How can we drive on this new floor?

[thefro526]

As I think more and more about this game I've come to a conclusion.

No matter what you do, you'll still be working with limited traction. Instead of worry about getting more traction, why not just embrace the lose of traction?

I think the question of "how can we drive on this new floor?" should be posed to the drivers. It'll require quite a bit of finesse and skill to master the lack of traction but those who do will be at a huge advantage.

Perhaps you should have your drivers research things like Drifting, ice driving, and driving in the rain to get some ideas. I personally, dabble in a bit of drifting myself so I'd like to see if I can apply that experience to driving a robot on this surface.

[Sam2197]

Originally Posted by thefro526

As I think more and more about this game I've come to a conclusion.

No matter what you do, you'll still be working with limited traction. Instead of worry about getting more traction, why not just embrace the lose of traction?

I think the question of "how can we drive on this new floor?" should be posed to the drivers. It'll require quite a bit of finesse and skill to master the lack of traction but those who do will be at a huge advantage.

Perhaps you should have your drivers research things like Drifting, ice driving, and driving in the rain to get some ideas. I personally, dabble in a bit of drifting myself so I'd like to see if I can apply that experience to driving a robot on this surface.

i totally agree with that. theres no way to increase traction. and i also do some drifting myself. main thing is you cant give a lot of power right away. otherwise you will just spin your tires(wheels). it will require some skills by the drivers

[robodude03]

Originally Posted by thefro526

As I think more and more about this game I've come to a conclusion.

No matter what you do, you'll still be working with limited traction. Instead of worry about getting more traction, why not just embrace the lose of traction?

I think the question of "how can we drive on this new floor?" should be posed to the drivers. It'll require quite a bit of finesse and skill to master the lack of traction but those who do will be at a huge advantage.

Perhaps you should have your drivers research things like Drifting, ice driving, and driving in the rain to get some ideas. I personally, dabble in a bit of drifting myself so I'd like to see if I can apply that experience to driving a robot on this surface.

You are absolutely right. Drivers will need to train themselves and adapt to the slick situation. Additionally, I believe that programming will also have a big part in this years game (i.e. Traction Control). Our team will be doing a lot of testing in terms of the best method of acceleration for our robot, inputting that into our system and applying that to our controls.

[Enigma's puzzle]

Sorry to break it too you all but tank drive is going to be a pain, Tank drive has an axis of rotation around the center of the robot. BUT you have a trailer, you are going to be dragging the trailer wheels side ways it will be a battle.

Also the trailer anytime that you backup you will jack knife almost immediately, then you will be unable to control your backwards motion, turning with the trailer.

[thefro526]

Originally Posted by Enigma's puzzle

Sorry to break it too you all but tank drive is going to be a pain, Tank drive has an axis of rotation around the center of the robot. BUT you have a trailer, you are going to be dragging the trailer wheels side ways it will be a battle.

Also the trailer anytime that you backup you will jack knife almost immediately, then you will be unable to control your backwards motion, turning with the trailer.

In theory though, you should be able to drag the trailer around because the wheels are the same non-grippy wheels that are on the robot. I'd also venture to guess that a trailer weighs substantially less than a robot, but then again I'm not entirely sure...

[Enigma's puzzle]

To add wieght with without adding wieght you could always fill up your trailer

[mray1031]

Yeah by adding to the trailer you gain mass - just not on your drive wheels. You'll gain momentum, just not traction. Plus you're giving the other team points.

[Enigma's puzzle]

Traction is detirmined by pounds per square inch, so more wheels is taking away from your traction on each one, so every non-drive wheel is a waste of potential traction theoretically.

All wheels have the same coefficient of friction so because of the wieght differential the trailer will move, but slowly

[Dracco1993]

I am a driver from the FRC team 1741. I like the idea of drifting to gain more control of the robots. My only concern is that with the trailer it will be very hard to turn quickly. Can you get enough speed to drift in the arena?

