While they cannot match the resolution that humans and other vertebrates get from our single-lens eyes, the multi-lens compound eyes carried by insects are much better at providing a panoramic view with very fast image processing in a small package.
That trade-off suggests a promising approach to the challenge of engineering small unmanned air vehicles with autonomous sense-and-avoid capability. Now, a team of Swiss, German and French researchers have built what they believe to be the first fully-functional curved compound artificial eye – and hope to have it flying indoors on a small quadrotor early in 2014.
The device, detailed in the 4 June 2013 issue of the Proceedings of the National Academy of Sciences of the USA, has been demonstrated to guide a small robotic rover along corridors and around corners disguised with a black-and-white checker board pattern that would severely test a human driver. Ramon Pericet-Camara of the École Polytechnique Fédérale de Lausanne (EPFL) describes the rover test as a “very early” trial verifying the eye’s sense-and-avoid capability in a relatively simple environment.
However, flight, he says, is one of the main objectives. With a volume of just 2.2cm³, weighing 1.75g, and having a maximum power consumption of only 0.9W, the hemispheric eye consisting of embedded signal processing gives a 180°x60° field of view with the ability to adjust to very local changes in light intensity. With 630 optical units, or ommatidia, its performance is comparable by many measures to the eye of a Drosophila fruit fly.
Pericet-Camara reckons that the sensor is ready. The next stage of the €2.73 million ($3.7 million) Curved Artificial Compound Eye (CurvACE) project, which has received €2.03 million from the EU’s framework 7 research budget, will be to develop the software needed to generate automatic responses to fast-approaching objects.
Pericet-Camara says the sensor was inspired by looking at how flying insects explore their environments. The idea now is to move towards semi-autonomous flight, where a vehicle would be radio-controlled, but employ its own sense-and-avoid ability. And, then, to develop fully-autonomous capability.
In fully-autonomous mode, a small rotorcraft could explore a collapsed building or damaged nuclear plant by finding its own way around in an unknown and possibly changing environment. Data collected during the flight could be brought back to base.
Ultimately, says Pericet-Camara, the sensor could be used outdoors on fixed-wing platforms.
In the meanwhile, the sensor’s embedded microcontrollers are programmable, and a simulator – freely available online to other researchers – will allow them to try out control codes without access to the hardware. The CurvACE sensor itself will be available to researchers who visit the laboratory at EPFL.
The small size and low power requirement of this sensor may also make it valuable in applications ranging from medical instruments, prosthetic limbs, home automation, surveillance, motion capture and even smart clothing.