GB2117937A

GB2117937A - A timing system

Info

Publication number: GB2117937A
Application number: GB08311011A
Authority: GB
Inventors: Redvers Albert Hocken
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-04-23
Filing date: 1983-04-22
Publication date: 1983-10-19
Also published as: GB8311011D0

Abstract

A system for on-board timing for a vehicle comprises a sensing coil for producing electrical control pulses in response to movement of the vehicle past a magnet or magnets provided at predetermined locations along a course to be traversed by the vehicle. The time taken for the vehicle to complete a predetermined distance, e.g. lap of a track, is calculated on the basis of the widths of successive pulses WA, WB and the time interval between selected edges of the pulses (such as E). <IMAGE>

Description

SPECIFICATION A timing system This invention relates to a timing system for providing on-board timing for a vehicle traversing a predetermined course and is particularly concerned with a timing system as disclosed in my prior patent applications Nos 8020899 and 81 13188, the disclosures of which are incorporated herein by reference.

Experiments with the system disclosed in the prior patent applications have indicated the need for more accurate definition and repeatability of the point at which timing is started and/or stopped. The experimental work revealed slight variations in the start/stop triggering points of the timing system, which variations were found to be dependent upon vehicle speed in particular. High speeds of the order encountered in Grand Prix motor racing were found to be especially troublesome in this respect.

In my prior timing system, the method of processing the voltage pulses induced in the coil essentially involved applying the pulses to a threshold detector for producing a timertriggering signal in response to the threshold level being attained. For a given speed, it was found that triggering of the timer always occurred at substantially the same position each time the vehicle passed the magnets. However, for different speeds the triggering position (i.e. the position of the coil relative to the magnets at the time the triggering signal is generated) differed and consequently small inaccuracies in lap timing could arise especially if the vehicle speed differed substantially on successive passes of the magnets.

The objects of the present invention are to overcome the problem referred to above.

According to the present invention a system for on-board timing for a vehicle traversing a predetermined course, said system comprising sensing coil means adapted to be carried by the vehicle for producing an electrical signal in response to sensing at least one magnet located at at least one predetermined position along said course, on-board timing means and on-board control means responsive to said sensing coil means for controlling operation of the timing means to provide a record of the time interval elapsing between successive or selected electrical signals produced by said sensing coil means, characterised in that, for each sensing coil signal, the control means generates leading and trailing control signals corresponding to defined amplitudes on each side of the peak of the sensing coil signal, operation of the timing means being controlled by said control signals such that the desired time interval is determined from measurements of the time between the leading control signal of one coil signal and the trailing control signal of an adjacent coil signal and the times between the leading and trailing control signals of those coil signals.

The invention is based on the recognition that the sensing coil signals are symmetrical about their peaks even though the duration peak, amplitude and rise and fall times of the coil signal are all dependent upon the speed at which the coil passes the magnet(s).

In the preferred embodiment of the invention, each coil signal is processed by amplitude threshold means whereby a pulse is produced whose width is governed by the points at which (in absolute terms) the coil signal exceeds the imposed threshold level. In this manner, the leading and trailing edges of the pulse correspond to defined amplitudes on each side of the peak of the coil signal and will be equally spaced from the axis of symmetry of the coil signal.

In practice, the width of successive pulses derived from successive passes of the coil past one or more magnets are likely to differ owing to speed variations. However, the desired time interval between the peaks of successive coil signals can be readily determined by appropriate mathematical calculation (as will be described hereinafter) even though the peaks themselves are eliminated by the threshold means.

Measurement of the desired time interval is dependent upon the detection of the leading and trailing edges of said pulses. In order that a time read-out can be provided in the absence of a trailing edge, the control means preferably includes means which, in response to a leading pulse edge, provides a first error signal in the absence of a corresponding trailing pulse edge within a preset time, the control means being operable in response to such first error signal to cause computation of the desired time interval to be based on a predetermined notional pulse width (which will usually be non-zero but may be zero).

Similarly, to enable a time read-out to be provided in the absence of a leading pulse edge, the control means conveniently includes means for providing a second error signal in response to a trailing pulse edge which has not been preceded by a corresponding leading edge, the control means being operable in response to such second error signal to cause computation of the desired time interval to be based on a predetermined notional pulse width (which will usually be zero but may be non-zero).

To promote further understanding of the invention and to enable other objects and advantages thereof to be appreciated, typical applications of the timing system to motorcar racing will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a schematic block diagram of part of the timing circuitry in one embodiment of the invention; and Figure 2 illustrates successive signals used in determining time intervals.

An important application of the timing system is in lap timing for car racing where a time readout is provided for each driver upon completion of each circuit. In this case, where the course to be traversed is circuitous, it is only necessary to provide a single triggering line at a suitabie point around the circuit. The triggering line may be substantially coincident with the official starting line or it may be at a separate location since the main concern is to provide lap timing rather than cumulative timing.

