GB2590429A

GB2590429A - Intelligent speed mapping

Info

Publication number: GB2590429A
Application number: GB1918633.7A
Authority: GB
Inventors: Stephen Mitchell John
Original assignee: Individual
Current assignee: Individual
Priority date: 2019-12-17
Filing date: 2019-12-17
Publication date: 2021-06-30
Also published as: GB201918633D0

Abstract

A vehicle speed mapping system comprises a receiver unit capable of receiving a first input of vehicle speed data calculated from location data and a second input of vehicle speed data measured from the vehicle, such as from an axle speed counter 60 or a speedometer analogue to digitally converted output signal 57. The system further comprises a processor 51 for calculating a ratio of the first input to the further input(s), a storage device for storing the ratio of input speeds, and a moderator unit 52 for mapping the ratio onto any of the further inputs in the event that the first input is removed. The system determines the vehicle speed based upon location data. A corresponding method of vehicle speed mapping is provided. The invention provides improved speed accuracy for use, for example, in a tunnel when GPS is unavailable. The invention is further aimed at reducing instances of congestion caused by long overtaking manoeuvres.

Description

Intelligent Speed Mapping This invention is directed to a system for providing an improved reading of vehicle speed using location data and, in particular, to how to map location data to alternative measurements of vehicle speed. The invention can be used in combination with a speed control system to permit more efficient overtaking.

Congestion, especially on all major multi-lane roads such as motorways, autoroutes, freeways and other main trunk roads, is increasing. Much of this congestion comes from vehicles travelling at similar, but slightly different, speeds leading to a high number of overtaking manoeuvres being required. Where the speed differential is only minimal, such overtaking manoeuvres take a long time, leading to faster vehicles behind being delayed.

The issue is common when a first slow (relative to the permitted road speed) vehicle is attempting to pass a second slow vehicle. Often lorries, HGVs, or other larger vehicles such as vans, minibuses, coaches and the like are speed regulated to restrict their maximum speed, for example to something of the order of 97kph (60 m.p.h) in the UK. Were they all to travel at exactly the same speed as a result of this legal limit, there would be very little overtaking and hence much reduced congestion, thus any queuing for cars attempting to make their way along such roads would generally be very much less.

However, although the vehicles may have a common maximum speed, the setting arrangements can deliver a noticeable small difference in the rate at which they travel along the roads. Such vagaries can occur for numerous reasons including: a) a small difference in the setting of maximum engine r.p.m.

b) the variation from one vehicle of a particular make/model as to how a particular r.p.m. setting translates into a given road speed.

c) how the tread depth -hence circumference-of a properly inflated tyre of the drive wheels causes difference in road speed for a given engine r.p.m.

d) differences in drive wheel tyre temperature and tyre inflation pressures may cause a variation of maximum speed of the vehicle even when it has the same engine r.p.m.

e) a gradual deterioration of performance/efficiency between servicing of the vehicle or just its age.

These, together with the large numbers of vehicle on the roads, especially HGVs, leads to a high number of overtaking manoeuvres.

If it is assumed that a vehicle's speed restriction is converted into a maximum number of engine revolutions per minute, this value for each different model of engine may well then be a standard figure conversion from 97 kph (60 m.p.h.) Even if all such lorries could be adjusted at some given time to have exactly the same maximum speed, whatever this turns out to be in engine revs per minute, small changes in the depth of tyre tread, or a change in tyre pressure may well cause some small difference in the speed along the carriageway, owing to a change in outer radius of the drive tyres. While there are such minor differences in carriageway speed between these HGV, overtaking will continue to occur. This proposal may have the effect of reducing the problems which such overtaking generates.

If a series of HGV's, each of length 16.0 metres, are travelling along a motorway closely behind one another, let us say with a gap of 4.0 metres between the nose of one and the tail-end of the next in front, the distance to be gained over the lorry being overtaken by the one doing the overtaking before it can move back into the nearside lane will be 40.0m. With a relative distance gained of just 20m its cab is now level with the front of the one which was leading. It will be a further 20m before it can move back in and provide a gap of 4.0m once again between them. In fact it is more than likely that the distance to be gained is more than this. If the relative speed of the one vehicle with respect to the other is 1.0 m.p.h. (0.444 m/s) this will take roughly 90 seconds to overtake just one lorry.

