Vision on separate board

[Joe Ross]

There are two major issues that may cause latency when using vision on the driver station, bandwidth limit and driver station CPU throughput. Both can have an impact even when doing vision on a separate computer, so it would be helpful for you to determine which was causing your issue, so you can avoid it with your new architecture (or even get it working with the old architecture).

The bandwidth limit on the field is 7mbps. As the bandwidth used approaches that limit, the latency increases. There is very good data about this in the FMS Whitepaper. This only affects data sent over the radio, so if your vision processing is completely limited to your onboard computer, this won't be an issue. However, most likely you will want to have vision feedback on the driver station, therefore you will need to worry about bandwidth. One thing the whitepaper doesn't cover is that dark pictures compress much easier and also are easier to process. See http://www.chiefdelphi.com/forums/sh...2&postcount=44

The classmate PC only has an atom processor which can be overloaded with just displaying high resolution images. If the CPU is overloaded, it will also affect network latency. You can look at the driver station CPU usage on the charts tab of the driver station. Whether you do driver station or onboard vision processing, you will need to carefully manage CPU usage, as vision processing very quickly consumes all available CPU time. Limiting the rate at which vision processing occurs is smart no matter what platform you use. Again, if you send the processed images back to the driver station, you will need to worry about driver station CPU usage regardless of where the processing occurs, if you are using the classmate.