By Techno Warriors Advanced FTC 3486 Topics Project Description Requirements Basics Drive Train Design Drive Train Types Testing ScienceEngineering Conclusions Project Description Built and tested seven drive train designs ID: 587704
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Slide1
FIRST Tech Challenge Drive Train Testing
By Techno Warriors Advanced
FTC #3486Slide2
Topics
Project Description
Requirements
Basics – Drive Train Design
Drive Train Types
Testing
Science/Engineering
ConclusionsSlide3
Project Description
Built and tested seven drive train designs
Simulated FTC match environments
Tested each design with added weight to mimic various robot weights
Compiled and analyzed data to find ideal configurations for each testSlide4
Requirements
Meets strategy goals for the game
Is built from available resources
Time
Cost
Tools for fabrication
Part 1 of game manual
Rarely needs maintenance
Is repairable within 4 minutes
Uses minimal amount of spaceSlide5
Basics – Drive Train Design
Decide strategy after kickoff
Speed
Power
Mobility
Decide how many motors will be allotted for drive train
Decide robot weight
Traction
Mobility
Speed
Offensive/Defensive abilitySlide6
Basics – Drive Train Design cont.
Build for durability and test
Find weak points
Practice driving
Have spare parts and assemblies
Develop a project plan
Allot time for development and building
Learn technology
Know motor capabilities and limitations
Know electrical capabilities and limitations.Slide7
Drive Train Types
Nimble:
2 wheel drive + 2
omni
caster wheels
Basic:
4 wheel drive, not connected
Unity:
4 wheel drive, connected
Robust:
10 wheel drive
Whirlwind:
6 wheel drive
AndyMark
Wedgetop
and Performance Treads
Track:
4 motors, connected
Direction:
4 motors, not connectedSlide8
Nimble: 2 wheel drive + 2 Omni caster wheels
Omni caster wheels
Driven wheels
Motor
Motor
This drive train uses two direct drive 4” wheels with two 3”
omni
caster wheels. This robot has a base weight of 7 lbs due to its 10”x18” 80/20 frame. Slide9
Basic: 4 wheel drive, not connected
DrivenWheels
Motor
Motor
Motor
Motor
This drive train uses four direct drive 4” wheels that are not connected to each other. This robot has a base weight of 7 lbs due to its 10”x18” 80/20 frame. Slide10
Unity: 4 wheel drive, connected
DrivenWheels
Motor
Motor
Motor
Motor
Chain
Chain
This drive train uses four direct drive 4” wheels that are connected to each other using chain (not drawn in
Creo
). This robot has a base weight of 9 lbs due to its 10”x18” 80/20 frame plus added chain and sprockets. Slide11
Robust: 10 wheel drive
Motor
Motor
Motor
Motor
Gears
Gears
This drive train uses 10 chain driven 3” wheels that are geared together with the 4 outer wheels raised. This robot was our competition robot from the 2014-2015 season which weighed 55 lbs. Slide12
Whirlwind:
6 wheel drive, 2 tread types
Motor
Motor
Motor
Motor
This drive train uses 6 chain driven 4” wheels with the outer wheels being the
AndyMark
omni
wheels and the inner wheels using either the
AndyMark
Performance Tread or the
AndyMark
Wedgetop
Tread (tested separately). This robot had a base weight of 22.5 lbs. Slide13
Tracks: Track drive, 4 motors
Motor
Motor
Motor
Motor
This drive train uses 4 direct driven 3” wheels wrapped with
Tetrix
tread. This robot had a base weight of 9 lbs due to the 10”x18” 80/20 frame.Slide14
Direction: 4 motors, not connected
Omni
Omni
Omni
Omni
Motor
Motor
Motor
Motor
This drive train uses 4 direct driven 3”
omni
wheels. Each wheel was driven individually to allow for multidirectional travel. This robot had a base weight of 7 lbs.Slide15
Testing
Straight
Line Speed
Test
Pull Test
Side
Drag
Test
Spin Test
Ramp
TestSlide16
TestingEach test was preformed on standard field tiles. The robot was weighed and tested at 10, 20, 30 and 40
pounds in addition to the weight of the robot itself. Slide17
Straight Line Speed TestThe Straight Line Speed Test tested the robot on how fast it would travel 16 feet.
The testing area had a starting area to allow the robot to reach full speed prior to the course.
