WildStang Videos

[Raul]

Check these out at:

http://www.wildstang.com/2001/video/video2002.htm

Comments?

[Ken Leung]

Originally posted by Raul
Check these out at:

http://www.wildstang.com/2001/video/video2002.htm

Comments?


VERY COOL swerve movement. Although I thought last year's music was better, I like this year's robot better ;)

With this kind of swerve movement, it should be really easy to get the balls with your ball collector. I especially like how you shoot the balls into the goal. Looks like the whole robot can store only about 12 balls, but the speed of dumping balls into goal compensate for that.

Is it hard to control the robot? I have always wondered how to successfully control a swerve drive... But it looks like the driver perfected their skills and the robot can grab the goal and balls easy. I see it can grab two goals, maybe even three if it wants to. Not especially fast speed, but plenty of pushing force and great maneuverability.

Should be your most complicated robot... Great job! Hope to see it in video, or at National. There is no question whether this bot is going into finals or not. There should be a spot reserve for you in the Championship event finals. With enough luck, you might find a good enough alliance partner in your division to push you far into finals. ;)

Too bad you have to damage your last year's robot at the end of the video ;)

[Wetzel]

Nice. Just the one joystick? Or am I confused after looking at to many control systems today...

[Don]

I am wondering about your drivetrain. I see the wheels that you use for your swerve drive, but looking at some pictures I also see that you have a small track system with cleats, powered by two chiphua motors. Is that an old design or are you somehow incorporating both? How does it work?

[Wetzel]

Originally posted by Don
I am wondering about your drivetrain. I see the wheels that you use for your swerve drive, but looking at some pictures I also see that you have a small track system with cleats, powered by two chiphua motors. Is that an old design or are you somehow incorporating both? How does it work?

I didn't notice that, but I went and looked at the photo gallery. From watching you move crab like, I assume that the treads rise up off the floor to crab, and lower for traction?
I also couldn't find a good pic of it on the bot, but I think I saw it burried in the middle.

[Raul]

Yes, it is an auxillary tank drive system. It gets deployed (lowered to the ground and actually raises the robot off its wheels) when we want to push hard. I am about to tell you more than you probably care to know about it.

It is geared down to the point where it can only move 8 inches per second max. It can produce approximately 2000 lbs of trust at stall. Needless to say, it will never stall - its not really possible to get enough traction to do that.

We would obviously only use it when we get in a pushing match when attached to a goal that is lifted enough to transfer some weight to our frame. We did not use it much in our practice competition. We only used it as an anchor so we could not be moved when we were happy with our position.

By itself it looks like a mini tank robot. There are lots of pictures of it here (its is a spare one we built): http://www2.wildstang.com/2002/invitational/wsinvite2002_page2.asp
You can navigate around our website and see lots more pictures and videos.

It is very modular. We can remove it by removing 2 pins, the seatmotor flex shaft which raises and lowers it and disconnecting the motor wires. It weighs about 16 lbs. So we can remove it when we want to add some other functionality and still be within the legal weight limits.

Its mounting scheme allows it to swivel in two independent axis so that it can always maintain flat contact with the carpet.

I hope that is enough details. We will have the spare to show at the competitions we attend.

[meaubry]

Raul,
Very impressive (as we are used to from you guys) Good Luck this year, Hope to get aligned with you many times. Oh, by the way - do you have to weigh in multiple times with various combinations of modules or can you weigh in once with all the stuff attached?

[Matt Reiland]

I am again amazed at how much stuff you guys get in there for 130 lbs.

[Raul]

Thanks Matt.

Mike,
We had to weigh ourselves 3 times last year during our inspection to cover our 3 possible configurations. Depending on how things go this year, we may have up to 5 unique combinations that we will have to weigh in with. But I doubt we will sue that many throughout any competition. The combinations we use will depend on strategy and what is working well to help us win with certain partners.

Our modular components are:
- Tank drive
- 2 goal hooks
- Ball accumulator and shooter
- Ball plow/concentrator
- "go-home device"
Some of these modules change out very quickly - like the hooks. Others can take a few minutes.
The last two need to be finished at the competition and the "go-home" device may not be used at all. This depends on how refs call entanglement in previous competitions - we will be watching this closely to decide if it will be a legal device or not.

[Mike Soukup]

Originally posted by Wetzel
Nice. Just the one joystick? Or am I confused after looking at to many control systems today...
I hope I'm not giving away any trade secrets, but I doubt it since many teams have developed their own crab / swerve drive.

The driver uses 2 joysticks. The right stick is a cross between a standard 1 stick robot drive and a car - forward moves the bot forward, back moves it backwards, right turns the front wheels right and the back wheels left, and left does the opposite. The left stick controls crab - move it left and all four wheels turn left, move it right and all four wheels turn right. Each crab motor has a feedback loop so when the driver moves the crab stick 1/2 way to the left, the wheels turn 45 degrees left and stop.

It's a lot easier to control than you may think. After an 30 mins, anyone used to driving a standard single stick drive would be fairly comfortable on it. Mastering the drive is another story, that takes time.

Mike

[Kevin Ray]

You guys should be this year's poster team for Inspiration. You define what FIRST is looking for. Great robot, can't wait to see it up at the Nats.

[foursixnine]

Maybe it's just my computer but I couldn't get the first video(Beware of Wildstang) to work maybe the link is broken.

[Raul]

Try doing a right click on the link and pick "Save Target As". Then run it from your computer.

[Ken Leung]

I got a few questions about the robot, after watching all the cool videos...

