2,810 research outputs found
Graph-Based Controller Synthesis for Safety-Constrained, Resilient Systems
Resilience to damage, component degradation, and adversarial action is a
critical consideration in design of autonomous systems. In addition to
designing strategies that seek to prevent such negative events, it is vital
that an autonomous system remains able to achieve its control objective even if
the system partially loses control authority. While loss of authority limits
the system's control capabilities, it may be possible to use the remaining
authority in such a way that the system's control objectives remain achievable.
In this paper, we consider the problem of optimal design for an autonomous
system with discrete-time linear dynamics where the available control actions
depend on adversarial input produced as a result of loss of authority. The
central question is how to partition the set of control inputs that the system
can apply in such a way that the system state remains within a safe set
regardless of an adversarial input limiting the available control inputs to a
single partition elements. We interpret such a problem first as a variant of a
safety game, and then as a problem of existence of an appropriate edge labeling
on a graph. We obtain conditions for existence and a computationally efficient
algorithm for determining a system design and a control policy that preserve
system safety. We illustrate our results on two examples: a damaged autonomous
vehicle and a method of communication over a channel that ensures a minimal
running digital sum.Comment: 56th Annual Allerton Conference on Communication, Control, and
Computin
Application of Correct-by-Construction Principles for a Resilient Risk-Aware Architecture
In this paper we discuss the application of correct-by-construction techniques to a resilient,
risk-aware software architecture for onboard, real-time autonomous operations. We
mean to combat complexity and the accidental introduction of bugs through the use of
verifiable auto-coding software and correct-by-construction techniques, and discuss the use
of a toolbox for correct-by-construction Temporal Logic Planning (TuLiP) for such a purpose.
We describe some of TuLiP’s current functionality, specifically its ability to model
symbolic discrete systems and synthesize software controllers and control policies that are
correct-by-construction. We then move on to discuss the use of these techniques to define a
deliberative goal-directed executive capability that performs risk-informed action-planning
– to satisfy the mission goals (specified by mission control) within the specified priorities
and constraints. Finally, we discuss an application of the TuLiP process to a simple rover
resilience scenario
Resilience in Platoons of Cooperative Heterogeneous Vehicles: Self-organization Strategies and Provably-correct Design
This work proposes provably-correct self-organizing strategies for platoons
of heterogeneous vehicles. We refer to self-organization as the capability of a
platoon to autonomously homogenize to a common group behavior. We show that
self-organization promotes resilience to acceleration limits and communication
failures, i.e., homogenizing to a common group behavior makes the platoon
recover from these causes of impairments. In the presence of acceleration
limits, resilience is achieved by self-organizing to a common constrained group
behavior that prevents the vehicles from hitting their acceleration limits. In
the presence of communication failures, resilience is achieved by
self-organizing to a common group observer to estimate the missing information.
Stability of the self-organization mechanism is studied analytically, and
correctness with respect to traffic actions (e.g. emergency braking, cut-in,
merging) is realized through a provably-correct safety layer. Numerical
validations via the platooning toolbox OpenCDA in CARLA and via the CommonRoad
platform confirm improved performance through self-organization and the
provably-correct safety layer
Cross-layer Optimized Wireless Video Surveillance
A wireless video surveillance system contains three major components, the video capture and preprocessing, the video compression and transmission over wireless sensor networks (WSNs), and the video analysis at the receiving end. The coordination of different components is important for improving the end-to-end video quality, especially under the communication resource constraint. Cross-layer control proves to be an efficient measure for optimal system configuration. In this dissertation, we address the problem of implementing cross-layer optimization in the wireless video surveillance system.
The thesis work is based on three research projects. In the first project, a single PTU (pan-tilt-unit) camera is used for video object tracking. The problem studied is how to improve the quality of the received video by jointly considering the coding and transmission process. The cross-layer controller determines the optimal coding and transmission parameters, according to the dynamic channel condition and the transmission delay. Multiple error concealment strategies are developed utilizing the special property of the PTU camera motion.
In the second project, the binocular PTU camera is adopted for video object tracking. The presented work studied the fast disparity estimation algorithm and the 3D video transcoding over the WSN for real-time applications. The disparity/depth information is estimated in a coarse-to-fine manner using both local and global methods. The transcoding is coordinated by the cross-layer controller based on the channel condition and the data rate constraint, in order to achieve the best view synthesis quality.
The third project is applied for multi-camera motion capture in remote healthcare monitoring. The challenge is the resource allocation for multiple video sequences. The presented cross-layer design incorporates the delay sensitive, content-aware video coding and transmission, and the adaptive video coding and transmission to ensure the optimal and balanced quality for the multi-view videos.
In these projects, interdisciplinary study is conducted to synergize the surveillance system under the cross-layer optimization framework. Experimental results demonstrate the efficiency of the proposed schemes. The challenges of cross-layer design in existing wireless video surveillance systems are also analyzed to enlighten the future work.
Adviser: Song C
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