Total robot amps were recorded for each run.
Time to drive the 16 feet was recorded for each run.
At least 4 tests were recorded for consistent results.Slide18
Pull TestThe Pull Test tested how much weight the robot could pull.Total robot amps were recorded for each run.
The amount weight lifted was recorded for each test.
The weight lifted was increased
until the wheels slipped or the motors stalled.Slide19
Side Drag TestThe Side Drag Test tested how much weight it took to pull the robot sideways.The amount of weight to pull the robot was recorded for each test.
Weight was added until the robot was pulled sideways.Slide20
Spin TestThe Spin Test tested how fast the robot could spin 360 degrees.Total robot amps were recorded for each run.
Time taken to spin 360 degrees was recorded for each run.
At least 4 tests were recorded for consistent results.Slide21
Ramp TestThe Ramp Test tested if the robot could climb a ramp.The ramp was a standard FTC ramp from the Cascade Effect Game.
Pass/Fail was given if the robot could drive up the ramp.Slide22
Science/Engineering
Estimated Robot Speed vs. ResultsSlide23
Estimated Robot SpeedWheel Diameter * Pi * Motor speed = Inch/min
4" * 3.14 * 150 RPM= 1884 inches/min
1884
inches/min /60
s
ec = 31.4 inches/sec
3" * 3.14 * 150 RPM = 1413 inches/min
1413 inches/min /60 sec = 23.5 inches/secSlide24
Actual SpeedTested Distance = 192 inches
Theoretical
time to run course with 4" wheels
192 inches /
31.4
inches/sec = 6.1 seconds
Theoretical
time to run course with 3" wheels
192 inches /
23.5
inches/sec = 8.1 seconds
Most robots at minimum weight tested at or faster than predicted speed.Slide25
Conclusions
Test
Data
Straight Line Speed Test
(Seconds/Amps)
Pull
Test (
Pounds/Amps)
Side
Drag Test (
Pounds)
Spin
Test (Time/Amps
)
Overall Robot PerformanceSlide26
Speed Test Results
Test Distance 16 FeetSlide27
Speed Test Results (Continued)Slide28
Pull test results
Track drive uses 3” wheels, and, therefore, gained at least 25% of power advantage compared to 4” wheelsSlide29
Pull test results (Continued)Slide30
Side drag test resultsSlide31
Spin test resultsSlide32
Spin test results (Continued)Slide33
Nimble: 2 wheel drive + 2 Omni caster wheels
+ Easy to design
+ Easy to build
+ Lightweight
+ Inexpensive
+ Long battery life
- Underpowered drive train
- Will not do well on ramps
- Easily pushed by other robots
- Not effective for defense
- Not able to support much weight
+
-
--
--
ManeuverabilitySlide34
Basic: 4 wheel drive, not connected
+
Easy to design
+ Easy to build
+ Lightweight
+ Inexpensive
+ Long battery life
+ Able to hold position
Not utilizing full potential out of all the motors
because they are not connected
- Not effective for defense
- Not able to support much
weight and move effectively
= Decent on ramps
= Decent maneuverability
+
-
=Slide35
Unity: 4 wheel drive, connected
+ Relatively easy to design
+ Relatively easy to build
+ Light weight
+ Able to holding position
+ Preforms well on ramps
+ Utilizes full potential of motors
because they are connected
Not able to support much
weight and move effectively
= Inexpensive
= Decent Maneuverability
= Battery life depends on weight
= Effective for defense
+
-
=Slide36
Robust: 10 wheel drive
+ Does well on ramps
+ Utilizes full potential out of all the motors
+ Very effective for defense
+ Supports robust robot well
-
Short battery life
- Difficult to design
- Difficult to build
- Expensive
= Decent Maneuverability
= Weight neutral
+
-
=Slide37
Whirlwind:
6 wheel drive, 2 tread types
+
Great at holding position
+ Does well on ramps
+ Utilizes full potential out of all the motors
+ Very effective for defense
+ Excellent battery life
+ Will support high gear ratio
-
Difficult to design
- Difficult to build
- Very expensive
= Weight neutral
+
-
=
++
++ Maneuverability: spins on axis well
++
Supports
robust robot wellSlide38
Tracks: Track drive, 4 motors
+ Easy to design
+ Easy to build
+ Lightweight
+ Long battery life
+ Able to hold position
Inconsistent turns make autonomous extremely
difficult
- Drive train needs to be geared up to reach
competitive speed
- Vulnerable, needs to be protected
=
Does decently on ramps with track treads
= Average Maneuverability
= Effective for defense
= Cost neutral
+
-
=Slide39
Direction:
Holonomic
+
Long battery life
+ Inexpensive
+ High Maneuverability
- Extremely difficult to program
- Not able to hold position
- Slow
- Not at all effective for defense
Cannot go up ramp
= Moderate weight
=
Moderate to
design
= Moderate to
build
+
-
=Slide40
Quick Reference Table Slide41
Detailed InformationSlide42
RequirementsSlide43
Requirements
The drivetrain can define a robot and is the most important element of a design; the strength of the robot's drivetrain can heavily influence its overall performance.