Such slow overtaking manoeuvres themselves also lead to congestion as the effect of the front few cars of a stream of faster vehicles being forced to slow down, for example due to an unexpected slow overtaking move, is well known. Particularly slowing down below a critical speed when reacting to such an event, a driver would force the car behind to slow down further and the next car back to reduce its speed further still. The result of this is that several miles back, cars would finally grind to a halt, with drivers oblivious to the reason for their delay. The traffic jam moves backwards through the traffic creating a so-called 'backward travelling wave', which drivers may encounter many miles upstream, several minutes after it was triggered. The main issue is around the smoothness of traffic flow. Heavy traffic will not automatically lead to congestion but can be smooth-flowing. The problem is the inherent time-delay in drivers' reactions, which lead to drivers braking more heavily than would have been necessary had they identified and reacted to a problem ahead a second earlier.

If the relative speed between such vehicles can be legally increased to 8 kph (5.0 m.p.h.) the time taken to overtake reduces to about 18 seconds, assuming that the lorry doing the overtake can quickly achieve this speed as it begins the manoeuvre, or build up this difference a short while in advance of it.

Given the difficulties of overtaking when vehicle are travelling at relatively close speeds, accurate measurement of the actual speed of travel of the vehicle becomes even more important to ensure that the overtaking vehicle does actually have the expected speed differential relative to the vehicle being overtaken.

The aim therefore is to reduce congestion by providing a more accurate reading of the vehicle speed. This may be used to provide an upper speed limit for a speed controlled vehicle thereby reducing overtaking manoeuvres and by permitting a speed limited vehicle to perform an overtaking manoeuvre in a much reduced time period, and thus to be using a space in an outer lane of a major trunk road for as little time as possible and hence reduce the present constraints to the passage of lighter vehicles in the outer lanes.

According to a first aspect of the present invention there is provided a speed mapping system comprising a vehicle location tracking device, a receiver unit capable of receiving a first input of vehicle speed data calculated from location data and, at least, a second further input of vehicle speed data measured from the vehicle; a processor for calculating a ratio of the first input to the further input(s); a storage device for storing the ratio of input speeds; and a moderator unit for mapping the ratio onto any of the further inputs in the event that the first input is removed to determine the vehicle speed based upon location data.

Location data can be used to calculate a vehicle's speed independently from factors such as tyre pressure and tyre tread depth. Measurements from the vehicle are an alternative source of speed values, these sources include the rotation of a vehicle's drive shaft and rotation of one or more of the wheel axles. These measurements can be used to approximate the vehicle speed by converting number of rotations in a given time period to distance travelled then dividing this by the time period. The use of vehicle measurements has an associated error depending on numerous factors including the condition of the vehicle, including the tyre conditions and duration between the last service, road and/or weather conditions, or even the weight of the vehicle.

Location data could take one or more different forms and the data used by the invention may come from a single course or from multiple sources. A global positioning system (GPS) uses satellite communication with a vehicle to determine the position of the vehicle at a particular time. Multiple location readings over a given time can be used to determine the vehicle speed.

GPS-calculated speed has the issue of approximating the surface of the Earth as a spheroid which does not account for the variation in road gradient, meaning the distance covered by the vehicle in a straight line may be different to the projected distance. It may also be less accurate when travelling up or down steep inclines, as the GPS system will likely account for the horizontal distance moved, rather than the actual (larger) distance travelled along the incline. The estimated error in speed calculation using GPS is 0.5% at an angle of 5.7° and 1.0% at an angle of 8.1°. Roadside systems such as those used on so called SMART motorways can determine the speed of a vehicle by measuring the time taken to travel between detectors which might be located at known positions, and therefore known separations, along a road.

If the vehicle were to enter a long tunnel or other area in which the location data became unavailable then the mapping system of the invention can use the stored speed data to calculate the speed of the vehicle using the input signal from the vehicle (rotation of the gearbox output shaft, rotation of the wheel axles, or the speedometer reading) and comparing it to the stored data to obtain a more accurate reading of the vehicle's true speed than might otherwise be obtained from the vehicle input signal itself, which would be subject to the possible variations discussed above.

