WO2002037932A2 - Drowsy operator detection process - Google Patents

Drowsy operator detection process Download PDF

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Publication number
WO2002037932A2
WO2002037932A2 PCT/US2001/047612 US0147612W WO0237932A2 WO 2002037932 A2 WO2002037932 A2 WO 2002037932A2 US 0147612 W US0147612 W US 0147612W WO 0237932 A2 WO0237932 A2 WO 0237932A2
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WO
WIPO (PCT)
Prior art keywords
head
operator
sensors
impairment
microprocessor
Prior art date
Application number
PCT/US2001/047612
Other languages
French (fr)
Other versions
WO2002037932A9 (en
WO2002037932A3 (en
Inventor
Philip W. Kithil
Roger D. Jones
John D. Maccuish
Original Assignee
Advance Safety Concepts, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Advance Safety Concepts, Inc. filed Critical Advance Safety Concepts, Inc.
Priority to AU2002235179A priority Critical patent/AU2002235179A1/en
Publication of WO2002037932A2 publication Critical patent/WO2002037932A2/en
Publication of WO2002037932A3 publication Critical patent/WO2002037932A3/en
Publication of WO2002037932A9 publication Critical patent/WO2002037932A9/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
    • B60R21/01—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents
    • B60R21/015—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents including means for detecting the presence or position of passengers, passenger seats or child seats, and the related safety parameters therefor, e.g. speed or timing of airbag inflation in relation to occupant position or seat belt use
    • B60R21/01512—Passenger detection systems
    • B60R21/01542—Passenger detection systems detecting passenger motion
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/11—Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/16—Devices for psychotechnics; Testing reaction times ; Devices for evaluating the psychological state
    • A61B5/18—Devices for psychotechnics; Testing reaction times ; Devices for evaluating the psychological state for vehicle drivers or machine operators
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
    • B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
    • B60N2/002—Seats provided with an occupancy detection means mounted therein or thereon
    • B60N2/0021—Seats provided with an occupancy detection means mounted therein or thereon characterised by the type of sensor or measurement
    • B60N2/0023—Seats provided with an occupancy detection means mounted therein or thereon characterised by the type of sensor or measurement for detection of driver fatigue
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
    • B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
    • B60N2/80—Head-rests
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
    • B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
    • B60R21/01—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents
    • B60R21/015—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents including means for detecting the presence or position of passengers, passenger seats or child seats, and the related safety parameters therefor, e.g. speed or timing of airbag inflation in relation to occupant position or seat belt use
    • B60R21/01512—Passenger detection systems
    • B60R21/0153—Passenger detection systems using field detection presence sensors
    • B60R21/01532—Passenger detection systems using field detection presence sensors using electric or capacitive field sensors
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B21/00—Alarms responsive to a single specified undesired or abnormal condition and not otherwise provided for
    • G08B21/02—Alarms for ensuring the safety of persons
    • G08B21/06—Alarms for ensuring the safety of persons indicating a condition of sleep, e.g. anti-dozing alarms
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
    • B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
    • B60N2/002—Seats provided with an occupancy detection means mounted therein or thereon
    • B60N2/0021—Seats provided with an occupancy detection means mounted therein or thereon characterised by the type of sensor or measurement
    • B60N2/0024—Seats provided with an occupancy detection means mounted therein or thereon characterised by the type of sensor or measurement for identifying, categorising or investigation of the occupant or object on the seat
    • B60N2/0027—Seats provided with an occupancy detection means mounted therein or thereon characterised by the type of sensor or measurement for identifying, categorising or investigation of the occupant or object on the seat for detecting the position of the occupant or of occupant's body part
    • B60N2/0028—Seats provided with an occupancy detection means mounted therein or thereon characterised by the type of sensor or measurement for identifying, categorising or investigation of the occupant or object on the seat for detecting the position of the occupant or of occupant's body part of a body part, e.g. of an arm or a leg
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
    • B60N2/00—Seats specially adapted for vehicles; Arrangement or mounting of seats in vehicles
    • B60N2/002—Seats provided with an occupancy detection means mounted therein or thereon
    • B60N2/0021—Seats provided with an occupancy detection means mounted therein or thereon characterised by the type of sensor or measurement
    • B60N2/0024—Seats provided with an occupancy detection means mounted therein or thereon characterised by the type of sensor or measurement for identifying, categorising or investigation of the occupant or object on the seat
    • B60N2/0029—Seats provided with an occupancy detection means mounted therein or thereon characterised by the type of sensor or measurement for identifying, categorising or investigation of the occupant or object on the seat for detecting the motion of the occupant
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60N—SEATS SPECIALLY ADAPTED FOR VEHICLES; VEHICLE PASSENGER ACCOMMODATION NOT OTHERWISE PROVIDED FOR
    • B60N2210/00—Sensor types, e.g. for passenger detection systems or for controlling seats
    • B60N2210/10—Field detection presence sensors
    • B60N2210/12—Capacitive; Electric field

Definitions

  • the present invention relates to systems and methods for detecting an impairment condition of a transportation vehicle operator and notifying the operator or others of the impairment condition.
