GB2152258A - Apparatus for maintaining alertness - Google Patents

Abstract

A system for inhibiting operator drowsiness comprising: an actuation switch in the form of a loot pedal which is normally pressed during system operation; and stimulus producing means producing intermittent stimuli to the operator, the stimulus producing means being responsive to stimulus responses entered by the operator via the actuation switch for determining the timing of subsequent stimuli, whereby relatively quick stimulus-response reaction time produces relatively long periodicity stimulus production. <IMAGE>

Description

SPECIFICATION Apparatus for maintaining alertness The present invention relates to an apparatus for maintaining alertness of an individual operating a device such as a motor vehicle.

It has long been recognized that lack of operator alertness is a major factor in serious motor vehicle accidents. Significant drops in operator alertness occur often during long trips on highways and are accompanied by drowsiness.

The patent literature contains a wide variety of proposals of apparatus and methods for combatting the effects of operator drowsiness.

U.S. Patent 3,922,665 describes an apparatus and method for maintaining operator alertness wherein successive stimuli are initiated intermittently at selectively variable time intervals inversely related to the time taken by the operator in responding to the previous stimulus. The time required by the operator to detect and respond to each stimulus automatically varies the timing for initiating the next stimulus. Each stimulus is produced with a gradually increasing intensity, such as by amplitude modulating the volume of an audio tone, until the operator actuates a response switch to terminate the series of stimuli. A much more severe stimulus, such as that produced by an alarm bell, is provided when no response is received within a given interval.

The apparatus proposed in U.S. Patent 3,922,665 has a number of serious deficiencies: The operator response is provided by manual engagement of a response entry switch located on the vehicle turn signal stalk.

Thus actuation requires the operator to remove his hand from the wheel and direct it to the switch. This actuation may also require eye attention of the driver and may result in driver distraction. Furthermore, in emergency situations when the driver does not wish to be distracted by the operation of the apparatus, he must remove his hand from the wheel in order to disable the apparatus, with the attendant distraction and danger. If he fails to achieve disabling, he is further distracted by audio alarms.

Furthermore, the technique of employing a tone of increasing amplitude may be very distracting to the driver particuiarly in crisis or near crisis situations.

U.S. Patent 3,611,344 provides a reaction actuator for vehicle operators wherein an operator response is entered by pressing down on a foot switch. This arrangement is inconvenient since it requires a separate switch for actuating operation of the system and a separate switch for entering operator response.

Also, the operator must keep his foot in the air or away from the foot switch except when entering a response. This is tiring and requires 3 certain amount of operator concentration.

U.S. Patent 3,794,968 is representative of patents which describe an operator response interlock for governing starting of motor vehicles. U.S. Patent 2,625,594 is representative of patents which describe apparatus and techniques for inhibiting drowsiness of a motor vehicle operator which do not provide variable response times as a function of response speed.

The present applicant is not aware of the commercial application of any of the above described proposed apparatus and methods.

An essential drawback of all of the systems described hereinabove is that the measured reaction time is the sum of two elements, the physiological response time which is representative of the alertness of the operator and the time for the operator 5 hand or foot to physically reach and engage the response switch.

This second element, which is not directly representative of driver alertness, and may vary for other extraneous reasons, is of at least the same order of magnitude as the first and thus distorts the correct indication and response to the state of driver alertness.

The present invention seeks to provide a system for inhibiting operator drowsiness comprising: an actuation switch in the form of a foot pedal which is normally pressed during system operation; and stimulus producing means producing intermittent stimuli to the operator, the stimulus producing means being responsive to stimulus responses entered by the operator via the actuation switch for determining the timing of subsequent stimuli, whereby relatively quick stimulus-response reaction time produces relatively long periodicity stimulus production.

Further in accordance with a preferred embodiment of the present invention, the apparatus also comprises auditory feedback producing means operative to provide audio feedback outputs of different tonal frequencies as a function of the speed of the stimulus-response reaction time. Alternatively, the arrangement may be such that no feedback is produced when the reaction time is within an acceptable threshold limit and feedback is produced when the reaction time is outside such threshold limit.

It is a particular feature of the present invention that the system is operative to cause an operator to regain alertness from a state of partial drowsiness and preferably, if this is not successful, to provide a warnirlg to the operator of the extreme state of his drowsiness.

This feature is provided Dy the highly accurate and easily recognizable feedback indications of the operator's state o drowsiness.

