best technical feature at GLR

[Ken Patton]

imho:

Wildstang's guidance system. I watched a match where in autonomous mode the robot hit a wall that it wasn't supposed to hit, corrected itself, climbed the ramp, knocked over some bins, and got into a position where it could defend a human player stack. Three things were obvious to me:

1. This robot knew where it was
2. This robot knew where it wanted to go
3. This robot had the means to get there

wow

Ken

[Brandon Martus]

yes, i agree.

wildstang's robot = wow.

[Tom Schindler]

Originally posted by Ken Patton
imho:

Wildstang's guidance system. I watched a match where in autonomous mode the robot hit a wall that it wasn't supposed to hit, corrected itself, climbed the ramp, knocked over some bins, and got into a position where it could defend a human player stack. Three things were obvious to me:

1. This robot knew where it was
2. This robot knew where it wanted to go
3. This robot had the means to get there

wow

Ken

Does anyone have video of this match? i'd LOVE to see it

Tom

[StevenT]

1. This robot knew where it was
2. This robot knew where it wanted to go
3. This robot had the means to get there

Thanks for the compliment and thanks for noticing! I'm so glad that someone not on our team realized what happened during that match. The students and adults that worked on our positioning system (called "Stang Positioning System" aka "StangPS") thought that was great but we figured that no one else would appreciate it.

Your three observations above are exactly correct.
1)The robot knows where it is by using our custom circuit (with a Motorola HC08 processor) that reads a homemade encoder wheel, the gyroscope and the wheel direction pot. The pot tells the custom circuit where the "crab" wheels are pointed relative to the frame of the robot. The gyro is integrated to tell us exactly where the robot is pointing on the field (like a compass). With that information, as the wheel moves, we can map our current location to an X,Y coordinate on the field. So, the custom circuit always knows where the robot is on the field (within about an inch...although position is reported to the RC in 2" increments).

2/3)The robot location is passed from the custom circuit to the RC, which is programmed up with a list of X,Y "waypoints" on the field. Each loop, the RC uses trigonometry (TAN) to calculate the angle the that the "crab" wheels need to be pointed so they are always aimed at the next target waypoint (what a great real world application of trigonometry!) Anyway, the robot can be pushed off course or twisted but we will continue to try and get to our next waypoint.

We also have some features programmed into the RC where we will determine the most efficient direction to aim the drive wheels to get to our next waypoint. I can go into details, but the idea is we don't program in how to drive the wheels, we program in waypoints and the RC figures out the most efficient way to get to that waypoint based on its current location on the field.

One other nice feature is that the robot is constantly correcting its angle (or compass reading) on the field so that it will hit the bins exactly square with the wings every time. The match you were talking about, we ended up getting turned so much by the wall that we couldn't correct fast enough, but in a normal run we will hit the bins perfectly straight every time. Even if we are hit and twisted, or a bin is placed in the way we will constantly correct.

There were numerous WildStang members at GLR that were taking video of the matches for soap108.com, so I'll make sure that someone posts a link to the video of this match.

I'll also have someone post screen shots of the computer program we have that allows you to click on points on the field and this program will output the waypoints that are programmed into the RC. This allows us to write new programs or make modification while at a competition.

We have a few students that wrote the majority of the software logic in the RC (with help from the engineers) to implement this autonomous operation and I am sure they would be happy to explain it in more detail either at the Midwest Regional or on this thread so feel free to post any questions you might have!

PS: Here is why we hit the ramp wall in the first place...Just prior to that match we had a problem with the chain on our wings and we were working like mad to fix it prior to the match. We were in the pits and actually saw the video feed of our match being setup on the field. We ran down the hallway and onto the field. In the rush, we didn't setup our wheels to be aimed in the correct direction. Since our wheels only have 360 degrees of rotation (not continuous turn) the RC ended up calculating that our only way to get the top of the ramp was to reverse the direction of the drive wheels (instead of the usually smooth arching turn we usually use) and this caused us to hit the ramp wall...for a bit!