  • the present invention alleviates the false alarm issue by using multiple indicators of impairment as determined from head motion and merging the data so as to provide an appropriate level of warning to a potentially impaired driver.
  • SUMMARY OF THE INVENTION (DISCLOSURE OF THE INVENTION)
  • the present invention is of an apparatus (and corresponding method) for detecting transportation vehicle operator impairment, comprising: one or more capacitive coupling sensors proximate a head of a transportation vehicle operator; a microprocessor receiving data from the one or more sensors; and resident microprocessor software, hardware, and/or firmware for analysis of a plurality of head motion characteristics.
  • at least two of the head motion characteristics operate over different time scales.
  • the ratio of area of drive electrode to detection electrode of each of the sensors is preferably at least 5:1, more preferably at least 20:1 , and most preferably at least 55:1.
  • the operator is uniquely identified by an average head location over a predetermined initial time period.
  • Each head motion characteristic is preferably reduced to an output in an interval between zero and one.
  • Parameters between zero and one, inclusive, are employed for adjusting sensitivity of each head motion characteristic, and preferably the sum of all the parameter means is one.
  • the outputs for each head motion characteristic are employed to produce a combined output also in an interval between zero and one, preferably wherein the combined outputs are averaged overtime to generate an output indicative of likely level of impairment of the operator, and the apparatus preferably additionally comprising a warning activation when the output indicative of likely level of impairment of the operator is above a predetermined threshold.
  • the head motion characteristics are preferably two or more of comparison to baseline wakeful head behavior, large head motions, stillness after large head motions, head drift to a side, head nods, and head orientation not straight ahead.
  • the invention preferably employs self- diagnostics such as one or more of determining saturated condition of an operational amplifier, determining failure or disconnection of one or more of the one or more sensors, detection of excessive moisture adjacent to a surface of one or more of the one or more sensors, and detection of excessive electronic noise.
  • self- diagnostics such as one or more of determining saturated condition of an operational amplifier, determining failure or disconnection of one or more of the one or more sensors, detection of excessive moisture adjacent to a surface of one or more of the one or more sensors, and detection of excessive electronic noise.
  • Fig. 1 is a diagram of the preferred capacitive sensor of the invention.
  • Fig. 2 is a block diagram of the preferred system of the invention.
  • the present invention is of a system and method for detecting an impairment condition of a transportation vehicle operator, and for notifying the operator or others of the impairment condition.
  • the system comprises sensing means for detecting range, position, and motion of the operator's head, processing means for processing signals from the sensing means, analysis means for analyzing the processed signals, and notification means for notifying the operator or others if the analysis indicates impairment of the operator.
  • the sensing means are capacitive coupling electrodes residing above the operator's head on the interior roof of a transportation vehicle.
  • the electrodes produce local electric fields, which are affected by an operator's head positioned in the local electric fields.
  • the changes in the local electric fields are transformed to range data representing the operator's head range to fixed points on the sensing means, using appropriate transfer functions.
