Marek Guzek

Uncertainty Study of Road Accident Reconstruction - Computational Methods

One purpose of accident reconstruction is to define the motion parameters of the participants before the accident. This paper examines some issues related to the assessment of computational accuracy concerning reconstruction of a vehicles motion from the threat occurrence until the accident or accident avoidance. The basic method of computation credibility assessment is experimental verification of models. In the case of errors resulting from inaccuracies of value assessments for parameters, there are several methods that allow for assessing an error in analysis. These methods include determined methods (e.g., total differential method and extreme values method) and probabilistic methods (e.g., Gauss method, methods with the use of stochastic processes, Monte Carlo method). These methods were compared on the basis of their application in the case of a braking process study of a vehicle in rectilinear motion. Also for the aforementioned case, the results obtained by means of various computational methods of vehicle motion (analytical and simulation models) were compared with the outcome of the experimental study. Findings indicate the failure to consider inaccuracies in data assessment may lead to a false hypothesis of the course for a given accident situation. However, the selection of the best method depends on the adopted model of the analyzed phenomenon and the possibility to define data. Limitations of each method should be considered when choosing a method.

Heart rate variability (HRV) and muscular system activity (EMG) in cases of crash threat during simulated driving of a passenger car

ObjectivesThe aim of the study was to verify whether simultaneous responses from the muscular and circulatory system occur in the driver’s body under simulated conditions of a crash threat.Materials and MethodsThe study was carried out in a passenger car driving simulator. The crash was included in the driving test scenario developed in an urban setting. In the group of 22 young male subjects, two physiological signals — ECG and EMG were continuously recorded. The length of the RR interval in the ECG signal was assessed. A HRV analysis was performed in the time and frequency domains for 1-minute record segments at rest (seated position), during undisturbed driving as well as during and several minutes after the crash. For the left and right side muscles: m. trapezius (TR) and m. flexor digitorum superficialis (FDS), the EMG signal amplitude was determined. The percentage of maximal voluntary contraction (MVC) was compared during driving and during the crash.ResultsAs for the ECG signal, it was found that in most of the drivers changes occurred in the parameter values reflecting HRV in the time domain. Significant changes were noted in the mean length of RR intervals (mRR). As for the EMG signal, the changes in the amplitude concerned the signal recorded from the FDS muscle. The changes in ECG and EMG were simultaneous in half of the cases.ConclusionSuch parameters as mRR (ECG signal) and FDS-L amplitude (EMG signal) were the responses to accident risk. Under simulated conditions, responses from the circulatory and musculoskeletal systems are not always simultaneous. The results indicate that a more complete driver’s response to a crash in road traffic is obtained based on parallel recording of two physiological signals (ECG and EMG).