Time to the top...

[Joe Johnson]

I know there was a thread on time to the top of the ramp in autonomous mode, but this is something different.

I want to know what times folks have actually seen robots make it to the top of the ramp (defined as touching the first bin).

Having seen 2 weeks of regionals, what were the best times and how many bins did they typically knock down?

We have all heard a lot of claims by teams. I am interested in how reality matches these claims. I suppose that many of the published times are 90% wishful thinking and 10% stop watch.

If this information is available in another thread, please point me to that thread.

If it is available on a scouting site, also, I would love to see the link.

Joe J.

[KenWittlief]

from reviewing the tapes of the Buckeye regional, we hit the wall consistantly in about 4.5 seconds.

we were only beaten to the wall once, by a bot that made it in 3.

From the calculations we did on energy and HP - 3.0 seconds should be the fastest - if anyone does better than that, have their bot re-inspected - they are cheating! :c)

[Andy Grady]

Times between NH and New England went down dramatically. In NH the fastest consistant robot (team 58) was making it to the top of the ramp in about 4 seconds. 157 was clocked at about 3.5 seconds in one round in NH. In CT, 571 was the fastest robot which clocked in at nearly 3 flat to the top of the ramp. Rage (173) was second at about 3 and a quarter, 157, 175, 126, and 716 each clocked in around 3.5 seconds. I don't have the actual times in front of me at the moment, but they were pretty fast, with all these robots taking down 4 to 5 stacks at a time. It was pretty impressive. If I remember correctly also, I believe that Paragon (571) even clocked in slightly under 3 seconds in a round. I can imagine with more tweaking time, these machines will only get faster.

Good Luck All,
Andy Grady

[sevisehda]

There is a video somewhere on CD that is a 12min video of the autonomous modes at BAE. After watching it and the webcasts. A few teams get there in 2-3 second and get 90% of the wall about 99% of the time. These teams are rare but very good. The next group is teams that get there in 5-10 seconds and take half the wall about half the time. Then there are teams that do something else or just sit there. I'd say there is very little middle ground, the teams who get there fast are also very consistent while the slower teams are less consistent. However as always there are exceptions.

[KenWittlief]

fast and consistant is the trick.

If your bot is fast you cant possibly follow the line

and the gyro limit is 180° in about 3 seconds (so if you turn faster than that, the gyro output is meaningless)

if these teams are hitting the wall in 3 seconds they most likely are running completely blind (dead recogning with no sensor inputs of any kind)

if they hit the wall in the center every time that is impressive

going that fast your wheels have to be slipping / spinning

can we get anyone to fess up? how do you find the wall that fast?

[Paul Copioli]

We scouted Cleveland and timed every round on Saturday. Team 27 was consistently at the bins in 3.5 seconds. The next times were around 4.2 - 5.0 seconds (about 10 teams).

In Pittsburgh, we were the fastest (team 217) at 3.2 seconds on Friday, but we got progressively slower due to our drivetrain starting to bind (using bevel gears) and we eventually levelled off at about 3.6 seconds consistently on Saturday.

Team 45 was at around 4.0 seconds and team 548 was at 4.1 seconds by the middle of Saturday competition. Many teams at Pittsburgh were from the 5.0 to 6.0 time range. We have all the times from Pittsburgh and I will try to have a list ready by Great Lakes.

-Paul

EDIT: I just saw Ken's post and I will try to respond to how we do it. We have 4 wheel drive with front wheel steering. We have a separate microcontroller (a PIC) which tells the robot what steering angle to be at. The wheels stay at this steering angle until the gyro indicates that the ramp has been hit (gyro used as a trigger), then we straighten the wheels and deploy the wings. After we hit the stack we shift gears into low and creep down the ramp. We use the Chips and Drills to drive with 4" wheels. Our gear ratio from the chips is around 6:1. Our tread material has a coefficient of friction with the carpet of 1.5.

-Paul

[Andy Grady]

If your bot is fast you cant possibly follow the line

I'm not completely sure, but I think Buzz (175) did, and they were lightning fast. Either that or it was a curved dead reconing program. As for the gyro, there is nothing saying that you have to use the gyro the whole 180, so if you mix it with some other means of sensor, you can get up the ramp in about 3-3.5.

Good Luck,
Andy Grady

[Solace]

You wanna know the secret? build a practice robot.

Yes, we run completely blind. We didn't choose to do it that way because we knew it would be fastest, but more because we were too lazy to do anything more complicated. But hey, it worked out.

[KenWittlief]

if you run completely blind / open loop

then how can your bot hit the center consistantly

with battery voltage changing between matches, esp in the finals?

if boxes are in your way?

if a wheel slips a bit?