The system is preferably retrofittable to existing vehicles.

The further input signal may be the speed calculated by the measurement of the rotation of the gearbox output shaft. The further input signal may be the speed calculated by the measurement of the rotation of one or more of the wheel axles. The further input signal may be the speed calculated by a speedometer.

The system may use location data provided by one of either GPS or by one or more roadside locators, such as on a SMART motorway.

Preferably the processor is configured to update the stored ratios when further vehicle transit occurs to include additional data.

Preferably the moderator unit is configured to switch to only use mapped data to calculate the speed of the vehicle when the gradient of a road exceeds a predetermined level. In such a configuration, the system may further comprise a tilt sensor for determining the gradient of the road on which the vehicle is travelling.

The moderator unit may output an error signal to a user in the event a programmed sufficiently large difference between input data and predicted mapped data is detected.

The system may have a service button provided for a user to reset the processor unit in the event that the vehicle tyres are replaced.

The system may further comprise a clock for determining the duration of inactivity of the vehicle. In such a system, the system may further comprising a reset device for automatically resetting either or both of the processor and the moderator should the duration of inactivity exceed a certain threshold.

In a further aspect of the present invention there is provided a method of mapping vehicle speed comprising the steps of receiving a first input of location data and calculating a vehicle speed from location data, receiving, at least, a second further input of vehicle speed data from the vehicle, calculating a ratio of the first input to the further input(s), storing the ratio of input speeds, mapping the ratio of input speeds onto further inputs in the event that the first input is removed, and determining the vehicle speed based upon the location data.

The present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a basic implementation of a vehicle speed control; Figure 2 is a further implementation of a vehicle speed control system with additional functionality including a speed adjuster; Figure 3 is a further implementation of a vehicle speed control system with additional functionality including a speed adjuster; and Figure 4 shows a schematic of a speed mapping system and which may be incorporated into the speed control systems of Figures 1 to 3.

Figure 1 illustrates a system 10 having a vehicle speed controller 11 (electronic throttle control unit), a speed adjuster 12, a location data receiver 13 (GPS or other suitable receiver), and a setting unit 14 for setting the absolute maximum speed of the vehicle.

The vehicle speed controller 11 is typically an electronic control unit fitted in the engine or connected to the engine to allow the speed of the vehicle to be controlled, often by controlling the amount of actuation of the throttle that is permitted. As engines become more and more computerised, the throttle may be an entirely electronic throttle. The vehicle speed controller receives a data signal from the location data receiver 13, which is typically some form of GPS device. The location data receiver 13 may obtain data from GPS satellites, or may obtain data from road side systems built into so called SMART motorways. The location data is used to determine the standard maximum speed of the vehicle for the given road type, so can vary as the vehicle moves from a more major to a more minor road (or vice versa). Additional information may also be used to determine the standard maximum speed, such as weather, time of day, vehicle load, driver ability or the like. Such information may be obtained via the location data stream, by a wireless signal transmitted to the vehicle or may be hard coded into the system. In this example, the location data is fed into a location/speed activator 15 which converts the location data into a standard maximum speed for the vehicle. A control signal is then fed to the vehicle speed controller 11 to ensure that the vehicle cannot exceed that standard maximum speed, unless the speed adjuster is activated as discussed below.

The speed adjuster 12 acts to allow the electronic throttle control unit to operate such that the vehicle can exceed the standard maximum speed to facilitate overtaking. The speed adjuster is typically operated by the driver directly, for example by actuating a button or lever within the vehicle. The speed adjuster may provide for the vehicle to have a speed increase for limited amount of time sufficient to complete an overtaking manoeuvre, or it may be unlimited. It is preferred that the speed increase permitted is only for a limited amount of time, so as to prevent continual "overspeeding", although it is undesirable for the speed to be reduced back to the standard maximum speed if the overtaking manoeuvre is not complete. Misuse of the speed adjuster can be monitored, as described in later Figures. Information can be recorded about the duration and frequency of the use of the speed adjuster and this can be fed to various bodies such as owners of the vehicle, employers of the driver, or vehicle insurance companies. In the case of an "unlimited" duration, one or more other information recording devices will be required so that misuse can be monitored The setting unit 14 is not essential, but provides a basic level of safety to prevent the vehicle to which the system is fitted exceeding a predetermined maximum, typically the highest national speed limit in the country of use. Other mechanisms could also be used to provide the ultimate maximum permitted speed of the vehicle including, but not limited to, location data from the GPS or other location provider, the road type, the country of operation or weather conditions. Such an element is helpful when location data is not available, for example when a vehicle is passing through a tunnel or forest, where a GPS signal may not be easily obtained. It also acts as a failsafe should the location system cease to operate correctly. The functionality of the setting unit 14 may be incorporated directly into the vehicle speed controller.

