Quote:
Originally Posted by cbale2000
That's my point though, the average team that uses PWMs is not going to go out and buy a bunch of these 16 pin connectors (which also adds to the cost of each controller), strip apart the ribbon cables, and splice each one with a 3-pin and 2 2-pin PWM cables, they're going to just plug a standard PWM cable into it, which seems like a terrible idea with this connector.
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Those connectors can be purchased for under $2 each but it would be another part to buy and keep in stock. They take some finesse and knowledge to assemble correctly. It can be pretty easy to short out adjacent wires or get the ribbon cable swapped like the ones for the DIO's a couple of years ago. As the person responsible for teaching the electrical skills on our team, I would not want to have to teach yet another fiddly skill and to have to do QC on it.
Plugging a PWM cable into the 16-pin connector can be dangerous because there is nothing on the case of the controller indicating which pin the Pin 1 of the cable should plug onto. One would have to refer to drawings or manuals which are not always available. It would be best if the cable connection had some sore of key to prevent a reverse connection or at least the product is self-documenting in a way that is clearly visible. The connector being on the side makes it very difficult to use any sort of alignment marks that may be on the enclosure.
Quote:
Originally Posted by mindsensors.com
The test program switches the direction at full speed every 200ms for a given amount of times, then runs for a few seconds and switches direction at full speed again..
This tests the responsiveness of the controller as well as the peak currents on the floating motors. This test was run for 15 minutes without failure.
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There have to be some objective test criteria for any test to be meaningful. What were the heat sink temperatures at the end of the 15 minutes? What were the peak and average currents during this test? Do the currents approach the maximum rated current (or current limit level, if there is such a feature)? What happens if the motors are run at "full power" for 1 or 2 seconds at a time for the full 15 minutes. The momentum of the robot will really come into play making it a more realistic test. How many drivers can switch directions 5 times in one second?
If the temperatures get as high as your published data shows, the service life of some of the parts in your product will drop from years to months or even weeks, most likely leading to failure of the controller. In our practice sessions our drivers will run until the batteries are noticeably weak (typically half an hour, depending on the total number of motors) then they will do a quick swap of the battery (1-2 minutes) and start practicing again. Some of the motors/controllers could be running at full load, essentially continuously, for a couple of hours at a time. I would not doubt that many other teams practice in the same way. Time is precious in this competition. No one can afford to wait for parts to cool down before continuing to practice.
I know I will never be part of an alliance this incredible, ever again (my apologies to all future partners, but you've got BIG shoes to fill.) - JVN [more] 
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