MEMS-based robotic eyes for 3D scanning with adaptive resolution
For this project The Fraunhofer Institute for Photonic Microsystems IPMS in Dresden contributed a novel MEMS scan technology as a key hardware component, enabling “relevant” objects in the surroundings to be detected with a higher resolution, similar to human vision, without having to increase the volume of data. A fully-functional prototype will be displayed at Photonics West in San Francisco (4-6th of February 2014).
Focusing on important vision data
Robots typically lack either spatial information that is resolved in real-time by humans or the necessary focus for artificial, three-dimensional seeing. Another issue is that often too much image information is recorded and can’t be processed quickly enough to be translated into action.
Researchers at Fraunhofer IPMS have developed an extremely compact scanning technology, dubbed LinScan, for ToF (time of flight) telemeter systems that allows a three-dimensional image acquisition with a flexible scanning rate and thus scanning with an adapted resolution.
3D camera systems equipped with LinScan could enable future generations of robots to roughly search their surroundings for objects that appear in their visual field and to only resolve the objects they are looking for at a higher accuracy. The robot would work with a relatively small volume of data and would still be able to gain a better understanding of its surroundings so as to better interact with everyday objects and our environment.
A precondition for the realization of this so-called principle of foveation is, however, that the robot knows what it is looking for and that it is also able to identify and interpret the objects being sought in a matter of seconds. Apart from the hardware (eye) it also needs corresponding image analysis software algorithms (brain).
What’s more, the robot should also be equipped with image sensors and software for three-dimensional seeing to gain a spatial idea of its surroundings and thus be able to navigate to objects precisely.
The novel adaptive camera system developed within the scope of European joint research project TACO relies on an optical scanner with five synchronously operated LinScan mirrors from the Fraunhofer IPMS. The MEMS scanner array guarantees the necessary receiving aperture for the Time of Flight (TOF) telemeter system of effectively 5mm and was designed for an adaptive 3D-camera system with an optical scanning range of at least 40°x60°, 1 MVoxel/s measuring rate of the TOF telemeter system with a 3mm measuring uncertainty at a measuring distance of 7.5m.
The quasi-static drive of the microscanner allows a line-by-line image formation with a variable refresh rate ranging from under 1Hz to 100Hz, whereby the vertical measuring point density in the relevant image section can be locally increased by reducing the scanning rate. The horizontal image acquisition by means of the gimbal-mounted 1.6 kHz resonant micro-mirror guarantees a larger receiving aperture compared to a 2D-quasi-static drive and thus a higher resolution of the TOF telemetry with a simultaneous larger optical scanning angle of up to 80°.
The TACO research project was co-financed by the European Union within the scope of the 7th general program. The project was launched in the first quarter of 2010 under the leadership of Technikon Forschungsgesellschaft mbH with a term of 36 months. Other project partners include Technikon Forschungs- und Planungsgesellschaft mbH (AT), Shadow Robot Company Limited (UK), Oxford Technologies LTD (UK), TU Wien (A), Fraunhofer-Gesellschaft (DE), Stiftelsen SINTEF (N), and CTR Carinthian Tech Research AG (AT).
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