Im not saying it cant be done, but getting an open loop system like that to be repeatable is not easy to do.

[Solace]

oh yeah, and one more thing. The rear two wheels on our robot pivot in order to conform to the ramp (we actually won the industrial design award at UTC for that). This helps our bot to stay on target even if it hits the ramp at an angle when going 12 ft/s. Its also pretty sweet to be able to spin in a circle even if we're straddling one of the angled drop offs at the top of the ramp

here's a picture http://www.chiefdelphi.com/forums/pictures.php?s=&action=single&picid=3996&direction=DESC&sort=date&perrow=3&trows=4&quiet=verbose


I think that in order to get there really quickly, you need to be running on four motors. I've seen bots that can go faster than us using only two motors, but the time required for acceleration negates their maximum possible speed because of the limited amount of space.

[seanwitte]

The program only ran through once, but we made it to the top in about 13 seconds. We integrated the gyro to make the turn and stay on course, and a line sensor array we built to detect the leading and trailing edge of the HDPE surface so we stopped on top. I think we could trim maybe 4-5 seconds off, the robot favors the left-hand side and we were not compensating for it. We will never be the fastest to the top, but we'll make it every time.

For the 3-second club, what happens when a robot hits the stack at that speed? Is there any feedback at all? At that speed (8-10 fps) you're nearly blind because the RC can't keep up.

[Andy Brockway]

We use the gyro (Team 716) only after we reach the top and go over the other side and only to tell the robot to stop. The rest is dead reckoning. We started to use the gyro to increase speed at the bottom of the ramp but found it too sensitive to bouncing. This caused the robot to think it had reached the top. It is not good to stop on your way up!

We were pretty consistent at taking the end three stacks using the two supplied batteries. We were lucky and had 1/2 to 1 hour between matches to ensure we had charged batteries.

The best matches are the ones when two robots reach the top at the same time and pass each other! We did this in a match against Buzz (175). Totes everywhere!

[Gope]

At St Louis we were never beaten to the top, i suspose we hit the bins in around 3 seconds.

While not incredibly fast, team 547 hit the boxes in around 5 seconds hand very consistantly got EVERY single box.

[Solace]

There are no sensors of any kind on our robot (besides limit switches) it can be done - our bot is living proof of that. (ok, so maybe not living...)

Ken is correct. changes in battery voltage do affect our autonomous mode. That's why we always put in a fresh battery before every match. That's easy to do in the qualification matches when there's time to charge up between matches, but in the finals we borrow competition batteries from other teams so that we can have enough.

boxes don't pose a problem. we've tested it succesfully with 4 boxes lined up behind it. more than that hasn't been tested, but i'd be surprised if another team could line them up in 10 seconds.

The front wheels are pneumatic and don't slip, but the back wheels are skyways and are supposed to slip.

Our bot starts backwards at an angle, goes straight in reverse, then makes a small correction to be lined up correctly and goes straight up the ramp and then makes a small correction before heading up the ramp at full speed. we have another program that lets us go in an arc, but it takes a good full second longer to get there. I'll see if i can dig up a movie of that or something.

sean, by the time we hit the wall we're going 12 ft/s. because we don't have any feedback, the RC doesn't have anything that it needs to keep up with.

For those out there who are still doubtful of dead reckoning, let me say that you were all correct - it is very difficult to do correctly. It took us three days of tweaking after the code was initially written before we could get it to work reliably. The tweaking was kind of random too - because it was difficult to predict what a programming alteration would do, we kinda just tweaked it at random until it tested out correctly.

We usually stick to our own side in order to not risk colliding with our alliance.

[Solace]

above all else, a practice robot and a practice field is a must. We didn't even start programming our code until at least a week after the competition robot shipped. Thank god for 173 and their practice field.

Personally I think that this years competition is a bit biased against rookie teams. Veterans who have the funds to build duplicate robots and have access to fully sized practice fields have an enourmous advantage over those who don't . I'm not complaining (being a member of one of those lucky teams), but I do think that its something FIRST might want to look into for the future.

[Solace]

One thing I would like to hear about are the robots how have arms that reach over the wall to knock down the bins without actually moving. How fast do those work? There haven't been any of those at the regionals that I've witnessed.

[Yan Wang]

At Annapolis, 25 was the fastest at < 4 seconds.

Our team got there between 4 to 4.5 seconds and was among the fastest. Most teams used dead reckoning. Depending on how the bot was build, a bin placed by a human player in the robot's path could have disastrous or no effects.

[Austin]

I'm not sure excatly what our time is, but at Pittsburgh we met with the thunderchickens at the top of the ramp, virtually the excat same time, although that was with HP bins placed in front of the ramp on their auto side. Ha!

