Up, not North - Quick and dirty Arduino kiwi drive robot (controlled by Wii nunchuck!) Months ago, for a larger project that is currently languishing in my “when I have time” pile, I built a very simple Kiwi-drive robot.
Since it likely won’t be “finished” for a long while (and has been sitting in my trunk for weeks), I figured I ought to at least document it. Very briefly, kiwi drive is a “holonomic” method of moving a robot, which basically means it can move in any direction without having to turn first. It accomplishes this using three omniwheels mounted at the points of an equilateral triangle. With some vector math, you can find rotational speeds for each wheen such that the robot will move in whatever direction you like.
I won’t go into the theory too much here, but here are some diagrams and here’s some math (via). In the video I’m controlling the robot with a Wii Nunchuck. The robot is dead simple. Parts Building it Attach your servo horns to your omniwheels using superglue or screws. And it’s built! Code Download some example code! View topic - Omnidirectional Remote Controlled Robot. I just did a very quick and rough assembly... and well... it works kinda, the wheels without any plastidip or similar on a wooden floor slip and slide a ton and my tiny DC motors with not much down-gearing in the gearbox spin way too fast, the robot moves in the expected direction reasonably well, but it's basically spinning at least 4 times the distance is moves if that makes sense, and since it has 4 wheels with no suspension or give what so ever going over anything makes at least one wheel free-wheel in the air.
And this is without the 300g battery, motor controller boards, arduino mega and second level on top, I expect the performance to get even worse with that weight on top. I'll need to find something like plasti-dip to coat the rollers with as well, clearly needs more traction. Quick sketch. Robot holonome. Qu'est ce qu'un robot holonome ?
En opposition aux robots a deux roues motrices differentielles (les plus courant pendant la coupe de robotique) qui possedent 2 degres de liberte sur un plan : une translation : avance ou recule une rotation : tourne vers la droite ou vers la gauche Un robot holonome ou robot omni-directionnel est un robot qui possedent 3 degres de liberte sur un plan. Deux translation : avance ou recule, va vers la droite ou vers la gauche une rotation : tourne vers la droite ou vers la gauche Il existe plusieurs sortes de robot holonome : Les robots a pattes (comme Pupuce pour les connaisseurs) Les robots rampants (comme The Chomp) Les robots à 4 roues omni-directionnelles Les robots à 3 roues omni-directionnelles C'est a ces derniers que nous allons nous interesser.
Exemples de roue omni-directionnelle : Ce sont des roues a galets qui peuvent tourner librement sur un axe perpendiculaire a l'axe de rotation de la roue.