2019 engineering binder

TABLE OF CONTENTS
STRATEGY 2
DESIGN 8
CONTROLS 34
Brainstorming Process 3
Potential Robots 5
Priority List 7
Drivetrain 10
Cargo Intake 14
Hatch Intake 17
Cargo Ejector 20
Hatch Intake 23
Elevator 26
Endgame 31
Sensors 35
Programming 36
THEORYVision 39

BRAINSTORMING
PROCESS
TECHNICAL BINDER | STRATEGY • 3
As always, our season began on January 7th, with the worldwide kickoff. This year was particularly important for 1241,
as we planned to implement several changes to our design process from previous years, particularly 2018 - POWER UP.
We watched the game reveal and animation as a team, and had our preliminary discussion together - giving each mem-
ber a chance to give their conceptual input. We then split into smaller groups and did a more in-depth discussion about
possible robot mechanisms, coming up with design archetypes and allowing us to imagine our robot without the bias of
prerequisites. After the initial discussion, our thinking becomes more game-centric, as we eliminate designs that don’t fit
our overall strategy, and home in on others that we feel do.
Later, we begin to estimate autonomous times and come up with a more concrete list of requirements for each mech-
anisms. One particular change we implemented from 2018 is greater focus on effective movement and scoring in au-
tonomous, as we found that being undefended in autonomous can give a potentially insurmountable lead for the tele-
operated period. Therefore, we based our requirements and movements list off of effective autonomous scoring. After
estimating scoring/movement times, and allocating points to each game object, we generated an overall profile of the
cycle times we’d need to have to be competitive, and used that to refine our mechanisms design.

CYCLE TIMES
MOVEMENTS
FIRST TEAM 1241: THEORY6

POTENTIAL
ROBOTS
STEPH CURRY
Compact scoring machine with level 3 capability, but built to optimize lower-level cycles (cargo ship and
rocket level 1), not capable of scoring high (rocket level 1/2).
PROS
- Lack of “tool” mechanism allows for scoring
optimization/quick level 3
- Less limited than previous years, as low scoring
accounts for more than 50% of game object scoring
- Inclusion of null hatch panels allows an alliance with
a “Steph Curry” archetype to raise scoring cap
- Low resource, timeline allows for driver practice to
take priority in a high-defense game
CONS
- Regardless of lower limitations, limitations still exist,
can potentially lead to robot capping out near district
championship or worlds level
- Inability to complete rocket individually doesn’t allow
robot to rank high individually
SHAQUILLE O’NEAL
Larger machine capable of scoring on all 3 levels, as well as climbing with another robot (via a triple
climb or a suction pad).
PROS
- Highest cap robot on the list, capable of filling all
scoring holes
- Inclusion of suction pad or triple climb allows for
guaranteed, important for tiebreaker against
equally competent scoring alliances, hab is
“guaranteed” scoring irregardless of defense
- Ability to complete rocket individually, as well as
ensure hab ranking point, allowing robot to be in
control of its own destiny
CONS
- High-resource, requires extensive funds
- Complex integration and overall robot design, can
detract from time allocated for driver practice and
autonomous tuning
- While hab climb poses itself as an effective tiebreaker,
can be ineffective if scoring output suffers
- High robot weight and design time allocated to end
game may retract from scoring mechanism quality
KAWHI LEONARD
All-around machine capable of scoring on all 3 levels, but optimized for fast cycling over climbing, only
capable of level 2/level 1 hab score.
PROS
- High cap robot, capable of scoring at all levels
- Lack of endgame focus allows for scoring
optimization
- Relatively low resource, timeline allows for a fair
amount of driver practice, more if timelines are met
- If scoring output is high enough, can overcome hab
scoring deficit as a tiebreaker
CONS
- May hit cap at very highest levels of play, overcoming
hab scoring requires very high scoring output, don’t
know if such scoring output is realistic
- Inability to guarantee HAB RP individually leads to
robot not being in control of it’s own destiny, has to
inherently depend on “Shaquille O’Neal” archetypes
for alliance picking
- If timelines are not met or scoring optimization takes
too long, practice advantage is lost

