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Augmenting human driving via steering wheel skin stretch haptics

Cars are growing smarter as they incorporate improvements in sensing, computing and communication. They increasingly are able to monitor the environment, detect impending events, and make decisions, sometimes with higher speed and accuracy than is possible for the human driver. While this helps drivers in many ways, it also reduces situational awareness and driver ability to respond to emergencies, and it remains an open question how best to communicate this information. This thesis examines haptic skin stretch at the steering wheel as a way to improve communication from car to driver and augment driving ability. A steering wheel with an embedded skin stretch display was designed that is compact, lightweight, and allows holding at any position. Rotational motion of the front surface of the rim produces lateral deformation of the skin of the hands, stimulating slowly- and rapidly-adapting mechanoreceptors. The resulting haptic stimuli communicate magnitude, direction, and speed information. This thesis describes a series of experiments with this device characterizing the abilities of humans to perceive the feedback and react appropriately in various driving scenarios. In the first, human ability to perceive directional information in a driving vehicle in suburban traffic was assessed, with results generally consistent with those in stationary applications; however, a higher and especially faster rate of stretch application was preferred. In the second experiment, tests are conducted to determine whether drivers can correctly perceive and react to skin stretch navigation cues, which are compared to audio navigation cues during an auditory distraction task simulating a phone call. Results showed haptic feedback was at least as accurate as audio feedback and was less distracting. In the third experiment, human ability to utilize skin stretch for obstacle avoidance is examined: in particular, whether they could predict the size and location of obstacles. Subjects were found to perform correct maneuvers with high accuracy, modifying both maneuver direction and size based on the stimulus. Finally, an experiment in a different application, medical needle guidance, provided general insight in how best to provide steering information through skin deformation. Particular attention is given to the ability of skin stretch to alert the driver about impending events, inform about direction, and communicate the magnitude of an event. Results show that all three types of information can be conveyed, with attention to details of how skin stretch is imparted in terms of stimulus pattern, frequency, and magnitude.