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45446Re: [SeattleRobotics] Neato wifi

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  • Weston Turner
    Jul 2, 2011
      Yes, using a smart-phone running Droid to interface with the robot would be very exiting. The Chumby just seems a little clunky, based on the blog and complaints about it being power hungry, needing active cooling, etc..

      I was under the impression that the USB and serial interfaces provided the same level of access to the VX-11. Since they don't, and one cannot retrieve sensor data via the serial interface, that pretty much requires using an intermediate controller with a USB stack such as the Chumby, smart phone, <insert controller>. Of course, one could implement a USB stack on a microcontroller of one's choice (back to the significant software development effort).

      It sounds like finding the smallest, cheapest, lowest power consuming, embedded computer with USB and on-board Wifi is the most straightforward approach.

      On Sat, Jul 2, 2011 at 3:33 PM, Nathan Monson <nmonson@...> wrote:

      On Sat, Jul 2, 2011 at 3:16 PM, Weston Turner <wstnturner@...> wrote:
      The data-sheet claims it "delivers up to 3 Mbps data rate for distances to 100M."

      This is the very module I used.  Maybe it was something about the environments I tested in.  Both at the apartment and in the office, performance was just peachy until line of sight was lost.  There are plenty of other things chattering at 2.4GHz in both places, and metal cubicle frames can't be too good.
      Using Wifi will give you much more bandwidth and flexibility but at a cost of a greater integration effort.

      I'm not so sure about this in the case of the XV-11.  One hacker found out that the XV-11 does have a UART, but it runs at a slow speed.  The 'high speed' sensor data can't exit this port.  The USB port is the only way to access the laser.

      Since you must have a USB host stack to get the laser sensor, the integration is already beyond just gluing things together.

      But a Chumby with WIFI is almost the perfect fit.  The Chumby recognizes the XV-11 as soon as you plug it in, and a couple of lines of shell scripting connects it over WIFI.  That's some nice integration!
      Also, I have doubts about the actual bandwidth needs of the application. Surely some pre-processing could be applied to the data stream to make it sparser.

      This is very true, and a good idea no matter what protocol is used.  The XV-11 seems to use verbose ASCII to send data, and quite a bit of the data is of dubious or unknown value, such as error codes and laser intensity values.

      Of course, the Chumby makes that pretty easy too.

      Cell phones are another interesting choice.  I met somebody who hacked his Droid (software) to be a USB host, so any Chumby code would work equally well on that platform.


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