We chose the Kawhi Leonard robot archetype, as we felt that our team’s
overall goals were better suited by a robot that could do everything and
was versatile enough in scoring to have choices at the end of the game,
whether to play defense or perform endgame scoring. Additionally, while
we felt that we would be able to complete the “Shaquille O’Neal”
archetype, it would be too intensive and retract from our scoring
output, which our team has had success with in the past. The simpler
design would allow us to focus on optimizing our scoring mechanisms
through prototyping and iteration.
FINAL ROBOT DESIGN
KAWHI LEONARD

PRIORITY
LIST
INTAKE
ELEVATOR
ENDGAME
DRIVETRAIN
● Traverse from platform and line up to rocket in <4 seconds
● High maneuverability for moving around defense
● No beaching on platforms/bumps
● Wide drivebase to manage CG effectively
● Strong, simple, robust and completed early in season
CARGO
● Pick Up from floor/ball depot, possibly from feeder
● Possible steal from other side of field
● Touch and Go
● Score into cargo ship and rocket, depending on tool
HATCH
● Pick up from floor
● Reorient to scoring position
● Pick up from feeder
● Able to score on all heights of rocket and cargo ship
● Able to possess and score both the cargo and hatch
● Rapid movement between scoring heights
● Get onto level 2 within 3 seconds of lineup
● Climb every match
● Low maintenance mechanism

TECHNICAL BINDER | DESIGN • 10
DRIVETRAIN
- Center Drop
- Wheel Diameter
- Free Speed
- Pushing Power
- Two speed output Torque/Speed
- Wheel choice (potential front/back Omnis)
- Maneuverability
- Center of Gravity
- Chassis Length/Height
- Modularity
- Robustness
- Wheel center-center
- Chain (#25 or #35)
- Tread choice/friction
- Acceleration
VARIABLES
PARAMETRIC STUDIES

- Found that placement of wheels would have to be integrated with elevator mounting
- Interferences with intake and elevator including clearance for drive gearboxes
- Overall quick prototype allowing for final drivetrain CAD to move on early
- 4 4” Colson wheels used to simulate movement, with a 3/16” drop for center wheels.
- 9.75” center to center distance for middle wheels and 8” center distance for front and back
wheels, ideal for .35 Chain
- Front/Back bumper assemblies placed to simulate movement
- Mounted on custom machined ½” round stock
PROTOTYPING
LESSONS LEARNED
DRIVETRAIN

● 8 Wheel drive with 4” colsons
● 1x2x0.100” Extrusion-based chassis optimized for lowest weight and
structural integrity
● Lightened, custom CNC’d .090” Aluminium Bellypan, with access holes
for elevator and gearboxes
● Mylar sheet across belly pan for electrical mounting
● Front and back .75x.75x⅛” extrusion for custom welded bumper
mounting
FINAL DESIGN
DRIVETRAIN

● 8 wheel west coast drive with 4” colsons (0.875” width front and back,
1.5” width middle)
● 4 NEO two speed Gearbox with a 2 stage, 9.26:1 Reduction for low gear,
and 4.76:1
● High gear has a top speed of 17ft/s
● Low gear has a top speed of 8.6ft/s
●#35 chain transmission with 12t sprockets to each wheel module
GEARBOX
DRIVETRAIN

CARGO INTAKE (BINTAKE)
- Wheel RPM
- Wheel Durometer Rating (Compliance)
- Wheel Diameter
- Cargo centering
- Coefficient of Friction
- Feed into elevator
- Sensor placement
- Motorized pivot (able to lift robot)
- Resting orientation
- Placement of hardstop
- Window of cargo acceptance
VARIABLES
PARAMETRIC STUDIES

TECHNICAL BINDER | DESIGN •15
- Pinch on cargo must be reduced to 1.5”
- Ratio for the rollers must be increased to prevent stall
- Belt system used for real design for efficiency and weight
- Static flaps needed to prevent ball popping out of bintake and sensor for automated pass
through
- Made from custom CNC’d plates made from .25” polycarbonate and .25” aluminum
- Overall 2.5” of pinch on the cargo
- Has one horizontal roller, with 1.875” banebot wheels to intake cargo, powered by a 775 pro
versa planetary consisting of a 12:1 ratio and chain sprocket transmission
- A set of side rollers with 1.875” banebot wheels to center the cargo, powered by 2 775 pro
versa planetaries consisting of a 12:1 ratio and chain sprocket transmission
- 1”x1” extrusion structure for ball travel
- Able to bolt onto drivetrain prototype and pivots for cargo pass through into elevator
PROTOTYPING
LESSONS LEARNED
BINTAKE