The vehicle speed controller 11 is also fed by an input signal 16 from the driver. This is typically simply the driver's input regarding how fast to make the vehicle travel. This would typically be related to the operation of the throttle or accelerator. An alternative would be where the vehicle was being remotely controlled, either within a convoy of vehicle or in a standalone "driverless" mode, where control is either provided by way of remote wireless signals to the vehicle or by way of electronic control signals generated within the vehicle or hard coded into the vehicle.

In one example of the invention, there may be a button/control switch, which a driver can operate to permit the maximum speed to rise temporarily by 8kph (5.0 m.p.h.) (or any figure considered to be optimum for safety versus time spent in the overtaking lane) and to permit a suitable time to elapse before the onboard speed limiting circuitry resumes its normal function/value. This control would over-ride the standard electronic throttle control unit 11 and raise the maximum permitted speed of the vehicle for a given period.

However, this system might be misused by some drivers by operating this switch continuously, hence the average speed of their journey might be artificially high and by a substantial degree.

A checking system 20 as shown in Figure 2 can be utilised, connected in this example such that a CPU 21 receives data from both the speed adjuster 12 and the speed controller 11, and would help to reduce the likelihood of such misuse. The checking system 20 incorporates a visual record (recorded digitally in a similar fashion to CCTV data storage) by a dashboard camera 22 to show that genuine overtaking is occurring, how often and for how long this circuit is operated. A clear record is preferably to be displayed in the driver's cab on a display device 23. It is vital that a clear statement of explanation of the unit and the consequences of misuse leading to criminal/driving offences of such misuse should ensure compliance should be known by all concerned, as well as the aim of the scheme. A clock 26 is also provided to allow time based information to be recorded such as duration and frequency of use of the speed adjuster 12.

Storage of digital data in a storage device 24, protected from intervention by drivers and by transport companies, which can be read via appropriate read out systems 25 by both vehicle owners/employers and police or other traffic or vehicle monitoring bodies may reduce the risk of such behaviour. Proper support from motorway/trunk route mobile police units should have a further deterrent effect upon such misuse.

Figure 3 shows a yet more enhanced system yet but keeps the important elements of Figures 1 and 2. The extensions to the basic circuitry which have been shown on Figure 2 include a position, time and/or speed recorder 31 for holding position, time and/or speed data of all journeys. This helps to manage the driver of the vehicle and ensure correct usage of the system and in particular to check for overuse of the speed adjuster 12.

A sonic distance measuring circuit 32, or other distance measuring device, may be included to ensure that vehicles do not get too close to vehicles in front when in the same lane of traffic.

Whilst one or more distance sensors may be used, the system may obtain distance data from a SMART motorway system.

A driver operated cruise control circuit 33 may be used to ensure that the vehicle does not breach speed limits lower that that expected for the given road e.g. roadworks 80kph (50 m.p.h.) sections, or 64/48kph (40/30 m.p.h.) road sections near big towns/cities. This gives the driver the ability to check for temporary reduced speed road sections, information about which had not been hardcoded into the system previously and which cannot be, or has not been, provided to the vehicle by way of the location data or other data streams which the system might receive. For example, although not shown, the present invention may receive controlling signals regarding temporary speed restrictions remotely, via either wi-fi, radio or other wireless systems.

Where "smart speed control sections" are employed on motorways, with variable speed limits owing to works or other congestion scenarios, these signals may be picked up by an appropriate data receiver 34 and be passed into the speed controller 11 unit automatically. A reduced maximum speed for all vehicles of a given vehicle type could be generated without drivers having to set any controls.