[goegan31]

Wow, that is really impressive. My team currently wants the same, rather, out mentor does. And as the team programmer, It hasn't been easy so far. I hope to have something only minutly close to what you have by houston, but wow! Good job. My hat off to you guys!

[RogerR]

stangPS sounds nuts, I can't wait to see it at nats.
how fast do ya'll ussually get up the ramp?

[Matt Reiland]

Wildstang was nuts out there, especially how it showed up at the end of autonomous ready to defend the stack. Wow, what a pain it was to try and get around them too. We ended up stuck on them for almost the entire match (Never thought of the robot going up that steep of an incline, the back bottomed out)

I think the 'only' logical way to beat Wildstang was to double team them from two angles, since they are so mobile with the steering, then like Truck Town in the finals, lock them in between the ramps.

I would definately like to know more about this positioning system, maybe after nationals you guys could explain it a little more in detail to all of us. We partnered with you guys a few times, and even though Raul said it would eventually find its way, I never realized it had that much intelligence. Every year I am amazed at the quality and content in the 111 robots. The machining and build is top notch, fantastic robot Wildstang.

[ntroup]

Thanks for all the compliments, everyone! I think Steve did a great job in the overall description of StangPS. We will definitely welcome everyone to come to our pits at Midwest and Nationals for a demonstration. It's been quite a rewarding accomplishment, and there's still more to come.

In regards to RogerR's question about how fast we can get to the top of the ramp, I think I can safely say that we can do it right around 4 seconds, give or take. After Great Lakes, we saw some great machines race to the top, and I think we are right around those times. Although, Baxter Bomb Squad (16), who we saw in St. Louis, is very fast!! I fear (and look forward) to competing against them!

[Adam Y.]

The gyro is integrated to tell us exactly where the robot is pointing on the field (like a compass). With that information, as the wheel moves, we can map our current location to an X,Y coordinate on the field. So, the custom circuit always knows where the robot is on the field (within about an inch...although position is reported to the RC in 2" increments).

We need to talk. I have been wondering about attempting the same thing on a few robotics projects of mine and It could help if I talk to you.

[Matt Reiland]

Originally posted by StevenT


Your three observations above are exactly correct.
1)The robot knows where it is by using our custom circuit (with a Motorola HC08 processor) that reads a homemade encoder wheel, the gyroscope and the wheel direction pot. The pot tells the custom circuit where the "crab" wheels are pointed relative to the frame of the robot. The gyro is integrated to tell us exactly where the robot is pointing on the field (like a compass). With that information, as the wheel moves, we can map our current location to an X,Y coordinate on the field. So, the custom circuit always knows where the robot is on the field (within about an inch...although position is reported to the RC in 2" increments).

Based on what you said above, if your robot is up against a hard barrier and is spinning it's wheels, will it throw off all of your calculations because your encoders would be still spinning? Or is your encoder non-powered so that it just follows the terrain and doesn't spin when against a barrier. I would definately like to know more about this 'Wild' system.

[StevenT]

Based on what you said above, if your robot is up against a hard barrier and is spinning it's wheels, will it throw off all of your calculations because your encoders would be still spinning? Or is your encoder non-powered so that it just follows the terrain and doesn't spin when against a barrier. I would definately like to know more about this 'Wild' system.

You are correct that "if" the wheels started spinning it would throw off our position calculations, but the wheels have a gummy belting on them that doesn't slip easily. When we run up against a wall on the carpet, we end up stalling the motors.

Early in design, stalling the motors became a major concern for us in autonomous mode so we also created a board that is capable of measuring current draw on our motors so we could detect a stall condition. We shipped the board with our robot but we haven't spent any time actually integrating it into the StangPS system. Our current monitoring is almost exactly what we used last year ("StangSense") to report motor current back to a Palm that was connected to the OI. We hope to work on integrating those two pieces together and have it working before Houston, but we haven't found that it as necessary as we expected during early design since we haven't run into a stall condition for more than a few seconds.

