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Augmenting spatial awareness with the haptic radar
Concept & Motivation
• Antennae, hairs and cilia precede eyes in evolutionary development
• Efficient for short-range spatial awareness (unambiguous, computationally inexpensive)
• Robust (insensitive to illumination & background)
• Easily configurable (hairs at strategic locations) and potentially omni-directional
Today’s MOEMS technology enables mass produced, tiny opto-mechanical devices...
An opto-mechanical hair?
• Hair shaft is a steerable beam of light (a laser-radar).
• Modular, but interconnected structure (artificial skin)
• Local, range-to-tactile stimulation
• Active scanning of the surrounding:
• Proprioception-based
• Automatic sweeping of the surroundings to extract important features (inspired by animal whiskers’ motion, two-point touch technique, etc)
Optical Hair module structure
Possible applications
Augmented spatial awareness & sensing
– Electronic Travel Aid for the visually impaired .
– Augmented spatial awareness for motorcycle drivers and workers in hazardous environments.
– Collision avoidance (robotic limbs, vehicles, etc).
– Augmented sensing & tele-sensing (texture, speed).
but also Human-Machine interface technology:
– “Hairy electronics”: versatile human- computer interface
– Sensitive spaces: human-aware “hairy” architecture
– Display: laser-based vectorial graphics, laser annotation on surrounding (augmented reality, attentional cues)
The haptic radar as a travel aid
A few fundamental questions:
– New sensorial modality: how easy to appropriate? (Would it be like re-exercising an atrophied one?)
– reflex reaction to range-to-tactile translation?
– Is the brain capable of intuitive integration of data from eyes on the back, the front, the sides…?
Prototype characteristics and limitations:
– Configuration studied: headband with few modules.
– Limitation: non-mobile beam
– Two prototypes built: one without range-finders (simulated maze exploration), another with range-finders (but short range).
a) Haptic Radar Simulator
Simulator features
• Six actuators & LED indicators
• No range-sensors (controlled virtual space)
• Adjustable horizon of visibility
• Perception modalities:
Simulator discussion
• orientation is rapidly lost => add compass?
• Interactive horizon of visibility is a necessary feature
• “proximity feel” mode disturbing if many actuators vibrate at the same time => compute center of gravity
• “open-space” perception mode interesting, but counterintuitive (needs training).
• continuous range-to-vibration function not easy to interpret = > discretize levels (3 or 4 levels).
• Too few actuators/sensors (annoying jumping effect)
• vibrators need to be calibrated to produce same perceived effect (motors characteristics differ, as well as sensitivity on each site)
Experiment Design / Results
• Hypothesis: participants can avoid an unseen object approaching from behind
• N=10 participants, each with 3 trials
• In 26 of 30 trials, participants moved to avoid the unseen stimulus (p=1.26*10^-5).
• In follow-up questionnaire, participants viewed the system as: more of a help (p=0.005), easy (p=0.005), and intuitive (p=0.005).
Discussion
Immediate problems & possible improvements
– Range detection too short (1 meter max) [Þ next prototype will use utrasound sensors (up to 6 meters), then laser rangefinders]
– Simultaneous stimulus confusing [Þ only one actuator active at any time, perhaps in the opposite direction (showing direction of clear path)]
– Low spatial resolution of actuators [Þ more vibrators / different actuators]
– Variable motor characteristics [Þ individual calibration]
– Range-to-tactile linear function too simplistic [Þ log scale / discrete]
– Effect of rotation is confusing in the simulator [Þ head tracking]
– Sense of direction is rapidly lost when there is no “reference background” [Þuse “interactive horizon” technique & add compass cue]