So this year the RoboBroncs tried to be really methodical about designing our robot. Last we built a good robot only to find that capabilities we had given it were not those that a robot really needed to be successful. This year we decided to record all the decisions we made and why we made them, and here are the results: http://www.chiefdelphi.com/media/papers/2457
Just as a note I did not include our end effector investigation or our motor/gearbox selection, because both were a little skimpy without the physical prototypes and testing recored.
I wondered how our system compared to that used by more experienced teams, I don’t know how a typical design process would work and based this off of my experience with the Project Lead The Way program at my high school. Does anyone else have records of their design process??
In case you wanted to see, this is the robot that this design process created:
Your design process is fine. I would have included 6 and 8 wheel skid steer in your drive selection options, but other than that everything looks good. The secret is in applying the correct weighting factors to each of your categories. We’ll know that your’s were correct if we see you on Einstein!
All the presentations were looking good, but I got to the drivetrain one, and I started thinking about what it looks like you guys do.
It appears that you were indentifying what you could do (ie mechanisms) before you knew what you wanted to do. We do the complete opposite here.
I also have a few questions about how you describe a few of the drivetrains. (note: I am not trying to criticise, I’m trying to learn.)
What makes mecanum “very stable at high speeds”? Ussualy, mecanum wheels are not round, seems like that would make them unstable to me.
As per the final tables at the end of your presentation, I’m curious what you might have been thinking.
What makes a swerve slow? I realize you talk about more internal friction, but many times, a swerve is done with fewer gear stages than a comparable 6wd or mecanum.
I’m really loving the use of more complex design matrixes (matrice?) and the “look back” or judgement based on the matrix, but not the final descision based on the outcome of the matrix.
A solid design process = a solid robot. Looking good for years to come and 2011 :D.
The Mecanum wheels were considered more stable at high speed, because when they sustain and impact from a wall or other player the wheel tend to drift. Skid drive and higher friction/torque drive trains tend not to slip and instead create higher lateral load which make a robot more likely to tip, or sustain damage.
Swerve drive I will be honest, is something I am very unfamiliar with. I have never built a swerve system or had the chance to see one up close. I believe my thinking on this was that the swerve would require more of the drive motors to be used for steering, and would then have less available wattage, and that the linkages to transfer the swerve power had difficulties with seizing and clogging. This was based primarily on observation of the Haywire Robotics 2010 robot which was noticeably slower than other robots, when it used swerve drive.
The reason we find all possible solutions first is because it doesn’t matter how objectively you can observe an idea, unless you can come up with the right idea in the first place. For instance take the arm made by team 842:
The basic concept for their arm using the stationary gear linkage, was never considered for our team before hand, because we never thought to use something like that on a FIRST robot. Unless you can see all of the options, how do you know you are picking the right one?
I hope this helps and clarifies people’s readings, I really more wanted to see how other teams handled the design process, since there does not seem to be a lot of material out there.