  • the range data are then processed to derive the operator's head location through triangulation.
  • the electrodes are formed on a dielectric substrate such that the electrodes are on one side of the substrate and electronic parts are on the other side of the substrate.
  • One electrode, or one pair of electrodes may be substantially smaller than the other electrodes, said smaller electrode(s) developing an electric field, which is used as a reference signal.
  • the reference signal is used to compensate for changes in environmental conditions that may affect the sensing means overtime.
  • each sensing means 10 in the preferred embodiment is depicted in Fig. 1 , with detection electrode 12 on a first side of the substrate, drive electrode 14 on the first side of the substrate, and signal processing circuitry 16 on the other side of the substrate. Multiple sensing means of similar shape are preferably provided on the substrate.
  • the drive electrode which is attached to the oscillator, is preferably a plate whose dimensions and area are an order of magnitude (or more) greater than the area of the detection electrode, which is attached to the signal processing circuitry.
  • the dimensions and area of the drive electrode is 1" x 10" or ten square inches, and the area of the detection electrode is 0.18 square inches.
  • the ratio in this example is thus about 55:1.
  • the drive electrode area is 11.0 square inches, resulting in a ratio of 61:1.
  • ADC analog-to-digital converter
  • the ratio is preferably at least approximately 5:1 , more preferably at least approximately 20:1 , and most preferably at least approximately 55:1.
  • the substrate may be a flexible material to allow the substrate to conform to curvature of the vehicle roof.
  • One or more grounded areas are provided on the substrate, to electrically isolate the electrodes from the electronic parts.
  • a connector is provided on the substrate to connect the sensing means to vehicle power, ground, and to provide for the transmission of data.
  • the connector may utilize a single wire or other transmission means from the vehicle.
  • the preferred system of the invention 20 employs microprocessor 22 or other information processing means (hereafter, "microprocessor”).
  • the microprocessor receives data from the sensing means and uses range and/or head location and/or motion information to determine impairment of the operator.
  • the microprocessor outputs a signal 24 that can be used to warn the operator, or others (e.g., via telecommunications), of the impairment condition, or to take other prophylactic safety measures.
  • the invention preferably includes an operator identification component and a plurality of impairment feature detectors for detecting impairment of the operator.
  • the operator identification component preferably identifies an operator by the average location of his/her head over an initial time period.
  • the feature detectors identify those features of head range, position, or motion that are associated either with aspects of impairment, or with behavior uncharacteristic of a particular operator's wakeful behavior.
  • Each feature detector has associated with it a parameter that can be used to adjust the sensitivity of the feature detector.
  • Each feature detector outputs a signal that can be normalized to the interval from zero to one. A high value indicates impairment and a low value indicates wakefulness.
  • TFO total feature output
  • a threshold is associated with the TFO. If the TFO signal exceeds the threshold, then a signal is outputted of amplitude equal to the TFO, otherwise the output is zero. A non-zero output indicates that the impairment detection has "fired”. Multiple "fired" TFO signals may be time-averaged to yield successive "fired” output values. Higher values indicate increased operator impairment. This output from the invention is then used to actuate appropriate notification measures.
  • Each feature detector operates over a time scale appropriate for the head motion events being detected by the particular feature detector.
  • the time scales are different for different features.
  • a preferred embodiment of each preferred feature detector is described below:
  • Feature 1 a detector of non-wakeful behavior. This detector identifies wakeful behavior from a baseline wakeful signal for the operator. The feature detector outputs a signal close to one when the measured signal is much different from the baseline signal. The detector outputs a signal near zero when the measured signal is similar to the baseline signal.
  • Feature 2 a detector of large motions.
  • the detector outputs a signal near zero when large head motions are being made and a signal near one when the head motion is similar to the baseline signal of Feature 1.
  • Feature 3 a detector of stillness after large motions.
  • the feature detector outputs a signal near one if the head becomes still after large head motions. Otherwise the signal is near zero.
  • Feature 4 a detector of head drift to the side.
