Chip & Dale · Beta Competition Robots

Early-season Over Under was largely a numbers game. Teams tried to Match Load as many Triballs as possible, move them onto their Offensive Zone, and score some beneath the Goal. Controlling a larger number of Triballs on the scoring side of the field was often more important than placing every Triball directly under the Goal.

By Worlds, the strategy had shifted. Strong teams introduced most of their Match Load Triballs during the 45-second Autonomous Period, then used driver control to clean up the field and place loose Triballs beneath the Goal. Triballs scored beneath the Goal were protected, while Triballs left outside the Goal could still be moved or stolen by an opponent.

Chip and Dale needed to win or contribute to the Autonomous Win Point, rapidly introduce Match Loads during autonomous, clear loose Triballs during driver control, cross the Barrier, and perform E and F-tier climbs. Both robots also needed to climb the same Vertical Elevation Bar without relying on each other.

The design and build needed to be completed in approximately four weeks of CAD work followed by a three-week manufacturing, assembly, programming, and testing schedule.

Transporting two robots to Worlds created another design constraint. Chip and Dale needed to separate into tote-sized subsystem assemblies and be reassembled after arrival, avoiding the cost and size of shipping two complete robots in a large crate.

• Prioritized a fast and reliable drivetrain because every scoring and climbing task depended on mobility
• Designed the intake around "touch it, own it" so Triballs remained controlled after entering the mechanism
• Used wings to introduce Match Loads during Autonomous and push groups of Triballs during field cleanup
• Designed both climbers for independent single high climbs and a double high climb on the same pole
• Planned autonomous routines around scoring Match Loads, completing the Autonomous Win Point, and setting up the driver-controlled period
• Avoided relying on Double-Zoning because the team expected more descoring robots at Worlds

I used master sketches and top-down design to manage the packaging of the drivetrain, intake, wings, PTO, climber, claw, electronics, and pneumatics within the compact chassis.

• Reused one core robot architecture across the 24" and 15" robots
• Controlled subsystem mounting locations from shared layout geometry
• Checked the intake's motion and starting configuration before fabrication
• Packaged the PTO and climb winch around the drivetrain gears
• Designed the rear chassis cutout around the Vertical Elevation Bar
• Integrated electronics, pneumatics, and wire-routing space into the climber base plates
• Used design reviews and Onshape version control to track changes before manufacturing
• Optimized custom parts around the team's CNC router, manual machining, and 3D-printing capabilities
• Divided each robot into removable subsystem assemblies for transportation
• Designed mounting points and subsystem connections around disassembly and reassembly
• Checked that the separated subsystems could be packed into totes instead of requiring a full robot shipping crate

Transporting two complete robots to VEX Worlds created a major packaging and logistics constraint. A conventional approach would have required shipping both assembled robots in a large robot crate.

I designed Chip and Dale so their major subsystems could be removed from the chassis and packed into totes. The subsystem mounting and overall robot architecture were developed around being easy to take apart before travel and put back together after arriving at Worlds.

This modular approach reduced the size and cost of shipping the robots while preserving the ability to transport both competition robots and their components. It also made individual subsystems easier to access during assembly and service.

• Used tank drive for simple, reliable, and predictable movement
• Powered each drivetrain with 6 x 11W motors using 600 rpm cartridges and a 36:60 reduction for a 360 rpm output
• Used four 3.25" omni wheels and two center traction wheels for turning performance and Barrier traction
• Ran every wheel on a 1/4" round dead shaft with ball bearings to reduce friction and backlash
• Built the 13.75" x 14.75" frame from 2 x 1 C-channel rails with C-channel and 1 x 1 angle cross bracing
• Joined the chassis rails with custom PETG boxing brackets
• Added PETG sleds to cross the Barrier and provide intake mounting points
• Added a rear cutout to straddle the Vertical Elevation Bar during climbing
• Added a front plate that acted as a Triball backstop and pneumatic mounting structure

• Used a pneumatic non-parallel 4-bar to move the intake over the Match Load Bar and down to field Triballs
• Actuated the intake with 2 x 2" stroke pneumatic cylinders for powered extension and retraction
• Used a single 5" diameter PETG live-axle roller driven by one 11W motor through a 16:16 chain drive
• Pocketed the printed roller to reduce weight
• Used exposed rubber bands for strong Triball contact and to let individual bands detach if entangled with another robot
• Used 3/8" aluminum standoffs as dead-axle front linkages
• Used double-stacked 1/4" polycarbonate plates as the rear linkages
• Integrated intake sleds into the printed 4-bar mounting brackets
• Added an optical sensor on a PETG bracket to detect when a Triball entered the intake
• Added 3/8" round aluminum cross bracing for structural rigidity

• Used pneumatically extended wings with rubber-band retraction for Match Loading and bulk Triball pushing
• Raised the wings 3" from the floor to clear the Match Load Bar and Barrier
• Actuated each wing with a 2" stroke pneumatic cylinder
• Mounted each wing between two 1/4" polycarbonate plates for strength and flexibility
• Ran the wing pivots on #8-32 screw dead axles
• Shaped the wings to move groups of Triballs while remaining compact when retracted
• Used the wings during autonomous to introduce Match Load Triballs and during driver control to clean up loose Triballs

• Used a pneumatic power take-off to connect the drivetrain motors to the climbing winch
• Actuated the shifting mechanism with a 2" stroke pneumatic cylinder
• Used beveled 48-tooth gears to engage and disengage the drivetrain from the winch
• Powered the winch with 2 dedicated climb motors during normal operation
• Added all 6 drivetrain motors when the PTO was engaged, providing 8 motors for climbing
• Used a 36:48 reduction for a 450 rpm winch output
• Pocketed the 1/8" aluminum shifter plates to reduce weight and preserve intake clearance
• Tested 1/2", 1", and 1.5" winch diameters before selecting the 1" configuration

• Used a 4-stage VEX linear-slide elevator with rubber-band extension and winched retraction
• Routed the extension bands through PETG pulley mounts and dead-axle pulleys on #8-32 screws
• Added standoff and 1 x 1 angle cross bracing to increase slide rigidity
• Lubricated the slides with white lithium grease for consistent extension and retraction
• Mounted the slides, Robot Brain, Radio, and Battery to two pocketed 1/8" aluminum base plates
• Used standoff cross bracing to route wires between both sides of the robot
• Added a PETG deflector to prevent the Horizontal Elevation Bar from interfering during a double high climb
• Held the claw down with two internal standoffs during the match
• Released the slides by closing the claw and disengaging it from the retaining standoffs

• Used a 0.5" stroke 0.75" bore pneumatic pancake cylinder for extension and retraction
• Designed an over-center linkage that mechanically locked after closing around the Vertical Elevation Bar
• Maintained the lock at pressures as low as 5 PSI
• Tested the claw while supporting 90 lbs
• Pocketed the 1/8" aluminum claw plates to reduce weight
• Used PETG spacers for lightweight structural spacing
• Ran the claw linkages on 1/4" aluminum shaft dead axles and 1/4-20 button-head bolt dead axles
• Allowed the claw to pivot upward while winching to prevent binding
• Prevented downward claw rotation so the linear-slide deployment remained consistent
• Manually milled the pneumatic clevis linkage with a #10-32 clearance hole
• Adapted the over-center concept from a design used by VEX U team PYRO

I created the 14-page Worlds Technical Binder used to explain Chip and Dale to judges and document the team's design process.

The binder included:

• Predicted Worlds game strategy
• Autonomous, teleoperated, and endgame plans
• Subsystem requirements
• Drivetrain specifications
• Pneumatic wing design
• PTO design
• Pneumatic intake design
• Linear-slide climber design
• Over-center claw design
• CAD renders
• Field diagrams
• Robot photos

I organized the technical information, wrote and edited the content, selected the supporting visuals, and designed the binder layout. The goal was to clearly communicate the strategy and engineering decisions behind the robots during the judges' interview.

I also produced the Chip and Dale robot reveal. I planned and filmed the robot footage, edited the final video, selected the shots used to present the robots and their mechanisms, and designed the YouTube thumbnail.

Alongside Chip and Dale, I began developing and prototyping a third robot concept under 6" tall. Its specialized role was to drive beneath the Goal and remove scored Triballs.

The descoring robot was included as a nice-to-have in the Worlds priority list, while completing Chip and Dale remained the main priority. I abandoned the concept before completing the robot because the remaining schedule needed to be focused on manufacturing, assembling, programming, and testing the two competition robots.