DEWBOT IX Design Team Page
Student Lead: Molly
Student Sub-Lead: Dhananjay (DJ)
Student Team Members: Jack, Kira, Pat C, Lucy, Tobi, Mike M, Pat D
- Integration-Systems Design Leads: Clem McKown, Siri Maley
- System/Sub-System Leads: Gary Deaver , Ben Kellom, Julie Christopher, Scott Featherman, Frank San Miguel
- Consultation/Components: Joe Morganto, Keith Williams, Session Linsey, Rich Kulik, Mike Rizzo, Mike Geldart, Andrew Weissman
- Post-Season Teachers: Clem McKown, Siri Maley, Julie Christopher, Ben Kellom, Gary Deaver, Mike Geldart, Keith Williams, Heather McKown, Andrew Weissman
- 1 Motor Specifications
- 2 A first look at climbing physics
- 3 Drive Train model adapted for pyramid corner climbing
- 4 Off-Season
Here are the motor specifications and performance curves for the 2013 motors.
A first look at climbing physics
Here is a first look at geometry, power and normal force requirements for climbing the pyramid's corner pole in the 2013 game.
Drive Train model adapted for pyramid corner climbing
The Minibot drive-train model was adapted to work with climbing the pyramid corner. For use as a design tool.
Mechanical Design Training Objectives
Different groups will be completing a of projects throughout the off-season, but there a few skills we're hoping to cover of everyone:
- Strategic Design - weighting objectives, spec'ing fuctions, laying out acceptance tests, systems integration, critical & final reviews, and "staying on the V"
- Electrical Power Considerations - motors, gearboxes, acceleration, speed, torque...not just the physics, but the reason we design differently in various tradeoffs and situations. For drivetrains particularly, but also manipulators.
- Structural Loading - why doesn't (or does) the robot fall apart? Why have different robots failed in different ways, and how could we prevent it (or why didn't we)? We'll be walking through some previous bots/chassis (DB9, DB9 Deux, DB8, DB7 & 5 chassis).
- Detailed Design Tips - different assembly techniques (materials, bolt/nut types, 80/20, welding, rivets) and uses, plus tips & tricks useful at the FRC fabrication levels. There's also rumor of some composite work.
- Steal from the Best - what do the best guys in FRC do, and why? What can (and can't) we do like them?
- Pivot Dynamics - In classic 1640 style, pivot drive is a great case study for off-season. We have several projects around it, but we also want to make sure everyone goes into the season with some background in swerve tradeoffs, structural design, and power/power transmission.
Lesson plans created in order to teach engineering analysis and synthesis on a level compatible with highschoolers.
Primarily as a just-in-time training approach (it's more fun that way!), we've got several FRC design classes in our back pockets. We aim to make them conversational, but if there's interest, just ask!
- Drivetrains: turning, balancing, racing, and pushing [Clem]
- Perennial Mechanisms: why do some teams just keep winning? Well, we don't know entirely, but there are certainly some basic designs and design tenets that just keep showing up. A blitz through the history of FIRST from a designer's eye. [Siri]
- Pneumatics: uses, non-uses, benefits and costs [Clem]
- Kickoff: Christmas for FRC! What happens on this early January game release day? What do we do--what have we done and what may we do differently? How do we read a game? What does the field mean? What do--and don't--the rules say? [Siri; expect a mock kickoff sometime late in off-season]
- Material Selection: composites [Gary], and more, based on interest
- CAD: this will be in some of our projects, but we're also open to running actual classes if there's interest. [Ben, Siri, Clem]
We call them "classes", but don't be surprised if they just sneak up on you in conversation. No lectures required!
Six (Eight) Wheel Drive
Mike Geldart is heading up a six-wheel drive design saga with [[Siri Maley and Andrew Weissman. The mission is a 6wd for 1640's strategy in the 2013 game. We've gone through the basics of KitBot style (fully supported) and West-Coast Drive (cantilevered) drives, live and dead axles, frame loading, gearboxes, and belts/chains. We've discussed the SPAM tradeoffs: speed, power (say torque), acceleration, maneuverability. The current mission: individually layout a 6wd chassis in CAD or by hand. Feel free to use simply geometric shapes and/or AndyMark, McMaster VEXpro CAD files. We're looking for frame design, wheel, gearbox, axle and chain/belt placement.
- The JVN Calculator: calculates your actual top speed and pushing power for 1 & 2 speed drivetrains. Also does 20 other things. You will literally hear people walking around Worlds saying "did you use the JVN calculator"? (John V-Neun is the global VP of Engineering for VEX).
- Clem's Chain/Belt Calculator: calculate how far apart your axles should be to achieve an even number of chain links (or a COTS belt size) given the size and pitch of your sprockets/pulleys.
- Siri's Turning Calculator: how's my turning? you'll find out!
Polygonal Swerve (n≠4)
We're examining the use of different swerve setups, in particular frames that have only 3 modules per robot. Triangles, Pentagons, Nonagons, etc--they all have potential with the new perimeter rules. We expect to build at least one frame this off-season (utilizing a past year's pivots, maybe DB7) to check it out. Future design investigations include tradeoffs on balance/stability, weight & cost, useable area, power (3 CIMS total? 6? shifting?), control/user interface, and tactics/robot-robot interaction. Mentors: Siri (CAD-overall), Ben, Clem, Gary.
- Under old rules (<= 2012), the largest circle which could be inscribed within the chassis perimeter was 28" diameter. If your contact points were at the perimeter corners, you could not tip unless the projected CoM fell outside this circle. Call this the minimum circle of stability.
- Under old rules, if I simply go to a 3-wheel isosceles triangle, the largest circle which may be inscribed shrinks to 19.524" (~70%).
- In reality, the wheel contact points are inside the perimeter, not at the corners. So this is all back of the napkin work. Our pivot drive wheelbases under 28" x 38" rules ranged from 20.27-21.5" in the 28" dimension and from 28-30.75" in the 38" dimension. This spread becomes wider when you consider earlier tank drive robots. A "selling point" of WCD is that it maximizes the minimum circle of stability (while improving agility). Our 2013 wheelbase was 22.25x21", while a triangular frame's wheelbase could be 31.4" on a side.