Determining new maneuvers to propel the AMPS

What kind of maneuvers are we trying to come up with?

Straight Maneuver

• Mimic human behaviour on wheelchairs.
• Give out different Propulsion costs among different surfaces and configurations.

Straight maneuver only considers the rolling of the wheels as the resistance. The wheels only roll but never scrub the ground, and the casters only roll but never swivel (seen in the figure below). To take the scrubbing of the wheels and the swiveling of the casters into account, a slalom maneuver is developed.

Slalom Maneuver

• A turning maneuver that forces casters to swivel with every push.
• A turning maneuver that forces wheels to scrub the ground consistently.

What is the process of inventing maneuvers?

I took several steps to develop the new maneuver: doing literature reviews, investigating human behavior through videos, and doing hundreds of experiments. Through the literature review, I know that people normally travel at a higher speed of 1 m/s and a lower speed of 0.6m/s. With the videotape from expert wheelchair users, I figured that people propel the push rim for around 1 second and coast for 0.5 seconds. People also propel for a longer time but reach a slightly lower velocity for the first push, after that they reach a “steady state”.

The AMPS uses PID control to control its velocity. We tested hundreds of trials intending to find the best configuration that does not throw an overshoot and reaches the target the fastest. We chose a sinusoid profile over a trapezoidal one because it better mimics human behavior, provides a smoother power profile, and maintains a more stable steady-state velocity.

Georgia Tech Spring 2021 Symposium

I am awarded the Best overall Poster Presentation in Georgia Tech 2021 Spring Undergraduate Research Symposium.