IL91267A

IL91267A - System and method for automatic vehicle location and an odometer mounted on a vehicle

Info

Publication number: IL91267A
Application number: IL9126789A
Authority: IL
Inventors: Marc Bienenstock
Original assignee: Ofek A T Technologies Ltd
Priority date: 1989-08-09
Filing date: 1989-08-09
Publication date: 1994-10-21
Also published as: IL91267A0; FR2650886A1; FR2650886B1

Description

SYSTEM AND METHOD FOR AUTOMATIC VEHICLE LOCATION AND A DIFFERENTIAL ODOMETER MOUNTED ON A VEHICLE.

OFEK A.T. TECHNOLOGIES LTD., Inventor: Marc Bienenstock C:08484 FIELD OF THE INVENTION The present invention relates generally to dead reckoning systems and more particularly to automatic vehicle location systems.

BACKGROUND OF THE INVENTION Various types of automatic vehicle location systems have been proposed. The state of the art as of 1971 is summarized in "Automatic Vehicle Monitoring Technology Review" Report MTR 6059 , The Mitre Corporation, Washington, Operations, 1971 » the contents of which and of the documents referred to therein are incorporated by reference herein.

The following U.S. Patents of Etak, Inc. all relate to various features of dead reckoning based on wheel rotation in an automatic vehicle monitoring system: 4 ,788,645 ; 4 ,737.863 ; 4 ,7 6, 1 1 · The contents of these documents, and of the documents referred to therein, particularly U.S. Patent 3.845 ,289 to French, cited in the above-referenced U.S. Patent 4 ,788, 645 · are incorporated by reference herein.

U.S. Patent 4,807,265 describes a recreation vehicle distance measuring device. Because of its recreation use, this vehicle is fitted with sensor actuating means positioned on the outer wheel rim, unlike the present invention in which the sensor actuating means are positioned on the inner wheel rim, where they cannot be easily reached and removed. Positioning the sensor actuating means as in the aforementioned U.S. patent is unsuitable for vehicles such as busses and lorries, with which the invention is particularly concerned, since it is required that the distance measuring means be not easily tampered with. Additionally, U.S. Patent 4,807,265 employs sensing means which must be very precisely positioned, with very little tolerance, in positioned relationship with the sensor actuating means. This, again, is unsuitable for use with heavy duty vehicles, which suffer many shocks every day, and which must be fitted with sensing apparatus which has a high tolerance and does not require precise positioning.

SUMMARY OF THE INVENTION The present invention seeks to provide a highly accurate cost-effective automatic vehicle location monitoring system.

There is thus provided in accordance with a preferred embodiment of the present invention an odometer system mounted on a vehicle and including sensor actuating means mounted on at least one wheel, and sensor means mounted in proximity to the magnets, at a location fixed with respect to an imaginary central axis of the wheel , about which axis the wheel rotates .

There is also provided in accordance with a further preferred embodiment of the present invention an automatic vehicle location monitoring system including odometer means including sensor actuating means mounted on at least one wheel, and sensor means mounted in proximity to the magnets , at a location fixed with respect to an imaginary central axis of the wheel, about which axis the wheel rotates, computer means for receiving inputs from the odometer means and for performing dead reckoning of the position of the vehicle, and communication means for communication of information regarding the location of the vehicle to utilization apparatus .

Further in accordance with a preferred embodiment of the present invention, the sensor actuating means include a multiplicity of sensor actuators mounted onto a rim of each of the at least one vehicle wheels and the sensor means includes at least one proximity sensor.

Still further in accordance with a preferred embodiment of the present invention, the sensor means is mounted on the cover of the brake drum.

Additionally in accordance with a preferred embodiment of the present invention, the multiplicity of sensor actuators are mounted on the inner rim of the vehicle wheel.

Still further in accordance with a preferred embodiment of the present invention, the multiplicity of sensor actuators are individually mounted on the wheel rim.

