Is grip strength related to neuromuscular admittance during steering wheel control?

Continuous haptic feedback can improve manual control task performance and application methods on steering wheel (haptic steering guidance) have been studied. However, the current haptic steering guidance systems assume there is an average, constant driver´s response to force (which can be quantified as the admittance). To improve the performance of haptic steering guidance, the guidance system should be adaptive to the inter and intra-driver variability in admittance. To achieve this we need to be able to get accurate, non-evasive estimates of driver neuromuscular admittance. We believe the gripping force with which drivers control the steering wheel might be a good parameter to estimate admittance. The goal of this paper is to investigate the correlation between grip strength and human admittance of a driver holding the steering wheel. A relax task and a position task with two different grip conditions, loose and tight, are performed. The results of the experiment show that there should be an inverse relationship between grip strength and admittance. Whether it is possible to differentiate admittance between tasks through grip strength alone remains to be seen as we could not measure grip strength directly. Future experiments with grip pressure sensors will be carried out to establish a quantitative correlation between grip strength and neuromuscular admittance.