The present invention will be understood and appreciated more fully frorn the following detailed description taken in conjunction with the drawing n which: Figure 1 is a block diagram illustration of a system for inhibiting operator drowsiness constructed and operative in accordance with a preferred embodiment of the present invention; and Figure 2 is a timing diagram illustrating operation of the apparatus of Fig. 1.

Reference is now made to Fig. 1, which illustrates a system for inhibiting operator drowsiness constructed and operative in accordance with a preferred embodiment of the present invention.

The system comprises an actuation and response switch 10, which according to a preferred embodiment of the present invention is a foot switch which is located to the left of the foot pedal controls on the floor of the driver's compartment in a motor vehicle.

Switch 10 is typically connected at one terminal thereof to a source of positive D.C. voltage and is coupled at its other terminal via an RC network 11 to a bus 12.

When switch 10 is initially depressed to initiate system operation, a positive voltage is supplied to an AND gate 14. AND gate 14 also receives a positive voltage from the Q output of a latch 1 8. Latch 18, upon initial energization of the system receives a positive voltage input pulse via a capacitor 1 9 and via an OR gate 1 6 at its S input, providing the initial positive voltage at its Q output.

Thus, initial depression of foot switch 10 produces a positive voltage output pulse via a bus 24 to a first timed output gate 26, which is operative to provide a positive voltage for a predetermined first time duration following the onset of the positive voltage input from AND gate 14. The output from gate 26 is supplied to an AND gate 28 which also receives an audio frequency signal of a first signal frequency such as 2KHz from a suitable signal generator (not shown). This signal is supplied via AND gate 28 and via an OR gate 29 and an amplifier 30 to a loudspeaker 32 for the first duration, providing an initial stimulus to a driver.

The output signal from AND gate 14 along bus 24 is also supplied to the rexet input of latch 18, for resetting same and terminating the Q output to AND gate 14, thus setting the stage for the provision of a further stimulus.

The output signal from AND gate 14 along bus 24 is also supplied to a second timed output gate 34, which is operative to provide a positive voltage for a predetermined second time duration following the onset of the positive voltage input from AND gate 14. The second time duration provided by gate 34 corresponds to a physiological delay which is provided to the operator for his response upon system actuation. This delay is repeated dur ing continuing operation of the system.

The output of gate 34 is supplied via an OR gate 35 to a third timed output gate 36, which is operative to provide a positive voltage for a predetermined third time duration following the termination of the positive voltage input from gate 34. Gate 36 provides its output to an AND gate 38 which also receives an input from a fourth timed output gate 40, which is operative to provide a positive voltage for a predetermined fourth time duration following the termination of the positive voltage input from switch 10.

It may be understood therefore that when the operator signals a response to the stimulus provided by AND gate 28, by lifting his foot from foot switch 1 0, he initiates operation of gate 40. Furthermore, if the operator lifts his foot from foot switch 10 during the delay provided by gate 36, i.e. providing a response to the stimulus within the prescribed time, AND gate 38 provides an output signal to a further AND gate 42, which also receives a tone input of a second frequency from a signal generator and passes it via OR gate 29 and amplifier 30 to loudspeaker 32, informing the operator that he has responded within the prescribed time and that he is deemed to be alert. Alternatively, no feedback signal is provided to the operator when his response is within the prescribed time following the stimulus.

In order to ensure that the duration of the feedback signal provided via timed gate 40 to the operator remains generally constant, there is provided an output from AND gate 42 via OR gate 35 to retrigger gate 36.

As an additional result of response by the operator within the prescribed time, the out put from AND gate 38 is also supplied to a fifth timed output gate 44, having Q and 0 outputs, and which is operative to provide a positive voltage at its 0 output for a predeter mined fifth time duration following the initiation of the positive voltage input from AND gate 38.

The output of gate 44 is supplied via an OR gate 45 to a sixth timed output gate 46, which is operative to provide a positive voltage pulse of a predetermined sixth time duration, typically a few milliseconds, following the termination of the positive voltage input from gate 44. The output of gate 46 is supplied to the set input of latch 18, via OR gate 16, for causing latch 1 8 to provide a positive voltage at its Q output.

The failure of the operator to respond within the prescribed time determined by gate 36, by lifting his foot, precludes the operation of gate 40 and AND gate 38 as aforesaid and thus no output is provided via AND gate 42.

The output of gate 36 is supplied via an OR gate 47 to a seventh timed output gate 48, which receives an enable signal from the Q output of gate 44 at its E input and which is operative to provide a positive voltage for a predetermined seventh time duration follow ing the termination of the positive voltage input from gate 36.

