Blastoise

2024–25 · FTC Into the Deep · Team 6417 Blu Cru

An all-in-one robot that intakes and scores with a single telescoping arm, eliminating the need for a transfer mechanism entirely. Evolved from our States robot, Wartortle.

• Peaked at 7th Offensive Power Rating worldwide
• Finished 9/64 at the World Championship
• Placed 13th of 40 at the Multinational Tech Invitational

Telescoping Arm

• Three-stage telescoping tube system with 34 inches of extension
• Cascade-strung with two sets of strings — the second is a backup that improves consistency
• Custom bearing blocks constrain both the inside and outside of the tubes
• Chain-and-sprocket pivot with a custom tensioner at a 152.7:1 ratio — 39 RPM, 205.2 kg·cm of torque
• Pivot is over 80% custom; the arm is pocketed to reduce weight

End Effector

• All-in-one intake/outtake removes the transfer mechanism entirely, embodying the KISS principle
• Active/passive combination: a belt-driven spinner for fast intaking plus a sample-conforming latch for reliable scoring
• Four degrees of freedom — pitch control for multiple scoring angles, rotating wrist for roll control from either side
• Sample-aligning geometry and a limit switch detect and square up blocks
• A scissor-linkage pusher (225 mm extension) was added after Qual 1 to reach vertical blocks at the submersible edge

Two-Stage Hang

• One-of-a-kind passively sprung two-stage hanger with magnetic hooks
• Level 2 uses a sprung bungee cord for instant extension, bracing on the submersible to minimize required torque
• Level 3 uses the extension's own speed to throw the magnetic hooks up, with a separate high-torque motor lifting the robot
• A dual-purpose servo acts as both latch and high-torque retraction winch

Drivetrain

• Custom CNC-machined plates with motors embedded into the sides to save space
• Motors lowered to drop center of mass, validated in Onshape center-of-mass simulation before building
• Two dead-wheel odometry pods for localization
• Polycarbonate covers and ramps stop samples falling into the robot

Software

• Affine transformation matrix inverse kinematics relate robot center to end-effector position
• Cubic Hermite splines smoothly control end-effector pathing
• Custom point-to-point PID pathing replaced Road Runner, which was slow and did not correct at the end of trajectories
• AprilTag localization corrects odometry drift, using a linked list of past positions to extrapolate around reading latency
• Voltage compensation normalizes motor power to 12V so behavior stays consistent as the battery drains