[Joe3]

If anyone has video of these 3-4 second runs to the top of the ramp, I'd like to see it. Sorry, but I'm just having trouble visualizing it. Also, how are you guys timing this...are you going my the FIRST official clock, or indepenent timing meathods. Also, I seem to remember team 25 more in the 5-6 second time range based on the FIRST clock. I dunno, but if anyone has video I'd appreciate it.

[sevisehda]

Here is the link for the video of BAE autonomous periods.

BAE AUTO Video (http://www.chiefdelphi.com/forums/showthread.php?s=&threadid=19077&highlight=bae+229)

[Solace]

yeah, and does anybody have movies of the robots at UTC? We were too stupid to tape them ourselves.

[Wayne C.]

for the record-

team 25 goes from activation to top of ramp in 3.6 sec one direction, 3.2 secs in the other. We actually slowed it down late in the game to put less stress on the drills but were still under 4. This is based on the second counter in my videos and a stopwatch the officials were using during our practice rounds.
(remember that there is a brief lag between the time the countdown ends and actual activation with the horn)

In either case it goes pretty fast and from Fri afternoon on we hit the wall as planned every time- and I think we can hold it together now!!!

WC

[JasonStern]

Our team taped the most of utc (we ran out of tape fri night :) ), but most of us are on spring break right now. however, I might be able to digitize select portions of the matches, if you have anything in particular you want to view....

[Serg]

I can prove team 25 at less than 4. They were over at the practice ramp testing there autonomous. They made it to the top of the HDPE with there robot in 3.5 seconds. Now there arm sticks out about 2 feet after deployment, making there bot reach the wall before there robot got there. Id say they pulled off 3 and a quarter.

[KenWittlief]

I gave the tape I had of Cleveland matches to someone else on our team. We timed our bot from the tape, from the time it started moving till we saw the first box flinch. It was consistant at 4.5 second. And yes, that one team that beat us to the wall was 3.0 seconds (I am humble in their awesome presence :c)

There was a bot at Cleveland that had a wally-arm - it took a little over 3.5 seconds to deploy and hit the wall, but it didnt take many boxes out, and it didnt knock them very far.

We started our auton mode using 7 (yes count em) retro banner sensors under the bot to follow the line. We had to stay late to test it - when the whole team was there they wanted to practice driving, or were tinkering with the trannies, so the sparkies were there till after midnight a few times.

Then AFTER the bot shipped I realized a better way is to do the V turn - start out backwards pointing towards the center of the operator stations- go back about a second, turn 45°, then warp speed scotty!

We use the gyro for closed loop steering - and was a simple step to simply add the output number in a 16bit variable ( VAR WORD) - always subtracting 127 to normalize it - and use that accumulated number as a compass heading. 45° comes out to be approx 3000. We can turn 45° dead on every time - the only drawback is you have to turn a little bit slower than you would without it (to keep below 75°/second sensor max) - but since we are only turning 45° - it doesnt take long. If you try to do a half circle with the gyro as compass, then it will take you 3 seconds just to make the 180° turn.

maybe we will give dead recogning a shot (without the gyro) at toronto if we have time to play with the timing of it.

[PMGRACER]

After 2 regionals, our Auton mode seems to work pretty well. We did fight with R/C controler issues at the GLR all weekend though. We have ordered a new one and should be ready to roll for Nats. Our time to the bins has been a consistant 3.2 seconds. We did add some code to drop the arm to pickup more rows, and may have our wrist rotate out to pickup another row. We are only running at 80% power. We still can turn it up if we need to. Dead reckoning has been working consistantly for us. Sometimes, simplicity may not be pretty, but it can be extremely effective.:cool:

[Joe Johnson]

I have heard a lot of folks say they are using "dead reckoning."

I am confused by the term.

It seems to me that some folks mean they output PWM values of PWM1 for T1 seconds, and then output a value of PWM2 for T2, etc. This entire process only requires a clock and uses no sensors whatever. (Note to the purist out there: PWMi is a vector of dim 16)

For others, they have rotational sensors on their wheels that they used to infer robot motion (distance and perhaps orientation). In this case, teams would vary their PWM output based on location. For example, PWM values PWM1 until X1, then PWM2 until X2, etc. (There are fancier control schemes with could plan paths, use proportion control, etc. but you get the idea).

Still others are using rotational velocity sensors (a.k.a. gyros a.k.a. yaw rate sensors) and inertial sensors (e.g. accelerometers) that they integrate (twice in the case of the inertial sensors) to get position. In this case, teams use the position information similarly to the way the rotational sensors are used.

In any case, I always wonder what a team means when they say they are using "dead reckoning" to control their robot.

