Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
2000-07-14
2001-10-16
Hofsass, Jeffery (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S575000, C340S573300, C340S691300, C340S693110
Reexamination Certificate
active
06304187
ABSTRACT:
The present invention relates to a process and device for continuous monitoring of the driver's watchfulness in an automotive vehicle, in order to detect and to prevent any possible sleepiness of the former.
We know that a significant, if not important, proportion of the road accidents are caused by total or partial (dizziness) sleepiness of an automotive vehicle's driver (personal car, utility vehicle, van, lorry) thus resulting in numerous deaths and casualties.
The issue consisting in triggering an alarm, notably a sound alarm, as soon as the driver is falling asleep, in order to wake him/her up, appears of paramount significance from a human as well as economic viewpoint.
To detect a driver's sleepiness, it has been suggested as follows, in an automotive vehicle
on the one hand, to detect any variation in a driver's controlling the steering wheel when falling asleep and
on the other, to detect any variation in the vertical movements of a driver's eyelids when falling asleep.
The present invention implements a detection of the second type above mentioned (monitoring the movements of the eyelids) and it is based upon a physiological observation, i.e. the modification in the blinking duration, as well as time intervals between two successive winks, hence the blinking rhythm as a person is switching from a woken condition to dizziness before he/she falls asleep: the duration of a person's wink is in the order of 100 to 200 ms (milliseconds) when he/she is awake and in the order to 500 to 800 ms when he/she is feeling sleepy whereas the time interval between two successive winks, which is more or less constant in woken condition, varies over relatively wide a range in a sleepy condition. It is the variation in the blinking duration which is essentially implemented within the framework of the invention.
The process and the device according to the invention detect the increase in the driver's blinking duration and trigger an alarm, a sound or other, when the said duration exceeds a set threshold, ranging in particular between 200 and 500 ms, for instance equal to 350 ms, whereby this threshold can be modified in relation to the driver's physiology.
In the French patent application n
o
96.09420 made on Jul. 26, 1996 and the international patent application (P.C.T.) PCT/FR97/01354 made on Jul. 22, 1997, while stressing the priority of the said French patent application, whereas the inventor of both these applications is also the present invention's inventor, we described a process and a device, operating in real time, for locating and circumscribing a zone in relative motion within a scene, as well as for determining the speed and the displacement direction.
Among the applications contemplated for this process and this device, we described in the said patent applications, the implementation of the said process and device for observing and monitoring a zone consisting of an automotive driver's head, in order to detect and to prevent the driver from falling asleep.
According to this particular application of the process and device of the said patent applications:
a video signal was produced, significant in real time of the successive pictures of the driver's eyes;
this video signal was processed in order to, successively and continuously,
detect, in the pictures of this driver's eyes, the vertical movements of the eyelids significant of their blinking;
determine the rhythm of these vertical movements and
locate the rhythms smaller than a given threshold, corresponding more or less to the blinking rhythm of a driver when fully awake; and
an alarm was triggered when this threshold was exceeded downwards by the said rhythms, in order to wake up the driver.
The purpose of this invention is to perfect the process and device of the patent applications mentioned above, as regards their application to monitoring an automotive driver, in order to detect his/her possible sleepiness.
The Hiroshi Ueno and Al article, title <<Development of drowsiness detection system>>, published in the Institute of Electrical and Electronics Engineers journal (IEEE) Aug. 31, 1994, pages 15-20, analyses several automotive driver drowsiness detection technics. Specifically, the use of a videocamera associated with a video image treatment calculator is mentioned, with a software realising, on one hand, detection of the driver face, particularly a rectangle including one eye, and, on the other hand, of the rate of the opened eyes and closed eyes durations to determine drowsiness criteria.
Moreover, the published German patent application DE-197 15 519 and the published corresponding French patent application n
o
2 747 346 describe a device and a process of estimation of the level of the dizziness of an automotive driver with a video camera located by the foot of the vehicle driver and a calculator for the treatment of the image produced by the camera, with a software detecting eyes blinks by the determination of the delay between the start and the end of the blinks. In particular a unit
10
of the calculator realises:
memorisation of the video image and its treatment in order to determine an area including the driver's eyes;
the detection of the time interval between the closure of the driver's eyes-lids and their complete opening;and
a treatment in a memory
11
and a calculation unit
22
, in combination with unit
10
, in order to calculate a ratio of slow blinks apparition.
Lastly, the published international application WO 97/01246 subject matter is a security system including a video camera arranged in an automotive vehicle interior mirror and a video screen at distance for analysing what is occurring in the vehicle and around it, and what occurred thanks to the recording of the video camera output signal. This is, in fact, a hidden camera (in the rear mirror), in order to escape intruder attention and which observes a wide area including the interior and the environment of the vehicle, the recording allowing a later knowledge of what occurred in this area (page 6, lines 13 to 19), and not a sensor which vision angle is sensibly limited to the driver's face in order to detect his possible sleepiness and waking up him.
It can be seen that those documents (above mentioned articles and applications) are using a genuine video camera and an external calculator, the eye blinks detection in this article and those French and German applications requiring a complex treatment unit while said international application does not solve the sleepiness detection problem, the driver if sleepy being not capable of looking at the video screen neither at the video recording. It can be seen that one can not combined this document to the two preceding documents as they do not belong to the same technical field.
Compared to those documents, the present invention realises a better approach of the driver eyes blinks duration measurement capture; as
it allows the use in the vehicle rear mirror of a simple sensor (eventually the sensor of a minute video camera), specially MOS sensor, which is not necessarily in the standard video format;
it realises a movement of the transducer optical axis linked to the rear mirror displacement by the driver in order to direct said axis toward driver's face;
it allows an integrated visual perception, an integrated circuit allowing an immediate detection of the eyes lids movements;
it uses a very simple processor for the treatment of the sensor information;
it allows the integration in an electronic chip of the sensor, its associated electronic circuitry and the calculator, all being arranged in the rear mirror;
it permits the possibility of associate such a chip in the rear mirror with a dashboard processor, the rear mirror being thus an intelligent sleepiness detection device at a moderate cost as it includes, compared to a standard interior rear mirror, simply a chip and a mechanical set for this additional chip orientation.
In those conditions, the object of the invention is first of all a process for con
Hofsass Jeffery
Holding B.E.V. S.A.
Nguyen Hung
Townsend and Townsend / and Crew LLP
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