The drivetrain must:
meet your strategy goals for the game
speed: The robot must be able to surpass the competition in any direction at any time.
traction: The robot must be able to effectively grip the various field elements without damaging the playing field or limiting maneuverability.
maneuverability: The robot must be able to quickly navigate the field, rotate on its axis, and escape out of harm’s way.
power: The robot must be able to conserve power usage to ensure maximum overall performance during a match.
offense/defense: The robot must be able to meet strategic objectives depending on team preference.
weight: The robot weight should maximize motor efficiency without compromising defensive/offensive abilities. Slide44
Requirements(continued)
be built with available resources
budget: The drive train construction costs should not exceed the team-defined boundaries of the budget.
tools required: The drive train should be designed to be built only with tools that each team actually has. (No rocket boosters unless you are sponsored by NASA)
time: The drive train should be easily assembled/dissembled for maintenance within a short time span.
rarely needs maintenance
durability: The drive train should be constructed to last so that repairs are minimal. The drive train must be protected from harm.
testing: Thoroughly test the drive train during construction to ensure that it can handle match conditions.
can be fixed within 4 minutes
easily replace motors between matches
easy to access critical components
Uses minimal amount of space
The drive train fits in designated space allotted by the system envelopeSlide45
BasicsSlide46
BasicsBrainstorming and Design resources:
Decide strategy after kickoff. What will you focus on?
Speed:
Power
Mobility
Decide how many motors you will use on drivetrain
4 motors is ideal (2 weakens a design and 6 causes connection issues)
chain/gear motors together to maximize power
Wire motors on separate ports on motor controllers to maximize power
Robot weight
What weight will maximize
traction
mobility
speed
defense (limit other robots pushing while playing offense)
Durability
put the drivetrain under stress to test the durability
identify weak points and correct them
driver practice
spare parts and assembliesDevelop a project planallot time for design, build, testing, software and driver practiceSlide47
BasicsTechnology
motor capabilities and limitations
AndyMark
NeveRest
40 Motor (am-2964)
Performance Specs
:
Gearbox Reduction: 40:1
Voltage: 12 volt DC
No Load Free Speed, at gearbox output shaft: 160 rpm
No Load Free Speed, motor only: 6,600 rpm
Gearbox Output Power: 14W
Stall Torque: 350 oz-in
Stall Current: 11.5 amps
Force Needed to Break Gearbox: 1478 oz-in
Minimum torque needed to back drive: 12.8 oz-in
Output pulse per revolution of Output Shaft (
ppr
): 1120 (280 rises of Channel A)Output pulse per revolution of encoder shaft (ppr): 28 (7 rises of Channel A)
Performance Specs, mounted to AndyMark dyno:Max Speed (under load of
dyno): 129 rpmNo Load Current (under load of dyno): 0.4 ampsStall Current: 11.5 ampsStall Torque: 396 oz-in
Max Output Power: 15 WattsTime to Failure at Stall: 2 minutes, 54 secondsMotor Case Temperature at Failure: 190 degrees F
electrical capabilities and limitationsEach motor controller should only power 1 drive train motor.Never connect more than motor to a
motor controller port.Slide48
Drivetrain Details
Nimble:
2 wheel drive + 2
omni
caster wheels
Basic:
4 wheel drive, not connected
Unity:
4 wheel drive, connected
Robust:
10 wheel drive
Whirlwind:
6 wheel drive
AndyMark
Wedgetop
and Performance Treads
Track:
4 motors, connected
Direction: 4 motors, not connectedSlide49
Nimble: Description and DetailsThis robot has two motors that directly drive two wheels. The drive wheels are 4 inch
Tetrix
wheels, and the non-powered wheels are 3 inch
omni
caster wheels.
