EP0793582A1

EP0793582A1 - Driver alertness monitor

Info

Publication number: EP0793582A1
Application number: EP95937131A
Authority: EP
Inventors: Deryk John Peter Williams; Benjamin Jeremy Walsh; Robert Goran Deliner; David Maynerd; Gregory Paul Rapson
Original assignee: Driver Alert Technology Co Ltd
Current assignee: Driver Alert Technology Co Ltd
Priority date: 1994-11-28
Filing date: 1995-11-28
Publication date: 1997-09-10
Also published as: GB9424116D0; WO1996016830A1

Abstract

A driver alertness monitor for measuring time taken by a driver to react to a stimulus generated while driving and comparing the measurement with a standard thereby to indicate the state of alertness of the driver also includes means for initially calibrating reaction time of the driver when in a state of alertness and a detailed control means for deciding when to test the driver during a journey and how to interpret and inform the driver of the results.

Description

Driver Alertness Monitor

This invention relates to a driver alertness monitor for measuring time taken by a driver to react to a stimulus generated while driving and comparing the measurement with a standard thereby to indicate the state of alertness of the driver. In this context, the term "driver" includes any person who is in control of land based or water or air borne transport.

In WO 93/08739 there is disclosed an alertness monitor comprising means for calibrating reaction time of a human subject in normal conditions to provide a standard, means for measuring reaction time of the subject when carrying out an activity and means for comparing the measured reaction time with the standard and for generating a warning signal when the measured reaction time is greater than the standard.

Such 'normal conditions' exist when the subject is in a state of alertness.

Although the monitor disclosed in WO 93/08739 adapts to the individual subject under test, the stimulus is presented at random intervals and there is no provision for taking into account whether the individual whose reaction time is tested subsequent to calibration is already in a state of alertness. If such a monitor were to be used to test the reaction time of a driver of a motor vehicle, for example, it cannot be assumed that the driver would welcome receiving random stimuli when in a state of alertness.

It is desirable, therefore, to provide a driver alertness monitor which is more sensitive than such monitors known hitherto. The invention is characterised in that there is provided a control means for controlling intervals of measuring reaction time so that measurement is carried out more frequently when deterioration of reaction time is determined and less frequently when the reaction time is less than the standard.

The invention thus provides a driver alertness monitor which becomes more sensitive as the driver's performance capability deteriorates but not being an irritating intrusion while the driver is alert.

The invention also provides a driver alertness monitor which monitors the driving performance capability of the driver and which provides information indicative of the performance so that the driver may make an informed decision.

The invention will test and compare to a standard or previous calibration and then decide how best to modify the test interval.

The monitoring of the driving performance capability is effected by means, in accordance with the invention, operation of which does not adversely affect the driver's control of the vehicle and operation of which can be effected by the driver in any hand position of hand control means while controlling the vehicle.

The invention also provides a facility for interactivity with the driver and for diurnal variation, in particular for increasing sensitivity for periods of a twenty four hour cycle when a driver is less likely to be in a state of alertness.

Following is a description, by way of example only and with reference to the accompanying drawings, of one method carrying the invention into effect.

In the drawings:- Figure 1 is a general arrangement of one embodiment of a driver alertness monitor in accordance with the present invention,

Figure 2 is a flow diagram indicating a method of calibration in accordance with the present invention,

Figure 3, 3a and 3b together comprise a flow diagram indicating a method of testing driver alertness in accordance with the invention,

Figure 4 is a diagrammatic representation of information as would appear on a coded light box and on an alphanumeric display of the monitor.

Figure 5 is a diagrammatic cross section of an embodiment of a manually operable transducer in accordance with the invention.

Figure 6 is a diagrammatic representation of another embodiment of a transducer in accordance with the present invention, and

Figure 7 is a diagrammatic representation of another embodiment of a transducer in accordance with the present invention.

Referring now to Figure 1 of the drawings, there is shown a general arrangement of one embodiment of a driver alertness monitor in accordance with the present invention comprising a central processing unit 1 located in a motor vehicle and having connected thereto a transmitter/receiver 2, and an audio amplifier 3 controlling a speaker 4. The transmitter/receiver 2 is adapted to communicate by cableless data transmission using ultrasonic, IR or RF signals with a coded light box 5 and an alphanumeric display 6, both included in or being located adjacent an instrument panel of the vehicle, and a transmitter 7 carried on a steering wheel 10 of the vehicle and operated in response to signals received from a transducer 9 in the form of a steering wheel cover and being operable when squeezed by a driver 8.

The arrangement is such that, when an audible stimulus is generated by the speaker 4, the driver responds by squeezing the steering wheel cover thereby operating the transducer 9. Such operation of the transducer 9 results in a signal being transmitted from the transmitter 7 to the transmitter/receiver 2 and the reaction time from generation of the stimulus to operation of the transducer 9 is calculated by the central processing unit 1. An indication of the reaction time is then provided by the coded light box 5 and the alphanumeric display 6 as a result of signals received from the transmitter/receiver 2.

Since the transducer 9 extends through 360° around the steering wheel, operation of the transducer can be effected without either hand of the driver being removed from the steering wheel in any position and the operation is effected while controlling the vehicle. The transducer 9 is also in communication with the central processing unit 1 to monitor the level of hand activity of the driver 8 on the steering wheel 10.

Referring now to Figures 2, 3a and 3b of the drawings, there is shown flow diagrams indicating control carried out by the central processing unit 1 including means to GENERATE A STIMULUS, more particularly the audible signal from the speaker 4, and means to MEASURE REACTION TIME consequential upon the driver operating the transducer 9 in response to the stimulus.

It is desirable to provide a calibration of the average reaction time and standard deviation of a driver in normal conditions, ie when the driver is in a state of alertness, and then to test the driver's reaction time at intervals during a journey and compare such reaction times with a standard reaction time carried out at the time of calibration. Such testing is carried out by reference to 'Population Norm' data contained in memory in the central processing unit 1 so that erroneous readings are rejected.

A system for effecting calibration is indicated in Figure 2 whereby an initial step is carried out to CALCULATE AVERAGE REACTION TIME AND STANDARD DEVIATION. In order to calculate the average reaction time, a predetermined series of measurements of reaction time is taken at the end of which ENOUGH REACTION TIME READINGS have been recorded. Until such time a series of stimuli are generated, each after a SHORT DELAY, and the driver reacts to each stimulus by operating the transducer 9. An initial screening process is carried out in respect of each test result by interrogating IS RESULT SENSIBLE? If the response is negative because the reaction time is outside of a predetermined range of reaction times, the erroneous reading is rejected and the process is repeated after a SHORT DELAY. If the answer to the question ARE ALL REACTION TIMES WITHIN A CERTAIN NUMBER OF STANDARD DEVIATIONS? is affirmative, the command STORE CALIBRATION PARAMETERS is effected, otherwise the process is repeated following on from REJECT ERRONEOUS READINGS and after a SHORT DELAY.

The procedure described above will be abbreviated if the driver's reaction time has already been calibrated and the information stored in the system. In such circumstances, the driver would operate the system to USE PREVIOUSLY OBTAINED CALIBRATION. It may be that the store would include a facility for storing reaction times of a plurality of drivers and in such circumstances the system would be operated to SELECT DRIVER AND RELEVANT PARAMETERS.

The system subsequently would CALCULATE RUN TIME PARAMETERS and is then in a ready state for testing driver alertness during a journey.

On each occasion prior to a driver undertaking driving a vehicle a test for reaction time is carried out. Preferably this would be an average of a series of tests taken in rapid succession rather than a single test. This would ensure that the driver is not starting out in a condition unfit for driving. If the last produced test result is consistent with a previous stored calibration, the stored data would be used.

A system for testing driver alertness during a journey is indicated in Figure 3a and 3b wherein the system would GENERATE A STIMULUS and would MEASURE REACTION TIME when the driver operates the transducer 9 in response to the audible stimulus from the speaker 4. The reaction time is screened by interrogating IS RESULT SENSIBLE?, for example, within a predetermined range of 150 ms to 750 ms.

