Journal: ACM Transactions on Cyber-Physical Systems

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Association for Computing Machinery

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2378-9638
2378-962X

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Publications 1 - 6 of 6
  • Event-Triggered Control with Intermittent Communications over Erasure Channels for Leader-Follower Problems with the Combined-Slip Effect
    Item type: Journal Article
    Mamduhi, Mohammad H.; Hashemi, Ehsan (2023)
    ACM Transactions on Cyber-Physical Systems
    In this article, we investigate the vehicle path-following problem for a vehicle-to-vehicle (V2V)-enabled leader-follower scenario and propose an integrated control policy for the following vehicle to accurately follow the leader's path. We propose a control strategy for the follower vehicle to maintain a velocity-dependent distance relative to the leader vehicle while stabilizing its longitudinal and lateral dynamics considering the combined-slip effect and tire force saturation. In light of reducing wireless communication errors and efficient usage of battery power and resources, we propose an intermittent V2V communication in which transmissions are scheduled based on an event-triggered law. An event is triggered and a transmission is scheduled in subsequent sample time if some of the well-defined path-following error functions (relative distance error and lateral error) exceed given tolerance bounds. Considering that the V2V communication channel might be erroneous or a transmission fails due to, e.g., vehicles' distance or low battery power, we consider data loss in the V2V channel. Our proposed control law consists of two components: a receding horizon feedback controller with state constraints based on a safe operation envelop and a feedforward controller that generates complementary control inputs when the leader's states are successfully communicated to the follower. To mitigate the effects of data loss on the follower's path-following performance, we design a remote estimator for the follower to predict the leader's state using its on-board sensor equipment when an event is triggered but the corresponding state information is not received by the follower due to a packet loss. Incorporating this estimator allows the follower to apply cautionary control inputs knowing that the path-following error had exceeded a tolerance bound. We show that while the feedback controller stabilizes the follower's dynamics, the feedforward component improves the safety margins and reduces the path-following errors even in the presence of data loss. High-fidelity simulations are performed using CarSim to validate the effectiveness of our proposed control architecture specifically in harsh maneuvers and high-slip scenarios on various road surface conditions.
  • Fast feedback control over multi-hop wireless networks with mode changes and stability guarantees
    Item type: Journal Article
    Baumann, Dominik; Mager, Fabian; Jacob, Romain; et al. (2019)
    ACM Transactions on Cyber-Physical Systems
  • Adaptive Real-Time Communication for Wireless Cyber-Physical Systems
    Item type: Journal Article
    Zimmerling, Marco; Mottola, Luca; Kumar, Pratyush; et al. (2017)
    ACM Transactions on Cyber-Physical Systems
  • Hybrid Modular Redundancy: Exploring Modular Redundancy Approaches in RISC-V Multi-Core Computing Clusters for Reliable Processing in Space
    Item type: Journal Article
    Rogenmoser, Michael; Tortorella, Yvan; Rossi, Davide; et al. (2025)
    ACM Transactions on Cyber-Physical Systems
    Space Cyber-Physical Systems such as spacecraft and satellites strongly rely on the reliability of onboard computers to guarantee the success of their missions. Relying solely on radiation-hardened technologies is extremely expensive, and developing inflexible architectural and microarchitectural modifications to introduce modular redundancy within a system leads to significant area increase and performance degradation. To mitigate the overheads of traditional radiation hardening and modular redundancy approaches, we present a novel Hybrid Modular Redundancy approach, a redundancy scheme that features a cluster of RISC-V processors with a flexible on-demand dual-core and triple-core lockstep grouping of computing cores with runtime split-lock capabilities. Further, we propose two recovery approaches, software-based and hardware-based, trading off performance and area overhead. Running at 430 MHz, our fault-tolerant cluster achieves up to 1,160 MOPS on a matrix multiplication benchmark when configured in non-redundant mode and 617 and 414 MOPS in dual and triple mode, respectively. A software-based recovery in triple mode requires 363 clock cycles and occupies 0.612 mm2, representing a 1.3% area overhead over a non-redundant 12-core RISC-V cluster. As a high-performance alternative, a new hardware-based method provides rapid fault recovery in just 24 clock cycles and occupies 0.660 mm2, namely, ∼9.4% area overhead over the baseline non-redundant RISC-V cluster. The cluster is also enhanced with split-lock capabilities to enter one of the available redundant modes with minimum performance loss, allowing execution of a mission-critical portion of code when in independent mode, or a performance section when in a reliability mode, with <400 clock cycles overhead for entry and exit. The proposed system is the first to integrate these functionalities on an open-source RISC-V-based compute device, enabling finely tunable reliability versus performance trade-offs.
  • Self-triggered Control with Energy Harvesting Sensor Nodes
    Item type: Journal Article
    Stricker, Naomi; Lian, Yingzhao; Jiang, Yuning; et al. (2023)
    ACM Transactions on Cyber-Physical Systems
    Distributed embedded systems are pervasive components jointly operating in a wide range of applications. Moving toward energy harvesting powered systems enables their long-term, sustainable, scalable, and maintenance-free operation. When these systems are used as components of an automatic control system to sense a control plant, energy availability limits when and how often sensed data are obtainable and therefore when and how often control updates can be performed. The time-varying and non-deterministic availability of harvested energy and the necessity to plan the energy usage of the energy harvesting sensor nodes ahead of time, on the one hand, have to be balanced with the dynamically changing and complex demand for control updates from the automatic control plant and thus energy usage, on the other hand. We propose a hierarchical approach with which the resources of the energy harvesting sensor nodes are managed on a long time horizon and on a faster timescale, self-triggered model predictive control controls the plant. The controller of the harvesting-based nodes' resources schedules the future energy usage ahead of time and the self-triggered model predictive control incorporates these time-varying energy constraints. For this novel combination of energy harvesting and automatic control systems, we derive provable properties in terms of correctness, feasibility, and performance. We evaluate the approach on a double integrator and demonstrate its usability and performance in a room temperature and air quality control case study.
  • Switching and Data Injection Attacks on Stochastic Cyber-Physical Systems: Modeling, Resilient Estimation, and Attack Mitigation
    Item type: Journal Article
    Yong, Sze Zheng; Zhu, Minghui; Frazzoli, Emilio (2018)
    ACM Transactions on Cyber-Physical Systems
    In this article, we consider the problem of attack-resilient state estimation, that is, to reliably estimate the true system states despite two classes of attacks: (i) attacks on the switching mechanisms and (ii) false data injection attacks on actuator and sensor signals, in the presence of stochastic process and measurement noise signals. We model the systems under attack as hidden mode stochastic switched linear systems with unknown inputs and propose the use of a multiple-model inference algorithm to tackle these security issues. Moreover, we characterize fundamental limitations to resilient estimation (e.g., upper bound on the number of tolerable signal attacks) and discuss the topics of attack detection, identification, and mitigation under this framework. Simulation examples of switching and false data injection attacks on a benchmark system and an IEEE 68-bus test system show the efficacy of our approach to recover resilient (i.e., asymptotically unbiased) state estimates as well as to identify and mitigate the attacks.
Publications 1 - 6 of 6