Difference between revisions of "DEWBOT IX Design Team Page"

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(More Mathier:)
(6/8 wheel drive, polygonal swerve, FRC toolkit classes)
 
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'''Student Lead''': tbd
+
'''Student Lead''': Molly
  
 
'''Student Sub-Lead''': Dhananjay (DJ)
 
'''Student Sub-Lead''': Dhananjay (DJ)
  
 
'''Student Team Members''':
 
'''Student Team Members''':
Jack, Kira, Tobi
+
Jack, Kira, Pat C, Lucy, Tobi, Mike M, Pat D
 +
 
 +
'''Mentors'''
 +
:'''Integration-Systems Design Leads''': [[User:MaiKangWei | Clem McKown]], [[User:Siri | Siri Maley]]
 +
:'''System/Sub-System Leads''': [[User:Gdeaver | Gary Deaver ]], Ben Kellom, [[User:Jcbc | 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''': [[User:MaiKangWei | Clem McKown]], [[User:Siri | Siri Maley]], [[User:Jcbc | Julie Christopher]], Ben Kellom, [[User:Gdeaver | Gary Deaver]], Mike Geldart, Keith Williams, [[User:HeatherM | Heather McKown]], Andrew Weissman
  
'''Mentors''': [[User:MaiKangWei | Clem McKown]], [[User:HeatherM | Heather McKown ]],[[User:Siri | Siri Maley ]], [[User:Gdeaver | Gary Deaver ]], Ben Kellom, [[User:Jcbc | Julie Christopher ]], Scott Featherman, Joe Morganto
 
  
 
==Motor Specifications==
 
==Motor Specifications==
Line 17: Line 22:
 
The Minibot drive-train model was adapted to work with [[media:Drivetrain_Model_DB9_Pyramid.xls | climbing the pyramid corner]].  For use as a design tool.
 
The Minibot drive-train model was adapted to work with [[media:Drivetrain_Model_DB9_Pyramid.xls | climbing the pyramid corner]].  For use as a design tool.
  
==[[Engineering 101]]==
+
=Off-Season=
Lesson plans created in order to teach engineering analysis and synthesis on a level compatible with highschoolers.
 
 
 
==3-Wheel Swerve Drive==
 
Email from Clem McKown to the team - 18-June-2013:
 
:''While putting together an updated drive-train lesson and thinking about why a 3-wheel drive robot was such a bad idea, I had an epiphany:  Under the 2013 robot perimeter rules, a 3-wheel drive robot is really not such a bad idea at all.  In fact, a 3-wheel drive pivot robot is perhaps a very good idea. I'll explain.''
 
  
:''The issue is stability.  No-one want their robot to fall over.  A robot will fall over if the gravitational projection of the robot's center of mass, adjusted for robot acceleration or incline, falls outside of the line described by the robot's contact points with the field (which we will call the wheel contact points). Remember, the gravitational constant is just acceleration, so we're adding (vector) apples and apples. Also, remember turning and stopping are also acceleration. Pretty simple, in principle.'' 
+
==Classes==
 +
===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, [[Swerve Central|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.
  
:''Under old robot perimeter rules (<=2006 through 2012), the robot perimeter was limited to 28" x 38".  Under these rules, the most stable robot you can make has at least 4 wheels as close to the corners of this rectangle as practical.  A 3-wheel drive robot under these rules seriously compromises stability.  This is the same reason for there being no 3-wheel automobiles in the US (safety - there is a Buckminster Fuller story here). ''
+
===[[Engineering 101]]===
 
+
Lesson plans created in order to teach engineering analysis and synthesis on a level compatible with highschoolers.
:''But the new (2013) perimeter rules allow up to 112" of total robot perimeter.  The shape of this perimeter is not specified.  When we designed our chassis, we saw this rule as allowing us flexibility in varying length versus width of a fundamentally rectangular robot (which we ended up making square).  DEWBOT's 2013 perimeter was 111" (27-3/4" square).  Our wheel-base ended up 21" (nominally wide) x 22.25" (nominally long).  A 112" square chassis would have sides of 28" ''
 
 
 
:''But if a side is eliminated, the other sides can become longer.  An equilateral triangle with a 112" perimeter would have sides of 37-1/3" long.  Pivots could be installed in the three corners to bring them as close to the perimeter as practical, increasing the wheel-to-wheel distance vis-à-vis DEWBOT IX.  Under these conditions, I would expect a 3-wheeel drive base with stability similar to this year's 4-wheel base (which was excellent).''
 
 
 
:''But with three pivots, not 4.  This would save significant weight (the 2013 pivots were 7.9 lb each, plus talons,...) which could be deployed elsewhere.''
 
  
:''Unlike tank or mecanum, I think pivot drive should work as well with 3-wheels as with 4.  But, this poses a new control challenge for us (sorry, programmers).''
+
===FRC Toolkit===
 +
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]
  
:''And a pointier robot (60° versus 90°) could break through defenders more easily.''
+
We call them "classes", but don't be surprised if they just sneak up on you in conversation. No lectures required!
  
:''I'm excited, but I'm easily amused. Let me know what you think.''
+
==Projects==
 +
===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 [https://www.andymark.com/ AndyMark], [http://www.mcmaster.com/# McMaster] [http://www.vexrobotics.com/vexpro/ VEXpro] CAD files. We're looking for frame design, wheel, gearbox, axle and chain/belt placement.
  
:''Best regards,''
+
:Tools
:''Clem''
+
:*''The'' [http://www.chiefdelphi.com/media/papers/2715 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!
  
===More Mathier:===
+
==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.
  
 +
===More Mathier===
 
: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 (<= 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%).   
 
: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).
+
: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.
 
 
:Now, in 2013, rules are changed to limit perimeter to 112".  With a square robot with contact points at corners, the minimum circle of stability is still 28"; with a triangle bot with 112" perimeter it drops to 21.55" (77%).  '''But I think we can get the contact points closer to the perimeter corners with a triangular chassis (and ambidextrous pivot modules) than with a rectangular chassis.'''  Needs proof.
 
  
 
==Design Team Page History==
 
==Design Team Page History==

Latest revision as of 22:56, 20 June 2013

Student Lead: Molly

Student Sub-Lead: Dhananjay (DJ)

Student Team Members: Jack, Kira, Pat C, Lucy, Tobi, Mike M, Pat D

Mentors

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


Motor Specifications

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.

Off-Season

Classes

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.

Engineering 101

Lesson plans created in order to teach engineering analysis and synthesis on a level compatible with highschoolers.

FRC Toolkit

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!

Projects

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.

Tools
  • 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.

More Mathier

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.

Design Team Page History