progress3

So i've installed the MaxBotix ultrasonic sensors and also upgraded the heart of the little rover to an Arduino Mega 2560 that i got cheap on ebay (au$37, to be exact!)... This was mainly to accomodate the various upgrades i forsee in the future (when it gets transplanted into the tank)....

the eyes: maxbotix ultrasonic sensors installed (for obstacle avoidance)

the upgraded brain: arduino mega 2560

38 kHz IR reciever installed (small board in foreground)

i've also removed the wii-joystick control (well, not entirely - can still see the plug hanging out the side there), and created a basic autopilot (which operates via the apple IR remote)... the mode is obstacle avoidance when you press the center button on the remote, and the +/- buttons control the max speed.... the center button again acts as a moto kill switch (sleep)!

after some calibration & testing, i've set the parameters to start the hardwired obstacle avoidance (i.e - turn in the direction of furthest sensor) at around 50 cm, and full stop occurs around twenty cm.

http://vimeo.com/31675146

http://vimeo.com/31675230

the little rover sometimes got stuck in corners with this simple routine, so i programmed a small "turn_left_until_free" routine which kicks in if the sensors detect an object close and is not turning to avoid it... on the other side of the coin, the speed-scaled-with-distance algorithms lead to some quite gentle & inquisitive explorations.... even as is, i would not hesitate transferring this program into the larger (50kg+) tank esky...

http://vimeo.com/31675532

the "turn_left.." routine is not optimal, as i think it leads to some repetitive exploratory behaviour - sometimes the robot gets caught in little spaces without realising theres a wider world out there!

http://vimeo.com/31675733

Next, it's time to work on the subsumption routines some more; see if the encoders will work (hopefully i didn't blow the board); and assess the possibilities of 2d mapping, localisation and mission control.    And to wait urgently for the delivery of the Polulu IR beacon pair that i am going to try and use for tracking a human... if possible, some more on-site user testing with the same landscapers as before... All in the next four days!??

Arduino .pde for the current stage can be downloaded here...

on a side note, been watching some excellent lectures by Nick Hawes, from the University of Birmingham... the lectures are on Lego NXT and LeJOS, which is easily transferred to arduino... plus, his teaching style reminds me of Rob :)