AnkleBiter (2023)

Summary

The AnkleBiter robot was built for the 2023-24 FIRST Tech Challenge competition season. In my role as a hardware lead, I delegated tasks, and designed parts for the robot.

My team captain directed me to design a novel swerve-type drivetrain system, where each wheel is indepedent, and capable of infinite steering. To accomplish this, I worked closely with Josh, our software lead, to design the motion control system required to operate a differential swerve drivetrain. It took several months of constant iteration to create the two competition ready swerve drive modules.

While exciting, and time consuming, the swerve drivetrain didn't end up being the most exciting part of AnkleBiter. Instead, the powerful robot arm affixed to the front defined our competitiveness.

AnkleBiter Lifter

A key element of AnkleBiter's success was its versatile and efficient lifting mechanism, designed to manipulate cones. The primary goals for the lifter were high stiffness, minimal reliance on complex linear motion components, low cost, and the use of easily sourced or fabricated parts.

My initial approach explored a linkage system inspired by desk lamps. However, I encountered issues with a "dead-zone" due to overextension and backlash, leading to a switch to a more direct drive system.

The final iteration utilized three motors for speed and power: two at the base (shoulder) with high gearing and one faster motor at the elbow. To maintain consistent claw orientation, a servo-driven "wrist" (C stage) was implemented. Notably, the elbow joint incorporated 3D-printed gears made from ABS and Nylon, where I leveraged the anisotropic properties of FDM 3D prints with special curved teeth.

For cone manipulation, I developed Pinchy. This entirely 3D-printed, modular claw required no custom metal components, relying on COTS bearings, and M3 fasteners. Pinchy offered good grip, low cost, ideal geometry with special tapered grippers, and quiet operation.

Keynote features of the AnkleBiter lifter included: