Society of Robots - Robot Forum
Mechanics and Construction => Mechanics and Construction => Topic started by: javafiend on August 18, 2008, 11:29:26 AM
-
So I'm currently using a cheap swivel caster that came in a four pack, and it doesn't seem to be swiveling as intended on my differential drive robot. The caster wheel is hard plastic and doesn't appear to produce much friction. However, the wheel angle when it does swivel has a noticeable effect on the direction my robot travels.
Does anyone have any tips to correct this besides switching to a ball caster or omni-wheel?
-
To make the caster swivel better, lubricate the swivel joint with white lithium grease (cheap at Home Depot).
To make the wheels more sticky you could wrap a thick rubber band or two around them or rough them up with some 60 grit sand paper. Or if you have any cheap toys with rubber wheels, you could cut a strip of rubber off the wheels and attach them to the caster wheels with CA glue (super glue).
You could CA glue just about any rubbery thing your hard plastic wheels to make them more sticky.
-
it was probably intended for more weight than that of your robot
-
You might also try adding more weight above the caster. I am planning on doing the same thing to my robot and have been concerned about the same issue. I would love to hear how you resolve this.
Mark
-
The best caster of all time in my opinion is the omniwheel:
http://www.acroname.com/robotics/info/ideas/omnicaster/omnicaster.html (http://www.acroname.com/robotics/info/ideas/omnicaster/omnicaster.html)
You can get them from acroname.com.
Just FYI, the orange one is nylon and has no grip so it works well as a caster, the black one is poly so its more grip, but also more money =P
-
Would more grip on the caster wheel equate to better performance?
-
I installed my cheap plastic swivel as a caster on my robot. I mounted my battery pack on top of the caster hoping that the extra weight would help the wheel swivel. It works great and the robot turns and accelerates after a turn like expected. Hope this helps.
Mark
-
the poly grip omniwheel is meant as more of a drive wheel for omniwheeled robots like Admin's Fuzzy.
the orange ones are good for casters, you don't want to add any more resistance to the ground.
-
I have a ball caster from this place http://www.hudsonbearings.com/Products.html (http://www.hudsonbearings.com/Products.html)
I found it at my local surplus store you may be able to find a distributor online to get one. These things are amazing! They work great even for small robots.
I just googled ball transfers and got this http://www.castersupply.com/NAV/stud_ball_transfers.htm (http://www.castersupply.com/NAV/stud_ball_transfers.htm).
I'm sure there are plenty of suppliers out there. Pololu has some but they didn't look like they were great quality.
-
good read
http://members.cox.net/rbirac2/Ebot/casters.htm (http://members.cox.net/rbirac2/Ebot/casters.htm)