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23 results on '"Xu, Patricia"'

2. High-bandwidth nonlinear control for soft actuators with recursive network models

Author

Manzano, Sarah Aguasvivas, Xu, Patricia, Ly, Khoi, Shepherd, Robert, and Correll, Nikolaus

Subjects
Computer Science - Robotics, Computer Science - Artificial Intelligence, Computer Science - Software Engineering, Electrical Engineering and Systems Science - Systems and Control, Mathematics - Numerical Analysis
Abstract

We present a high-bandwidth, lightweight, and nonlinear output tracking technique for soft actuators that combines parsimonious recursive layers for forward output predictions and online optimization using Newton-Raphson. This technique allows for reduced model sizes and increased control loop frequencies when compared with conventional RNN models. Experimental results of this controller prototype on a single soft actuator with soft positional sensors indicate effective tracking of referenced spatial trajectories and rejection of mechanical and electromagnetic disturbances. These are evidenced by root mean squared path tracking errors (RMSE) of 1.8mm using a fully connected (FC) substructure, 1.62mm using a gated recurrent unit (GRU) and 2.11mm using a long short term memory (LSTM) unit, all averaged over three tasks. Among these models, the highest flash memory requirement is 2.22kB enabling co-location of controller and actuator., Comment: International Symposium on Experimental Robotics (ISER) 2020, Malta

Published
2021
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6. Frailty as a Predictor of Outcomes in Subarachnoid Hemorrhage: A Systematic Review and Meta-Analysis

Author

Fortunato, Michael, primary, Lin, Fangyi, additional, Uddin, Anaz, additional, Subah, Galadu, additional, Patel, Rohan, additional, Feldstein, Eric, additional, Lui, Aiden, additional, Dominguez, Jose, additional, Merckling, Matthew, additional, Xu, Patricia, additional, McIntyre, Matthew, additional, Gandhi, Chirag, additional, and Al-Mufti, Fawaz, additional

Published
2023
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18. Stereolithography for personalized left atrial appendage occluders

Author

Robinson, Sanlin S., Aubin, Cameron A., Wallin, Thomas J., Gharaie, Saleh, Xu, Patricia A., Wang, Kaiyang, Dunham, Simon N., Mosadegh, Bobak, Shepherd, Robert F., Robinson, Sanlin S., Aubin, Cameron A., Wallin, Thomas J., Gharaie, Saleh, Xu, Patricia A., Wang, Kaiyang, Dunham, Simon N., Mosadegh, Bobak, and Shepherd, Robert F.

Published
2018

20. Elastomeric passive transmission for autonomous force-velocity adaptation applied to 3D-printed prosthetics.

Author

O'Brien, Kevin W., Xu, Patricia A., Levine, David J., Aubin, Cameron A., Yang, Ho-Jung, Xiao, Michael F., Wiesner, Lennard W., and Shepherd, Robert F.

Subjects
CONTINUOUSLY variable transmission, ARTIFICIAL hands, SINGLE-degree-of-freedom systems, FINGERS, PROSTHETICS, ENGINEERING design
Abstract

The force, speed, dexterity, and compact size required of prosthetic hands present extreme design challenges for engineers. Current prosthetics rely on high-quality motors to achieve adequate precision, force, and speed in a small enough form factor with the trade-off of high cost. We present a simple, compact, and cost-effective continuously variable transmission produced via projection stereolithography. Our transmission, which we call an elastomeric passive transmission (EPT), is a polyurethane composite cylinder that autonomously adjusts its radius based on the tension in a wire spooled around it. We integrated six of these EPTs into a three-dimensionally printed soft prosthetic hand with six active degrees of freedom. Our EPTs provided the prosthetic hand with about three times increase in grip force without compromising flexion speed. This increased performance leads to finger closing speeds of ~0.5 seconds (average radial velocity, ~180 degrees second−1) and maximum fingertip forces of ~32 newtons per finger. [ABSTRACT FROM AUTHOR]

Published
2018
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