How can we drive on this new floor?

[samir13k]

I replaced the wheels on a 30-40ish lb kitbot today that was previously made with the new kitbot wheels, and tried it out on the "regolith" surface, and so far....its not looking so well. The bot can be kicked around and will slide sideways really easily. Of course, there are many different factors going into play, especially the low mass.

[=Martin=Taylor=]

Originally Posted by JagWire

that's cool to hear. how is it set up? tank-drive?

"Long" drive configuration with a wheel at each corner. Normal tank-steering.

Geared for around 8 fps.

Originally Posted by samir13k

I replaced the wheels on a 30-40ish lb kitbot today that was previously made with the new kitbot wheels, and tried it out on the "regolith" surface, and so far....its not looking so well. The bot can be kicked around and will slide sideways really easily. Of course, there are many different factors going into play, especially the low mass.

Weight makes a HUGE difference.

Also realize that other bots won't be able to push you as hard as you can kick.

Crashes are a different story.

[Jbrown1011AZ]

Do you give any hints to people who have no experince with driving in the snow oricy conditions

[pfreivald]

I live in the land of ice and snow, and tips for driving in these conditions are relatively self-explanatory, governed by this rule:

If you lose static friction, you lose control.

Driving a *car* in such conditions means that you:
A. Go easy on the accelerator to avoid slipping.
B. Go easy on the brake, for the same reason.
C. Turn gradually, slowing down much more than you normally would.
D. If you start to skid, turn into the direction of the skid to allow your wheels a chance to catch again.

Now, how this applies to different drive train configurations in Lunacy is another matter!

Patrick

[Ben Bastedo]

I live in the land of ice and snow, and tips for driving in these conditions are relatively self-explanatory, governed by this rule:

If you lose static friction, you lose control.

Driving a *car* in such conditions means that you:
A. Go easy on the accelerator to avoid slipping.
B. Go easy on the brake, for the same reason.
C. Turn gradually, slowing down much more than you normally would.
D. If you start to skid, turn into the direction of the skid to allow your wheels a chance to catch again.

Now, how this applies to different drive train configurations in Lunacy is another matter!

Patrick

Thanks for the tips Patrick. Don't get too much of that weather down here in Texas.

Ben

[pfreivald]

No worries.

On another note, I think it would be a huge mistake to try to design a robot that is going to maintain traction all the time -- because it won't, especially when it gets hit by high-speed *other* robots. It would be much better to *know* that you are going to slide, and then try to figure out how you can use this to your advantage in controlling your bot. Driver practice will be paramount.

Someone suggested finding a video game (I think it was MarioKart(?), although I am sure there are others) that involve driving on slippery surfaces, just to get used to the general idea of how things handle.

Patrick

[Ben Bastedo]

HA, basing how a robot drives off a video game! That is new, but an awesome idea!

[pfreivald]

You could easily go too far with that idea, methinks, but it's not a bad way to get those of you who reside in warmer climates more accustomed to this kind of driving.

Patrick

[Enigma's puzzle]

Your Normal Force is a set number, however much your robot mass. That is divided by the surface area that is touching the ground "Theoretically" (It actually depends on Weight Distribution too). The Mass that is supported by each wheel can actually be measured by load cells (And then divide by the surface touching the surface area making contact with the ground to find pounds per square inch.)

Adding or subtracting wheels (if all are powered) doesn't actually make the difference in total, It changes the pounds per square inch of each wheel but not the traction because your total mass is still the same and the friction is still the same.


However if all wheels are not powered then you lose traction because whenever you try to drive not all of your mass is being used to effect friction.

SO more wheels doesn't really help except for the stability of the robots. you won't gain more traction from more wheels.

The hieght of the trailer (the posts around the outside) goes linearly from 42 to 34 inches, I am not sure if that is from the floor or the base of the trailer.

[Elgin Clock]

Use springs.

[Matthew2c4u]

i still see alot of constrained thinking about the drive train,Thinking outside the box has helped us the most.
Also, USB Joystick, not last years joystick.

[eschanz]

Originally Posted by thefro526

But what about momentum? Changing directions with a heavier bot it's going be be a bit harder I think... Or maybe not, I'd like to get some input on this.

it is because "whats in motion tends to stay in motion" physics 101

[Enigma's puzzle]

Mario cart, SHERBET LAND!

The biggest tip to people not used to icy condition, is Don't break traction, accelerate slower than you think you need to, because if you try to accelerate too fast you will spin and lose traction, causing you to have to slow down your wheels to recover. essentially making you accelerate slower.

[Bob Steele]

Just a small note from me...

I believe that one has to think of this game more in terms of thrust vectoring rather than driving.

These robots will behave much more like spacecraft than they will cars.

In your brainstorming... think about applying force in the direction you want the robot to change its acceleration.

Earlier another post showed that the maximum acceleration (assuming a 120 pound robot and .o6 coefficient of friction) that could be achieved is around .588 m/s2...

Apply that thrust in the direction you want to change the robots acceleration.

This would seem to require that powered wheels (and all wheels need to be powered to get maximum traction) are capable of changing their vectors in 360 degrees. This is because the only thrust that the robot is capable of is from these wheels...

The only other thrust would come from those same wheels turned sideways..and that only would be when the robot is moving and it would be in the negative direction to the motion. This would bring the higher transverse coefficient of friction into play and could be a very good way to de-cellerate the robot. It could conceivably de-cellarate the robot with nearly twice the magnitude as the powered wheels...

just something to think about.

don't think driving... think piloting...and think piloting of a space craft..

thanks

good luck at the competition!!!
May the Net Force be with you!!!

[nat2]

hi think slow for now we can predict all we want but the real test is going 2 come at regional, the ones that drive the best will do the best in my opinion. my idea learn fast.