Jonathan Poulter

For my master's thesis project, I designed, programmed, and built a robotic assistive knee brace prototype, designed to aid wearers with a sit-to-stand motion. I completed it as a solo project but worked with my advisor from the IRON Lab within the ATLAS Institute at the University of Colorado in Boulder.

The platform the brace was built upon was a simple off-the-shelf knee brace purchased from a pharmacy. Using 3D-printed brackets, two linear actuators were mounted on either side to provide consistent, even force to the wearer's joint to allow motion. Limit switches were installed in the 3D-printed brackets to ensure motion stopped in the same position each time. The microcontroller used to operate the system was an Adafruit Feather, programmed in C++ through the Arduino IDE.

Initially, control of the knee brace required a PC-based user interface through both hardwired and Bluetooth connections. The final version incorporated electromyography (EMG) sensors, which can detect muscle activity. With sensors attached to the muscles of the brace wearer's leg, the controller could tell when the user was trying to bend or straighten their leg and actuate accordingly.

Self-locking, vibration-resistant bolts are of great interest to those in the aerospace and defense industries. With an increased focus on in-space servicing, assembly, and manufacturing (ISAM), the use of safety wire fasteners is not realistic. Automating the installation of fasteners that don't require safety wire could be crucial for building space infrastructure.

Working with a team of mechanical engineers at Enduralock, we designed a custom end effector that could be installed on any robotic arm and interface with Enduralock's fasteners. Given that the projected environment is in space, gravity and friction could not be relied upon to retain the fasteners before installation or after removal. Using an electromagnetic clutch and brake, a cam system was developed that could retain Enduralock's Silver Lock fastener without interfering with the locking mechanism.

Using an Arduino MEGA 2560, a Mountz torque tool, and the previously mentioned clutch and brake, a full prototype was built and demonstrated on a Yaskawa robotic arm. A full installation and removal cycle was performed autonomously to meet the project requirements.

While working for Alliant Techsystems (now Orbital ATK), the company was contracted to develop the third-stage rocket motor for NASA's Lunar Atmosphere and Dust Environment Explorer (LADEE) mission. As a member of the avionics team, I was tasked with leading the commissioning of the Electrical Control Unit (ECU) and Electromechanical Actuators (EMAs). This started with writing an in-depth test plan and test procedure for approval by all interested parties.

Throughout the performance of the test procedure, functional tests were performed on a custom set up, requiring the actuators to perform pre-programmed maneuvers. Data from these tests were collected and analyzed using custom MATLAB functions to ensure performance metrics were being met. These performance tests were performed before and after vibration resistance tests and before, during, and after environmental survival tests, including thermal cycling and thermal vacuum testing.

After all of the testing was completed, I was responsible for writing a test report detailing the results of all of the testing that had been required. Upon approval, the ECU and EMAs were mounted to a rocket motor and utilized to put a satellite in orbit around the moon in 2013.