JPH04122242A - Awake state judging device - Google Patents

Abstract

PURPOSE:To judge the correct awake state by judging the pulse interval of signals indicating the angular velocity of steering to determine the steering action interval, and judging that the awake level of a driver is lowered if the action interval is long. CONSTITUTION:When the signal indicating the steering angle delta is differentiated by a differentiator 5, a signal indicating the angular velocity alpha of steering is obtained. Since steering actions are intermittent, the signals indicating the angular velocity alpha of steering are scattered pulses. A pulse interval measuring unit 6 measures the interval of the pulses. A judging unit 7 compares the peak values of the pulses with the preset value T0, and it outputs an awakening stimulation action signal A for a preset time when a pulse with the peak value larger than T0 arrives. When the interval of steering actions by a driver 2 is longer than the preset interval T0, it is judged that the awoke level is lowered, and an awakening stimulation device 8 is operated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an arousal state determining device, and more particularly to a device for determining a driver's arousal state based on the dynamic characteristics of a steering operation.

[Conventional technology]

In order to prevent so-called drowsy driving, a device that objectively determines the driver's alertness is required. Several types of devices have been proposed as such wakefulness determining devices. The first type of device determines the driver's wakefulness state by attaching electrodes to the driver's head and observing physiological signals such as brain waves. With this device,
It becomes possible to objectively determine the state of wakefulness based on physiological information emitted by the driver. The second type of device determines the driver's wakefulness state by determining the driver's reaction time αj. For example, at predetermined intervals, the driver may be given visual stimulation, such as by lighting a lamp, or auditory stimulation, such as by the sound of a buzzer. For example, the reaction time required to perform an action (such as pressing a predetermined button) is measured. If the reaction time becomes longer, it can be determined that the level of alertness is decreasing. A third type of device also monitors steering operations;
When the angular velocity of the steering wheel is high, that is, when a sudden steering operation is performed, it is determined that the alertness level is low. In addition, devices that combine these three types of devices have also been proposed. For example, Japanese Patent Application Laid-Open No. 55-164529 discloses an alertness determining device that combines the second type and the third type.

[Invention or problem to be solved]

However, all three types of devices described above have problems. In the first type of device, it is necessary to attach electrodes to the driver's body, which is very cumbersome and hinders driving.

The second type of device requires the driver to perform a predetermined operation such as pressing a button, which forces the driver to perform an extra operation that is not originally necessary for driving, which also hinders driving. arise. It is also dangerous because the driver is distracted by things other than driving. On the other hand, in the third type of device, no electrodes are attached or unnecessary operations are imposed, so there is no problem with operation. However, with this device, there is a high possibility that an erroneous determination will be made. In other words, this third type of device either determines that the alertness level has decreased due to a sudden steering operation, or even if the alertness level is high, it immediately takes action to avoid danger. Sudden steering link operations may also be required. If such a danger avoidance operation is performed, this device will incorrectly determine that the alertness level has decreased.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a device that can accurately determine the state of wakefulness without causing any hindrance to driving.

[Means to solve the problem]

The present invention provides an awakening state determination device that includes: means for detecting a steering angle of a vehicle; means for time-differentiating this steering angle to obtain a pulse indicating a steering angular velocity; means for measuring an interval between the pulses; and means for determining the alertness level of the driver based on the pulse interval.

[For production]

In the wakefulness determination device according to the present invention, the steering angle is detected. Generally, the driver's steering operation is
Since the steering operation is an intermittent rotational operation, when the steering angle is time-differentiated to obtain a signal indicating the steering angular velocity, this signal becomes a discrete pulse-like signal. The time when the pulse exists corresponds to the time when the driver performs a steering operation. Therefore, the trick pulse interval corresponds to the steering operation interval of the driver. According to the present invention, when the driver's alertness level decreases,
Focusing on the fact that the steering operation interval becomes longer, the alertness level is determined based on this pulse interval.

〔Example〕

The present invention will be described below based on illustrated embodiments.

