Sebastian
BujarskiHardware & robotics, drawn to spec

A soft continuum robotic arm inspired by an elephant's trunk, built for Cornerstone Engineering II with teammates Yonas and Karl. The arm has two independently bendable sections, each pulled by four tensioned strings routed through a stack of 3D‑printed disk and spool segments — so each section curls in any direction depending on which strings are pulled taut.

I modeled and dimensioned the disk and spool components in SolidWorks (drawings at right), sized so string channels stayed aligned through the full range of bending without binding. Four DC gearmotors per section, housed in a wired control base, act as winches to pull the strings; an onboard LED strip marks which segment set is active.

Ongoing research with Northeastern's Transformative Robotics Lab (TRL), under Professor Jeffrey Lipton, alongside graduate students and a collaborating professor's group abroad. The project builds a bistable, radially-expanding hexagonal structure — a "2.5D" cylindrical form made of repeating chevron unit cells that snap between a compact and an expanded state as the cylinder is extended vertically.

The graduate team fabricates the unit cells several different ways — laser-cut from a few different materials, and 3D-printed in a few different materials — to see how fabrication method and material change the bistable response. My role has been testing and characterizing those units: manual measurement, motion-capture-tracked deformation, straightforward visual/qualitative testing, and full stress-strain characterization on an Instron tensile tester.

To make that Instron testing possible, I designed and fabricated two things myself: a small connector piece that joins each end of a unit cell together, and a mounting fixture that clamps a test sample into the Instron and lets it rotate freely as it deforms (the CAD model and sketch at right). The resulting stress-strain curves show the repeated snap-through peaks that give each layer its "click" between states, feeding results back to the team's next design pass.

Two years with the National Eclipse Ballooning Program (NEBP), coordinating a team of eight across five high-altitude balloon launches. Payloads reached the edge of space, past 100,000 ft, on multiple flights, and instrumentation from one launch contributed to research on atmospheric gravity waves during a solar eclipse — work presented at the American Astronomical Society conference.

I designed the payload housings in SolidWorks and built them from foam-core panels, then built and programmed the ozone sensor module in C++ for onboard readout and logging. Each payload carried an Iridium satellite modem and GPS for tracking, recovered afterward with a portable ground station and directional antenna. I also helped coordinate launch-day logistics and team roles across the five missions.

With Renewable Energy at Northeastern (RENU), I designed the blade pitch-control mechanism for a three-person team's entry in a collegiate competition wind turbine build. Instead of a fixed blade angle, each blade mounts to a rotating shaft through a bearing housing, so pitch can be actively adjusted to the wind rather than staying fixed across every condition.

I modeled the full pitch assembly in SolidWorks — the bearing housing, mounting bracket, shaft, and hub — sized so the blade could rotate freely under load without binding. Active pitch control measured roughly an 8% efficiency gain over a fixed-blade baseline across varying wind speeds.