  • the detector outputs a signal near one if the operator head is slowly moving in a lateral direction, otherwise the signal is near zero.
  • Feature 5 a detector of head nods.
  • the detector outputs a signal near one if the head dips on a time-scale of about one second; otherwise the signal is near zero.
  • An alternative embodiment includes the use of range signals to identify when the operator's attention is momentarily diverted from the driving task due to looking at the vehicle mirrors, gauges, radio or CD player, etc.
  • changes in lateral head position may also be used in combination with the range signals to identify when the operator's head is oriented other than at the roadway. If the operator's attention is diverted for a period of time that is potentially dangerous, one or more notifications are activated.
  • the invention is applicable to equivalent constructions, methodologies, and applications, including the following: (1) Detection of intoxicated or drug impaired operators; (2) Detection of inattentive operators; (3) Detection of operators distracted by instrumentation, cell phones, radios, etc.; (4) Detection of unauthorized operators - operator identification; (5) Employing sensing means other than overhead electrodes; (6) Employing measurements of head range, position, or motion other than by converting changes in sensing means signals into range data and by triangulation of the range data ⁇ other measurements could be derived directly from sensing means voltages, or from direct observation of optical measurements, electromagnetic or microwave measurements, acoustic measurements, etc.; and (7) omitting the operator identification module, instead utilizing baseline head proximity, position, or motion characteristics, which are generalized for a population of operators.
  • a diagnostic function detects an anomaly in performance, the function provides notification to the vehicle operator and also may trigger an alternative processing means which temporarily omits utilization of the anomalous component until the condition either self-corrects or is serviced.
  • the diagnostic functions include detection of: saturated condition of an operational amplifier; electronic part or sensor electrode failure or disconnection; excessive moisture adjacent to the surface of the sensor, which blocks the sensor; and detection of excessive electronic noise in the system due to interference from outside sources.
  • alternative processing means upon detection of an anomaly such as excessive noise, the system may select one or more different operating frequencies until a frequency is found which minimizes the noise coupling into the system.

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Abstract

An apparatus and method for detecting transportation vehicle operator impairment comprising one or more capacitive coupling sensors (10) proximate a head of a transportation vehicle operator, a microprocessor (22) receiving data from the one or more sensors, and resident microprocessor software, hardware, and/or firmware for analysis of a plurality of head motion characteristics.

Description

DROWSY OPERATOR DETECTION PROCESS
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of the filing of U.S. Provisional Patent Application Serial No. 60/246,658, entitled "Drowsy Operator Detection Process", filed on November 7, 2000, and the specification thereof is incorporated herein by reference.
BACKGROUND OF THE INVENTION
Field of the Invention (Technical Field):
The present invention relates to systems and methods for detecting an impairment condition of a transportation vehicle operator and notifying the operator or others of the impairment condition.
Background Art:
Prevention of roadway accidents can be substantially reduced if an effective means of detecting operator impairment were available. A certain amount of work has been done employing use of overhead capacitive sensors to determine head position and deduce impairment from certain types of head motions. See, e.g., U.S. Patent Nos. 6,275,146 and 5,691,693. However, such work has revolved around using a single indicator of impairment and has not adequately dealt with means for reducing false alarm rates.
