Abstract
Long-haul truck drivers often need to deal with time pressure, repetitive tasks and drowsiness. Most of these influences are job-inherent and cannot be changed easily. Due to the fact that the vehicle is a trucker’s workplace, it should be a matter of concern to design the truck as comfortable as possible for the driver. In this context it is necessary to identify objectified parameters which are responsible for tiring the driver. These parameters should be integrated into an optimized vehicle development approach with respect to the driver’s tiring process. To support this vehicle development process and to benchmark existing trucks, tools to evaluate the vehicles influence on the driver need to be developed. The aim of the present paper is to present first approaches how vehicle measurements can be used to determine the drivers load and -tiring process. To initially identify which problems the drivers actually have to cope with, a study with a sufficient number of participants concerning vibrations in trucks, driving safety, different disturbances and others has been carried out. The results of this survey were used to recommend suitable measuring equipment in the vehicle.
A tractor-trailer combination of 40 tons gross load weight was driven as a testing vehicle on various roads and highways. It was proposed to drive a typical “trucker day” to achieve realistic conditions. The trip included motorways and national highways with an appropriate mixture of straights and curves, inclines and declines. The truck was equipped with various measurement devices such as acceleration and vibration sensors, shifting-force and -travel sensors, and sensors for handling the clutch, brake and accelerator. Furthermore two video cameras were used for monitoring the driver and the roadway in front of the vehicle. Fuel consumption was recorded as well as steering angle and torque.
Additionally the driver’s level of stress and drowsiness was measured by using a mini electrocardiogram (ECG) and recording the heart rate variability (HRV). Furthermore a self-evaluation of the level of tiredness was made by using the 8-digit Stanford Sleepiness Scale (SSS). Moreover the measured steering wheel angle was analyzed in time and frequency domain, to figure out the level of drowsiness.
The recorded and analysed measurements of vehicle and driver were used to develop methods that show the correlation between the vehicle’s influences and the driver’s reaction. These methods are used to evaluate vehicles concerning their “stressing- and tiring potential” to the driver.
The basics of these methods and selected results from them will be presented.