Tuesday, April 28, 2009 at 5:44PM After having the first version of the PCB roll off we noticed a few errors. Here's a picture of the new board after the break:
Arduino, Hardware Design, Seaduino, Seawolf Monday, March 30, 2009 at 10:56AM A PID controller is a piece of code which is designed to help your robot move smoothly. It's roots come from a "critically damped" second order differential equation. After, stating that, I'm going to try my best to stay away from getting overly mathy in this description of a PID. To make it easier to explain, I'm going to use my specific application of reaching a certain depth as the system by which the PID was acting on.
So here's the problem, we have Seawolf floating at 1 foot below the surface, we want it to head down to 5 feet. There's a few ways to go about this, we could simply design a basic controller that would turn the motors on and then kick them off when we got to 5 feet, but the Seawolf is naturally buoyant, meaning the motors would kick on, then off, then on then off, granted, we could figure out power is needed for the motors to hold steady, but every time we changed the load at all it would be totally thrown off. Also, we're engineers, we're smarter than a dumb system that has to keep oscillating, and besides, we're trying to be nice to the vision system here.
Friday, February 20, 2009 at 10:47PM As you may find, there's a developing theme, here at the NC State Underwater Robotics Club we're good at finding solutions that come close enough to our needs that they can be made to work. You may also find... we usually make them work. Todays post is on dealing with PWM signals from an Arduino to an Seabotics Brushed motor. This presented a couple of complications.
Wednesday, February 18, 2009 at 5:47PM I know it's been a while since my last post but I assure you my work has by no means slowed down. We have now designed a fully functioning dip compatible arduino with USB that that's still packing the DIP 168 (Allowing you to throw the 328 in if you're so inclined). The final layout is found below:
Arduino, Hardware Design, Seawolf Wednesday, February 18, 2009 at 4:07PM One of our big secret wepons this year.... is a big secret weapon that does signal processing using a BlackFin. (I'm not giving more than that away...). We're using an Ez-Lite BlackFin development board for time time being and needed a way to firstly get the thing booted (didn't want to use the usual route and boot it off EEPROM because we wanted to maintain SPI serial access for debugging and possibly for command sending purposes down the road). Thankfully Analog Devices does a good job of documenting how their products work (erm... even if it is midly cryptic at times.. I'll try and explain at least the way we did it a bit more clearly than the official doc manages too).