If the operator responds by lifting his foot after the first prescribed time determined by gate 36 but within a second or subsequent predescribed time, determined by gate 48, AND gate 50 receives an output from gate 48 and from gate 40 and provides an output to a further AND gate 52 which also receives a tone input of a third frequency, causing this tonal output to be transmitted to the operator via amplifier 30 and loudspeaker 32.

Similarly to the above description in connection with AND gate 38, the output of AND gate 50 is supplied to an eighth timed output gate 54, which is operative to provide a positive voltage for a predetermined eighth time duration following the initiation of the positive voltage input from gate 50. This output is supplied via OR gate 45 to gate 46, which is operative to set latch 1 8 as described above.

It is appreciated that any suitable desired plurality of response stages may be provided by the circuitry of Fig. 1, by addition of suitable sets of gates corresponding in configuration and connections to gates 47, 48, 50, 52 and 54. Each such stage corresponds to an operator response within a predetermined time frame beyond the initially prescribed time frame. Operator response within the time frame corresponding to each stage is indicated to the operator by an audio signal of a frequency characteristic of each stage. Such plurality of stages may be added for example where indicated by the possible break 70 shown in Fig. 1. If desired the third frequency tone may be used for all of these additional stages, or alternatively any other tone or combination of tones may be employed.

Should the operator fail to respond to the stimuli by raising his foot from the foot switch after a final delay determined by gate 48, the signal normally supplied by gate 48 to AND gate 50 and via an OR gate 49 to a ninth timed output gate 56 is terminated. Upon this termination a short (0.01 second) output signal is provided to an AND gate 58 which receives inputs from gate 56 and from bus 1 2 and provides an output signal to an AND gate 60 which also receives one or more alarm signals intended to elicit an operator response in all circumstances. The output of AND gate 58 is also supplied via a tenth gate 62 which is operative to provide a positive voltage for a predetermined tenth time duration following the termination of the positive voltage input from AND gate 58, i.e. when the operator finally does respond.

The output signal from AND gate 60 is also supplied as an input to OR gate 49 for providing retrigger of gate 56. Gate 56 also receives an enable signal input at its E input from the Q output of gate 54.

It is a particular feature of the present invention that the operator receives differentiated feedback and reinforcement, indicating to the operator that his alertness is decreasing even before it reaches a critical stage. This enables the operator to take corrective measures before a danger situation occurs. This differentiation may be tone differentiation or differentiation by the presence or absence of feedback tones, for example.

It is noted that gates 44, 54, and 62 and the respective time durations defined thereby determine the time separation between subsequent stimuli.

It is appreciated that the time durations of the various gates may be selected at will and may be variable if so desired for matching the apparatus to particular applications and operators. Particularly the time duration of gate 34 may be adjusted to correspond with the characteristic reaction speed of each operator.

For clarity and completeness of understanding there is provided in Fig. 2 a voltage timing diagram of the various signals indicated as V 1-V 1 8 in Fig. 1. It is appreciated, however, that the illustrated durations therealong are not necessarily in scale.

The typical duration between the onset of a positive signal V 4 and the onset of a signal at V 1 6 is of the order of tenths of a second.

The typical duration of the signal at V 10 is the order of a few seconds. The timed output gates may typically be It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather the scope of the invention is defined only by the claims which follow.

Claims (7)

1. A system for inhibiting operator drowsiness comprising: an actuation switch which is normally pressed during system operation; and stimulus producing means producing intermittent stimuli to the operator, the stimulus producing means being responsive to stimulus responses entered by the operator via the actuation switch for determining the timing of subsequent stimuli, whereby relatively quick stimulus-response reaction time produces relatively long periodicity stimulus production.

2. A system according to claim 1 and also comprising means for providing audio feedback signals of different tonal frequencies as a function of the stimulus-response reaction time.

3. A system according to claim 1 and also comprising means for conditioning the provision of audio feedback signals as a function of the stimulus-response reaction time.

4. A system according to claim 2 or claim 3 and wherein said means for providing feedback signals also comprises means for providing an alarm signal in the absence of response within a predetermined time following stimulus provision.

5. A system according to any of the pre ceding claims and wherein said actuation switch is also operative for deactivating operation of the system.

6. A system according to any of the preceding claims and wherein said actuation switch comprises a foot switch.

7. A system for inhibiting operator drowsiness, constructed and adapted to operate substantially as herein described with reference to, and as illustrated in, the accompanying drawings.