Page 198 - Mechatronics for Safety, Security and Dependability in a New Era

Ch38-I044963.fm Page 182 Tuesday, August 1, 2006 8:18 PM
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182 Page 182 Tuesday, August 1, 2006 8:18 PM
The purpose of this study is to fabricate a driving simulator and establish the methods to evaluate the
driving performance with the simulator under the condition of drunk driving or talking driving with a
cell phone.

2. DRIVING SIMULATOR
The driving simulator is rebuilt as an automatic shift car from the components of a car taken apart.
The simulated driving is assumed to be conducted on a one-way highway in the suburb, therefore no
traffic signals and no intersections appear. The road patterns of straight and curve are designed to
appear at random. The other car, which runs with speed increased and decreased in the range of 40 to
60km/h in front of the car simulator, is displayed on the same lane. If the distance between the car
simulator and the preceding car in front of it becomes more than 70m, another following car is
designed to cut in 10m ahead.

3. EVALUATION METHODS FOR DRIVING PERFORMANCE

In this study two indices are proposed to evaluate the driving performance under the conditions of
drunk driving or talking driving with a cell phone. One is the degree of unsteadiness of the driving
path and the other is the reaction time in pressing the brake pedal with a foot.
3.1 Unsteadiness of Driving Path

The degree of unsteadiness of the driving path is defined newly in this study as composition of the
degree of weaving from side to side per unit time (A w,-) and the degree of fluctuating of the distance
between cars per unit time (Afi ). The unit time is defined as 0.2s. The unit of Aw, and Afi is meter.
Tn this study the degree of unsteadiness U of the driving path is defined as the composition of Aw,-
and Afi as follows:

X logjA u,) X lo glll { Afi + {a • Aw, f \
(1)

where n=300 for one minute drive. Au t is unsteadiness of the driving path per unit time. The weight
A
(a = 6) was obtained as the ratio of | /1 to \ Aw .

Figure 1: Geometric illustration of unsteadiness of the driving path per unit time