Re: Hanging vs. Manipulating 2x balls
 

If you want to control the game, get one or two of the Big Balls, Hang High, and then decide if you need to score them for both you or the opposing alliance (Stationary goals). You can then easily add points to the opposition. (You also might be able to uncap the oppositions stationary goal.)

This was the winning strategy in 2000 by team 255. Get the balls, Hang on the Bar, and then score them.

Is this mechanically feasible - I don't know. A team that does this needs to rely on its partner to score the small balls. A perfect robot would be able to hang, score big balls, herd little balls - and this is pretty challenging.
Just buildng a robot that can climb the big steps and hang is a challenge.

A smart development plan would be to design by objective:

1. Build moving platform cable of herding, releasing
2. Add Arm for big ball manipulation
3. Add stair climber
4. Add hang ability

6 weeks, 5, 4, 3, 2, 1 ship.......

Re: Hanging vs. Manipulating 2x balls
 

alright i also think that if you create a good arm you could actually pull yourself over the platform from the ground floor and lift yourself up.

Re: Hanging vs. Manipulating 2x balls
 

it will be interesting to see how many teams try this

because having one mechanism that performs two functions violates one of the Golden Rules Of Engineering (GROE)

"a subsytem should have ONE function, and be optimized to perform that function"

when you increase the number of functions a subsystem has (N), you increase its complexity N^N

so the complexity of a subsystem with one function is 1

the complexity of a subsystem with two (different) funcitons is 2^2 = 4

the complexity of a subsystem with 3 functions is 9...

it gets out of control REALLY quick!

Re: Hanging vs. Manipulating 2x balls
 

Our team has already drawn out a device that can do both the ball and the arm.

Re: Hanging vs. Manipulating 2x balls
 

The mechanism that extends the arm, if powerful enough, whe reversed can lift the robot (1 motor, two functions) Once you latch the bar, you only have to lift a little to hang. I don't think a lot of teams will try to win by
messing with robots trying to hang. You want to score points, not try to prevent your opponents from scoring points.

A simple way to do this is a chain drive elevator using the door motor.



--- 2000 robot using chain elevator to lift scoring mechanism, hanging from bar.

Re: Hanging vs. Manipulating 2x balls
 

there is also the possibility of creating a small hanging device (schematics forthcoming, plan already designed) and then having a large manipulator arm. this would allow a team to both hang, and while hanging knock off a ball from one (or either) side if stragegists deemed necessary.


Just a thought

Re: Hanging vs. Manipulating 2x balls
 

good start - now draw out what it takes to do each one separately

if you need incentive - if your 2X ball arm is damaged while playing, you have lost your 50 point hanging function too

thats called a single point failure - if one device does both functions, then one single failure in the arm cost you BOTH functionalities (another reason for the Golden Rule)

think about what it will take to do each function separately. You will find the complexity of the two devices is much lower than the single dual purpose one.

Re: Hanging vs. Manipulating 2x balls
 

Otherwise, build robust and prepare to fix parts on that major component.

Re: Hanging vs. Manipulating 2x balls
 

The key word is FUNCTION and not necessarily ONE. A ramp in the sidewalk has one function, but it has many uses. The function is---simply---a ramp, but folks with wheelchairs use it, as do Coke delivery men with dollys, as do Segway's that must cross the road.

My intent here is that if you define your one function properly, it can have multiple applications. Function does not necessarily have to be defined as hanging or ball removal. That could be the application.

To continue with the analogy, if the function of a ramp in the side of the road was to allow Coke delivery men to move their cokes from a truck to the machines in a building, the ramp would only need to be wide enough for a typical dolly. Unfortunately, a wheel chair or Segway wouldn't fit up such a narrow ramp.

I know this analogy is simplicistic, but I hope it highlights my point.

Re: Hanging vs. Manipulating 2x balls
 

That's my point exaclty!

Re: Hanging vs. Manipulating 2x balls
 

I would chose the 2x mult because it can do a lot more than just score points for your alliance. My team ran some "stubot"(student robot) games and discovered how efectivley it could keep the opponent from scoring in thier goals because their is no way in them. By capping the goals when they have no balls in them, they lose a significant amount of time to score. If you can defend the capped goals then remove the caps so you can use them near the end of the game, your opponent will have little to no points from the balls. Also the bar this year is far less accessable than before because of the platform and the narrow room beside the goals. Thus, you dont only need the abbility to lift and hang yourself from it, but either a narrow robot that can maneuver well and climb the stair, or one that can get over the larger ledge to the section of the platform the bar sits on and still be able to get under the bar. The bar is far more trouble than its worth, because 5 5-point balls and a cap can match its points. And needless to say the goals can hold many more than 5 balls, and their are the 4 10-pointers as well. I beleive that the bar takes up to much game and build season time for what it is worth and that the 2x balls are possibly the most pivotal objects in the game.

Re: Hanging vs. Manipulating 2x balls
 

Do the 2X balls have to be inflated? Maybe you can pop the ball and put them in the goal.

Re: Hanging vs. Manipulating 2x balls
 

Your not allowed to intentionally damage the field, so yes they have to be inflated.

Re: Hanging vs. Manipulating 2x balls
 

OK, thanks.

Re: Hanging vs. Manipulating 2x balls
 

I dont see how you can define the function of controlling the large 2X balls:

-acquiring ~2' dia, 3 lb ball from a goal, from the center platform, or from the floor
-placing them on the 4 foot or 6/8 foot goals
- removing them from the goals
-holding them securly during the match to retain possesion

the same as climbing the bar:

-reaching straight up 10 feet
-latching onto a 3" dia pipe
-lifting a 130 lb machine straight up

this is what I was talking about with complexity going 4X when you try to combine the two - the degrees of motion required are different - the end effector is different - the amount of weight to be moved is different - the direction of motion is different

combining the two will make the resulting mechanism much more complicated than it needs to be. I can picture a very simple spring loaded mechanism that can be released once to extend up 10', and capture the bar - and pull the bot up - it only needs strength in the downward direction

but to move the balls you need something like a robot arm - making that strong enought to lift the bot with instead of only moving a 5 lb ball around is a whole nuther ball of wax.

and again, if your multi function arm breaks - you lose big time - you lose BOTH functions on your machine in that match - sure you can fix it later, but you cant get those points back.