The present invention alleviates the false alarm issue by using multiple indicators of impairment as determined from head motion and merging the data so as to provide an appropriate level of warning to a potentially impaired driver. SUMMARY OF THE INVENTION (DISCLOSURE OF THE INVENTION) The present invention is of an apparatus (and corresponding method) for detecting transportation vehicle operator impairment, comprising: one or more capacitive coupling sensors proximate a head of a transportation vehicle operator; a microprocessor receiving data from the one or more sensors; and resident microprocessor software, hardware, and/or firmware for analysis of a plurality of head motion characteristics. In the preferred embodiment, at least two of the head motion characteristics operate over different time scales. The ratio of area of drive electrode to detection electrode of each of the sensors is preferably at least 5:1, more preferably at least 20:1 , and most preferably at least 55:1. Preferably, the operator is uniquely identified by an average head location over a predetermined initial time period. Each head motion characteristic is preferably reduced to an output in an interval between zero and one. Parameters between zero and one, inclusive, are employed for adjusting sensitivity of each head motion characteristic, and preferably the sum of all the parameter means is one. The outputs for each head motion characteristic are employed to produce a combined output also in an interval between zero and one, preferably wherein the combined outputs are averaged overtime to generate an output indicative of likely level of impairment of the operator, and the apparatus preferably additionally comprising a warning activation when the output indicative of likely level of impairment of the operator is above a predetermined threshold. The head motion characteristics are preferably two or more of comparison to baseline wakeful head behavior, large head motions, stillness after large head motions, head drift to a side, head nods, and head orientation not straight ahead. The invention preferably employs self- diagnostics such as one or more of determining saturated condition of an operational amplifier, determining failure or disconnection of one or more of the one or more sensors, detection of excessive moisture adjacent to a surface of one or more of the one or more sensors, and detection of excessive electronic noise.
Objects, advantages and novel features, and further scope of applicability of the present invention will be set forth in part in the detailed description to follow, taken in conjunction with the accompanying drawings, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated into and form a part of the specification, illustrate one or more embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating one or more preferred embodiments of the invention and are not to be construed as limiting the invention. In the drawings:
Fig. 1 is a diagram of the preferred capacitive sensor of the invention; and
Fig. 2 is a block diagram of the preferred system of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
(BEST MODES FOR CARRYING OUT THE INVENTION) The present invention is of a system and method for detecting an impairment condition of a transportation vehicle operator, and for notifying the operator or others of the impairment condition. The system comprises sensing means for detecting range, position, and motion of the operator's head, processing means for processing signals from the sensing means, analysis means for analyzing the processed signals, and notification means for notifying the operator or others if the analysis indicates impairment of the operator.
In the preferred embodiment, the sensing means are capacitive coupling electrodes residing above the operator's head on the interior roof of a transportation vehicle. The electrodes produce local electric fields, which are affected by an operator's head positioned in the local electric fields. The changes in the local electric fields are transformed to range data representing the operator's head range to fixed points on the sensing means, using appropriate transfer functions. The range data are then processed to derive the operator's head location through triangulation. In the preferred embodiment, the electrodes are formed on a dielectric substrate such that the electrodes are on one side of the substrate and electronic parts are on the other side of the substrate. One electrode, or one pair of electrodes, may be substantially smaller than the other electrodes, said smaller electrode(s) developing an electric field, which is used as a reference signal. The reference signal is used to compensate for changes in environmental conditions that may affect the sensing means overtime.
The preferred electrode shape of each sensing means 10 in the preferred embodiment is depicted in Fig. 1 , with detection electrode 12 on a first side of the substrate, drive electrode 14 on the first side of the substrate, and signal processing circuitry 16 on the other side of the substrate. Multiple sensing means of similar shape are preferably provided on the substrate.
The drive electrode, which is attached to the oscillator, is preferably a plate whose dimensions and area are an order of magnitude (or more) greater than the area of the detection electrode, which is attached to the signal processing circuitry.
In an exemplary embodiment, the dimensions and area of the drive electrode is 1" x 10" or ten square inches, and the area of the detection electrode is 0.18 square inches. The ratio in this example is thus about 55:1. As another example, for a sensor with 5.75" overall diameter and drive electrode of 3.75" diameter, the drive electrode area is 11.0 square inches, resulting in a ratio of 61:1. This sensor geometry offers reduced noise because the AC gain necessary to utilize the full range of an analog-to-digital converter (ADC) is significantly less than when the drive electrode and detection electrode are similar to each other in area. The ratio is preferably at least approximately 5:1 , more preferably at least approximately 20:1 , and most preferably at least approximately 55:1.
