The AMPS (Wheelchair Tester)

The Anatomical Model Propulsion System (AMPS) is a robotic wheelchair tester. It has several sub-systems:

  1. User Interface

    • The laptop "head" of the robot runs custom LabVIEW scripts

    • Data processing utilizes custom MATLAB functions

  2. Propulsion

    • Brushed DC motors on each arm are meshed directly to custom PVC push-rims on each wheel

    • A RoboteQ motor controller (model HDC-2460) runs a basic P-I-D controller with feedback from the motor-mounted encoders (for velocity control) or from armature current sensors (for motor torque control)

  3. Data Acquisition

    • A LabVIEW-compatible data acquisition board (USB-6341, National Instruments) collects data from various sensors on the system and sends the desired motor trajectory to the motor controller

    • The sensors around the system include: wheel speeds from hub-mounted encoders; propulsive forces from wrist-mounted load cells; motor current (and torque) from armature current sensors; motor voltage (and shaft speed) from voltage sensors; vibrations of the chair frame from multiple accelerometers

Tissue Indentation Tester

This instrument quantifies tissue compliance using inexpensive sensor modules and swappable 3D-printed shells for different tissue types. The tester can interface with multiple styles of data acquisition including Arduino (or similar microcontrollers) and LabVIEW-compatible hardware like the myRIO / myDAQ system.

Pictured here is a calibration rig to test the repeatability of the compliance of a "phantom" tissue model, made from an elastomeric gel.

Also pictured are 3D-printed models of anatomical MRI scans of the buttocks, thighs, and bony anatomy of the hip and lower spine.

"Orphan Assistive Technologies"

As a member of REAR Lab, I work with members of the greater Atlanta community like Lekotek of Georgia to renovate, redesign, or repair toys for children with disabilities.

Additionally, I mentor or advise at least one Capstone Design team per semester to focus on some product or problem in the field of rehabilitation engineering and assistive technology. Often, finalized and functional devices designed around a single user (certain toys, wheelchairs, braces, etc.) are given away freely. For these projects, fabrication package are made available on REAR Lab's Instructables page for other members of the community to adapt and make themselves.

Contract Work

Early Design

The water monitor project with JJ Obrien, another REAR Lab member, was an exercise in programming, circuitry and enclosure design. The original model was large and rectangular with a touchscreen and antenna for cellular connectivity. The enclosure was machined from aluminum and shown at an international conference in late 2019.

Final Design

The final model was slimmed down by selecting a smaller board (Particle's Photon board) with cellular capabilities. Everything was placed on a custom PCB and fitted into an off-the-shelf enclosure with silk-screened diagrams and labels.