As in my prior patent application No.

8113188, the triggering line may be constituted by a series of permanent magnets arranged in spaced apart relation along a line extending perpendicularly of the track. For this purpose, the magnets are conveniently located below the track surface within a tube, the magnets each being oriented in the same way as the others with the axis joining its N and S poles extending generally parallel to the direction of travel of the vehicles along the course. As mentioned above, the triggering line may be located at any suitable point around the circuit but is preferably located along the starting/finishing straight so as to extend across not only the track proper but also the branch-off track which runs through the "pits" parallel to the main straight.

Each vehicle will be provided with a sensing coil, detection circuitry and time readout means which, apart from the modifications described herein may be substantially of the same form as disclosed in my prior patent applications to which reference should be made for further details.

Thus, each time the vehicle completes a circuit by passing the triggering line (either along the main straight or through the pits), the triggering voltage pulses induced in the coil control the timing means to provide the driver with a readout of the lap time for the circuit just completed.

Referring now to Figures 1 and 2, the output of the coil 40 is processed by circuitry 42 which serves to amplify the coil signal and reject unwanted signals largely by imposing an amplitude threshold on the signal. The output of the circuitry 42 is a substantially square wave pulse 44 (see Figure 2) whose width W is governed by the width of the coil signal at the threshold level.

Thus, the leading and trailing edges L and T of each pulse 44 corresponds to the points at which the coil signal crosses the threshold level at each side of the peak of the coil signal and because of the symmetry of the coil signal, the midpoint M of each pulse 44 corresponds to the peak of the coil signal. In other words, the symmetry of the coil signal results in the positive and negative-going threshold crossings being equidistant from the coil signal peak, i.e. the instant of magnet crossing.

The output from the circuit 44 is applied to a microprocessor 46 via interface circuitry 48. The microprocessor 46 serves to measure certain time periods and compute the desired time interval for display on the visual display 50.

Referring now to Figure 2, this illustrates two successive pulses 44A and 44B produced on successive laps completed by the vehicle. To obtain the true lap time for the vehicle, the micro processor 46 is programmed to measure the width of each pulse and the duration D between the trailing edge TA of pulse 44A and the leading edge LB of pulse 44B and compute the desired time interval T between MA and MB according to the formula: T=D+(WA+WB)/2.

From this it will be observed that T will be independent of any variation in the widths of pulses WA and WB caused by the vehicle passing the magnets at different speeds. An alternative approach is to measure the duration E between the leading edge LA of pulse 44A and the trailing edge TB of pulse 44B and compute the desired time interval according to the formula: T=E-(WA+WB)/2.

Yet another possibility is to measure the intervals D and E and compute T=(D+E)/2. Whichever approach is followed it will be seen to essentially involve measuring the durations WA, WB and D even though in the last-mentioned case WA and WB are effectively measured collectively together with D rather than individually.

The interface circuit 48 serves to discriminate between the leading and trailing edges of the pulses 44 and provide outputs to the microprocessor to cause the same to measure the required durations according to which of the above-mentioned computations is to be performed. Thus, in the case of the firstmentioned formula, the microprocessor is interrupted on the rising edge of each pulse. At this point, measurement of the preceding interval D is terminated, D is read and stored and the measurement of W for the current pulse is commenced. An interrupt on the falling edge of the current pulse terminates the measurement of W, starts measurement of the next interval D and the processor also carries out the computation based on the stored value for D and the values W measured for the just-terminated pulse and the previous pulse.

In addition to the above function, the micro processor is conveniently programmed to allow for the allowing contingencies: 1. the situation where the processor receives a leading edge interrupt (indicating the start of the magnet crossing sequence) but no subsequent trailing edge interrupt is found within a given time window. In this case, a pseudo interrupt is generated internaily by the processor corresponding to a preselected notional pulse width (e.g. the width of the time window) and calculation proceeds on the basis of the notional pulse width.

2. the situation where a trailing edge interrupt is received by the microprocessor without there having been a corresponding leading edge interrupt. In this event, the pulse width for the pulse in question is given a notional value (e.g. zero) and calculation proceeds on this basis.

It will be seen from the foregoing that this embodiment also in effect detects the turning point or peak in the coil signal since the peak is for all practical purposes equidistant from the leading and trailing edges of the corresponding pulses. In this manner, timing is based on the interval between successive coil signal peaks giving a high degree of accuracy which is not affected by speed variations as the vehicle passes the magnets since, for all practical purposes, the peaks will always correspond to the vehicle being in a given positional relation with the magnets irrespective of vehicle speed.

In order to enable the lap times recorded onboard the vehicles to be relayed to an external point, e.g. official trackside time recording equipment, each vehicle is conveniently equipped with a transponder such that, in response to reception of a coded signal from the trackside equipment, the last recorded lap time is transmitted from the vehicle to the recording equipment which may be arranged to display and store the lap times received from each vehicle.The recording equipment is conveniently designed to communicate with the transponders of the vehicles in a sequential manner through the agence of a single transmission channel preferably at a rate which allows the sequence to be repeated at least twice per circuit so that, if contact is not made with any particular transponder during one sequence, a further attempt or attempts may be made before the current lap time stored in the timing system of that vehicle is updated. Those transponders which have already responded on any particular lap may be omitted during the subsequent sequence or sequences.

Conveniently as a safeguard against the possibility of no lap time being recorded at all on the trackside equipment for any particular vehicle, means may be provided to produce a warning signal in the event of non-receipt of a lap time from any vehicle after a certain number of attempts have been made to call up its transponder. The warning signal may then alert the officials to resort to auxiliary timing equipment or hand timing in order to obtain the lap time for that particular vehicle.

As well as recording lap time, the on-board equipment may also be arranged to incorporate a lap counter which is incremented by the triggering pulses produced by the pickup coil. The lap count information may be transmitted to the trackside equipment along with the lap time information.

In practice, there are like to be other magnetic sources present in the vicinity of most circuits, e.g. overhead or underground electrical conductors and the like. To minimise the risk of false triggering of the timing system, means may be provided to allow the timing means to be operated only when the associated vehicle is in the immediate vicinity of the triggering line, i.e. so that the timing system is effectively "gated-on" only when the triggering line itself is likely to be the source of any pulses capable of triggering the timing system.Such gating may be implemented for example by providing an rf aerial at or adjacent the triggering line such that a receiver on the vehicle picks up the rf signal as it approaches the triggering line and its timing system is gated-on by the rf signal so that for a limited duration of time, determined for example by a monostable multivibrator or other internal circuitry, any pulse induced in the pick-up coil is processed for the purpose of controlling the timing means.

Thereafter the timing system resorts to a gatedoff condition in which it will not respond to any triggering pulses induced in the coil, that is until it is gated-on again as the vehicle approaches the triggering line on the next lap. In a particuiarly convenient arrangement, the rf signal may be constituted by a cable or wire threaded through the same tube as that which accommodates the magnets forming the triggering line.

In car racing for example, it may be desirable for the timing systems of all of the vehicles to be started simultaneously at the beginning of the race. To cater for this possibility, means may be provided for producing a starting signal which initiates simultaneous operation of all the timing systems independently of the triggering pulses produced by passage over the triggering line. The starting signal may be a coded radio signal which is relayed to each timing system via a receiver provided on each vehicle and each timing system conveniently includes means for initiating timing in response to reception of the signal and for temporarily preventing normal triggering of the system as the vehicle passes the triggering line for the first time. Thereafter, normal triggering of the system is resumed for the remainder of the race.

The lap time (and count if made available) may be presented to the driver by means of a visual readout which for convenience may be located on the steering wheel of the vehicle, e.g. at the centre or hub thereof. Additionally or alternatively, the lap time/count may be read out in audible form to the driver via an electronic voice synthesiser and headset provided in the driver's helmet.

Although the invention is described above with particular reference to car racing, it will be appreciated that many of the developments described are also applicable to the timing system when used in other circumstances where timing of vehicle motion is required, e.g. in waterskiing as described in my prior applications.

Claims

1. A system for on-board timing for a vehicle traversing a predetermined course, said system comprising sensing coil means adapted to be carried by the vehicle for producing an electrical signal in response to sensing at least one magnet located at at least one predetermined position along said course, on-board timing means and onboard control means responsive to said sensing coil means for controlling operation of the timing means to provide a record of the time interval elapsing between successive or selected electrical signals produced by said sensing coil means, characterised in that, for each sensing coil signal, the control means generates leading and trailing control signals corresponding to defined amplitudes on each side of the peak of the sensing coil signal, operation of the timing means being controlled by said control signals such that the desired time interval is determined from measurements of the time between the leading control signal of one coil signal and the trailing control signal of an adjacent coil signal and the times between the leading and trailing control signals of those coil signals.

2. A system as claimed in Claim 1 in which each coil signal is processed by amplitude threshold means whereby a pulse is produced whose width is governed by the points at which (in absolute terms) the coil signal exceeds the imposed threshold level.

3. A system as claimed in Claim 1 or 2 in which the control means includes means which, in response to a leading pulse edge, provides a first error signal in the absence of a corresponding trailing pulse edge within a preset time, the control means being operable in respect to such first error signal to cause computation of the desired time interval to be based on a predetermined notional pulse width.

4. A system as claimed in Claim 3 in which the control means includes means for providing a second error signal in response to a trailing pulse edge which has not been preceded by a corresponding leading edge, the control means being operable in response to such second error signal to cause computation of the desired time interval to be based on a predetermined notional pulse width.

5. A timing system as claimed in Claim 1, substantially as hereinbefore described.