● Top and side rollers powered by 1 775 Pro with an overall 8.33:1 belt
reduction and bevel gear transmission for side rollers
● 1.875” Banebot wheels and 2” green compliant wheels used
● Custom CNC machined 2x1x0.100” extrusion structure in order to take
impact and lift robot onto level 2
● Intakes and centres cargo, then pivots to feed cargo into elevator
carriage in an automated process utilising a Balluff photoelectric sensor
● Pivot is powered by 2 775 Pros (477.75:1 Reduction) and is also used to
lift Zapdos onto level 2
FINAL DESIGN
BINTAKE

HATCH INTAKE (HINTAKE)
- Wheel RPM
- Wheel Diameter
- Hatch centering
- Feed into elevator
- Sensor placement
- Motorized pivot
- Resting orientation
- Placement of hardstop
- Window of hatch acceptance
VARIABLES
PROTOTYPING

TECHNICAL BINDER | DESIGN •18
- Spatula plate on ground must be thin and chamfered for faster hatch pick up
- Ratio for the rollers must be increased for more torque to retain hatch while pivoting
- Belt system used for real design for efficiency and weight
- Bearings added on the side of the spatula for hatch centering when intaking off center
- Made from custom CNC’d plates made from .25” polycarbonate
- Has one horizontal roller, with 4” compliant wheels to intake hatch, powered by a 775 pro
versa planetary consisting of a 49:1 ratio and chain sprocket transmission
- Able to bolt onto drivetrain prototype and pivots for hatch pass through into elevator
LESSONS LEARNED
HINTAKE

● Horizontal roller powered by one 775 Pro with an overall 21:1 reduction
● 2” green and blue compliant wheels
● 1x1x0.090” extrusion structure and .25” polycarbonate mounting plates
● ⅛” chamfered polycarbonate spatula that rides against the ground to
intake hatch
● Intakes and centres hatches utilising .75” bearings on the spatula, then
pivots to feed hatch into elevator carriage in an automated process
utilising a Balluff photoelectric sensor
● Pivot is powered by one 775 Pro (550:1 Reduction)
FINAL DESIGN
HINTAKE

CARGO EJECTOR (BEJECTOR)
- Wheel RPM
- Wheel Diameter
- Cargo acceptance from cargo intake
- Sensor placement
- Cargo resting position
- Scoring position variability
VARIABLES
PARAMETRIC STUDIES

- Pinch on cargo must be reduced to 1.5”
- Feeder roller and shooter rollers must be moved closer together to remove deadzone
- Direct gearing used for real design, removing the need for versa planetaries
- Shooter wheels moved further forward to prevent deadzone when scoring into rocket
- Made from custom CNC’d plates made from .25” polycarbonate
- Overall 2.5” of pinch on the cargo
- Has one horizontal roller, with 2.875” banebot wheels to feed cargo from cargo intake
powered by a 775 pro versa planetary consisting of a 12:1 ratio and chain sprocket
transmission
- A set of vertical rollers with 2.875” banebot wheels to shoot the cargo, powered by 2 775 pro
versa planetaries consisting of a 12:1 ratio and chain sprocket transmission
- 2”x4” wood structure
- Able to bolt onto elevator prototype for various scoring heights and cargo feeding heights
PROTOTYPING
LESSONS LEARNED
BEJECTOR

● Feeder roller with 2.875” Banebot wheels powered by 1 775 Pro with
an overall 21:1 reduction using a versa planetary and plastic gears
● Vertical shooter rollers with 2.875” Banebot wheels powered by two
775 pros with an overall 10:1 ratio
● Overall 1.5” of pinch on cargo
● Feeds ball from cargo intake using feeder roller in an automated
sequence utilising a Balluff Photoelectric sensor in the carriage
● Holds ball between feeder roller and vertical rollers until scored
● Custom CNC machined 1x1x0.090” extrusion structure
FINAL DESIGN
BEJECTOR