Any driver responses to be monitored, including inboard camera systems to check use of mobile 'phones or texting (including using 'in cab CCTV') could be recorded throughout any journey by a driver monitoring system 35 which may include cameras or other sensors.

Figure 4 illustrates an enhanced speed determining system 50 according to the invention and which may provide a further input relating to the actual speed of travel of the vehicle to a speed regulator system 72. The speed reading may be provided to a regulator system, such as that shown in Figure 3, as an input to the electronic throttle control unit 11, position recorder/ speed recorder 31, or to some other part of the system 10.

The speed determining system 50 includes a processor unit 51 and a moderator unit 52. Either or both of these may include a data storage device 53 which may be any form of suitable accessible memory device.

The processor 51 typically has numerous inputs. One input is a location data based speed signal 54, which may be calculated by a calculating unit 55 receiving GPS or other location data 56 and determining the vehicle speed from the location data.

One or more vehicle based speed signals are also provided. The vehicle based speed signals may be either or both of a speedometer reading 57 or a measurement corresponding to wheel RPM reading 58. The RPM reading may be measured from the rotation of the axle from the gearbox, the gearbox output shaft, the stub axle or the wheel itself. The wheel axle RPM signal 58 may be obtained from a counter 60 associated with one or more of the axles connected to the wheels, such that the RPM counted is representative of the actual speed of the vehicle. The RPM reading may be calculated from the measurement of rotation by relating to a clock 69 in the processor unit 51 and/ or moderator unit 52.

When the vehicle is driven around corners the measured rotation of the wheel on the inside of a bend in a road will be slower than the rotation of the wheel on the outside of a bend, in this situation an average of the two measurements may be taken as the speed signal.

The speedometer signal 57 input to the processor 51 is typically a digital signal, so may pass through an analogue to digital converter 59 prior to the processor 51.

Further inputs to the processor unit 51 may include meteorological data 61 such as air temperature and any further vehicle based speed data 62 from the vehicle such as the power drawn by an electric or hybrid vehicle.

The system can be automatically or manually updated to account for external changes to the vehicle. A change in the diameter of a tyre is understood to change the speed of a vehicle across the terrain for a given rate of rotation of the output drive shaft from the gear box of the vehicle. The system may be reset in the event that, for example, new tyres are fitted, by a user input in the form of a service button. The reset preferably overwrites some or all of the stored data, such that more accurate mapping data can be generated using the newer equipment. A clock 69 in the system may be used to register the time that the vehicle is not in use and automatically reset some or all of the data should a predetermined period of inactivity be detected. Lack of activity of a vehicle may be indicative that there has been little or no maintenance, and for example, tyre pressures may be significantly different once activity restarts. The different tyre pressure would relate to a change in tyre diameter. This data may be used in the system to account for variations in the speed mapping due to the temperature of the tyres changing during use.

The processor unit 51 can, using location data and at least one of the vehicle based speed inputs, carry out a speed mapping process, whereby a comparison is made between the location data calculated speed 54 and one or more of the vehicle based speed inputs 57, 58, 62. The processor can determine a ratio between the location data and any or each of the speed inputs. More such data is preferably taken again a short period of time later, such that the processor can build up a store of data, for example a series of ratios, reference tables, graphs or the like, concerning how the speed of a vehicle determined by location data relates to physical measurements that can be taken from the vehicle itself This data may be updated over time, for example, as tyre wear alters how the vehicle based speed data maps to the location based data. For example, the processor may use only the data generated over a given period of time (e.g. a week), or distance travelled (e.g. 200 miles), such that the ratios are as realistic to the current vehicle state as possible. Using data over a relatively short duration, e.g. one hour or 20 miles, will likely result in various speeds not being actively measured and so providing reduced accuracy. This data may be output to the moderator unit 52 as enhanced speedometer ratio 65 and/or enhanced axle ratio 66 The moderator unit 52 also has numerous inputs including one or more of the vehicle based speed signals 57, 58, and the raw location data 54. The moderator unit 52 then determines the appropriate enhanced speed signal 68 to output to the vehicle speed regulator unit 11, which may have an output 70 to the CPU 21 or to another system requiring the vehicle's actual speed.

