# Physiological Driver Monitoring Using Capacitively Coupled and Radar Sensors
## 3 Results
### Experimental Results from Capacitively-Coupled ECG and Bio-Impedance
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Subj.**} & \multirow{2}{*}{**Traffic**} & \multicolumn{5}{c}{**ECG after Motion Arterial Algorithms**} & \multicolumn{2}{c}{**Respiration**} \\ \cline{3-8}  & & \begin{tabular}{c} **R-R Interval Mean** \\ **Absolute Error (ms)** \\ \end{tabular} & \begin{tabular}{c} **R-R Interval Mean Absolute** \\ **Perceptual Error (\%)** \\ \end{tabular} & \begin{tabular}{c} **95 th Percentile** \\ **Absolute R-R** \\ **Linearized Error (ms)** \\ \end{tabular} & \begin{tabular}{c} **SDNN Mean** \\ **Absolute Error (ms)** \\ \end{tabular} & \
\begin{tabular}{c} **Coverage R-R Interval** \\ **within 5 ms** \\ \end{tabular} &
\begin{tabular}{c} **Coverage** \\ **Weightian Rate** \\ **within 3 bp** \\ \end{tabular} \\ \hline \multirow{2}{*}{1} & highway & 18.67 & 1.39\% & 25.39 & 52.43 & 91.16\% & 68.57\% \\ \cline{2-8}  & city & 25.44 & 1.98\% & 52.73 & 64.77 & 90.15\% & 61.36\% \\ \hline \multirow{2}{*}{2} & highway & 28.64 & 2.54\% & 23.24 & 119.12 & 93.85\% & 26.67\% \\ \cline{2-8}  & city & 25.00 & 0.84\% & 50.78 & 58.11 & 94.61\% & 25.00\% \\ \hline \multirow{2}{*}{3} & highway & 5.21 & 0.39\% & 1.95 & 10.09 & 95.93\% & 68.75\% \\ \cline{2-8}  & city & n/a & n/a & n/a & n/a & n/a & n/a \\ \hline \multirow{2}{*}{4} & highway & 1.48 & 0.11\% & 1.95 & 0.13 & 97.50\% & 26.09\% \\ \cline{2-8}  & city & 5.43 & 0.41\% & 5.86 & 8.17 & 94.34\% & 47.37\% \\ \hline \multirow{2}{*}{5} & highway & 67.72 & 4.05\% & 391.21 & 88.34 & 59.37\% & 66.67\% \\ \cline{2-8}  & city & 130.40 & 6.38\% & 369.48 & 132.58 & 58.94\% & 64.10\% \\ \hline \multirow{2}{*}{Median} & highway & 18.67 & 1.39\% & 23.24 & 52.43 & 93.85\% & 66.67\% \\ \cline{2-8}  & city & 25.22 & 1.41\% & 51.76 & 61.44 & 92.25\% & 54.37\% \\ \cline{2-8}  & overall & 25.00 & 1.39\% & 25.39 & 58.11 & 93.85\% & 61.36\% \\ \hline \multirow{2}{*}{Mean} & highway & 24.34 & \({}^{*}\) & 88.75 & 54.02 & \({}^{*}\) & \({}^{*}\) \\ \cline{2-8}  & city & 46.57 & \({}^{*}\) & 119.71 & 65.91 & \({}^{*}\) & \({}^{*}\) \\ \cline{2-8}  & overall & 34.22 & \({}^{*}\) & 102.51 & 59.30 & \({}^{*}\) & \({}^{*}\) \\ \hline \end{tabular}
\end{table} 
Table 3: Beat-to-beat R-R interval performance metrics (after motion artefact algorithms), and respiration performance (without motion artefact algorithms). \({}^{*}\) The mean is not calculated for numbers expressed as percentages since the sample sizes are not identical. Figure 5 shows example signals from the capacitive ECG and respiration and reference signals while driving. It can be observed that the signals are robust to vibration noise from driving, both at high speed (120 km/h) and low speed (30 km/h) as well as during acceleration. Only when the driver's body moves during the acceleration phase (in this case being 'pushed' back against the seat and hence generating electrode interface changes), motion artefacts are visible in the ECG signal. Similar behavior was observed in sudden deceleration as a cause of the back of the driver moving forward relative to the seat. Figure 5: Example of ccECG and ccBIOZ signals acquired from a driver (**a**) driving at constant speed of 120 km/h and (**b**) starting from stationary position from a traffic light to a speed of 30 km/h. It is seen that slight distortion is caused by the transition between stationary and the constant speed as a consequence of the back of the driver moving in relation to the seat backrest. Reference motion signals from the car confirm the abrupt speed change.