Consequently, the sensor operates at a more favorable signal-to-noise ratio, resulting in better sensitivity to nearby conductive objects (such as the driver's head) and sensitivity at a greater distance. The substrate may be a flexible material to allow the substrate to conform to curvature of the vehicle roof. One or more grounded areas are provided on the substrate, to electrically isolate the electrodes from the electronic parts. A connector is provided on the substrate to connect the sensing means to vehicle power, ground, and to provide for the transmission of data. The connector may utilize a single wire or other transmission means from the vehicle.
Referring to Fig. 2, the preferred system of the invention 20 employs microprocessor 22 or other information processing means (hereafter, "microprocessor"). The microprocessor receives data from the sensing means and uses range and/or head location and/or motion information to determine impairment of the operator. The microprocessor outputs a signal 24 that can be used to warn the operator, or others (e.g., via telecommunications), of the impairment condition, or to take other prophylactic safety measures.
The invention preferably includes an operator identification component and a plurality of impairment feature detectors for detecting impairment of the operator. The operator identification component preferably identifies an operator by the average location of his/her head over an initial time period.
The feature detectors identify those features of head range, position, or motion that are associated either with aspects of impairment, or with behavior uncharacteristic of a particular operator's wakeful behavior. Each feature detector has associated with it a parameter that can be used to adjust the sensitivity of the feature detector. Each feature detector outputs a signal that can be normalized to the interval from zero to one. A high value indicates impairment and a low value indicates wakefulness.
The feature detector signals are then combined in a multiplicative fashion to yield the output of the total feature output ("TFO"), which is a signal that also lies in the interval zero to one, low values indicating wakefulness and high values indicating impairment. A threshold is associated with the TFO. If the TFO signal exceeds the threshold, then a signal is outputted of amplitude equal to the TFO, otherwise the output is zero. A non-zero output indicates that the impairment detection has "fired". Multiple "fired" TFO signals may be time-averaged to yield successive "fired" output values. Higher values indicate increased operator impairment. This output from the invention is then used to actuate appropriate notification measures.
Each feature detector operates over a time scale appropriate for the head motion events being detected by the particular feature detector. In the preferred embodiment, the time scales are different for different features. A preferred embodiment of each preferred feature detector is described below:
Feature 1 , a detector of non-wakeful behavior. This detector identifies wakeful behavior from a baseline wakeful signal for the operator. The feature detector outputs a signal close to one when the measured signal is much different from the baseline signal. The detector outputs a signal near zero when the measured signal is similar to the baseline signal.
Feature 2, a detector of large motions. The detector outputs a signal near zero when large head motions are being made and a signal near one when the head motion is similar to the baseline signal of Feature 1.
Feature 3, a detector of stillness after large motions. The feature detector outputs a signal near one if the head becomes still after large head motions. Otherwise the signal is near zero.
Feature 4, a detector of head drift to the side. The detector outputs a signal near one if the operator head is slowly moving in a lateral direction, otherwise the signal is near zero.
Feature 5, a detector of head nods. The detector outputs a signal near one if the head dips on a time-scale of about one second; otherwise the signal is near zero.
Each feature signal is then taken to the power of the sensitivity parameter for that feature and then multiplied together to yield the TFO. In most applications the sum of the sensitivity parameters is one. An alternative embodiment includes the use of range signals to identify when the operator's attention is momentarily diverted from the driving task due to looking at the vehicle mirrors, gauges, radio or CD player, etc. In this embodiment, changes in lateral head position may also be used in combination with the range signals to identify when the operator's head is oriented other than at the roadway. If the operator's attention is diverted for a period of time that is potentially dangerous, one or more notifications are activated.
The invention is applicable to equivalent constructions, methodologies, and applications, including the following: (1) Detection of intoxicated or drug impaired operators; (2) Detection of inattentive operators; (3) Detection of operators distracted by instrumentation, cell phones, radios, etc.; (4) Detection of unauthorized operators - operator identification; (5) Employing sensing means other than overhead electrodes; (6) Employing measurements of head range, position, or motion other than by converting changes in sensing means signals into range data and by triangulation of the range data ~ other measurements could be derived directly from sensing means voltages, or from direct observation of optical measurements, electromagnetic or microwave measurements, acoustic measurements, etc.; and (7) omitting the operator identification module, instead utilizing baseline head proximity, position, or motion characteristics, which are generalized for a population of operators.
