Effectiveness of Casters

[Cory]

The only reason that I would ever stick a castor on a robot would be to help turn. I would use a cylinder to engage or retract it, but I would never let two of them be in constant contact with the ground. If you had been around in past years, you would see robots with two driven wheels and two castors like you said. Basically, they would spin around like crazy, with very little control.

Cory

[Alavinus]

Our team is going with two wheels in the back and skids up front. (Gives a new definition to skid steer- doesn't it ) The skids will be made of Delrin and give omnicaster like abilities with the neccessary machining complexities.
You might want to consider this method over the infamous castor, or you will have a story to add to it.

[Will Hanashiro]

i also would not recommend casters. four wheel drive is sufficient, six wheel drive may be going overboard. if you're looking for on-the-dime turning, why not try a trick wheel? for those of you who dont know, a trick wheel is a normal wheel, but with a whole lot of miniature discs going around the perimiter. the miniature discs allow the wheel to slide sideways, yet they provide sufficient traction for rotating foward.

[ryan_f]

When our team used casters on past robots, it worked well. We went in straight lines and didn't have any problems with them. I think the wobbly factor that some of you are talking about is maybe because there is not enough weight on the castor or it is not parallel to the ground. If you are going to go up the steps, then i wouldn't suggest casters, go with 4-6 wheel drive for that

[Cory]

Originally Posted by Will Hanashiro

i also would not recommend casters. four wheel drive is sufficient, six wheel drive may be going overboard. if you're looking for on-the-dime turning, why not try a trick wheel? for those of you who dont know, a trick wheel is a normal wheel, but with a whole lot of miniature discs going around the perimiter. the miniature discs allow the wheel to slide sideways, yet they provide sufficient traction for rotating foward.

Search for "omniwheels" to get more information on such a "trick wheel"

Cory

[ngreen]

Originally Posted by Cory

The only reason that I would ever stick a castor on a robot would be to help turn. I would use a cylinder to engage or retract it, but I would never let two of them be in constant contact with the ground. If you had been around in past years, you would see robots with two driven wheels and two castors like you said. Basically, they would spin around like crazy, with very little control.

Cory

Yeah, castors that extend and retract are great for a robot with four wheel and too much traction. We were tripping breakers when we turned until we put the casters on. Just a tip, get sturdy casters and if you use pneumatic cyclinders do everything you can to protect the rod. They don't like side loads and the machine shop guys get tired of bending them back. Also, only lift so that the turning wheels touch and the others barely touch.

[Aignam]

Team 103, the Cybersonics, used two casters in their 2003 robot. That machine gave more or less every robot a run for their money. I'm not too certain of the specifics, or how it worked, but you most certainly can build a competetive and successful robot using casters.