Haiku: Nimble...
This nimble robot...
It can move, but not too well;
Try it with low weight.Slide50
Nimble: Specificationstwo AndyMark NeveRest
40 motors
two 4in
Tetrix
wheels
two 3in
Tetrix
omni
wheels
two 1010 aluminum extrusions 18" long
five 1010 aluminum extrusions 10" longSlide51
Nimble: PTC Creo DesignSlide52
Nimble: Straight Line Speed Data Slide53
Nimble: Pull Test Data Slide54
Nimble: Side Drag Test Data Slide55
Nimble: Spin Test Data Slide56
Nimble: SummaryThis drive train is easily constructed, but not necessarily the best choice for any robot. Due to a low weight, it draws less amps than other drive trains, promoting good battery life. Unfortunately, nothing else stands out. Its straight line speed is only average, it has low pushing power, it can be easily pushed around by an opposing robot, and it has trouble spinning under any weight. Overall, this drive train is not recommended for any game.Slide57
Basic: Description and DetailsThis robot is powered by four motors that directly drive the four 4"
tetrix
wheels. The motors on each side are not chained together in this design.
Haiku:
Basic...
It may seem basic...
Connect the wheels with chain please...
That might work better.Slide58
Basic: SpecificationsFour AndyMark NeveRest
40 motors
Four 4"
Tetrix
wheels
two 1010 aluminum extrusions 18" long
five 1010 aluminum extrusions 10" longSlide59
Basic: PTC Creo DesignSlide60
Basic: Straight Line Speed Data Slide61
Basic: Pull Test Data Slide62
Basic: Side Drag Test Data Slide63
Basic: Spin Test Data Slide64
Basic: SummaryThis drive train can maneuver around the field under heavy weight, but it is only at average or below average speeds. It is easily constructed and does not draw a large number of amps during movement. It can push/pull an average weight, but it is easily pushed around by other robots. It is thus effective and passable, but not the absolute best option for any task. It is recommended to connect the wheels together as in our 4 Wheel - Connected drive train configuration.Slide65
Unity: Description and DetailsThis robot is very similar to the previous robot in that four motors are directly driving four 4"
tetrix
wheels, but this time the motors are chained together on each side.
Haiku:
Unity...
Together we spin...
Connected by lengths of chain...
Unity is key.Slide66
Unity: Specificationsfour AndyMark NeveRest
motors
four 4in
Tetrix
wheels
four
Tetrix
sprockets
two sets of .25
Tetrix
chainSlide67
Unity: PTC Creo DesignSlide68
Unity: Straight Line Speed Data Slide69
Unity: Pull Test Data Slide70
Unity: Side Drag Test Data Slide71
Unity: Spin Test Data Slide72
Unity: SummaryThis drive train can maneuver around the field under heavy weight, but only at average or below average speeds. It is easily constructed and does not draw a large number of amps during movement. It can push/pull an average weight, but it is easily pushed around by other robots. It is thus effective and passable, but not the absolute best option for any task. Slide73
Robust: Description and DetailsFor this design, we used an already assembled robot from the previous year instead of building a new drive train for testing. This design has five wheels on each side that are driven by chain with a total of four motors. The middle three wheels are in contact with the ground at all times and the outer two are raised up off of the ground and are used for stabilization and to help the robot go up a ramp with ease.
Haiku:
Robust...
This robot is stout;
Dieting plans have been tried.
They were all failures.Slide74
Robust: Specificationsfour AndyMark NeveRest
40 motors
ten 3in
Tetrix
wheels
four tooth gears
six tooth gears
four sets of .25
Tetrix
chain
twelve
Tetrix
sprocketsSlide75
Robust: PTC Creo DesignSlide76
Robust: Testing Data
Robot test weight - 55 lbs.
Straight line test (@55 lbs) - 6.4 Seconds
Stall Weight test (@55 lbs) - 25 lbs.
Slide test (@55 lbs)- 65 lbs.
