2) Method of sensing the animal's speed.

The speed of the animal is indicated by the position of a spring-mounted arm (E) which lies perpendicular to normal direction of travel. Increased speed of the animal causes increased air or water flow (F) over the animal and greater deflection of the arm. The arm has a small magnet (G) attached to the unattached end so that arm position can be sensed by an adjacent linear Hall generator (H). Increased air or water flow causes the arm to change position with respect to the Hall generator. This changes the magnetic flux in the vicinity of the sensor. The Hall generator produces a voitage proportional to magnetic flux.

(3) Time elapsed and data storage.

The information on the animal's heading and speed with respect to time may be stored on integrated circuits incorporating a time base.

In another embodiment the outputs from the Hall generators are used to drive an array of light emitting diodes (leds) (I), suitable for recording on a photographic film. The film (J) travels across the leds (or a suitable slit or focus derived from them) and the relative motion between the film and the leds is provided by a clockwork drive or a stepping motor, or other appropriate mechanism (K). All the recorded variables output data from the Hall sensors are recovered from the film by standard densitometry. In particular the the output of the led from the velocity sensor may be made a known approximately 'inear function of velocity and he blackening of the film trace at a given position (or time) will then be a known function of its velocity.

Claims

CLAMS

1. A dead reckoning automatic sensor for attachment to animals consisting of a fluid compass and Hall generators and a flowmeter as described with Hall sensors.

2. A dead reckoning automatic sensor and recorder as claimed in Claim 1 where the output of the Hall sensors drives a light emitting diode array which is used to record information on moving film as a function of time.

3. A dead reckoning automatic sensor and recorder as clalmed in Claim 1 where the Hall sensors are used as inputs to integrated circuits so that the information is stored In an integrated circuit memory.

4. A dead reckoning automatic sensor and recorder substantially as described herein with reference to Figure 1 of the accompanying drawling.