Further in accordance with a preferred embodiment of the present invention, the multiplicity of sensor actuators are disposed in mutually spaced relationship in a ribbon which is mounted on the wheel rim.

Still further in accordance with a preferred embodiment of the present invention, the multiplicity of sensor actuators are mounted on the wheel rim by means of spring clamps .

Additionally in accordance with a preferred embodiment of the present invention, the sensor means includes first and second spaced sensor elements, which are operative to provide an output indication of the direction of rotation of an adjacent magnet bearing wheel .

Further in accordance with a preferred embodiment of the present invention, the multiplicity of sensor actuators includes a toothed disk.

Still further in accordance with a preferred embodiment of the present invention, the disk is formed of an electrically conductive material and the proximity sensor includes an inductive proximity switch.

Additionally in accordance with a preferred embodiment o e presen nven on, e prox m ty sensor nc u es an ultrasound proximity switch or a capacitive proximity switch.

Further in accordance with a preferred embodiment of the present invention, each individual one of the multiplicity of sensor actuators includes a magnet.

In accordance with a further preferred embodiment of the present invention, there is provided a method for mounting odometer means on a vehicle, the method including the steps of mounting sensor actuating means on at least one wheel, and mounting sensor means in proximity to the magnets, at a location fixed with respect to an imaginary central axis of the wheel, about which axis the wheel rotates.

In accordance with a further preferred embodiment of the present invention, there is provided a method for automatically monitoring vehicle location including providing odometer means, the step of providing including the steps of mounting sensor actuating means on at least one wheel, and mounting sensor means in proximity to the magnets, at a location fixed with respect to an imaginary central axis of the wheel, about which axis the wheel rotates, receiving inputs from the odometer means and performing dead reckoning of the position of the vehicle, and communicating information regarding the location of the vehicle to utilization apparatus.

In accordance with yet a further preferred embodiment of the present invention, there is provided a vehicle including odometer means , the odometer means including sensor actuating means mounted on at least one wheel of the vehicle, and sensor means mounted in proximity to the magnets, at a location fixed with respect to an imaginary central axis of the wheel about which axis the wheel rotates.

Further in accordance with a preferred embodiment of the present invention, the vehicle includes a bus.

Still further in accordance with a preferred embodiment of the present invention, the sensor means defines an imaginary axis extending perpendicularly to a sensing end of the sensor means and wherein the orientation of the imaginary axis relative to the wheel of the vehicle is radial.

Additionally in accordance with a preferred embodiment of the present invention, the sensor means defines an imaginary axis extending perpendicularly to a sensing end of the sensor means and wherein the orientation of the imaginary axis relative to the axis of the wheel of the vehicle is parallel.

Additionally in accordance with a preferred embodiment of the present invention, the sensor means includes a single sensor element.

Still further in accordance with a preferred embodiment of the present invention, the at least one wheel of the vehicle includes at least a right wheel and a left wheel thereof and the odometer system includes a differential odometer system.

The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which: Fig. 1 is a simplified block diagram illustration of an automatic vehicle location monitoring system constructed and operative in accordance with a preferred embodiment of the present invention; Fig. 2A is a generalized plan view illustration of the mounting of individual magnets on the inner rim of a wheel; Fig. 2B is a detailed sectional illustration taken along the lines B -B of Fig. 2A; Fig. 3A is a generalized plan view illustration of the mounting of a multiple magnet containing strip on the inner rim of a wheel; Fig. 3B is a detailed sectional illustration taken along the lines B - B in Fig. 3A; Fig. 3C is a pictorial illustration of the arrangement of magnets in the multiple magnet containing strip of Fig. 3A; Fig. is an illustration of a preferred location and relative orientation of the magnets and the sensor apparatus.

