Thread: CAN Nerf Robot
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Unread 03-08-2010, 21:26
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Re: CAN Nerf Robot

My impression was that the CANipede had these all on a single device, much like a central controller. I'm proposing small units which would be dedicated to an actuator, to supplement the Jaguars.
Did I misinterpret the description? Is the CANipede actually several devices?

Personally I don't see the utility of putting sensors into ADCs on a CAN bus when we have a cRIO. IMHO I think the CAN bus should only be used for actuators that have their own feedback. If the Jaguars didn't have PID and encoder inputs, I wouldn't bother. However, since they do, it's theoretically less processing that the cRIO has to do, and the processor time can then be used on other (presumably higher-level) tasks. Likewise, putting too many things on the CAN bus can create a chokepoint there, and reduce the performance of the system. For example, the gyro and accelerometer are sensors that require high sampling rates in order to be useful. Thankfully we have an FPGA to integrate the gyro, but if we want to know something with the accelerometer like "how hard did we hit that wall?" or "what was the impact coming off that bump", we must poll that analog input very rapidly. Such an action on a CAN bus would be either sporadic, or block out all other communication (including the messages that keep the Jaguars enabled).
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Last edited by kamocat : 03-08-2010 at 21:29.
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