[HH] Rethinking LinuxPC Robot -- the Linux PI Robot

[markw at mohawksoft.com]

> markw at mohawksoft.com wrote:
>> What about a functional cluster of PI systems on the robot? Tied
>> together
>> with an ethernet switch? Use something like MPI for distributed
>> processing
>> across multiple PI devices, and use each PI as a specialized I/O module.
>
> I would think your I/O needs exceed your processing needs. And you've
> previously established that the Pi is poor for I/O.

Yes, 1 PI is poor for I/O, but 4 PIs may be able to handle it. One PI for
motor control. 3 for camera I/O. Use the GPIO pins in a distributed way.
Use MPI t distribute the processing.

>
> Seems the more natural solution is to blend technologies, using Arduino
> or something similar, as function-specific controllers, which are then
> coordinated by a Pi, that provides a UI, and perhaps also handles a more
> processing intensive task, like video processing for vision.

I have an Arduino already, but I am using it as a USB I/O controller more
than a processor.  I may move motor control to the Arduino, but I still
need a steady USB communication for the deadman switch.

>
> Would the communication between the Pi and the Arduino's tax the Pi's
> USB bus?
>
The PI despite having two USB slots is pretty underpowered. If I
understand correctly, these is only one USB controller with a built in usb
hub. The two USB ports and the network interface all go through the USB.

>
>> Right now, I use an Intel Atom CPU to do everything and it is loaded
>> with
>> all the cameras and controls.
>
> Ah...multiple cameras? Perhaps a Pi per camera.
>
>
>> Given the cost of a DC ATX power supply...
>
> I've ran across some of these lately. They seem to be increasingly
> popular with builders of mini-ITX systems that want to power their
> system with a cheap 12 V "brick-on-a-rope" external power supply.
>
> For example, here's an 80 W DC-to-DC converter selling for $20:
> http://www.amazon.com/Mini-Box-picoPSU-80-Output-Input-Supply/dp/B005TWE5E6/

$20 dollars? Wow, that's really cheap. 80 watts is nothing to sneeze at
either.  The rub is that it must operate between 8 and 14 volts if you
want to run off a battery.

>
> Often paired with a $11 12 V @ 6 A supply made for LCD displays.


>
>  -Tom
>
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