Figs. 5A and 5B are illustrations of a first preferred orientation of the sensor apparatus relative to the wheel and relative to the poles of the individual magnets; Figs. 5C and 5n are illustrations of a second preferred orientation of the sensor apparatus relative to the wheel and relative to the poles of the individual magnets; Fig. 6 is an illustration of the superimposition of two sensor elements over an arrangement of multiple magnets on a vehicle rim; Fig. 7 illustrates typical output signals derived from the two sensor elements of Fig. 6, as a wheel bearing multiple magnets mounted on its rim moves therepast; and Fig. 8 illustrates a further preferred embodiment of the invention wherein the magnets of Fig. 2A are replaced by a toothed disk.

Reference is now made to Fig. 1, which illustrates in generalized block diagram form an automatic vehicle location monitoring system constructed and operative in accordance with a preferred embodiment of the present invention. In the preferred embodiment illustrated, at least one sensor, and preferably two sensors 10 and 12, each comprising a pair of sensor elements, are mounted in sensing communication with a multiplicity of magnets 14 which are mounted in precisely azimuthally distributed orientation onto the rim of at least one and preferably each of a pair of opposite wheels of a vehicle. Preferably the magnets I are mounted on the non-driven wheels, to minimize slipping.

Each of the pair of wheels is typically equipped with the same number of magnets, typically (for a standard sized truck wheel) approximately 20 magnets per wheel. When the vehicle is headed straight, the sensor 10 which is in sensing communication with the right wheel will thus provide an approximately equal number of pulses as will the sensor 12 which is in sensing communication with the left wheel. When the vehicle heads right, more pulses will be emitted by the sensor at the left wheel and, conversely, when the vehicle heads left, more pulses will be emitted by the sensor at the right wheel.

The number of pulses originating from each wheel is proportional to the distance covered by that wheel. The change in heading of the vehicle is related to the difference between the distances covered by each wheel by the following equation: Theta = [D - D ]/T left right where : Theta = change in heading D , D =the distance covered by the left and right wheels, left right respectively T= the distance between the two wheels (vehicle track), and may be computed accordingly.

Differences between the outer perimeters of the left and right tires may be automatically adjusted for by examining the output of the sensors with reference to the distances and angles specified in the vehicle's itinerary, using known methods.

According to an alternative embodiment, magnets 14 are mounted as above onto the rim of a single one of the vehicle's wheels. Indication of distance covered by the vehicle is obtained as described herein in connection with the embodiment in which magnets are mounted on both wheels. If desired, the indication of distance may be combined with an indication of heading as described herein, to obtain indication of the vehicle's location. The indication of heading may be obtained e.g. from flux gate compasses 22. Alternatively, the location of the vehicle may be identified by matching the pattern of distances traveled by the vehicle with a reference pattern. For example, in the case of a bus which opens its doors at every, or almost every, bus stop along a known route, the pattern of distances between the door openings may be matched with a reference pattern of the bus- stops along the route, thereby to automatically identify the location of the bus.

The output signals of the sensors 10 and 12 are supplied to respective up/down counters 16 and 18, which output to a microcomputer which is compatible with the environment in a particular application, such as an IBM PC. Microcomputer 20 can, if desired, receive additional data from auxiliary sensors 22 (e.g. flux gate compasses). Microcomputer 20 can also, if desired, receive an independent indication of location from any commercially available auxiliary vehicle location system (not shown) such as a LORAN or GPS location system, which indication can be used in conjunction with the location indication derived by microcomputer 20. Microcomputer 20 is associated with the auxiliary system via an input/output port 2k . Microcomputer 20 is typically mounted on-board the vehicle and may include an onboard terminal 26 accessible to the vehicle operator.

According to a preferred embodiment of the present invention, the microcomputer 20 communicates via a radio link including a mobile transceiver 28 and a central transceiver 30 with a central computer 3 at a fixed location which may supply data to a video display unit 3^ or to any other suitable utilization apparatus .

Alternatively, the microcomputer 20 may communicate directly with a central computer 3 and a video display unit 3^ located on the vehicle.

Operation of the system and particularly of microcomputer 20 may be in accordance with conventional teachings, such as those incorporated in and referred to in the aforesaid MTR-6059. the contents of which and the contents of the references noted therein are hereby incorporated by reference.

