Canon PowerShot G9
ƒ/2.8
7.4 mm
1/60
200
unveiled today at Stanford
7 responses to “Junk in the Trunk”
-
Hmmm…… It clearly is using Trimble’s differential GPS system, but how does it handle the ephemeris data acquisition sampling times. Particularly the long sampling time? WAAS? Differential GPS clearly has much better resolution in static applications like surveying where a reference unit can sample for a prolonged period, but I have never seen it used in as dynamic a system as a moving high speed car.
Also, why the WiFi access point in the car? There is already an omni-directional antenna on the roof which does not connect to the WiFi hub in the trunk. What is its function?
-
wow… thats some sound system! 😉
Really though, thats some comprehensive kit involved there.. Also surprising that VW research were using an Audi as the test vehicle. Surely a Golf or similar would be ‘flying the flag’
-
@rocketmaverick: The usual technique is to use a GPS for absolute positioning at relatively low speed, and a inertial navigation system (electronic gyroscopes and acceleration sensors) for short term high speed relative positioning. The inertial system is subject to drift, the GPS isn’t, but it’s slow. If both systems are coupled, you end up with a fast, accurate system that auto-calibrates all the biases, and can cope with temporary GPS drop-outs.
-
Got it. Thank you obskura. I have another project that involves a drone I am working on that I have been wrestling with this problem. It might be useful to talk with the team that built the vehicle system. Are you associated with the project?
Our velocities are much higher (Mach 3-5) so not sure the 6DOF rate gyros can handle the g loading, particularly associated with accelerations associated with changes in direction at these velocities.
We need to accomplish sinusoids with the vehicle between 180,000 and 400,000 FT MSL, as our payload systems are focused on the atmosphere in these areas. Ballons will not reach this portion of the atmosphere, and we need to have accurate Z axis data, which generally is less accurate without differential GPS. -
@rocketmaverick – no, I’m not associated with the project, but I work in robotics, and I’ve been exposed to inertial navigation systems through a project on miniature autonomous submarines (http://serafina.anu.edu.au).
Obviously the higher the dynamic range of the sensors, the less precision you’ll get at the low end. I’ve only worked with "low-speed" systems so far (submarines, helicopters), so I don’t know what accelerations you’d be looking at. This sensor here http://www.analog.com/en/sensors/inertial-sensors/adis16405/prod... is pretty good quality for the money, and it senses up to 18g. The gyros should still be useful at that range as well, but the max. angular rate of 300 deg/sec is maybe too low. -
rocketman – I can connect you with Sebastian Thrun; he should know who to talk to.
Or see him tomorrow:
"ME302/CS532 – The Future of the Automobile" which will be held this
coming Wednesday and focus on autonomous vehicles:
Can Robotic Cars Save The World?
Technology – Politics – Society
Brad Templeton, Chairman of the EFF, Founder of the Earliest Dot-Com,
Tech Blogger and Futurist
– Lecture open to all students, faculty, staff, affiliates –
Wednesday, October 28, 4:15-5:30pm
Stanford University, Building 260, Room 113
Leave a Reply