Having seen them work so well in Ypsilanti, I am especially curious to learn what team Rush (#27) means by the term. It is hard for me to believe they could be as repeatable and effective as they were by using just time, but I admit I have been wrong once or twice in the past.

Joe J.

[Jeff_Rice]

dead reckoning
n.
A method of estimating the position of an aircraft or a ship (or, in our case, a robot) without astronomical observations(sensor inputs), as by applying to a previously determined position the course and distance traveled since.

I think this definition works; if you have no sensor inputs, then you know you started in the gray area, and you know to get up the ramp you have to go around the edge of the ramp. If a robot uses sensors that indicate its position, then it isn't a dead reckoning. For example, you're on a ship with Captain Nathaniel Bowditch. He sights the sun, and you are in the Atlantic, knowing precisely your position. Fog comes up, and it is so thick you cannot see. He can only guess his approximate speed and heading. That is dead reckoning.

[DougHogg]

Originally posted by Solace
One thing I would like to hear about are the robots how have arms that reach over the wall to knock down the bins without actually moving. How fast do those work? There haven't been any of those at the regionals that I've witnessed.

We move a bin in the stack with our arm at 1.97 seconds (59 frames in our video at 30 frames per second).

Here's a picture from our first match at the Arizona Regional with the big screen in the background showing the official clock at 1:58 and our arm bumping the stack.

(We were 4th seed in Arizona. We would have been higher; We didn't make any "arrangements".)

Our robot, "Yoda", making first contact at the Arizona Regional (http://www.chiefdelphi.com/forums/pictures.php?s=&action=single&picid=4615&direction=DESC&sort=date&perrow=3&trows=4&quiet=verbose/)

There are some videos on our team web site:

Team 980 (http://www.team980.com/)

For anyone coming to Los Angeles for the S. Calif. Regional next week, see you here.

Otherwise, look for us in Houston.

[PMGRACER]

Originally posted by Joe Johnson
I have heard a lot of folks say they are using "dead reckoning."


Having seen them work so well in Ypsilanti, I am especially curious to learn what team Rush (#27) means by the term. It is hard for me to believe they could be as repeatable and effective as they were by using just time, but I admit I have been wrong once or twice in the past.

Joe J.
Hey Joe. I am not the programmer, just the designer/fabricator/machinist/whatever needs to done guy. I donot know all the particulars of the code, but the way we define dead reckoning is this. We have a segment disc (4 Black, 4 White segments) attached to both the front wheels and use a Banner sensor for each. We have the program set to drive x direction so many "transitions" then change direction, drop the arm and scream forward so many "transitions". I believe it is something similar to how the Chiefs count the number of rotations on the Bosch motor. Although you guys have a higher precision sensing device.

The Electronics and Programming sub teams had discussed using some sort of encoder to keep track of the wheel poisition, but decided it was simpler to use the Banner Sensor. Granted you have some variation in the precise postion of the 'Bot due to carpet adhesion, battery voltage, initial machine position, but how close do you have to be? After all, we are not trying to dock the Space Shuttle. Our method has been consistant. As in most anything, consistantcy is the key. And believe it or not, we were really concerned before the season started with FIRST giving us the EduBots and the sensors a month early. We knew they would have something complicated for us to do. We did not want to be the ones left out in the cold, not knowing how to apply the sensor technology to the game. So we went to work for the next 10 weeks, exploring how Banner sensors worked and what code you needed to write to make the 'bot do what we wanted it to. I think we took our biggest weakness and turned it into one of our best strengths.

[David.Cook]

MOE, if you are doubtful about auton bots getting to the stack in 2-3 seconds, then you didn't watch the Fla Regional. I think it was team 312 that did it consistently. I was totally amazed, but they did it several times (at least - I didn't see everything)

Regarding the possibility of slipping on the carpet, we had that difficulty in our testing before we shipped, so we created what we called "MotorSave" code. This is a special algorithm that runs in all modes. The last thing you do before you actually output a new motor command, is compare it to the previous motor command. Obviously, you must do each motor independently. You limit the maximum change in motor command to some value 10, 20, 30, 40, whatever you think is best.

The first thing we noticed when we did that is we didn't hurt our clutches nearly as much, so they last longer. The second thing is you can find the value that keeps your wheels from slipping on the carpet when you jam the joystick to full. Best of all, our driver says he has the best control he has ever had. (At first he was worried that the response was slow)

This goes a long way towards making auton work better. The other thing we do is change the battery between every match. Even in Elimination rounds we have the guys running to the pit to keep them charged.

