Machine Design

Radar keeps walkers out of harm's way

A fusion of anticollision radar and video sensors detects pedestrians on the, walk.

Take several video sensors and a smidgen of forward-looking radar; mix well with software in a digital signal processor. The result: An automotive driver alert and accident-mitigation system for less than $100/car. So claims Cambridge Consultants, Boston, during demonstrations of their new software that lets radar and video imaging sensors work in tandem. The combination system reduces the amount of real-time processing. So the software can run on a low-cost DSP originally developed for mass consumer appliances.

The radar technology, CCLSoftcar, is a pulsed radar system that operates in the 5.8-GHz band rather than 24 or 77 GHz as used by other automotive radars. Lower frequencies mean less expensive hardware and reduced overhead for the precision assembly needed to produce higher frequencies.

The software classifies objects based on radar-scatter information, object motion, shape, and color matching to distinguish humans from other moving and nonmoving objects. The video system processes images for that part of the view that holds the most dangerous objects as determined by the radar. The limited view reduces the demand on the image processor and speeds processing times.

Real-time analysis of the detected objects takes place 10 to 20 times a second. The update rate coupled with the 20 to 25-m range of the radar system gives enough time margin for active-safety measures. Full-commercial applications using DSPs with faster clocks should boost that rate to 50 times a second

Among the impact mitigation measures under consideration are tilting the hood to lessen impact severity, firing external air bags, and assisting with braking.

Cambridge Consultants Inc., (617) 532-4700,

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