HAPTIC INTERFACES TO AUGMENT HUMAN MACHINE INTERACTIONS IN SPACE ACTIVITIES A. Raj 1 , L. Roetzer 1 , P. Fatolitis 1 , R. Cholewiak 2 , S. Kass 1 , and A. Rupert 3 1 Institute For Human and Machine Cognition, University of West Florida, Pensacola Florida, 32501, 2 Cutaneous Laboratory, Princeton University, 3 Neurosciences Laboratory, Johnson Space Center. INTRODUCTION When determining orientation in 1-g environments, the human brain utilizes input from a number of sensory channels, predominately proprioception (includes vestibular and somatosensory inputs) and vision. In aerospace environments, however, the proprioceptive sense often provides useless or illusory information. As a result orienting in such environments is currently performed by vision alone. This leads to significant workload levels for individuals flying aircraft, performing extravehicular activities (EVA), or interacting with robotic devices, as all actions, including orientation, must be performed visually. We are developing the Tactile Situation Awareness System (TSAS) as a method to allow an operator to utilize the sense of touch to perform some of the orientation and situation awareness tasks. In this manner, TSAS allows the operator to utilize multiple sensory inputs to reduce overall workload (as measured by performance on multiple tasks) and allow tasks that require the sense of vision (such as reading alphanumeric displays) to be performed more effectively. The sense of touch has several limitations, however; these include limited bandwidth (the peak sensitivity of the Pacinian Corpuscles, for instance is only 250Hz, other receptors are sensitive to even lower frequencies), resolution (e.g, two point discrimination) and susceptibility to habituation (which occurs centrally as the brain filters out constant signals) and adaptation (which occurs peripherally when the skin itself becomes less sensitive to constant stimuli). We are endeavoring to determine the ideal tactile transducer (tactor) that will minimize these limitations. We have developed appropriate experimental hardware and have conducted three pilot studies to evaluate sensory threshold of various tactors across a number of frequencies. CURRENT STATUS OF RESEARCH Methods In all three tests, male and female subjects from 18-56 were tested following receipt of informed consent (eleven subjects in the first study – 3 female, 8 male; ten subjects in the second – 1 female, 9 male; 10 subjects in the third – 1 female, 9 male). Base line sensory threshold levels were obtained using a Brüel & Kjær (Denmark) vibration transducer in contact (200gm constant force) with the each subject’s left thenar eminence. Digitally generated white noise was low-pass filtered to 180 Hz (Optimus 12-2112, Ft. Worth, TX) and then attenuated until the sensory threshold was reported by the subject. Repeated measures were used where the signal attenuation was increased or decreased to determine average sensory threshold level (SL). Two tactors in each study were presented in a balanced order fashion for comparison to the baseline SL. The tactors were activated with waveforms according to manufacturer specifications at 20, 40, 60, 80 and 120 Hz in the first two studies; measurements were also taken at 90, 100, and 110 Hz in the third. In the first study, two different pneumatically activated tactors were evaluated, one with a hard nylon casing and one with a soft vinyl casing (model P1H and P1S, respectively, Steadfast Technologies, Tampa, FL). Sinusoidal waves at 80% maximum amplitude by specification (±8 Volts DC) were presented via either the P1H or P1S to each subject for 200ms, alternating with 200 ms bursts of white noise on the Brüel & Kjær transducer. The tactors under test were placed on the torso over the costovertebral angle on either the right or left side using an elastic belt. The white noise was attenuated (again in decreasing or increasing fashion) until sensory a match was reported by the subject. The attenuation match determined for each repeated measure on each tactor at each frequency was then corrected for attenuator error and then compared to the corrected SL. A similar procedure was used in the second study where the P1H was tested against a solenoid type electromechanical tactor (TDI-15, Trans Dimension, Inc, Irvine, CA). The TDI-15 was activated with a unipolar square wave with a 50% duty cycle (according to manufacturer’s specification). Since the perceived strength of the TDI-15 at the manufacturer specified signal strength exceeded the maximum strength of the Brüel & Kjær full signal, the TDI-15 was run at 40% of the specification (+2.8 volts DC). The P1H was run at 100% of the specification (±10 volts DC) in this comparison. The third study compared a button type electromechanical tactor, the C1 (Engineering Acoustics, Inc, Winter Park,