[Lesman]

There seems to be a lot of confusion going on about some physics, I think this should help:
ForceFriction = Mass*Gravity*CoefficientOfFriction
surface area is not a part of the calculation, as increased surface area means the normal force (force of the ground pushing up) is more spread out.
Force = Mass*Acceleration
thus
Mass*Gravity*CoefficientOfFriction = Mass*Acceleration
mass cancels
Gravity*CoefficientOfFriction = Acceleration
which shows that maximum acceleration is a function of nothing more than Gravity and the Coefficient of Friction, neither of which can be changed. Any team that powers all wheels in contact with the ground will have a top acceleration of .588 assuming no slippage (.06 cof) or .49 with slipping (.05 cof). The top speed assuming you drive straight across the regolith is approximately 2.2 meters per second, or about 5 miles per hour. The trip would take about 4.5 seconds.
By the way, where is everybody getting the coefficients of friction? How accurate are they? Doe anybody know the cof of the wheels on carpet?

[Akash Rastogi]

Originally Posted by Enigma's puzzle

Sorry to break it too you all but tank drive is going to be a pain, Tank drive has an axis of rotation around the center of the robot. BUT you have a trailer, you are going to be dragging the trailer wheels side ways it will be a battle.

Also the trailer anytime that you backup you will jack knife almost immediately, then you will be unable to control your backwards motion, turning with the trailer.

Hate to break it to you, but a lot of teams have some innovative programming planned. *hint hint* *wink wink*

There are always ways to work around obstacles...even if they're on the moon.

Originally Posted by Akash Rastogi

Hate to break it to you, but a lot of teams have some innovative programming planned. *hint hint* *wink wink*

There are always ways to work around obstacles...even if they're on the moon.

Eh, figure it's time to stick my nose in here.

Anyway, Titan's idea about augmenting the robot's downward force is an interesting one. Keep working on that, you really could have something there.

Folks, FIRST just took the box we've all been thinking in and ripped it to pieces. Even a kit chassis is stuck in the high traction environment we've had. It's time to shed all these ideas of how we used to move, and really DESIGN around CONSTRAINTS, much the way the real world works. What you're all seeing and experiencing is a valuable skill, so don't blow this one off.

That being said, I have absolutely NO idea what to advise my team to do... I've spent all of today doing different designs, all of which end halfway when I realize different factors.

[Adam Y.]

Originally Posted by robodude03

You are absolutely right. Drivers will need to train themselves and adapt to the slick situation. Additionally, I believe that programming will also have a big part in this years game (i.e. Traction Control). Our team will be doing a lot of testing in terms of the best method of acceleration for our robot, inputting that into our system and applying that to our controls.

That could be a problem. In general PID controllers have always been a robust and great way to move your robot. The problem is that the ideal way to control the motors is with some type of ramp input meaning that the integrator may or may not work as exactly the same.

[cj.reeves]

is the coefficient of friction independent of surface area or not?

i think more wheels equals more friction

[sbrumund]

In simple physics terms friction is independant of the surface area.

In reality because we are on a textured surface it may not be.

If the wheels are the same as last years kit wheels the surface is a soft compound. With sufficient weight on each wheel the soft compound will conform the the bumpy surface producing more friction than a wheel riding on the top of the bumps.

The question then is what is then optimal load on a wheel to obtain the most friction. A simple experiment can be designed to determine the optimal loading and therefor the optimal number of wheels.

If allowed the vacuume design is possible. Many schools physics departments have a 4' diameter hovercraft where the lift is achieved with a battery powered leaf blower. The leaf blowers run well for 10 minutes on a charge and can easily support a 250 lb load. I believe the battery supplied has sufficient energy to power the leaf blower and drive motors and increase the normal force and friction. You would need a fully charged battery for each match.

Since we are simulating 1/6 gravity on the moon and there is no atmosphere on the moon I suspect a vacuume design wil not be allowed.

It is possible to get used to driving on a low friction surface. Those who are used to driving on ice and snow understand the limitations. Keep in mind that when driving a car on ice you are in the car and have a, seat of your pants, feeing of what is going. You do not have this sensor input at a remote driving station.

It is possible and easy through programming to limit how fast you can accelerate and turn. It takes some time to get used to, like the first time you slam on the brakes of a car with anti lock brakes.