First Embodiment FIG. 1 is a block diagram showing the basic configuration of an arousal state determining apparatus according to a first embodiment of the present invention. A driver 2 driving the vehicle 1 operates a steering wheel 3. The steering angle δ of the steering wheel 3 is measured by a steering angle measuring device 4. As the steering angle measuring device 4, a device such as a potentiometer or an encoder may be used. A signal indicating the measured steering angle δ is given to a differentiator 5 and differentiated with respect to time. The differential value α of the steering angle δ is a value indicating the angular velocity of the steering.

The signal indicating the steering angular velocity α is a discrete pulse-like signal. The pulse interval measuring device 6 measures the interval of pulses constituting the signal indicating the steering angular velocity α. The measured pulse interval T is given to the determiner 7. The determiner 7 outputs the awakening stimulation operation signal A for a predetermined period of time when the pulse interval T becomes equal to or greater than a predetermined set value TO.

The arousal stimulation device 8 operates based on the arousal stimulation operation signal A, and provides an arousal stimulation to the driver 2. The above is the basic configuration of this device. The differentiator 5, pulse interval measuring device 6, determining device 7, and arousal stimulation device 8 are all devices installed in the vehicle 1, but in FIG. 1, for convenience of explanation, they are shown outside the vehicle 1. Indicated by blocks.

Next, with reference to FIG. 2, this device will be explained. , the specific operation will be explained. FIG. 2(a) is a time chart showing changes in the steering angle δ measured by the steering angle measuring device 4 over time t.

Generally, the steering operation by the driver 2 is intermittent as shown in this time chart. When the signal indicating such a steering angle δ is differentiated by the differentiator 5, we get
A signal indicating the angular velocity α of the steering as shown in FIG. 2(b) is obtained. Since the steering operation is intermittent, the signal indicating the steering angular velocity α is in the form of discrete pulses as shown in the figure. The larger the peak value of this pulse, the more abrupt the steering operation was performed. The pulse interval measuring device 6 measures the pulse interval shown in FIG. 2(b). FIG. 2(C) shows this pulse interval T
This is a time chart showing the vertical axis. That is, the peak value of the pulse shown in FIG. 2(C) is the same as that in FIG. 2(b).
The pulse interval Tl shown in T2°T3. Corresponds to... The determiner 7 compares the peak value of each pulse shown in FIG. 2(C) with a predetermined set value TO, and when a pulse with a peak value greater than TO arrives, the value shown in FIG. 2(d) is determined. The arousal stimulation operation signal A is outputted for a predetermined period of time.

That is, if the pulse interval T is greater than the setting @TO,
In other words, when the interval between steering operations by the driver 2 is longer than the predetermined interval TO, it is determined that the level of alertness has decreased, and the alertness stimulating device 8 is activated. In the example shown in FIG. 2, since the pulse interval T5 exceeds the set value TO, the wakefulness stimulation operation signal A is output accordingly. It is preferable that the set value TO be set to a different value depending on the driver, and generally TO-0, 4.
It is preferable to set it to ~1 second.

Any device may be used as the arousal stimulation device 8 as long as it can provide arousal stimulation to the driver 2. For example, it may be possible to give the driver 2 a simulated vibration similar to the vibration caused when driving over a step, or the engine sound or wind noise from outside the vehicle may be introduced into the vehicle to stimulate the driver's sense of hearing. The rear wheels can also be steered in phase to increase yaw gain and alertness to the maneuver.

Second Embodiment FIG. 3 is a block diagram showing the basic configuration of an arousal state determining apparatus according to a second embodiment of the present invention. The configuration of the device shown in FIG. 3 is almost the same as the device of the first embodiment shown in FIG. 1, and the same components as in FIG. 1 are designated by the same reference numerals. The difference is that instead of the determiner 7 in the device of FIG. 1, the device of FIG. 3 uses the determiner 7.
1.72 and an AND gate 73. Similar to the determiner 7, the determiner 71 determines whether the pulse interval T exceeds a predetermined set value TO. Judgment device 7
Step 2 determines whether the angular velocity α exceeds a predetermined set value α0. Then, the AND gate 73 outputs the awakening stimulation operation signal A only when T>TO and α>α0. Here, the set value TO
It is preferable that α0 and α0 can be set to different values depending on the driver.

