Welcome to my project portfolio!
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Epoxy Bond-Strength Test Setup for Undergraduate Research with Global Engineering and Research (GEAR) Lab
Machined aluminum adaptors for Instron tensile testing machine
Waterjet cut + machined tube clamp functions as a compliant mechanism
Precision bond-line method for repeatable tension tests
custom Instron adaptors
CAD model of testile test setup
glue plate (left), CFRP tube, clamp plate (right)
Steering System for Solar Car "Gemini"
Responsible engineer for a system of 25 unique components, from concept development through critical design review and into manufacturing
Designed steering geometry considering vehicle dynamics and packaging
Mentored four underclass students in component design
Skills Learned
Planning long-term design project
Teaching mechanical design
Configuration management
Managing a BOM
Systems thinking
Vehicle dynamics
Components Include
Quick release steering hum
Steering wheel shaft
Shaft bearing mounts
Steering column tube
Universal joints
Pinion spline adaptor
Rack and pinion
Rack and pinion mount
Rack extender tube
Tie rod mount/prismatic joint
Tie rods
Steering arms
MUCH BETTER PHOTOS COMING SOON!
Steering Arms for Solar Car "Gemini"
Description Coming Soon
First Design Iteration: Machined 7075 Aluminum
Second Iteration: 4130 Steel Plate Weldment
Weldment FEM stress analysis under steering load
Steering Prismatic Joint to Stiffen Rack Linkage for Solar Car "Gemini"
Description Coming Soon
First Design Iteration: machined aluminum tie rod mount in machined acetal block
Vehicle Dynamics Project for 2.671 Measurement and Instrumentation
Abstract: Measuring the effects of vehicle weight distribution on dynamic steering behavior is essential to preventing dangerous understeer and oversteer behaviors. A mechanics-based model indicates that front-heavy vehicles will understeer, back heavy vehicles will oversteer, and neutral weighted vehicles will maintain neutral steer. By varying the weight distribution of a small-scale test vehicle and controlling it to drive in circles, these different steering behaviors are measured. An onboard accelerometer and gyroscope measures yaw rate and centripetal acceleration to characterize the vehicle’s dynamic behavior by determining a calculated radius of turn. A correlation was discovered between oversteer and front-heaviness, and between understeer and rear-heaviness, directly contradictory to the model hypothesis. Therefore, some other mechanism not considered by the model—likely due to the test vehicle’s rear-wheel-drive configuration—is responsible for the observed steering behavior.
Experimental setup comprising 6-axis IMU, Legos, Arduino microcontroller, and servo motor
Click to view poster in full screen
T_06_Roach_J_SteeringDynamics.pdfClick to view paper
roach_jonathan_steering_dynamics_finalpaper.pdfInjection Molded Yo-Yo for 2.008 Design and Manufacturing II
Built for the 2.008 Design and Manufacturing II design and build challenge
Each yo-yo contains 6 injection molded parts and two thermoformed parts
Molds were designed and machined from aluminum
Yo-yos were assessed for overall quality, consistency, and durability of interference fits given a drop-test (no adhesive allowed in design)
Production run produced over 80 yo-yos
Brake Pedal Assembly for Solar Car "Gemini"
Designed a novel brake pedal assembly for solar car Gemini to reduce weight and packaging size
Mechanical and hydraulic advantage calculations
Human factors to select ergonomic pedal motion
Selection of off-the-shelf brake system components
Minimum weight design of a load-bearing structure
Design for manufacturing and assembly
2.007 Competition Robot
Built for the 2.007 Design and Manufacturing I robot competition
Creative material selection: utilized Masonite (high density fiberboard) for low-friction low-profile four-stage telescoping linear slide for ‘beaver lift’ challenge.
Front wheel suspension mechanism: ‘leading-arm’ style rubber-band-sprung servo mounts allowed vehicle to crouch while completing lift challenge, thereby directing load into the ground through the bottom of the chassis to alleviate suspension forces.
"Dead reckoning" autonomous mode + RC control for drive wheels and lift winch
Successfully completed all mission objectives and placed in top 16 contestants
Suspension “crouched” position directs load into the ground through the bottom of the chassis to alleviating suspension forces
Parking Brake for Solar Car "Nimbus"
Design Goals
Reliably hold the car in place according to ASC regulations
Manufacturability: minimize the number of machined parts, number of welds.
Serviceable/adjustable brake line pressure
Easy to toggle on/off
Lightweight
Inexpensive
Constraints
Mounting/access holes were already on the car
ASC Regulations
Deadline
Design
I produced a simple, elegant design which utilized an inexpensive of-the-shelf toggle clamp for the most complicated part of the mechanism. All other parts were cut on a water-jet from aluminum and bolted together.
Outcome
Manufacturing proved quick and simple which allowed further optimization of the design after an initial prototype. The final parking brake passed inspection and testing at American Solar Challenge 2021. SEVT drivers complimented its reliability and ease of use. Future improvements may include further decreasing weight.