Sparky takes ~4 seconds to get to the top and knock bins. I believe we could get there in 3 seconds given time to test things, but we do a couple things that slow us down.
First, we don't go full speed until we finish our turn and are heading up the ramp. Second, we slow down (yeah, that's right) just before we contact the bins. It yields a better bin-fall when you go slow. Third, we make a pretty wide turn. It took a lot of tweaking to get the turn radius the same in left and right-hand modes, so we won't be mucking around with that.

Final comment: Getting to the top of the ramp first does not guarantee a win. We have not been first in many matches we won. It is the remaining 1:45 that really makes the difference.

Final Final Comment: <rant> Why doesn't anyone really try to maximize the score by balancing the bin count on both sides?????
I mean, even if both teams have only a two stack left, you still really want to win with 20 bins on one side and 21 on the other - YOU GET WAY MORE QP THAT WAY. But every match I see the same thing, the team gets 95% of the bins on their side, and then make the ultimately unintelligent move of proceeding to clear the rest of the bins off the opponents side. Geez, those are 2-for-1 points you are losing. If you take out the 4x multiplier, you have divided you QP adder by 8! I really thought teams would understand that you absolutely WANT a close match. I am not talking about fixing matches - BOO! I just think before the drivers get caught up in the Battlebot mentality they should consider whether they want enough points to be able to pick their alliance at the end of the day. </rant>
Sorry if I drifted off topic a little *cheesy grin*.

[Disclaimer: the rant which preceded is not necessarily the view of Tucker HS or the rest of team Sparky, just the ravings of one slightly frustrated mentor.]

[Stephen Kowski]

hehe yeah we hit the entire wall in three seconds or less consistently, but it isn't dead reckoning (definitely not line tracking either). ;)

[Paul Copioli]

Joe,

To directly answer your question, the Thunderchickens give a preprogrammed steering angle (actually potentiometer value) based on where we want to hit the ramp (near, far, center) and full throttle until the gyro detects the ramp (threshold value). After detection, we can do various things based on what we select prior to the match. All the processing is done using a PIC and bit values are communicated to the RC and it uses a fairly simple case statement to determine what to do. After the ramp is detected we use a timer in the PIC to put wings down, up, change gears, and stop.

-Paul

[Gope]

At Mid-West the fastest were

16 - 2.75 seconds (my team woot)
217 - 3.1 seconds
111 - 3.4 seconds

We repeatedly timed these teams and they consistantly had these times.

[Paul Copioli]

We also timed teams, and got very similar results. Although we timed 16 at 2.6 seconds on a couple of occasions.

-Paul

[Joe Johnson]

So, with 4 of 5 Regional weekends behind us, it seems to me that 2.5 Seconds to the top of the ramp is the "World Class Target."

I know a lot of teams who have had less than stellar performances to date (Chief Delphi included) be aiming for better times in Texas. Time will tell if we've hit our marks.

From what I have seen on the web and with my own eyes, it will take a 2.5 second ramp run to win this thing (plus the ability to stay upright if an opponent meets you at the top plus the abiltiy to fight for the top at the end plus the ability to empty the opponent's carpet area plus the cool headedness to know what to do when plus, the most important ingredient, luck)

Luck and fast ramp runs to us all...


Joe J.

[Paul Copioli]

Joe,

We were discussing this with our team during the MidWest Regional. We decided to slow the robot down slightly to get better repeatability. We were asking ourselves, "How fast is fast enough?"

We came close to getting the answer at MidWest. Semifinal 1, match 2 we decided to go head to head with 16 (normally we go to the center of the ramp and put our wings down). 16 consistently went tight around the ramp getting the three columns closest to them (3,4,5 bins each). We decided to go to the inside to see what kind of stalemate we could create (did not put wings down).

Even though they beat us to the top by about 0.4 seconds, we got there fast enough to create a stalemate (2 or 3 bins fell into 16's scoring zone and most just went straight up ... pretty spectacular). What mattered more is what the drivers did after the stalemate. Anyone who was watching knows we got smoked when the human control started.

So, to make a long story short, I think anyone around 3 seconds will be very competitive and will put their drivers in a good position to win the match.

-Paul

[David.Cook]

Paul - I like your last post. You aptly point out that the match was won/lost during driver control. At the risk of being a little judgemental, it really seems that teams are obsessing about speed to the top. IMHO, although it is a factor, it does not presuppose the outcome of the match.
See you at Houston - we finally got school board approval for the trip, even though they have cancelled many other field trips due to the war.
Go Sparky!

[Powers]

we make it in and around 3.5 consistently, until we foolishly try to change our routine, in which case we dont make it, then lose..... o well.... we use dead reckoning, b/c w/ 2 wheel steering it is just easier than following a line, although it will look like we are following it.

