Describe and control the up-and-down (heave) motion of a bagged air cushioned vehicle.
This project involved modeling the heave motion of an air cushioned vehicle (ACV), and analyzing its stability with respect to track-height disturbances. It was performed as part of the 2017 ECE Capstone Competition at Northeastern University, and was done in partnership with Paradigm Hyperloop (Northeastern and Memorial University of Newfoundland collaboration).
The pod has four bagged air-skates (red fabric components).
There exists gaps between the track plates, and the plates them selves drift in height.
Track profile when the pod moves at 60 mph.
Track profile when the pod moves at 400 mph.
We developed a nonlinear model based on a Forchheimer porosity approximation for the heave motion of the bagged ACV. The model matches experimental findings of the pod dynamics: the pod is stable at atmospheric pressure and tends to oscillate (approaching instability) at tube (near-vacuum) pressure. We developed a control strategy and certified stability using a sum-of-squares verified Lyapunov function. The controlled pod rejects the track height disturbance and results in a smooth ride.
Heave, speed, and bag pressure as the pod moves at 400 mph.
Relevant Publications:
Conference Articles
CCTA
A Model of Heave Dynamics for Bagged Air Cushioned Vehicles
This paper presents a simple model of the heave (up-and-down) dynamics of an air cushioned vehicle. A set of nonlinear differential equations are extended to the case of a bagged air skates using a Forchheimer porosity approximation. The model exhibits stability under atmospheric pressure, and a tendency towards instability in near-vacuum conditions. Inner estimates of regions of attractions are found to verify stability in atmosphere, and track simulation shows system disturbance rejection under a drifting subtrack height and gaps.
@inproceedings{miller2019acv,author={Miller, Jared and Shafai, Bahram},booktitle={IEEE Conference on Control Technology and Applications (CCTA)},title={{A Model of Heave Dynamics for Bagged Air Cushioned Vehicles}},year={2019},volume={},number={},tag={acv},pages={976-981},doi={10.1109/CCTA.2019.8920508},url={https://ieeexplore.ieee.org/document/8920508},html={https://ieeexplore.ieee.org/document/8920508},bibtex_show={true},slides={CCTA_ACV_Levitation.pdf},abbr={CCTA}}