Apart from determining when next to test the driver, the system also monitors driver hand activity on the steering wheel 10 and, when there is little activity, is adapted to test the driver reaction in abnormal circumstances. In any event, the system ensures, as far as possible, that tests are carried out when the interrogation IS DRIVER BUSY? is answered in the negative, ie when there is little hand activity of the steering wheel 10. If the driver is busy, A SHORT DELAY will be initiated before a succeeding stimulus is generated.

If the reaction time is within the predetermined range an indication is provided on the coded light box 6 and the alphanumeric display 7, the data indicated being as shown in Figure 4. If the REACTION TIME is IN BAND 1, ie 150 ms to 300 ms, an indication is provided as a double green light in box 5 and "Excellent" in the display 6 and since the reaction time would be an improvement on the calibration figure and the system responds to INCREASE DELAY TIME and DECREASE REACTION TIME AVERAGE whereby the interval between generation of successive stimuli is increased. If, however, the REACTION TIME is IN BAND 2, eg 300 ms to 370 s, the reaction time is satisfactory and an indication is provided as a green light in box 5 and "Good" in the display 6 and the situation is such that the SYSTEM AND DRIVER are STABLE, as a result of which the interval between generation of successive stimuli is unaffected. A REACTION TIME in BAND 3, eg 375 ms to 450 ms, would indicate a deterioration in the driving performance capability as a result of which an indication is provided as an amber light in box 5 and "Plan a break" in display 6, ie the system responds to WARN OF SLOW REACTION TIME and adjusts SO as to REDUCE DELAY TIME FOR NEXT TEST. If the REACTION TIME is IN BAND 4, eg 450 ms to 750 ms, a red light appears in box 5 and "Change drivers/Urgent break required" in the display 6, ie the system responds to WARN OF URGENT BREAK REQUIRED and RE-TEST URGENTLY. If the reaction time fails to improve and a MAXIMUM NUMBER OF RETRIES, eg four, are EXCEEDED a flashing red light appears in box 5 and "STOP DRIVING NOW" in the display 6 and an ALARM is sounded. The visual display for reaction times in Bands 1 to 4 is accompanied by a corresponding one or more "Beeps" from the speaker 4.

In the case of there being an increase or reduction of the delay between successive stimuli, the system responds to CALCULATE REACTION TIME THRESHOLDS FROM REACTION TIME AVERAGE AND STANDARD DEVIATIONS and all outputs resulting from testing in the four bands are further tested to ADJUST PARAMETERS FOR DIURNAL VARIATION followed by ADJUST PARAMETERS FOR RUN DURATION and DELAY BY CALCULATED AMOUNT.

The system also has provision for interaction by the driver, for example if the driver is conscious of onset of a sleep episode, whereby the system recognises that there is an affirmative answer to the question DRIVER FLAGGED SLEEP EPISODE? A further adjustment is provided to INCREASE SENSITIVITY.

Referring now to Figure 5 of the drawings, there is shown in transverse cross section a rim 11 of the steering wheel 10 and the transducer 9 covering the rim 10. The transducer 9 comprises a flexible sheath 12 which extends circumferentially of the rim 11 in plan but only partially circumferentially of the rim 11 in transverse cross section and thus terminates in walls 13, 14 are which spaced apart by a gap 15 to permit assembly of the transducer 9 on and removal of the transducer 9 from the rim 11 and to accommodate spokes of the steering wheel. The walls 13, 14 and an opposite facing surface of the rim 11 have secured thereto complimentary components 16, 17 which are adapted to removably secure one to another whereby the sheath 12 is locatable on the rim 11 in non-slip condition. The sheath 12 includes a plurality of cells 18 at least some of which contain components (not shown) of an electrical circuit including switch means (not shown) which is operable when the sheath 12 is squeezed by the hand or hands of a driver of the vehicle while the driver is steering the vehicle.

The electrical circuit would include a power source contained in one of the cells 18 and switch means would be operable in response to change of air pressure contained in at least some of the cells 18 as a result of the squeezing action by the driver. Alternatively, the electrical circuit may include resistive or capacitive components contained in one or more of the cells 18, the electrical properties of which components vary when the sheath 12 is squeezed by the driver. The electrical circuit would also include a cableless data transmission system using ultrasonic, IR or RF signals.

