Let's Make Robots!

4 wheels or not to 4 wheels

I want to add 2 extra (fixed) wheels to my bot (front end) but wonder how that would behave when steering. Steering will be done by the motors on the rear wheels.


I'm redoing the base, it will have some suspension underneath the turret and a bit more batman like features (as I'm waiting on my servos still).


It's 55x39 cm's and the wheels are 15cm in diameter, i'm affraid it will drag the frontwheels over the floor when turning?

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You could consider adding power to the front wheels as well making it a 4WD with skid steering. Any other solution than 2 powered wheels + caster wheel(s) will result in a somewhat irregular turning, but it's marginal with 4WD. Look up old Mr. Basic videos on LMR to see how 4WD skid steering behaves. 

Hi Telefox,

yes I am using one now on the lazybee. It's just a bit wiggly when the robot arm extends (as I use one in the front middle now). Think the big wheels look better too. But 2 caster wheels it will be.

Hi Vince,

yeah, got that as a souvenir when visiting Istanbul (Turkey). Probably will kill your motivation instead of giving you inspiration when using it the "Dutch"-way. Confusing stuff ;)

:) Well I lived in Istanbul for 6 years so I've see a fair share of them ;) Thats kinda the basic souvenir!  
Just wondering ... is that a shisha in the back ?? Actually might be useful for some quick inspiration ! :) 

The dragging effect shouldn't be too bad when turning in a smooth arc, but it could definitely cause some trouble when trying to turn on the spot, especially if the bot's on carpet or another high-friction surface.

Have you considered using castor wheels, roller balls or omni-wheels?