Question about ultrasonic sensors and velocity sensors...

Hey guys, I am working on my senior design project and I need to incorporate sensors that will detect dynamic objects like cars, walls, etc... within a
reasonable range from a device (so we were thinking about using sonar sensor(s) for this)... we also need to somehow track the position of the device (possibly using a compass module and a velocity sensor because we kinda want to stay away from GPS)...
Any suggestions for particular modules would be much appreciated. Please email me at snipped-for-privacy@exobitnetworks.com.
I was looking at Devantech's Ultrasonic Ranger SRF08 (http://www.robot-electronics.co.uk/shop/Ultrasonic_Ranger_SRF082001.htm ). This module only has a maximum range of 3 meters though.
I was also looking at Polaroid's Environmental Grade Sonar Ranging Package (http://www.acroname.com/robotics/parts/R135-SONAR4.html). Supposedly this module is capable of doing up to 35 feet but I wasn't able to find a range rating for the transducer itself. This transducer seems to have a somewhat spread range too which looked nice (our project has to kinda be able to detect objects over the frontal 180 degrees of the device).
I only started looking briefly but I wasn't able to find any velocity sensors that track the velocity of the device. Anyone have any ideas?
Thanks in advance,
Rob L snipped-for-privacy@exobitnetworks.com
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incorporate
Have a look at Sick's LMS (Laser Measurement System) range of laser distance scanners at www.sick.de . From what I can tell, these devices will do exactly what you want.
In their simplest form, they give a 4-20mA continuous output of the distance to an object over the scanning range. You then use your software to calculate the relative velocities of the incoming objects based on the analog distance at each scan angle.
These devices are not cheap, but they are extremely robust and reliable in all kinds of conditions.
Good luck with your project!
Cameron:-)
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