[Kojib]

Originally posted by KenWittlief
from reviewing the tapes of the Buckeye regional, we hit the wall consistantly in about 4.5 seconds.

we were only beaten to the wall once, by a bot that made it in 3.

From the calculations we did on energy and HP - 3.0 seconds should be the fastest - if anyone does better than that, have their bot re-inspected - they are cheating! :c)

Not true. We timed 2 Minute Warning at 2.75 seconds and when we posted it, Thunderchickens said they clocked us at 2.6 seconds. The key is a strong drive-train and dead reckoning. Many of our team-members have worked on Lego League teams and in that time we discovered that sensors usually, if not always, slow you down. Another way to increase speed is put more than one motor on a wheel. Lastly, curving, not forward, turn, forward drastically increases speed.

[Jack Jones]

Check out:

http://www.soap108.com/2003/movies/il/
Q-matches 20, 33, 44, 56

Appears to me that 2.5+ will just earn a slap in the face; twice, in fact, when the second half of the "one-two" punch comes @ ~5 sec.

I like the idea of knowing what to do when => Go to plan "B" against #71

Jack J.
BTW - Joe, I put together a CD that includes the above - see M. Martus for your copy.

[KenWittlief]

If you make it to the wall in less than 3 seconds my hats off to you!

If you draw out the line your bot follows from starting position, to the boxes, and calculate the max possible acceleration, including the turn, then you are pushing the laws of physics to get there in less than 3 seconds.

Im not saying it cant be done ( didnt you see the :c) in my post?)

if you are getting there really fast you must have sacrificed something, accuracy, weight (how heavy is your bot?), number of boxes you can hit...

Getting to the wall first is not the whole story - you want to take out 3 or 4 columns, push ALL the boxes into your scoring zone, do it consistantly

and still have a bot that is able to push other bots around, hold its own on top of the ramp...

I wouldnt be too sure about a 180 turn being faster than a V turn. either way your bot starts out heading south, and it has to accelerate to head north - whether its by a sweeping 180 turn, or a back and forth V turn - you are still converting all the momentum of your bot from one direction to the opposite direction.

Gettting their first makes a big difference:

1. you hit the boxes first, you send them flying in the direction you choose - sometimes over the top of the slower robot coming up the other side

2. you have more momentum when you hit the slower bot

3. you are on your way DOWN when you hit the slower bot - gravity is on your side

4. your bot is more stable hitting another on the way down, then being hit on the way up - less likely to be tipped over backwards.

Our general strat at the Canadian regional was to let our auton mode hit the wall fast (we got it down to about 4 seconds) - our flying squirrel spanned 5.5 feet and always took out at least 3 columns - the bot stopped in the scoring zone so the boxes were all 'keepers'

and then we pretty much stayed on our side of the ramp to get as many boxes in the zone, protect our stack, build a stack if we needed to

then hit the ramp at the end.

We were doing very well with this strat in Canada. We were ranked 8th in our second last seeding match, and were averaging 140 points (winning most of the time).

We lost our last match and dropped to 16th, but we were picked in the first draft by the 5th ranked team.

[DougHogg]

Kingman, Team 60, joined the "3 second to the top" club Thursday at the S. Calif. Regional.

They were clocked 3 times getting to the bins in 3.1 seconds.

[Gope]

Originally posted by KenWittlief
If you draw out the line your bot follows from starting position, to the boxes, and calculate the max possible acceleration, including the turn, then you are pushing the laws of physics to get there in less than 3 seconds.

The problem with your calculations is that you most probably did everything with linear movements which are very slow at turning. However, if you use radial movements (maybe a turret wheel or a deployable caster) your turning speed as considerably higher and thus it is very possible to hit the boxes in 2.5 seconds or maybe even less.

[Joe Matt]

My philosophy on ramp speed is this: slow and steady wins the race, sometimes. You have to find out how well your opponents do on the ramp to accurately get on top and do some programing on the fly. I think if you go slower than usual and get more bins and are more accurate, then that's the best idea for slower opponents. But for a fast bot, a one time sprint would be worth it in the long run. I stand by our mentor Mr. Cook in saying that auton is a PART of the solution of the game. The rest is robot capabilities and driver control.

This game cannot be won by auton. Ever. I even have proof if you don't believe it.

[KenWittlief]

getting there first isnt everything,

unless you are 100mS too late and end up inverted

ask Code Red!

http://www.chiefdelphi.com/forums/pictures.php?s=&action=single&picid=4722

PS: thats us with the blue lightning striking the wall, 578

[Kojib]

Originally posted by KenWittlief
If you make it to the wall in less than 3 seconds my hats off to you!

If you draw out the line your bot follows from starting position, to the boxes, and calculate the max possible acceleration, including the turn, then you are pushing the laws of physics to get there in less than 3 seconds.

