5 research outputs found
Identifying Single-Input Linear System Dynamics from Reachable Sets
This paper is concerned with identifying linear system dynamics without the
knowledge of individual system trajectories, but from the knowledge of the
system's reachable sets observed at different times. Motivated by a scenario
where the reachable sets are known from partially transparent manufacturer
specifications or observations of the collective behavior of adversarial
agents, we aim to utilize such sets to determine the unknown system's dynamics.
This paper has two contributions. Firstly, we show that the sequence of the
system's reachable sets can be used to uniquely determine the system's dynamics
for asymmetric input sets under some generic assumptions, regardless of the
system's dimensions. We also prove the same property holds up to a sign change
for two-dimensional systems where the input set is symmetric around zero.
Secondly, we present an algorithm to determine these dynamics. We apply and
verify the developed theory and algorithms on an unknown band-pass filter
circuit solely provided the unknown system's reachable sets over a finite
observation period.Comment: 8 pages, 1 figure, published at the 62nd Conference on Decision and
Control (CDC 2023
Online Learning and Control Synthesis for Reachable Paths of Unknown Nonlinear Systems
In this paper, we present a novel method to drive a nonlinear system to a
desired state, with limited a priori knowledge of its dynamic model: local
dynamics at a single point and the bounds on the rate of change of these
dynamics. This method synthesizes control actions by utilizing locally learned
dynamics along a trajectory, based on data available up to that moment, and
known proxy dynamics, which can generate an underapproximation of the unknown
system's true reachable set. An important benefit to the contributions of this
paper is the lack of knowledge needed to execute the presented control method.
We establish sufficient conditions to ensure that a controlled trajectory
reaches a small neighborhood of any provably reachable state within a short
time horizon, with precision dependent on the tunable parameters of these
conditions
Guaranteed Reachability on Riemannian Manifolds for Unknown Nonlinear Systems
Determining the reachable set for a given nonlinear system is critically
important for autonomous trajectory planning for reach-avoid applications and
safety critical scenarios. Providing the reachable set is generally impossible
when the dynamics are unknown, so we calculate underapproximations of such sets
using local dynamics at a single point and bounds on the rate of change of the
dynamics determined from known physical laws. Motivated by scenarios where an
adverse event causes an abrupt change in the dynamics, we attempt to determine
a provably reachable set of states without knowledge of the dynamics. This
paper considers systems which are known to operate on a manifold.
Underapproximations are calculated by utilizing the aforementioned knowledge to
derive a guaranteed set of velocities on the tangent bundle of a complete
Riemannian manifold that can be reached within a finite time horizon. We then
interpret said set as a control system; the trajectories of this control system
provide us with a guaranteed set of reachable states the unknown system can
reach within a given time. The results are general enough to apply on systems
that operate on any complete Riemannian manifold. To illustrate the practical
implementation of our results, we apply our algorithm to a model of a pendulum
operating on a sphere and a three-dimensional rotational system which lives on
the abstract set of special orthogonal matrices
Comparison the Effects of Ephedrine and Lidocaine in Treatment of Intraoperative Hiccups in Gynecologic Surgery under Sedation
Background: This study aimed to evaluate and compare the therapeutic effects of ephedrine and lidocaine in treatment of intraoperative hiccups in gynecologic surgery under sedation. Materials and Methods: This randomized clinical trial in Isfahan was done on fifty female patients referring to Shahid Beheshti Hospital who needed to have sedation for medical interventions and they afflicted hiccups during surgery or sedation. Patients divided into two groups of 25 randomly assigned to one of the two groups of ephedrine or lidocaine. Ephedrine group received 5 mg/kg of medicine, while the lidocaine group was under treatment with 1 mg/kg lidocaine. Patients were monitored about systolic and diastolic blood pressure, MAP, heart rate, duration of hiccup, frequency of betterment, duration of intervention, and recovery at 15-min intervals of surgery and recovery. Results: Hiccups were resolved in 14 cases (56%) in the lidocaine group, while the improvement of such problem was achieved in 24 cases (96%) in ephedrine group (P < 0.001), so that the two groups did not have any significant difference in terms of the time of onset but the stop time of hiccups (relative to its start time) in the ephedrine group with the mean value of (2.40 ± 1.16) was significantly lower than the lidocaine group with the mean of 19.64 ± 22.76 min (P = 0.014). In addition, no complications were observed in the two groups. Conclusion: Ephedrine has been more successful than lidocaine as a stimulant in controlling hiccups, and it has been able to suppress hiccups in a higher percentage of patients at a shorter time