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Control-Oriented Learning for Dynamic Tracking and Stability Analysis of Soft Pneumatic Actuators
Nithin S. Kumar,
Eric J. Barth
Currently Under Review
Video
We develop a control-oriented learning framework that combines a nonlinear static model
with learned residual dynamics for real-time 3D control of soft pneumatic actuators.
Experiments achieve ~1 mm RMSE at 10 mm/s and <10 mm RMSE at 100 mm/s,
while enabling stable user-guided motion exceeding 25 m/s² peak acceleration
and real-time obstacle avoidance. The learned model also
predicts closed-loop stability, successfully distinguishing stable,
marginally stable, and unstable behavior prior to deployment.
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Task-space model-based control of pneumatic soft actuators
Nithin S. Kumar,
Joshua Gaston, D. Caleb Rucker, Eric J. Barth
Currently Under Review
We extend a planar discrete elastic rod model for real-time dynamic task-space
control of soft pneumatic actuators. The sparse formulation efficiently handles
holonomic and nonholonomic constraints, enabling a 10-rod model and observer to
run at 1 kHz while achieving ~2 mm RMSE on precision
trajectories and stable tracking up to 2 Hz and 37 cm/s.
We demonstrate model generalizability across three different actuator geometries,
real-time tracking of user-generated references, and observer-based control that
reduces tip-tracking error by 45% on average without direct tip sensing.
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Constrained Lagrangian-Based, Nonholonomic Modeling and Validation of a Pneumatically
Actuated Wheeled Soft Robot
Nithin S. Kumar,
John E. Peters, Sung Y. Kim, Joshua Gaston, D. Caleb Rucker, Eric J. Barth
Journal of Mechanisms and Robotics, 2026
Video
We develop a constrained Lagrangian model to capture the highly dynamic, non-holonomic based
locomotion of a pneumatically actuated
wheeled soft robot. The robot achieves speeds up to 22 cm/s (1.38 body lengths/s)
and demonstrates forward, reverse,
and circular locomotion. We validate the modeling framework across
three different robot designs, accurately reproducing their
experimentally observed configuration and velocity trends.
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Data-driven dynamic modeling and control of pneumatic soft actuators with stability
analysis
Nithin S. Kumar,
John E. Peters, Thomas Beckers, Eric J. Barth
ASME Letters in Dynamic Systems and Control, 2026
We develop a data-driven modeling framework that combines a nonlinear
feedforward map with EDMDc residual dynamics for control of
soft pneumatic actuators. Experiments achieve 2 mm RMSE
on shape-rich trajectories and <10 mm RMSE at tip speeds exceeding
100 mm/s. The learned model also enables
closed-loop stability prediction without requiring an explicit
first-principles dynamic model.
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Touching is Believing: Contact Sensing to Enhance Situational
Awareness for Concentric Tube Robots
Nithin S. Kumar,
Jason A. Shrand,
Susheela Sharma,
S. Duke Herrell III,
Nicholas L. Kavoussi,
Ahmed Ghazi,
Eric J. Barth,
Ipek Oguz,
Alan Kuntz,
Robert J. Webster III
Hamlyn Symposium on Medical Robotics (HSMR), 2025
We develop an impedance-based contact sensing method that enables a concentric tube
robot to collect tissue surface points for robot-to-anatomy registration during
endoscopic procedures. Experiments in an anthropomorphic prostate phantom
achieve a mean surface registration error of
2.11 ± 1.01 mm, demonstrating contact sensing as an
additional source of information for improving situational awareness in
robot-assisted surgery.
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