[Don Wright]

BTW...your robot was my (and my dad's) absolute favorite at the GLR hands down. I was very disappointed when you didn't make it further. I just wish I made is over to your pit to check it out in person. Maybe I'll make it to Houston and check you out there!!

Thanks for the inspiration to create something as awesome as this next year!

Good Luck!!!

[WernerNYK]

This is a system that is very similar to what we have. We have what is called INS, Inertial Navigation System. Not being a part of the electrical design team, I do not know the fine details of it all, but I can give a brief overview, and a detailed whitepaper is in the works.

We spent very much time debating how we should approach the autonomous time. After some debate, it was determined that dead reckoning and line tracking would not be very accurate or very quick, respectively. An encoding wheel was discussed, but again... if we are up against a solid stop and the wheels spin on the carpet, our calculated position is no longer the same as our actual position.

Soooo, using a gyro chip and dual-axis accelerometer, we are able to determine our exact position on the field. Our gyro operates in very much the same way as 111's, securing us with "heading hold" to ensure that we are perpendicular (or parallel depending on how you look at it) to the ramp, and if we get spun around will take the most efficient wheel path to correct itself. The dual-axis accelerometer reads the X-Y acceleration of the robot on the field. We take the double integral of these values to read X-Y position. By converting these "INS units" to real-life units, we are able to tell the robot where to move on the field, using knobs on our human control station; we can chose X and Y position -- the ability to choose which side of the ramp to go up, and how far to go along the ramp. We also account for the angle of going up the ramp, because our acceleration is now being miscalculated because of the 32 ft/s downward acceleration which now becomes a component of the X-Y coordinates. Possibly under development is way to detect if we are flipped during autonomous which would allow us to self-right ourselves autonomously!

I am not too sure of WildStang's drive system, but it too seems as if it may be similar to ours. Our robot name this year is "King CrabGoat 2k3." Perpendicular to our main drive wheels, we have a fully redundant driveline that is known as the "crab system." These 4 kicker wheels drop down in 0.2 seconds and lift the entire robot with an over-center mechanism, so we are able to almost instaneously change our direction of movement 90 degrees.

Up to this point, I had not heard of any other team using an actual "guidance system" such as we have done. I give congrats out to WildStang, and would definitely love to see it in action.

[JVN]

Originally posted by WernerNYK
Up to this point, I had not heard of any other team using an actual "guidance system" such as we have done. I give congrats out to WildStang, and would definitely love to see it in action.

Well,
Wildstand USED StangPS this past weekend. I was under the impression that the CragGoat still utilized a simple dead-reckoning based code in competition up until this point.

Maybe by Seattle you'll have your INS working?

Great Job Stang!
It's amazing to see your system really working! It's amazing to think that even if your robot hits a wall, it is "smart" enough to correct itself.
Do I "sense" a technical award coming your way?

[Mike Soukup]

Originally posted by JVN
Great Job Stang!
It's amazing to see your system really working! It's amazing to think that even if your robot hits a wall, it is "smart" enough to correct itself.
Do I "sense" a technical award coming your way?

Thanks John (and everyone else) for the kind & encouraging words. It was exciting to see the robot perform in competition (well, I actually came back home on Friday morning so I only saw it in practice) and hear what others had to say about it. The software/firmware students & engineers have been working on StangPS almost daily since mid-January and we're happy we finally saw it in action somewhere other than our practice field. All the hard work was certainly worth the results.

I don't know the full story about the judges & awards at GLR since I wasn't there, but the story I heard is that the judge who talked to our students didn't want to hear about our custom circuit or autonomous program because he was a mechanical engineer. Oh well, maybe we'll get an EE or CompE to talk to us next time. I just want our students to get the chance to describe to the judges the system we're all so proud of

Mike