progress2

In accordance with my sprint1, all the parts have arrived, the preliminary research has taken into account and the prototyping has begun.  I have decided to build a model that incorporates the most-requested features from the user research, but most importantly has the capacity to be upgraded / modified to any future situations.  It's basically a prototyping platform for the larger tank/esky created in the device lab. Prior to any wiring, i planned out the arduino pin mappings, seeROVER PINOUT document for current allocations.  This allowed me to know which pins are free, and what mode to attach sensors in.

Here's how the dagu rover5 arrives

So my little dagu rover5 along with it's four channel ESC & quadrature decoder arrived a few days ago in the mail... It's the 2 motor / 2 encoder version, just the thing for prototyping the various possibilities of the personal autonomous tracked mobility device.   The first thing was to install the higher capacity 6v 1.3AH SLA battery... This required cutting the chassis with a dremel tool to accomodate the larger size, along with the installation of a suitably rated DPDT switch and charging points.  A large green led was installed via 150 ohm resistor to indicate current flowing in the circuit.  Main battery to motor controller is connected via relay, so as to switch on afterarduino powers up (to avoid any wierd behaviours).

charge points & led in rear. led via 150 ohm resistor to main battery...will be upgraded to battery state monitor later

battery and wiring installed, note cutaway in chassis to fit battery - it is just big enough for the 6v SLA to clip in..

With the internals wired, the (recycled three ply) platform goes on the top like so:

the platform, with arduino, screwshield and the 4ch dagu motor controller

dagu motor controller mounted on brass stand-off's

For the initial test, a simple servo example was used, sending key commands from the Arduino IDE via serial:

http://vimeo.com/31182283

After spending an hour or two modifying the original tank's code from servo pulses to 0-255PWM, and writing my own tread mixing routines and dead-band adjustment of the joystick....

Download .pde sketch for arduino + dagu ESC here

But when taking the rover for it's first real test drive, i managed to short circuit one of the mosfets in the motor controller (grr! had the wiimote just hanging there, in my hand and didn't notice the smoke of the metal plug shorting out two pins !! )...

damage to dagu motor controller

Close up of burned SP8M3 mosfet

a frantic search on the internet turned up no similar boards in australia (i bought the last one from robotshop) and not even the same chip (SMD DIL 8pin SP8M3) in any of the parts suppliers (digikey, farnell, jaycar etc) in aus... ....so the solution is to use the original Robo Claw 2x10a from the deviceLab Tank.... holy how frustrating to be at this point and to have to start again from scratch, especially after modifying all that code and writing all the algorithms (because the dagu unit did not do auto calibration / mixing)...

Here's the link for the .pde of the Robo-claw version for arduino....

http://vimeo.com/31182570

http://vimeo.com/31183136

Next week: sprint2....

-&c