Ramp test - Pass
Spin Test (@55 lbs) - 2.1 Seconds
NOTE: This was our competition robot from last year, so we were unable to fully collect data for various weights.Slide77
Robust: SummaryIn summary, this robot is a very strong defensive
bot
, and is not easily pushed around the field. It is also very stable and not easily tipped. However, it draws a significant amount of current and so the battery quickly drains during a match. It is also expensive and rather complicated to build. Slide78
Whirlwind: Description and Details
This drive train consists of four motors that are driving a total of six wheels with three on each side by chain. Four of the six wheels in this design are 4" Omni wheels from
AndyMark
and the remaining two are
AndyMark
high performance wheels. We tested the
wedgetop
treads and the performance treads separately, as demonstrated by the data below.
Haiku:
Whirlwind...
It spins really fast.
Like a furious whirlwind...
Super-duper spin.Slide79
Whirlwind: Specificationsfour AndyMark NeveRest
40 motors
two
AndyMark
high performance wheels
four
AndyMark
Omni wheels
two sets of .25
Tetrix
chain
two 1010 aluminum extrusions 18" long
five 1010 aluminum extrusions 10" long
six 1010 aluminum extrusions 4" longSlide80
Whirlwind: PTC Creo DesignSlide81
Whirlwind: Straight Line Speed Data Wedgetop Tread: Slide82
Whirlwind: Pull Test DataWedgetop Tread: Slide83
Whirlwind: Side Drag Test DataWedgetop Tread: Slide84
Whirlwind: Spin Test Data Wedgetop Tread:Slide85
Whirlwind: Straight Line Speed Data Performance Tread: Slide86
Whirlwind: Pull Test DataPerformance Tread: Slide87
Whirlwind: Side Drag Test DataPerformance Tread: Slide88
Whirlwind: Spin Test Data Performance Tread:Slide89
Whirlwind: SummaryIt was incredibly good at spinning no matter how much weight we added, making it very maneuverable. This would be a good offensive robot with decent defensive capabilities, as it took a lot of weight to move it. It is also optimal to gear up this drive train for different strategies, as its overall effective performance would carry over to any strategy. Slide90
Tracks: Description and DetailsThis robot is powered by four motors that are connected together by
tetrix
conveyor/tank tread.
Haiku:
Tracks...
Tracks are quite nifty;
They can pull a lot of weight;
But don't go up ramps.Slide91
Tracks: Specificationsfour AndyMark NeveRest
40 motors
four
T
etrix
tread sprockets
two sets of
T
etrix
tank tread
two 1010 aluminum extrusions 18" long
five 1010 aluminum extrusions 10" longSlide92
Tracks: PTC Creo DesignSlide93
Tracks: Straight Line Speed Data Slide94
Tracks: Pull Test Data Slide95
Tracks: Side Drag Test Data Slide96
Tracks: Spin Test Data Slide97
Tracks: SummaryThis drive train performed well in all but one of the tests. Due to its 3" wheels, it's average speed is lower than the other drive train which all had 4" wheels (except for the holonomic). It successfully pulled 45 lbs at max added weight, giving it the top score in push/pull power. It was not very efficient at power usage, and it could not travel up the ramp at any weight. Overall, this drive train is useful for pushing power, but if used, it must be highly protected and concealed within the robot frame so that the tracks do not break upon contact with an opposing robot. Slide98
Direction: Description and DetailsThis robot is a 4 wheel
holonomic
drive robot. Each wheel is powered independently to allow for multi-directional travel.
Haiku:
Direction...
My path I know not;
Anywhere I can travel.
But how do I choose...Slide99
Direction: Specificationsfour AndyMark motorsfour 3in
T
etrix
omni
wheels
1 18" square base plate - 1/8" aluminumSlide100
Direction: PTC Creo DesignSlide101
Direction: Straight Line Speed Data Slide102
Direction: Pull Test Data Slide103
Direction: Side Drag Test Data Slide104
Direction: Spin Test Data Slide105
Direction: SummaryThis robot is highly agile at low weight, but it struggles under high stress. It is unable to go up a ramp or pull much weight, so it is only good at scuttling around. This drive train can be easily pushed around, so it's not recommended for defensive strategies. Slide106
FIRST Tech Challenge Drive Train TestingCreated by FTC Team #3486
Techno Warriors Advanced
Feel free to contact us!
Engineering Notebook:
bit.ly/FTC3486
Email:
twa3486@gmail.com
Twitter: @
technowarriors