A-arm Tube Joint for Solar Car "Nimbus"
Design Goals
Properly constrain the motion of the front suspension upper A-arm tubes.
Ensure that major forces are delivered to members in axial loading
Manufacturability
Lightweight
Constraints
ASC Regulations
Deadline
Design
Previous iterations did not properly constrain the a-arm tubes, either allowing for an extra degree of freedom, or holding the tubes in constant bending. The new design entirely constrained one of the tubes, while allowing the other tube one degree of freedom by utilizing a clevis joint. This provided built-in adjustability of the A-arm lengths and ensured the severe suspension loads would be transmitted axially.
Outcome
I learned a lot from the manufacturing process of this part. First, the initial design was unnecessarily complex which resulted in a higher number of mill operations. Even after simplifying the part, lack of experience in manufacturing resulted in many mistakes. In the end, creative solutions allowed successful installation of the joint. The part performed well and the front suspension has seen over a thousand miles without significant maintenance. In one instance, Nimbus spun out on the track and the suspension took extreme loads. This caused the deformation of one of the threaded rods but the joint was undamaged and is predicted to last the full lifetime of the car. Future improvements could include optimization of the shape to improve the strength to weight ratio.
First design
Final design (clevis not shown)
Marvin - 2018
Objective: Construct a wooden, robotic, 15-foot-tall, artificial-intelligence-driven Connect 4 game for play at the 2018 World Maker Faire in New York.
Constraints: cost, deadline, limited tools
Result: MARVIN became the top hit at the World Maker Faire in NYC in 2018. It was featured in over a dozen separate publications about the faire and won Editors' Choice and Best in Class awards. It also hold the unofficial world record for the largest Connect-4 board.
Reflection: For about a year, my friend Ben and I spent our weekends in the garage building MARVIN's components, and at the beginning of the summer we constructed him for the first time. Using a 4 foot pole, a human player places an 11 inch diameter colored game disk at the top of the column of their choosing. The disk placement is recorded by optical sensors that transmit its location to an Arduino.
On September 22 and 23 MARVIN was displayed at the New York Hall of Science as part of the "Greatest Show (and Tell) on Earth". During setup, we encountered some fundamental issues related to our use of infrared sensors in the outdoors (they don't work). However, no problem is too large when you have access to the brainstorming power of hundreds of makers with great ideas. Together, we came up with a few creative hacks (thanks Mike from Hackaday) that fixed our problem. Once Marvin was up and running, he started winning, and finished the weekend with a winning percentage of 78% (better than any Major League Baseball season record in history). Kids and adults alike flocked from around the fair to come play him and although usually defeated, they walked away happy. Marvin became a huge crowd pleaser and received four Editors' Choice awards.
Selected Media Links:
RFiClimb - 2017
Vision: Combine the ever-growing worlds of technology and indoor rock climbing by creating the world's first RFID-based tracking system for climbers.
My partner, Ben Lehrer, and I are pleased to announce that we have licensed our technology to Climbalytics. A consumer version is now available!
RFiClimb debuted at the 2017 World Maker Faire, earning "Best in Class" and three Editors' Choice awards. Read more about our story here.
Operation - 2019
Objective: Design and build an arcade-sized version of the Hasbro game "Operation" using an electronic 3 axis CNC-style arm for a remote surgery twist.
Concept: Controlling the arm with the arcade-style control unit, which features a live close-up video feed, players attempt to remove game pieces with an electromagnet while avoiding the metal edges.
"Sergio" was a big hit at the Philadelphia Maker Faire and other events. Read more about this project here or hear what others have to say:
Watch my friend Ben try his hand at remote surgery!
Ben and I spent months designing and building this complex robotic game but the work was fun and the result was well worth our time!
Sailboat - In Progress
Goal: Design and build a 12-foot sailboat from wood and composite.
This has been a fun, hands on challenge in designing a minimum-weight structure which meets strength and stiffness requirements. So far, the internal composite skeleton and the wooden hull are finished. The fiberglass layup of the hull and deck as well as the rigging installation are awaiting sponsor funding. Check back here for updates!
Tractor-Engine Car 2020
The goal of this project was to design and build a low-speed car for two passengers. A lack of metalworking resources necessitated a wooden chassis and a tight budget limited us to a ride-on lawnmower motor and homemade wheels. Still, it was highly educational to reverse engineer a lawnmower and the constraint of working with wood was a fun challenge. In the end, the car drove pretty well and everything I learned about vehicle design has proved useful for my work on the MIT solar car team.
Electronic Saxophone 2016
Beginning as a simple Arduino circuit, and evolving over the course of a year, this project culminated as an award-winning spectacle at the 2016 World Maker Faire. The saxophone body is fiberglass, formed over a hand carved mold. Electronic keys and a pressure-sensing mouthpiece provide a realistic playing experience. A peripheral light tower displays the note that is played from the saxophone's built in speaker, headphones, or amp. According to PC Magazine, it was one of "The Coolest Projects at Maker Faire 2016."