omni wheels

[littletim979]

i just recently got some rotocaster omni wheels. what do you think i should build - also i'm going to build the killough platform but i don't have a PSP-NX remote which is what most people use to remote control it so what should i do for remote control?

[mightor]

You could try making it autonomous

- Xander

[pbenco]

Hello littletim979
Depending your programming environment, you could use bluetooth remote application to give orders to your robot.
Or if you have some skills on sordering, consider use a power function infra red receiver hacked like philo demonstrate here: http://philohome.com/pfnxtremote/pfnxtrem.htm, and you will have cheap (15$) solution, with 9 differents variables [(-1,0,1)²]
Or if you have 2 NXT kit, you could build a joystick with one NXT, and give orders to your second NXT which deals with the killough platform: http://philohome.com/nxtjoystick/joystick.htm.
Hope this help, best regards
Ben

[littletim979]

with the X and Y output of the joystick - how do i get speeds of 3 wheels - i know it has something to do with SIN and COS (which i have blocks for in NXT-G) but i don't know how to use them.

[hassenplug]

Well, I've figured it out, but I don't recall everything. However, maybe I can help get you started.

The three wheels are evenly spaced around a circle, or 120 degrees apart. So, the values you need are 0, 120 and -120.

Take the sin of those values, and multiply it by the X value, and the cosine of them and multiply it by the Y value, and add those numbers together to get your three speeds.

like: m1 = sin(120) * x + cos(120) * y

If you can understand what's happening, you can do more cool stuff with compass values...

Steve

[pbenco]

Dear littletim979
Maths, always some maths! You give a consigne to the robot, if this is a "simple one", with 2 wheels on an axle, you can make it simply, but if you use some more complicated locomotion architecture, prepare the math's geometry and odometry
Once again, google is your friend: http://www.rjmcnamara.com/2010/08/contr ... -platform/
first result of "nxt killough" search in google!
Bye
Ben