Given the safety-critical nature of the invention, an improvement in reliability is achieved by incorporating into the invention self-diagnostic functions. If a diagnostic function detects an anomaly in performance, the function provides notification to the vehicle operator and also may trigger an alternative processing means which temporarily omits utilization of the anomalous component until the condition either self-corrects or is serviced. In the preferred embodiment, the diagnostic functions include detection of: saturated condition of an operational amplifier; electronic part or sensor electrode failure or disconnection; excessive moisture adjacent to the surface of the sensor, which blocks the sensor; and detection of excessive electronic noise in the system due to interference from outside sources. As example of alternative processing means upon detection of an anomaly such as excessive noise, the system may select one or more different operating frequencies until a frequency is found which minimizes the noise coupling into the system.
Although the invention has been described in detail with particular reference to these preferred embodiments, other embodiments can achieve the same results. Variations and modifications of the present invention will be obvious to those skilled in the art and it is intended to cover in the appended claims all such modifications and equivalents. The entire disclosures of all references, applications, patents, and publications cited above are hereby incorporated by reference.

Claims

CLAIMSWhat is claimed is:
1. An apparatus for detecting transportation vehicle operator impairment, said apparatus comprising: one or more capacitive coupling sensors proximate a head of a transportation vehicle operator; a microprocessor receiving data from said one or more sensors; and means resident on said microprocessor for analysis of a plurality of head motion characteristics.
2. The apparatus of claim 1 in which at least two of the head motion characteristics operate over different time scales.
3. The apparatus of claim 1 wherein a ratio of area of a drive electrode and a detection electrode of each of said sensors is at least 5:1 , preferably at least 20:1 , and most preferably at least 55:1.
4. The apparatus of claim 1 additionally comprising means for uniquely identifying an operator by an average head location over a predetermined initial time period.
5. The apparatus of claim 1 wherein said resident means comprises means for generating for each head motion characteristic an output in an interval between zero and one.
6. The apparatus of claim 5 wherein said resident means comprises parameter means for adjusting sensitivity of each head motion characteristic, each said parameter means comprising a real number between zero and one, inclusive, and preferably wherein a sum of all said parameter means is one.
7. The apparatus of claim 5 wherein said resident means combines said outputs for each head motion characteristic to produce a combined output also in an interval between zero and one, preferably wherein said combined outputs are averaged over time to generate an output indicative of likely level of impairment of the operator, and said apparatus preferably additionally comprising means for generating a warning when said output indicative of likely level of impairment of the operator is above a predetermined threshold.
8. The apparatus of claim 1 wherein said resident means analyze a plurality of head motion characteristics selected from the group consisting of comparison to baseline wakeful head behavior, large head motions, stillness after large head motions, head drift to a side, head nods, and head orientation not straight ahead.
9. The apparatus of claim 1 additionally comprising self-diagnostic means selected from the group consisting of determining saturated condition of an operational amplifier, determining failure or disconnection of one or more of said one or more sensors, detection of excessive moisture adjacent to a surface of one or more of said one or more sensors, and detection of excessive electronic noise.
10. A method for detecting transportation vehicle operator impairment, the method comprising the steps of: providing one or more capacitive coupling sensors proximate a head of a transportation vehicle operator; receiving data from said one or more sensors with a microprocessor; and analyzing via the microprocessor a plurality of head motion characteristics.
PCT/US2001/047612 2000-11-07 2001-11-07 Drowsy operator detection process WO2002037932A2 (en)

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WO2005052878A1 (en) * 2003-11-30 2005-06-09 Volvo Technology Corporation Method and system for recognizing driver impairment

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GB2389215A (en) * 2002-05-27 2003-12-03 Malachi Christopher Mckenna Monitoring the condition of a vehicle driver
WO2005052878A1 (en) * 2003-11-30 2005-06-09 Volvo Technology Corporation Method and system for recognizing driver impairment
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