1. Is this the most complicated robot you've ever built?

2. How many goals can you get? 2 or 3?

3. What makes you decide how much balls this robot is going to hold? Was it weight, space, resources, strategy?

4. How many motors are you using? (I heard all except the torque!) And how do you deal with drawing too much current?

And the question I want answer the most:

5. Why why why are your robots so cool looking all these years?

[Mike Soukup]

Originally posted by Ken Leung
I got a few questions about the robot, after watching all the cool videos...

1. Is this the most complicated robot you've ever built?
No idea, but it sure does look complicated.

2. How many goals can you get? 2 or 3?
We are limited to two because we use the window motors to drive our hooks. We can put the two hooks in any of 3 places: back, right, & left.

3. What makes you decide how much balls this robot is going to hold? Was it weight, space, resources, strategy?
This was dictated by strategy. Some on the team wanted only a couple of balls. Others wanted a lot. We compromised on ~12.

4. How many motors are you using? (I heard all except the torque!) And how do you deal with drawing too much current?
Yes, we're using all the motors except the torque motor. Don't quote me on this, but I think we can get away with this because we don't use them all at once, and they usually aren't under heavy load. Obviously the 4 drive motors & the two crab motors get a lot of use and are under large loads. The tank motors will have a big load, but we usually won't be running many other motors when these are going. The window motors that control the hooks don't get run much at all. And the motors for the accumulator / convayer / shooter do not have much of a load and are almost spinning freely.

And the question I want answer the most:

5. Why why why are your robots so cool looking all these years?
This is an easy one. It must be because of the software team. Sorry Raul, I couldn't resist. Seriously, it's because we have some outstanding mechanical engineers & students who come up with good designs, and we have the resources to turn those designs into a real robot.

Mike

[Raul]

Let me expandon or correct my good SW friend, Mike Soukup:
1) It depends. 2001 rampbot was way more complex mechanically - it required more engineering analysis for strength vs. weight versus power than we have ever done. Electrically, this year's is more complex since we can now monitor current to all our high load motors.
4) We also are not using the small Johnson,and no pneumatics

[Paul Copioli]

Hey Mike and Raul,

Your scheme for crab vs monster steering is very similar to ours. BTW, monster steering is 4 wheel steering, like a monster truck. We decided (or shall I say the students decided) that it would be cool to do all of this with 1 joystick. We do basically the exact same thing as you, but we have the students push the top joystick button to switch between monster and crab.

P.S. - I like the way you guys get the balls from the floor.

Hope to see you at Chicago again this year.

-Paul

[SSwaszek]

I really like your robot. You did a great job in designing it. I'm wondering if I you could tell me what you use to make the wheels turn like they do and how you did it. Also is the software to make the robot drive in the 360 degrees of motion complicated?

[Raul]

Paul,
We will see you at Great lakes and Midwest regionals. We use the botton on the joystick to control two ranges of speed.

SSwaszek,
I was just going to ask you to stop by and see us and I would explain. Unfortunately, your team will not be at any of the events we will attend unless we see you at Epcot.
We use the globe motors to control the angle of the wheels with a chain drive in pairs. Mike explained the feedback controls in a previous post above. The SW is not that complicated unless you attempt to incorporate non-linear response to the joysticks. In 4-wheel steering mode (vs. crab mode) the response is touchy at high speeds unless you use a non-linear response to reduce the sensitivity at low angles.

[Matt Lundberg]

Another Cool Wildstang Robot. Can't wait to see it in a few weeks in IL.

[Matt Reiland]

sswaszek

I posted our code for four wheel steering the the Programming forum it should help you get a basic idea of how to calculate the angle and how to apply speed to the steering motor. The worst part of it is calculating the inverse SIN or COS

[1first]

Hey! Awesome modular design. I was just wondering how fast your robot goes (feet per second)? Do you have only two speeds or more ...? Hope we get paired up with you guys again this year! Thanks for all the awesome memories at Ypsilanti last year.

[Raul]

Only 7 feet / sec.

I guess we are conservative when it comes to running our motors on the low torque side of the power curve. We prefer to be safe and not blow a fuse or burn out the motors.

I am amazed some teams can get away with going more than 10 feet/sec. I guess thats what CVT's or other shifting does for you. Crab or swerve do not mix well with shifting.

Engineering - it's all about compriomises.

[Ricky Q.]

Raul-

Looks nice, you guys have some stuff similar to ours and it should be an interesting competition in a few weeks in IL. Hopefully we both can perform as well as last year. :D

[Perseus]

Whoever did that video with tthe half life music:

THat is one kick a$$ video and i congratulate whoever worked on it.

P.S. Your bot looks awesome and i hope to see you at nationals(hopefully as your partner)

[Jim McGeehin]

You guys make excellent videos. I enjoyed it entirely (not to mention d/ling it in 3 seconds. I still don't know how I did that). We still watch it in the animation studio, 'cause it never gets old.

[Harrison]

I really like the Wildstang's vids...It was a lot of fun watching the bot in action at EMU.

As for speed, our bot we had geared for 10fps...and we had enough pushing/pulling power for sure...But If we had to do it agiain we might slow it down to 8.5 or so, and get that little bit more power.

Getting to the goals quickly seemed to be as important as being able to get in a tug-of-war...10 seemed to fit that balance for us well enough...Afterall 4th aint bad...lol

[Perseus]

How many balls can you get in one "basket"(or whatever the thing is called) full?

also, how many can you gey in like the first 30 sec? minute?

[Harrison]

My teams bot doesn't have ball pick-up...

We're just goal grabbers.

[Mike Soukup]

Realistically we can fit 10-12 balls in our chute. I'm not sure how many we can grab in 30-60 secs, but if I recall correctly, we usually scored 8-15 balls from the floor during our qual matches.

Mike