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  • 'Bug Eyes' Offer Potential for Collision Warning

Photonics Spectra
Apr 1997
R. Winn Hardin

ADELAIDE, Australia -- Austrailian researchers at the Centre for High Performance Integrated Technologies and Systems at the University of Adelaide have developed a decision-making optical sensor on a single- chip system with a little inspiration from the insect world.
The scientists have developed a "seeing, thinking" microchip that mimics an insect's eye to detect objects and their motion and to raise red flags in case of imminent collision without the intensive computing required by traditional image-processing cameras.

Watching for shadows

The key characteristic of insect vision detectors is that they do not have to necessarily see an object itself -- just the shadows the object casts as it moves. Charge-coupled device (CCD) cameras make a full image of an object that requires heavy-duty computations to process into a usable form.
Out in the wild, an insect detects the moving edges of objects within its field of view. For simple collision- avoidance tasks -- such as vision systems sought for intelligent automobile collision warning systems, autonomous robots in the home or at the plant, or to assist the blind -- insect vision chips offer a cheaper, more efficient alternative, said "bug eye" chip developer Derek Abbott. And because the bug eye chip does not depend on intensive computing, Abbott estimates that an insect chip with combined optics, detectors and logical circuits would cost approximately 10 to 20 percent of what a CCD camera costs.
"For simple collision avoidance tasks, this rudimentary vision is all that is needed," said Abbott. "Insects have been successfully doing it for billions of years."

A cue from Mother Nature

Taking their cue from Mother Nature's design of an insect's eye, the centre's team uses photodetector circuits with a direct logarithmic response, eliminating the need for a bulky mechanical iris. Insect eyes remain compact by dispensing with variable focusing. The centre's bug eye detector uses a fixed focal length gradient index lens glued to the surface of the chip. Abbott said he expects future versions to include an integrated microlens. Each photodetector's output has its own automatic gain control and is processed in parallel, enhancing performance in low-contrast conditions.
In a working system, data from the device is logged by a simple single-chip microcontroller that tracks the movement of light and dark patches. The chip uses the data to determine relative velocity, bearing and time-to-impact of a moving object. Based on these parameters, the microcontroller can be programmed to make simple decisions for anticollision warning, said Abbott.
The Australian Federal Government and Britax, a multinational manufacturer of car vision systems, have funded the bug eye chip. Britax, Abbott said, hopes to use the low-cost motion detection chip for detecting blind spots and monitoring braking distances in intelligent vehicle systems. However, he said, the methodology behind the chip lends itself to a wide range of uses. Not only could the chip offer basic senses for everything from autonomous vacuum cleaners to robot forklifts, but the bug eye detector can be made to "see" in any wavelength band including radar and millimeter-wave.

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