HATCH EJECTOR (HEJECTOR)
- Hatch acquisition from feeder
- Hatch ejection onto cargo ship bays and
rocket
- Securing hatch while driving
- Holding hatch for starting configuration
- Compensation for driver alignment
- Compensation for bumper cut-out at cargo
bays, not present at rocket
VARIABLES
PROTOTYPING

- Optimum design for structural rigidity, found weakpoints with continuous testing
- Changed Finger design and shape to better fulfill capture requirements and “touch-and-go”
principle
- Changed overall plate design to avoid conflicts with bejector structure
- Increased bearing spacing from extrusion to avoid twisting
LESSONS LEARNED
HEJECTOR

● Hatch ejector assembly mounted onto a .25” aluminum plate able to
slide in and out of carriage using a 6” stroke, ¾” bore cylinder
● Tray is centered using four 1 ⅛” round bearings sliding on the inside of
the carriage structure and centered vertically by ⅝” round bearings on
the carriage structure
● Custom machined ¾” delrin fingers for hatch possession actuated by
two 2” stroke, ¾” bore cylinders
● Two 5” stroke, ¾” stroke pistons for hatch ejection, ensuring hatch
scoring without perfect driver alignment
FINAL DESIGN
HEJECTOR

ELEVATOR
- Travel Speed
- Bearing Size
- Width of Elevator (Ball pass through)
- Cascading vs Continuous
- Structural Rigidity
- Maximum Height (Starting configuration)
- Bearing Mounts
- Controllability
VARIABLES
PARAMETRIC STUDIES

- Interferences with intake and drive to be fixed for final design
- Optimal Heights for hatch and cargo scoring
- Structural weak points and deficiencies
- 2x4” wood tower and A-Frame structure with variable carriage mounting points to test
scoring and cargo possession
- Mounted onto drivebase to check interferences
PROTOTYPING
LESSONS LEARNED
ELEVATOR

● 8 Wheel drive with 4” colsons
● 1x2x0.100” Extrusion-based chassis optimized for lowest weight and
structural integrity
● Lightened, custom CNC’d .090” Aluminium Bellypan, with access holes
for elevator and gearboxes
● Mylar sheet across belly pan for electrical mounting
● Front and back .75x.75x⅛” extrusion for custom welded bumper
mounting
FINAL DESIGN
ELEVATOR

● 2 775pro Gearbox with a 2 stage, 18:1 Reduction centrally mounted on
a 2”x1”x1/16” extrusion across the drivetrain
● Elevator linear speed of 6.9ft/s
● Belt transmission to both sides of the elevator using a 24t x 15mm wide
HTD timing pulley
● Magnetic encoder mounted onto output shaft for position feedback
GEARBOX
ELEVATOR

● Carriage holds the hatch and cargo scoring mechanisms for travel up
and down the elevator
● Has .75” outer diameter bearings that ride inside of the elevator
c-channels on all 3 faces of the channel
● 2”x1”x0.100” extrusion structure allowing for the mounting of scoring
mechanisms
● Ratchet strap is clamped onto the back of the carriage and elevator
cross brace allowing it to travel continuously up with the elevator
CARRIAGE
ELEVATOR

ENDGAME (DINGUS)
- Piston bore
- Piston Stroke
- Placement on drive
- Angle relative to hab
- Mounting durability
VARIABLES
PARAMETRIC STUDIES

● Two 8” stroke, 1.25” bore double acting cylinders
● Mounted on a custom 3D printed ABS block positioned behind the front
most wheel of drivetrain
● Specified angle so that piston is perpendicular to hab surface when
robot is climbing onto level 2
● Climbing onto level two is an automated sequence in which the cargo
intake comes down onto level 2, while the drive travels backwards
while the cylinders on the front of the drive extend
FINAL DESIGN
DINGUS