With this configuration, it is determined that the degree of arousal has decreased and the arousal stimulation device 8 is activated when the two conditions of the steering operation interval T being long and the steering angular velocity α being large are both satisfied. Become. By making two conditional judgments in this way, it becomes possible to more accurately judge whether the alertness level has decreased. The reason for this will be explained by taking four patterns shown in FIG. 4 as examples.

The four patterns shown in FIG. 4 are all time charts in which the horizontal axis is the time axis t, the vertical axis is the angular velocity α, and shows pulses corresponding to the angular velocity α of the steering wheel.

In the normal operation of pattern a, both the value of the angular velocity α (the peak value of the pulse in the figure) and the value of the pulse interval T are normal values. In other words, the driver performs steering operations of appropriate magnitude at appropriate intervals. This is a pattern seen when driving on normal roads. In the monotonous operation of pattern b, the value of the angular velocity α is a normal value, but the value of the pulse interval T becomes large. In other words, although the driver is performing a steering operation of an appropriate magnitude, the interval between operations becomes long.

This is a pattern seen when driving on monotonous roads such as expressways. In the risk avoidance driving of pattern C, the value of the angular velocity α becomes large, or the value of the pulse interval T becomes a normal value. That is, either the driver performs steering operations at appropriate intervals, or the amount of steering operation at one time is large. This is a pattern seen when avoiding danger, such as avoiding obstacles. The above three patterns a, b, and c do not necessarily mean that the level of alertness is decreasing. On the other hand, in the alertness reduction operation of pattern d, both the value of the angular velocity α and the value of the pulse interval T become large. That is, the interval between steering operations by the driver is long, and the amount of steering operation per time is large. This is a pattern that occurs when the driver is driving with a reduced level of alertness, which is what is called drowsy driving.

The chart shown in FIG. 5 has the operation interval T (pulse interval) on the horizontal axis and the angular velocity α on the vertical axis, and each axis is divided into two by predetermined set values TO1α0 to define four regions.
This is a chart in which the four patterns described above are assigned to each region. In the conventional third type of alertness determination device described above, since the alertness level reduction is determined based only on the angular velocity α of the steering wheel, it is difficult to distinguish between pattern C danger avoidance driving and pattern d reduced alertness driving. could not be done. Furthermore, in the device of the first embodiment described above, since the determination of a decrease in alertness level was made based only on the steering operation interval T, it is necessary to distinguish between monotonous driving in pattern b and driving with decreased alertness level in pattern d. I couldn't do anything. In the device of the second embodiment described here, since the alertness level reduction is determined based on both the angular velocity α of the steering wheel and the operation interval T, the danger avoidance driving of pattern C and the monotonous driving of pattern b are performed. When performing this, it will no longer be mistakenly judged as a decrease in arousal level, making it possible to make accurate judgments.

The present invention has been described above based on the illustrated embodiments, but
The basic idea of the present invention is to determine the steering operation interval by measuring the pulse interval of a signal indicating the angular velocity of the steering wheel, and to determine that the alertness level has decreased if this operation interval is long. Therefore, the present invention is not limited to the embodiment ρ1 described here, and any configuration may be adopted as long as it realizes this basic idea.

〔Effect of the invention〕

As described above, according to the present invention, in the wakefulness determination device, the steering operation interval is determined by measuring the pulse interval of the signal indicating the angular velocity of the steering wheel, and when this operation interval is long, the driver's alertness level decreases. Since it is determined that the driver has woken up, it is possible to accurately determine whether the driver is awake or not, without causing any hindrance to driving.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of the wakefulness determining device according to the first embodiment of the present invention, FIG. 2 is a graph explaining the specific operation of the device shown in FIG. 1, and FIG. FIG. 4 is a block diagram showing the basic configuration of the wakefulness determination device according to the second embodiment of the present invention. FIG. The chart in FIG. 5 is a chart showing four operation patterns with the operation interval T (pulse interval) on the horizontal axis and the angular velocity α on the vertical axis.

Claims (1)

[Claims] means for detecting the steering angle of the vehicle; means for differentiating the steering angle with respect to time to obtain a pulse indicating the steering angular velocity; means for measuring the interval between the pulses; and means for awaking the driver based on the pulse interval. An apparatus for determining an awake state, comprising: means for determining the degree of wakefulness.