It is a particular feature of the present invention that the magnets 14 are mounted on the vehicle wheels and that convenient and cost effective means and techniques are provided for mounting of the magnets thereon. Reference is made in this context to Figs. 2A and 2B, which illustrate the mounting of a multiplicity of discrete magnet units 40 onto the wheel rim 42 by means of individual spring clamps 44, as shown. It is seen that magnet units 40 may be configured with a suitable recess 46 for receiving and retaining clamps 44 and with a suitable protrusion 48 for secure seating in the corresponding recess formed by the wheel rim 42. Alternatively, magnet units 40 may be retained by use of an adhesive or by any other suitable technique.

Reference is now made to Figs. 3A - 3C, which illustrate an alternative technique of magnet mounting on vehicle wheel rims in accordance with the present invention. Here a continuous strip or ribbon 50 is provided having precisely spaced magnets 52 embedded therein. It is seen that ribbon 50 may be configured with suitable recesses 6 for receiving and retaining clamps ^ and with suitable protrusions 58 for secure seating in the corresponding recess formed by the wheel rim. Alternatively, ribbon 50 may be retained by use of an adhesive or by any other suitable technique.

It is seen from Fig. 3B, which is also applicable to the embodiment of Figs. 2A and 2B, that a sensor 60 is fixedly mounted, typically on the coverplate of the brake drum 9» by suitable means such as a bracket 63. Sensor 60 is disposed within a distance of approximately 1G mm from the magnets as they pass the sensor. Alternatively, the sensor 60 may be mounted at any other convenient attachment location which is in proximity to the magnets so as to allow magnetic communication between the sensor and the magnets, and which is fixed relative to an imaginary central axis 6l of the wheel (Fig. 3A) . In other words, the sensor is arranged so as to remain at a fixed location relative to the magnets (a) if the wheel is vertically displaced due to faults in the road; and (b) if the wheel pivots due to steering of the vehicle.

Referring now to Figs. 4 and 5A-5D. the sensor 60 defines an imaginary axis 80 perpendicular to the sensing end 82 of sensor 60. The magnet 40 defines an imaginary axis 86 joining its two poles.

The orientation of axis 80 relative to the wheel is preferably radial, as shown in Figs. 5A and 5Β· The pole of the magnet adjacent to the sensing end 82 is seen to be the south pole, but can alternatively be the north pole. Alternatively, sensor 60 may be oriented parallel to the axis 61 of the wheel, adjacent the inner surface thereof, as in Figs. 5C and 5η· The orientation can even be intermediate between the two described orientations, the only condition being that the magnet and sensor apparatus be suitably oriented and distanced relative to one another, as described herein. In Figs. 5A_5D. i is seen that the sensor axis 80 and the magnet axes 86 are always parallel .

Reference is now made to Figs. 6 and 7· As illustrated schematically in Fig. 6, the sensor 60 typically comprises a pair of sensor elements 62 and 6k, which are typically separated from passage relative thereto by a distance a/4, where a is the distance separating respective leading edges of adjacent magnets from each other along the direction of magnet passage. Each magnet is preferably of a virtual length (i.e., of a length as perceived by the sensor 60) of a/2 along this direction. Each time the magnets move a distance of a/4, one of sensor elements 62 and 64 changes its state from "off" to "on" or vice versa. This results in formation of a leading edge or a trailing edge, respectively, of a signal emitted from the above-identif ed one of sensor elements 62 and 64.

Fig. 7 illustrates typical output pulse trains A and B produced by sensor elements 62 and 64 respectively in response to rotation of a magnet-bearing wheel in magnetic communication therewith. It may be appreciated that there is always a 0 degree phase shift between the two pulse trains. This provides an indication of wheel rotation direction. Specifically, there is a +90 degree phase shift between pulse trains A and B if the wheel is rotating forward, and a - 0 degree phase shift therebetween if the wheel is rotating backward. Therefore, up/down counters l6 and l8 give an indication of the algebraic distance traveled by the vehicle. According to an alternative embodiment, only a single sensor element may be provided, instead of the two sensor elements 62 and 64, in which case no indication of wheel rotation direction is provided. Indications of distance and of change of heading are obtained as in the two-sensor element embodiment described hereinabove.