● High resolution at 4096 ticks per revolution directly wired to the talon SRX speed
controller
● Placed on drivetrain (One on each gearbox), one on elevator and one on bintake
pivot
● Provides position and velocity feedback used for autonomous and teleop
movements
MAGNETIC ENCODER
NAV X GYROSCOPE
● Used on drivetrain to determine the angle of the robot relative to starting
position
● Allows for s-curves and turns in autonomous
OPTICAL SENSOR
● Used on cargo intake and carriage to detect cargo presence
● Used for the automated cargo pass through sequence. Upon detection of cargo
in the bintake, intake rollers are stopped, and pivot is brought up to feeding
position, after which both the intake rollers and carriage feeding rollers run until
the carriage optical sensor detects the cargo
● Connected to LEDs to signal driver that we have possession of the cargo
ULTRASONIC RANGE FINDER
SENSORS
TECHNICAL BINDER | CONTROLS • 35
● Used on drivetrain to determine the distance away from hatch feeding and
scoring positions
● Used to automate hatch feeding and scoring in autonomous and teleoperated
movements. Once the vision system locks onto the field targets, the drive
automatically drives toward the target until within a specified range, upon which
the hatch is either acquired or scored

● Drive straights and turns controlled though a custom PID controller
● Field is mapped in a point coordinate system relative to the left corner
on the alliance station. Points are updated using drive encoder and
gyro feedback
● Driving is passed to the robot in the form of points, and the path is
automatically generated relative to the current position of the robot on
the field
● Cumulative error in autonomous paths is limited as paths are relative
to the last position of the robot and points are reset at determined
scoring and feeding positions
● While driving to feeding and scoring the positions, the robot uses a
combination of the vision tracking and ultrasonic range finder to lock
onto targets and drive towards them until a specified distance. This
ensures the robot arrives at the exact same positions every time, no
matter the previous movements that have occured
AUTONOMOUS PATH NAVIGATION
PROGRAMMING
MOTION PROFILING
● Elevator consists of 6 setpoints for scoring and intaking at different
heights
● Cargo intake pivot consists of intaking, feeding and resting positions for
possession and pass through of cargo
● Motion profiling allows us to specify acceleration, cruising velocity and
deceleration for the elevator and cargo pivot as it travels to setpoint
ensuring smooth travel and reduced chance of robot tipping and jerk

● Models a tank-drive robot pose (x position, y position and heading)
based on left and right wheel speeds
● Allows for testing autonomous routines without the physical robot
● Able to configure simulator to current robot (length, width, top speed)
● Enables troubleshooting for logic and testing new ideas to implement;
used when we changed how we convert robot yaw and point
coordinates to an angle setpoint
● Interfaces with a file or programmatically, allowing for flexibility of user
input and not requiring a programmer to use (especially useful for
strategic decisions, kickoff)
PROGRAMMING
AUTONOMOUS PATH SIMULATION

● Travels from either the left or right level two platforms onto the carpet
● Placement of two hatch panels on the rocket, one close and one far
● Placement of two hatch panels on the cargo ship, one close and one
mid
● Placement of two hatch panels on the cargo ship, one on front bay and
one on close side bay
● Optional driver controlled sandstorm driving in case of unexpected
sensor failure
PROGRAMMING
AUTONOMOUS ROUTINES

● Custom vision processing software run on roboRio, utilizing a Microsoft
LifeCam
● Optimized for minimal CPU usage and memory consumption,
completed by starting/stopping a separate calculation thread on
command
● Computes the angle relative to the robot using the OpenCV library
● Full control over hue, saturation and value of colors detected, camera
settings and filters for detected targets through Shuffleboard and code
Used for:
● Autonomous alignment (creates an angle setpoint based on what the
vision pipeline calculates and the current robot angle, then PIDs the
robot to that setpoint)
● Autonomous hatch panel feeding and scoring (maintains an angle like
above while driving based on the rangefinder’s distance away and
grabbing/ejecting the hatch panel when within distance)
● Using simple geometry, able to differentiate targets from being “left”
and “right” and correctly identifying pairs to track
● On-the-fly capable tuning and complete customizability of TheoryVision
makes it robust and easy to use
THEORY
VISION

theory6.ca
Written by Angad Bajwa & Jai Prajapati
Designed by Keeva Szeto
Photos by Eddy Gunawan & Kourosh Kadivar

2019 engineering binder

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