| Research Abstract |
[Purpose]
Drivability is different greatly what kind of tire a car mounted with. Driver realizes drivability as a feeling of response from steering wheel operation. Physiological and psychological driving stress of the driver is different by a kind of the tire. In this study, we make an evaluation method of drivability by measuring electromyograms(EMGs) of muscles of arms.
[Study method]
We chose that subjects are the skilled drivers that have evaluated tires in tire manufacturer. The drivers drive the driving course of double lane change with speed 90km/h. We used one vehicle that 3 kinds vehicle dynamics by mount with the tires that a physical characteristic of back wheel tires was different from front wheel tires. The 3 kinds of vehicle dynamics are neural steer(NS), over steer(OS) and under steer(US). As the physiological response, Megs of 5 kinds muscles of both arms: the biceps muscle, the triceps, the deltoid muscle, extensor and flexor were selected. During driving, the EMGs were
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measured by unipolar derivation. Ag-AgCl electrodes were attached to skin surface on the muscles. The EMGs were amplified by the bio-amplifier (MP 100WS (EMG100A), BIOPAC Inc. ), A/D-converted with a 500 Hz sample frequency, and recorded into a computer. After driving, we set out a questionnaire to the drivers about concentration / devotion, stress, mental strain and achievement degree of driving subject.
[Results]
The following knowledge was obtained from this studies.
・ As a result of questionnaire, neural steer was the best in stability and handling, and, subsequently, was order of OS, US.
・ In the bicipital muscle, triceps and deltoid muscle, the load for the muscles was big by order of NS, OS, US. That is a same order as the questionnaire result. As for the muscle activity of the bicipital muscle, triceps and deltoid muscle and vehicle dynamics, an adequate correlation is obtained. These 3 muscles are the muscle used for handling.
・ The extensor isn't used to steer. The EMG of like spikes was observed before doing steering of lane change, This suggests that an activity of an excessive muscle happened by mental strain
・ A personal habit about steering was shown such as to steer only by the dominant hand. Less
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