It will be appreciated that the switch means may be located in a plurality of the cells 18 so that the switch means is operable in any hand held position throughout 360 degree positioning of hands on the steering wheel.

Referring now to Figure 6 of the drawings, there is shown another embodiment of a transducer 19 in accordance with the present invention. The transducer comprises a strap 20 to be worn on the wrist of the driver 8. The strap. 20 carries a sensor strip 21 on an inner surface thereof, a processing unit 22, a power source 23 and a transmitter 24. The sensor strip 21 is adapted to respond to muscle or nerve activity at the wrist of the driver 8 when the driver squeezes a steering wheel when controlling a vehicle as a result of which a signal is generated by the transmitter 24 and is received by the transmitter/receiver 2.

The transducer 19 may be incorporated into a watch or be a dedicated wrist band.

Referring now to Figure 7 of the drawings, there is shown another embodiment of a transducer 25 in accordance with the present invention. The transducer comprises a clip 26 for attachment to a watch strap or bracelet, a sensor strip 27 adapted to respond to muscle or nerve activity at the wrist of the driver 8 when the driver squeezes a steering wheel when controlling a vehicle, a processing unit 28, a power source 29 and a transmitter 30.

The transducer 25 operates in a similar manner to the transducer 19.

It will be appreciated that a monitor in accordance with the present invention may provide visual stimuli instead of audible stimuli.

It will also be appreciated that the system may include a visual display similar but additional to the display 6 for the purpose of providing public information. Such a display would be advantageous for public service vehicles since it would provide an indication to passengers of the vehicles as to the state of alertness of the driver.

It will also be appreciated that the system may include a memory and playback facility such that the driver response profile during a period prior to an accident could be analysed to determine if fatigue was a factor in the accident. It will also be appreciated that the system may include a variable pitch alarm.

It will also be appreciated that the system may include a tachograph connection

It will also be appreciated that the system may be included in the engine management control of a vehicle.

It will also be appreciated that the system may be adapted to be communicated to a control network at a remote location.

It will also be appreciated that the system may be amplified and frequency auto-varied to penetrate ambient noise.

It will also be appreciated that the system may be included in a head-up display.

It will also be appreciated that the system may include digitised voice production.

Claims

1. A driver alertness monitor comprising means for calibrating reaction time of a driver in normal conditions to provide a standard, means for measuring reaction time of the driver when the driver is driving and means for comparing the measured reaction time with the standard and for generating a warning signal when the measured reaction time is greater than the standard characterised in that there is provided control means for controlling intervals of measuring reaction time so that measurement is carried out more frequently when deterioration of reaction time is determined and less frequently when the reaction time is less than the standard.

2. A monitor as claimed in Claim 1 characterised in that the control means is adapted to adjust the intervals of monitoring reaction time in accordance with a period.

3. A monitor as claimed in Claim 2 characterised in that the period is the duration of a journey undertaken by the driver.

4. A monitor as claimed in Claim 2 or Claim 3 characterised in that the period is diurnal.

5. A monitor as claimed in any one of the preceding Claims characterised in that there is provided interactive means for effecting driver feedback adjustment for fine tuning.

A monitor as claimed in any one of the preceding Claims characterised in that the means for measuring reaction time comprises an actuation device adapted to be carried by hand operated controls of a vehicle such that the device is actuable by the driver without moving hands from the controls and in any hand position on the controls.

7. A monitor as claimed in any one of the Claims 1 to 5 characterised in that the means for measuring reaction time comprises an actuation device adapted to be carried on the person of the driver so as to respond to hand movements of the driver when operating hand operated controls of a vehicle.

8. A monitor as claimed in Claim 6 or Claim 7 characterised in that the actuation device includes a cableless data transmission transducer and the control means includes a cableless data receiving transducer for receiving signals for the transmission transducer.

9. A monitor as claimed in any one of the preceding Claims characterised in that there is provided a display for indicating information indicative of the driver's state of alertness.

10. A monitor as claimed in any one of the preceding Claims characterised in that there is provided recording means for recording and playback of data from the control means.