The moderator unit 52 will preferentially use the location data speed signal 54, as this is inherently more accurate as discussed previously. In the absence of location data 54, for example due to failure of the location data system within the vehicle, or the absence of an available location data signals due to the vehicle travelling in a tunnel or other concealed location, the moderator unit can take a vehicle speed input 57, 58 and, using the respective enhanced ratios 65, 66, determine the vehicle's actual speed by mapping the vehicle speed input to the more accurate location data.

Additionally, the moderator unit and /or the processor unit 51 may include either an input from, or contain itself, a tilt sensor 71 or any other device capable or indicating the incline or decline along which the vehicle is travelling. The incline information can then be used either to generate further ratio data whereby location data against vehicle speed input is modified to take account of the variation in horizontal distance travelled when moving up or down hill. The moderator and/or processor may only concern itself with incline data if the incline is above a threshold value such as 5° As a safety check, the moderator unit 52 preferably determines how close the various input data are to each other and determines an error value. If an error of a sufficiently large value is detected between the various input data to the moderator unit 52, then an error signal 70 is preferably generated, which can either alert the driver on his usual display, or may trigger an alternative speed determining process to occur, e.g. if the location data suddenly becomes "unusual, then the system would for example stop updating the location data/vehicle speed data ratios and revert to using either only the vehicle based speed data, or the vehicle speed data adjusted using earlier stored ratios.

The moderator unit 52 and the processor unit 51 may be embodied in separate devices or maybe embodied in the same device such as a processor or ASIC or the like.

The applicant hereby discloses in isolation each individual feature described herein and any combination of two or more such features, to the extent that such features or combinations are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or combinations of features solve any problems disclosed herein, and without limitation to the scope of the claims. The applicant indicates that aspects of the present invention may consist of any such individual feature or combination of features. In view of the foregoing description it will be evident to a person skilled in the art that various modifications may be made within the scope of the invention.

Claims

CLAIMS1. A vehicle speed mapping system comprising: a receiver unit capable of receiving a first input of vehicle speed data calculated from location data and, at least, a second further input of vehicle speed data measured from the vehicle; a processor for calculating a ratio of the first input to the further input(s); a storage device for storing the ratio of input speeds; and a moderator unit for mapping the ratio onto any of the further inputs in the event that the first input is removed to determine the vehicle speed based upon location data.
2. A system according to claim 1, wherein the further input signal is the speed calculated by the measurement of the rotation of the gearbox output shaft.
3. A system according to claim 1 or 2, wherein the further input signal is the speed calculated by the measurement of the rotation of one or more of the wheel axles.
4. A system according to any preceding claim, wherein the further input signal is the speed calculated by a speedometer.
5. A system according to any preceding claim, wherein the location data is provided by one of either GPS or by one or more roadside locators, such as on a SMART motorway.
6. A system according to any preceding claim, wherein the processor is configured to update the stored ratios when further vehicle transit occurs to include additional data.
7. A system according to any preceding claim, wherein the moderator unit is configured to switch to only use mapped data to calculate the speed of the vehicle when the gradient of a road exceeds a predetermined level.
8. A system according to claim 7, further comprising a tilt sensor for determining the gradient of the road on which the vehicle is travelling.
9. A system according to any preceding claim, wherein the moderator unit outputs an error signal to a user in the event a programmed sufficiently large difference between input data and predicted mapped data is detected.
10. A system according to any preceding claim, wherein a service button is provided for a user to reset the processor unit in the event that the vehicle tyres are replaced.
11. A system according to any one of the preceding claims, further comprising a clock for determining the duration of inactivity of the vehicle.
12. A system according to claim 11, further comprising a reset device for automatically resetting either or both of the processor and the moderator should the duration of inactivity exceed a certain threshold.
13. A method of mapping vehicle speed comprising the steps of: receiving a first input of location data and calculating a vehicle speed from location data; receiving, at least, a second further input of vehicle speed data from the vehicle; calculating a ratio of the first input to the further input(s); storing the ratio of input speeds; mapping the ratio of input speeds onto further inputs in the event that the first input is removed; and determining the vehicle speed based upon the location data.