Im not saying it cant be done ( didnt you see the :c) in my post?)

if you are getting there really fast you must have sacrificed something, accuracy, weight (how heavy is your bot?), number of boxes you can hit...

Getting to the wall first is not the whole story - you want to take out 3 or 4 columns, push ALL the boxes into your scoring zone, do it consistantly

and still have a bot that is able to push other bots around, hold its own on top of the ramp...

I wouldnt be too sure about a 180 turn being faster than a V turn. either way your bot starts out heading south, and it has to accelerate to head north - whether its by a sweeping 180 turn, or a back and forth V turn - you are still converting all the momentum of your bot from one direction to the opposite direction.

First of all, in my opinion literally impossible and "pushing the laws of physics" basically means it can't be done, but like I said that was my opinion. Secondly, our robot weighs approx. 129 lbs (depends on elevation and scale), we sacrificed accuracy to a certain extent, but we're always within a few inches either way at the top of the ramp. Third, I don't see how a 180 degree turn isn't faster than a V. Although you are converting all your momentum from one direction to another, you constantly have momentum in a 180, which gives you a consistently higher speed (you have to stop in a V, not a 180). Add this to the fact that unless you make a very wide V, you cover less distance in a 180 and the 180 is definitely the faster option.

[David Lantz]

It seems to me that our V shapped path has worked well. Not only are we very consistant with hitting the bins but we are able to "aim" the bot acording to it's origional position. We've also found that our bot will pick up it's front two wheels when turning do to the drastic change in speed.

[ryanspensley]

Originally posted by David.Cook
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Final Final Comment: <rant> Why doesn't anyone really try to maximize the score by balancing the bin count on both sides?????
I mean, even if both teams have only a two stack left, you still really want to win with 20 bins on one side and 21 on the other - YOU GET WAY MORE QP THAT WAY. But every match I see the same thing, the team gets 95% of the bins on their side, and then make the ultimately unintelligent move of proceeding to clear the rest of the bins off the opponents side. Geez, those are 2-for-1 points you are losing. If you take out the 4x multiplier, you have divided you QP adder by 8! I really thought teams would understand that you absolutely WANT a close match. I am not talking about fixing matches - BOO! I just think before the drivers get caught up in the Battlebot mentality they should consider whether they want enough points to be able to pick their alliance at the end of the day. </rant>
Sorry if I drifted off topic a little *cheesy grin*.



That is a good point. Someone suggested we make our arms longer so we can take them all but, this is why we didn't make our arms longer. Our robot goes up the ramp and we take out the 5 stacks of bins in the middle in about 5 seconds. That gives us a good share of them, but leaves some to fall on the other side.

[DougHogg]

We changed our robot location and our autonomous program, and our long arm is now getting to the stack at about 1.5 seconds. (It turns out that we hit the stack faster one way than the other since the motor is slower in reverse.) We also knock the bins down much faster, hitting the whole stack at once (except the last column).

As to what happens when a bot hits the bins from the other side at 2.6 seconds right after our arm, hm...I don't know, but I hope we make it to the finals to compete against Team 16 and find out. And then there is Team 71's arm hitting the stack in 2 seconds, last video I saw. What happens if our arm is competing against theirs. Hope to see that "quick draw" contest also.

Of course, there are a number of other teams who get to the top at around 3 seconds, so...it should be an interesting weekend at the Nationals.

We look forward to seeing you all there.

[Stephen Kowski]

Originally posted by KenWittlief
fast and consistant is the trick.

If your bot is fast you cant possibly follow the line

and the gyro limit is 180° in about 3 seconds (so if you turn faster than that, the gyro output is meaningless)

if these teams are hitting the wall in 3 seconds they most likely are running completely blind (dead recogning with no sensor inputs of any kind)

if they hit the wall in the center every time that is impressive

going that fast your wheels have to be slipping / spinning

can we get anyone to fess up? how do you find the wall that fast?

no no no if you hit the wall accurately in 3 seconds you do not HAVE to be running blind.....we have sensor inputs that makes us accurate every time in 3 seconds. plz stop by our pit I'll explain it....it is actually pretty simple.

[Powers]

we use dead reckoning, but we also have front wheel steering, so we powerslide

[Ricardo@314]

Hey all of you guys look at this. I am from team 314 you guys are boasting about your speed well think of this you don't have to go up the hill to hit the stack. We sit in place launch an arm out like a baby gate and sweep over the stacks. we hit 5 of the seven stacks every time. The cool thing about it is robots have tried running into us, but it doesn't affect us like team 71. we start our robot in low gear and drive in reverse as it is sweeping then drive forward and reel it in. And the amazing thing is we hit the stack in 2sec> so stop being cocky if you want you can see us at the ford sweet repeat and the kettering kickoff and we will put you in your place!

