In the design of the tactile output we were able to use the following dimensions:
1) number of actuators: each of the six actuators could be used independently; 2)
intensity: the intensity of each actuator could be controlled independently from an offstate
up to level 5; and 3) timing of the signal: the actuators could receive signals at
any time. This enabled us to create static output (e.g. switching on the left side of the
steering wheel with a medium intensity for 2 seconds) as well as dynamic patterns
(e.g. activating vibration in a circular pattern moving clockwise, with 1 actuator always
on and a brief overlap during transitions).
For our comparative studies, we mainly focused on static patterns because our current
setup with only six distinct locations (actuators) for the signal limited the fidelity
of dynamic patterns and the speed of the traveling signal. Our static pattern consisted
of two different vibration signals: 1) vibration on the right side (actuators 2 and 3
turned on) indicating that the driver should turn to the right; and 2) vibration on the
left side (actuator 5 and 6 turned on) indicating a left turn.