Sensor elements 62 and 64 are typically proximity switches, such as the reed-type proximity switches available from Hamlin Inc. (catalog no. 59025-020) .

Fig. 8 illustrates an alternative preferred embodiment of the present invention, wherein the sensor actuators comprise the teeth of a toothed disk 70 preferably formed of an electrically conducting material, and the magnetic sensors of Figs. 2A-6 are replaced by proximity switches 72. Switches 72 may be inductive, according to a preferred embodiment, or may alternatively be capacitive or ultrasound type switches. Any suitable commercially available proximity switch with a range of approximately 10 mm may be used. The disk 70 is preferably secured to the rim of the wheel as by clamps 7^ · Alternatively or in addition the disk 70 (or the magnet assembly of Figs. 3A and 3C) may be induced to securely engage the rim by slightly increasing its perimeter or by any other suitable deformation process . In other respects , such as the relative orientations of the various components and the relationship between the various dimensions of the system as illustrated in Fig. 6 , the embodiment of Fig. 8 resembles the embodiment of Figs. 2A-7 .

It will be appreciated that the preferred method of mounting the sensor actuators may vary somewhat as a function of the type of wheel rim. In general, the sensor actuators may be retained by any suitable technique such as the technique employed for mounting and securing counterbalancing weights on a rim of that particular type.

It will be appreciated by persons skilled in the art that the present invention is not limited by what has been . the present invention is defined only by the claims which follow:

Claims

1. 600/90 CLAIMS : I An odometer system mounted on a vehicle, comprising one or more magnets acting as sensor actuating means, the said magnets being mounted on the inner wheel rim of a vehicle wheel, and sensor meatis mounted in proximity to the sensor actuating means, the said sensor means being positioned in the inner side of the vehicle wheel in actuating positioned relationship with the magnets at a location fixeo1 with respect to an imaginary central axis of the wheel, about which axis the wheel rotates, thereby sensing one or more magnets for each wheel rotation.

2. An odometer system according to claim 1, character zed in that at least a right wheel and a left wheel are provided with sensor actuating means and with sensor means, as claimed in claim 1.

3. An odometer system according to claim 1 or 2, characterized in that the sensor means is mounted on the cover of the brake drum.

4. A system according to any one of claims 1 to 3, characterized in that the magnets are individually mounted on the wheel rim.

5. A system according to any one of claims 1 to A, characterized in that a plurality of magnets are disposed in mutually spaced relationship on a ribbon which is mounted on the wheel rim.

6. A system according to any one of claims 2 co 5, wherein the odometef means comprise differ nt ial odometer means mounted on at least a right wheel and a left wheel. 1 600 / 90 912 67 / 2

7. A system according to claim 1 or 2, wherein the magnets are replaced by non-magnetic sensor actuating means and the sensor means comprises a proximity sensor.

8. A system according to claim 7, wherein the sensor actuating means are made of an electric conductive material and the proximity sensor comprises an inductive proximity switch .

9. A system according to claim 7, wherein the proximity sensor comprises an ultrasound proximity switch.

10. A system according to claim 7, wherein the proximity sensor comprises a capacitive proximity switch.

11. A system according to any one of claims 1 to 10, wherein the proximity switch is a reed switch.

12. A method for automatically monitoring a vehicle location, comprising providing odometer means according to any one of claims 1 to 11, receiving inputs from the said odometer means and performing dead reckoning of the position of the vehicle, and communicating information regarding the location- of the vehicle to utilization apparatus .

13. A vehicle comprising an odometer system according to any one of claims 1 to 11.

14. An odometer system, essentially as described and illustrated, with particular reference to the drawings. l u is sn b TIN w w a L U Z Z A T T O & L U Z Z ATTO