1. Field of the Invention
The present invention relates to a consciousness judging apparatus which can exactly detect a drop in consciousness (concentration) of a driver caused by sudden drowsiness while driving a vehicle.
2. Description of the Related Art
An automobile has various means operated by a driver, such as a steering wheel, an accelerator, a brake pedal, a gear-shift lever, a winker lever, a wiper switch, and a light switch.
When the number of operations of these operation means is decreased, driving becomes monotonous and the driver becomes drowsy and may fall asleep during driving.
It is known that the consciousness level is reduced while changing periodically (25–251 sec) until a driver falls asleep (refer to Theses of Mechanics Society of Japan, September, 1997).
There is a known apparatus, which infers a driver's consciousness (concentration) by inputting the data output from each operation means into a fuzzy inference means after averaging at every certain time (5 minutes, for example) (refer to U.S. Pat. No. 3,039,327).
There is another known apparatus, which infers a driver's consciousness (concentration) considering the individual driving characteristics of the driver, by inputting the average value of meander quantity in the initial driving operation as a reference value (refer to U.S. Pat. No. 2,830,475).
However, in the apparatus of the above U.S. Pat. No. 3,039,327, the data input to the fuzzy inference means is the average of 5-minute data.
In the apparatus of U.S. Pat. No. 2,830,475, the data input to the fuzzy inference means is the average of 10-minute data.
A driver may suddenly become drowsy before the above certain time, for example, 5 minutes. For example, there is a case that consciousness (concentration) is suddenly lowered by drowsiness in about 1 minute.
In such a case, as disclosed by U.S. Pat. No. 3,039,327, the data input to the fuzzy inference means is the average value of the detection time set relatively longer. Thus, the traceability of estimating concentration may be lowered for the sudden drop of consciousness (concentration) caused by sudden drowsiness.