[KenWittlief]

if you run a 180° arc to get to the ramp, then most robots (if they use tank steering) must have the motors on one side running backwards to make the bot turn that fast

but if you do a V turn you can use all motors full speed in one direction, make a very small turn, then use all motors full speed in the other direction. the end result is you get faster acelleration because your motors are working together, instead of fighting each other during that long turn.

BTW - momentum wont carry you through a turn - try it with a toy car sometime- turn the front wheels and give it a push - it wont go all the way around a circle from momentum alone.

The laws of physics remain intact - if you start out in one direction and end up going in the other, then somehow you had to overcome all the kinetic energy from the first, and add enough to accelerate in the other direction. All that energy had to come from the battery, and with the 120A breaker, you have about 2HP to work with. To get to the wall in less than 3 seconds you need to have your wheels pulling more than 1g of acceleration - not impossible, but it takes a great deal of careful design to pull it off.

BTW - the fastest possible way would be to have your BOT leapfrog over the edge of the ramp and hit the wall- it would take the same amount of energy to get from the starting point, to the wall, and you would be taking the shortest possible path (a straight line).

The wally arms are cool - but I have not seen one yet that does anything but knock part of the wall over, leaving the bins still on the ramp. If a bot is coming the other way with a plow, they are going to push the fallen boxes over the ramp and into their scoring zone - you dont get any points for knocking the wall over.

you need to push them into the scoring zone to get points, and if your bot is still in the starting box at T=15, you have a lot of catching up to do to get to your side of the field.

[RogerR]

Originally posted by Ricardo@314
...we will put you in your place!

I find it amusing that your apperently superior robot was unable to qualify for nationals

[DougHogg]

Originally posted by KenWittlief
The wally arms are cool - but I have not seen one yet that does anything but knock part of the wall over, leaving the bins still on the ramp. If a bot is coming the other way with a plow, they are going to push the fallen boxes over the ramp and into their scoring zone - you dont get any points for knocking the wall over.

you need to push them into the scoring zone to get points, and if your bot is still in the starting box at T=15, you have a lot of catching up to do to get to your side of the field.

Actually I just reviewed a video of our "wally arm" and even with a robot coming the other way, we still got 10 of the bins into our scoring zone with about 10 more on the ramp. True, the robot coming the other way in this case didn't have a big plow. We will have to see if robots at the nationals can catch the bins and push them back over the top during autonomous.

Also we don't stay in our starting box. We stow our arm and head for the ramp.

[The Lucas]

Originally posted by KenWittlief
if you run a 180° arc to get to the ramp, then most robots (if they use tank steering) must have the motors on one side running backwards to make the bot turn that fast

but if you do a V turn you can use all motors full speed in one direction, make a very small turn, then use all motors full speed in the other direction. the end result is you get faster acelleration because your motors are working together, instead of fighting each other during that long turn.


V turn is does not necessarily faster then a 180 arc. For a V turn you have to accelerate the motor, decelerate motor, turn, then accelerate the motor in the opposite direction. We tried it initially on our tank drive bot and it took about a second longer.

We have a decently fast bot for a internal stacker (If we went much faster we would probably tip :D ). In our main auto mode (we have like 5) we take bout 5 secs to hit the bins and take out all but one or two three-stacks.

A better way to make the turn is with some sort of steering other than tank, so u can go full forward with both sides the whole way. Whether it is front wheel steering, swerve or crab drive steering, the turn will involve less wheel slippage and more power than tank. Some robots can pull off a slide (with casters perhaps) and that works very well too.

[KenWittlief]

stopping the motors and accelerating the motors is nothing compaired to accelerating the whole robot - try it with your wheels off the ground. the motors (and wheels) have very little mass compaired to the rest of the Bot.

If nothing else, this years auton mode sure has been a great format for the physics of motion, energy, power...

[Joe Johnson]

You would be surprised how much energy is stored in the motor armature when it is spinning at 20,000 RPM.

I * Omega^2 terms can get to be a significant fraction of the total energy of a system.

Just my two cents...

Joe J.

[Ricardo@314]

hey man why are you trying to put us down?
we didn't go to nationals because we ran out of money.
We went to four regional and we are going to two off season tournaments one of which we set up.
So like i said come to the ford sweet repeat in Rochester hills, MI
or to the Kettering kickoff in our home town flint, MI.

And get put in your place!

[J Flex 188]

i dont necessairly think he was trying to put you down.. but the connotation of "put you in your place" is somewhat arrogant and superior. which is exactly what you told other teams to stop doing when they were discussing their own robots..