Abstract
The goal of the research described in this paper is to assess and quantify the relation between driver’s mental workload and his subjective evaluation by using heart rate measures. This could reveal part of the drivers perception expressed in his evaluation. Therefore electrocardiography (ECG)-measures are taken with two drivers while driving different manoeuvres at a test track. In addition, the tyre characteristics are changed to induce different vehicle behaviour. Both mental and physical workload are quantified for the different manoeuvres by the drivers using the Rating Scale Mental Effort and related to derived values of the ECG. For the time domain, the Inter Beat Interval (IBI) is used. For the frequency domain, spectral analyses of the IBI are performed. The results obtained in this research showed that mental workload of a driver during outdoor testing can be quantified by using heart rate measures. Although the mean IBI can give an indication of mental workload, it is shown that other factors can influence the IBI, especially physical workload, making this measure less reliable. Spectral analyses of the IBI and using the LF/HF ratio seems to be a better candidate for indication of mental workload. The rating of the mental workload done by the driver on the RSME corresponds well with this ratio. Spectral analyses of IBI does requires more data processing and does not allow too many artefacts in the ECG data, which is more difficult to prevent in applied automotive settings than in laboratory setting.
Keywords: Mental workload, IBI, HRV, driver model