Similar Systems
 

I always hate tooting my own horn, but I have to on this one.

We have a system that is very similar to WildStang's. We implemented our's slightly differently due to the lack of crab steering on our robot, though.

Unfortunately, we didn't work as well as we could have at the GLR since we had some mechanical issues in the system (our measurement wheel was losing contact with the ground), some electrical issues (an ESD filter caused us to miss some wheel rotations), and some software issues (a systems bug caused us to shift gears at the wrong time in our first 5 matches).

As is typical with our team, we finally got it together just before pit close on Friday night (check out our team record at our 1st regional of every year and you will see that this is what we always do - but we always get much better VERY quickly). Our autonomous mode ran nearly perfectly in our ONLY match on Saturday, which was just too late to matter (esp. considering the match was the 2nd to last match so probably no one was watching).

Anyway, we do a couple of other cool things that I don't even think WildStang does, which we haven't shown yet. I would like to invite everyone at the West Michigan Regional (we're going now!) to come check them out. We know we'll be using them there.

Sorry for the shameless plug (not really),

Chris

I have posted a zip file containing screen shots of WildDraw in our public forums at http://www2.wildstang.org/phpBB/view...hp?p=4050#4050

WildDraw allows us to generate waypoint lists that are downloaded into the robot controller. We can accurately make additions and modifications to our existing lists with a fiew mouse clicks.

WildDraw is a constantly evolving application, so stop by at the Midwest Regional or Houston and we'll be happy to give a demo.

Very Cool
 

Dave,

That's a great system you guys have. We don't do a waypoint map. Since we don't have crab steering, the way we did it seems to make more sense for us.

We did all of our autonomous controller in Matlab/Simulink and it was auto-coded using TargetLink from dSPACE. We developed a mathmatical robot model so that we can simulate the robot path in Simulink before we upload any desired paths to the controller. By doing it this way, we actually have 128 different paths in our controller and we have room for up to 123 more. It usually takes us about 5 minutes to create a path, test it in simulation, and then upload it to the robot controller.

After the simulation is done, we can plot all of the results just like in the attached plot.

I wish we didn't have all of the previously mentioned problems on Thursday and Friday, but we should be ready to rock once we get to West Michigan. I hope people can come check it out.


-Chris

Re: Re: StangPS
 

Matt,
Sorry I missed talking to you between all the times we were in each other's pit. We are using the same system many teams were using for counting rotations. Two light sensors aimed at alternating reflective/non-reflective spots on the wheel. For those not familiar with the system, two encoders placed such that the outputs are in quadrature (i.e. 90 degrees apart) will allow both direction and tach to be determined. Our sensors do have some limitations but the errors are minimal for the required 15 seconds of autonomous mode. In looking at other teams, we are not entirely unique in looking at the problem or solving it. It seems that at least 20 teams at GLR had a good way to determine length traveled and direction. Many will tell you that non-stacking robots were the rule, but those that did stack were engineering marvels and true crowd pleasers. No doubt about it, GLR is a good (and difficult) regional, no wonder it filled up on the first day. Hope to see you all in Chicago for the Midwest. If you have any questions before you come, drop me a line.

Chris

That's pretty neat. Simulation is an important tool in engineering. We are working on incorporating some into our system.

How do you feed Matlab the information on where to go? Where does your auto code get loaded? I'm assuming it goes onto a custom circuit. What is your interface to the RC? Does it end up being a dead reckoning system?

Dave

Our system
 

Dave,

Instead of waypoints, we use more of a "path following" technique where we know the shape of the path so we can set the control algorithm up to stay on the path.

The generated code is run on a Motorola HC12 on a custom circuit (all Thursday we struggled with a micro reset issue that we finally tracked down after our 3rd practice). The custom controller sends a 0 - 5 V signal to the RC and the RC just simply reads the signal at the A/D and spits it out to the PWM. We also use the digital inputs to control the arms and other stuff.

Every part of the algorithm is closed loop, so it's not at all dead reckoning. Once during testing we forgot that a stack of chairs was sitting in the path of our right arm; we were able plow through the chairs and track our path without problem.

I was talking to Mike Soukup at the Regional and we were comparing controllers. It seems that they're quite similar (we're using the same measuring techniques as well). We found that one nice thing about have a guidance system is that we can test it on concrete or carpet, good or bad battery, high or low gear, and it really doesn't make much difference to the result. The only real difference is that carpet adds more damping so our settling time is faster on carpet than on concrete.

Anyway, good luck to you guys this week and at Houston.

-Chris

Re: Re: best technical feature at GLR
 

Tom & others who have asked for it, here's the video. It's obviously not our team's finest moment since it wasn't an excellent match, but it's a good showcase for how StangPS can almost always help us recover from bins/walls/robots in our robot's path.

http://www2.wildstang.org/2003/video/gl_062.asf

wow i am so glad we someone else decided to do something other than dead reckoning. Our Machine (yes it happens to be pink) uses the same gyro and counting wheel to determine direction and distance, it can move up the ramp and fight almost intelligently. The only thing we lack is a smart custom circut, all we have is one that reads the holofect sensor on the counting wheel (it uses a magnet to measure passes in 8in intervals) and tells the base control chip that it has gone 8 inches, the chip then counts and we can tell how far we have gone, in the same time the chip calculates that if the robot hasn't moved in so many cylcles and the motors are at full it backs up and trys again, and it fought and spun out a robot @ UCF.

Congrats on your design, i should like to see it in action, you going to nationals???

Yes, we'll be there. We'd love to have you stop by if you have time. I'm looking forward to checking out all these teams who did something other than time-based dead reckoning! As a side note, while our setup may seem overkill, I should point out that it was basically a requirement for us. The way our crab drive works, our orientation often drifts when we try to drive in a certain direction (especially sideways). Because of this drifting, time-based dead reckoning probably wouldn't work at all for us, or at least it would be very inconsistent. I guess I don't know for sure though as we commited to our current method 100% from the beginning. We never even tried a time-based program...

Wow! I didn't know both 308 and 'Stang used a guidence type system!! That is extremely cool!! Never thought of using an NC path type system. Of course all this fancy electronic, Black magic stuff is still a little out of our reach. Our arm driver and the coach, worked on the autonoumous process during the build season and decided Dead reckoning was the best way we could go with without having to create custom circutry. Seems to work pretty well. Our Auton mode is extremmely fast and consistant(when the Controller is functioning properly!) 33,217, 226 and 65 were also very fast and consistant. And those are only the ones I can name off the top of my head, I know there are many fast, consistant machines out there. I believe we are all in the 3.15 to 4.5 second range.

I was in 111's pit several times marvelling at the craftsmenship and awesome engineering invested into 2 complete chasiss!! You guys are amazing!! I love all the press brake and waterjet work done on your machine. Then to top it off you have this really cool tracking system. Maybe you guys should be building the next Terminator! Truly amazing. Team 27 would also like to thank-you for letting us use your drill press this weekend. You guys are truly gracious and it was an honor to play with you this weekend. Our match is one of my two favorite matches this last weekend. The other was with 302 in Qualifying match #102. Good luck in Chicago! Hope to meet you again in Houston. :cool: