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Comprehensive Approach of Estimating Power-Peaks of Partially Shaded PV Strings with Overlapping Bypass Diodes

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Comprehensive Approach of Estimating Power-Peaks of Partiall...

IEEE Energy Conversion Congress and Exposition

作者： Zaid Alqaisi Yousef Mahmoud Department of Electrical Computer Engineering Worcester Polytechnic Institute Worcester MA USA

A Photovoltaic (PV) modules with overlapping bypass diodes have different electrical characteristics under partial shading than in PV modules with non-overlapping bypass diodes. The performance analysis of PV modules with overlapping bypass diodes is complicated due to the existence of mutual PV cells that are connected with two bypass diodes. Under partial shading, the power-voltage (P-V) curve of the PV string has multiple power-peaks due to the exploitation of the bypass diodes. The locations of shaded parts have significant impacts on the maximum power that can be extracted from PV modules with overlapping bypass diodes, whereas the output power of a PV string with non-overlapping bypass didoes has not been affected by the location of shaded part. This paper develops a fast modeling approach of power peaks for partially shaded PV modules with overlapping by using LAMBERT function. Mathematical expressions for estimating power-peaks of PV string under various environmental conditions without the need to scan the entire P-V curve of the system are derived. The proposed power peaks estimation approach was verified using Matlab Simulink.

关键词： Mathematical model Software packages Computational modeling Electric variables computer aided software engineering Photovoltaic systems

An Interactive LiDAR to Camera Calibration

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An Interactive LiDAR to Camera Calibration

IEEE Conference on High Performance Extreme Computing (HPEC)

作者： Yecheng Lyu Lin Bai Mahdi Elhousni Xinming Huang Department of Electrical and Computer Engineering Worcester Polytechnic Institute Worcester MA USA

Recent progress in the automated driving system and advanced driver assistant system has shown that the combined use of 3D light detection and ranging (LiDAR) and the camera is essential for an intelligent vehicle to perceive the driving scenarios. LiDAR-camera fusion systems require precise intrinsic and extrinsic transformation between sensors. However, due to the limitation of the calibration equipment and susceptibility to noise, algorithms in existing methods tend to fail in finding LiDAR-camera correspondences in long-range terms. In this paper, we introduced an interactive LiDAR to camera calibration toolbox that estimates the intrinsic and extrinsic transform parameters. This toolbox automatically detects the corner of a planer board from a sequence of LiDAR frames and provides a convenient user interface to annotate the corresponding pixels on camera frames. Since the toolbox only detects the top corner of the board, there is no need to prepare a precise polygon planar board or a checkerboard with different reflectivity areas as in the existing methods. Furthermore, the toolbox uses genetic algorithms to estimate the transforms and supports multiple camera models such as the pinhole camera model and the fisheye camera model. Experiments using Velodyne VLP-16 LiDAR and Point Grey Chameleon 3 camera show robust results.

关键词： Laser radar Cameras Calibration Genetic algorithms Three-dimensional displays Sensors Transforms

Opportunistic Synthesis in Reactive Games under Information Asymmetry

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Opportunistic Synthesis in Reactive Games under Information ...

Annual Allerton Conference on Communication, Control, and Computing

作者： Jie Fu Department of Electrical and Computer Engineering Robotics Engineering Program Worcester Polytechnic Institute Worcester MA USA

Reactive synthesis [1]is used to synthesize a provably-correct strategy (controller) with respect to a given Linear Temporal Logic (LTL) specification in a dynamic, potentially adversarial environment. The core idea of reactive synthesis is to model the interaction between a controlled agent (called the robot) and its dynamic and uncontrollable environment as a two-player turn-based zero-sum game. In particular, players' Boolean payoffs are specified by temporal logic formulas [2]-a rich language that can expressive properties such as safety, liveness, stability, and temporally extended goals.

关键词： Games Robots Task analysis Game theory Vehicle dynamics computer security

Opportunistic Synthesis in Reactive Games under Information Asymmetry

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Opportunistic Synthesis in Reactive Games under Information ...

IEEE Annual Conference on Decision and Control

作者： Abhishek N. Kulkarni Jie Fu Robotics Engineering Program Worcester Polytechnic Institute Worcester MA USA Faculty of the Department of Electrical and Computer Engineering with affiliation to Robotics Engineering Program Worcester Polytechnic Institute Worcester MA USA

ISBN: (数字)9781728113982

ISBN: (纸本)9781728113999

Reactive synthesis is a class of methods to construct a provably-correct control system, referred to as a robot, with respect to a temporal logic specification in the presence of a dynamic and uncontrollable environment. This is achieved by modeling the interaction between the robot and its environment as a two-player zero-sum game. However, existing reactive synthesis methods assume both players to have complete and symmetrical information, which is not the case in many strategic interactions. In this paper, we use a variant of hypergames to model the interaction between the robot and its environment;where the latter has incomplete information about the specification of the robot. We propose a novel method of opportunistic synthesis defined over the hypergame model to identify a subset of hypergame states from where the robot can leverage the asymmetrical information to achieve a better outcome, which is not possible if both players have symmetrical and complete information. By assuming the environment to play a stochastic strategy in its perceived sure-winning and sure-losing regions of the game, we show that by following the opportunistic strategy, the robot is ensured to only improve the outcome of the game-measured by satisfaction of sub-specifications-whenever an opportunity becomes available. We demonstrate the correctness and optimality of this method using a robot motion planning example in the presence of an adversary.

关键词： Robots Games Task analysis Computational modeling Game theory Planning Stochastic processes

An interactive LiDAR to camera calibration

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arXiv 2019年

作者： Lyu, Yecheng Bai, Lin Elhousni, Mahdi Huang, Xinming Department of Electrical and Computer Engineering Worcester Polytechnic Institute WorcesterMA01609 United States

Recent progress in the automated driving system (ADS) and advanced driver assistant system (ADAS) has shown that the combined use of 3D light detection and ranging (LiDAR) and the camera is essential for an intelligent vehicle to perceive and understand its surroundings. LiDAR-camera fusion requires precise intrinsic and extrinsic calibrations between the sensors. However, due to the limitation of the calibration equipment and susceptibility to noise, algorithms in existing methods tend to fail in finding LiDAR-camera correspondences in long-range. In this paper, we introduced an interactive LiDAR to camera calibration toolbox to estimate the intrinsic and extrinsic transforms. This toolbox automatically detects the corner of a planer board from a sequence of LiDAR frames and provides a convenient user interface for annotating the corresponding pixels on camera frames. Since the toolbox only detects the top corner of the board, there is no need to prepare a precise polygon planar board or a checkerboard with different reflectivity areas as in the existing methods. Furthermore, the toolbox uses genetic algorithms to estimate the transforms and supports multiple camera models such as the pinhole camera model and the fisheye camera model. Experiments using Velodyne VLP-16 LiDAR and Point Grey Chameleon 3 camera show robust results. Copyright © 2019, The Authors. All rights reserved.

关键词： Optical radar

Optimal Secure Control with Linear Temporal Logic Constraints

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arXiv 2019年

作者： Niu, Luyao Clark, Andrew Department of Electrical and Computer Engineering Worcester Polytechnic Institute WorcesterMA01609 United States

—Prior work on automatic control synthesis for cyberphysical systems under logical constraints has primarily focused on environmental disturbances or modeling uncertainties, however, the impact of deliberate and malicious attacks has been less studied. In this paper, we consider a discrete-time dynamical system with a linear temporal logic (LTL) constraint in the presence of an adversary, which is modeled as a stochastic game. We assume that the adversary observes the control policy before choosing an attack strategy. We investigate two problems. In the first problem, we synthesize a robust control policy for the stochastic game that maximizes the probability of satisfying the LTL constraint. A value iteration based algorithm is proposed to compute the optimal control policy. In the second problem, we focus on a subclass of LTL constraints, which consist of an arbitrary LTL formula and an invariant constraint. We then investigate the problem of computing a control policy that minimizes the expected number of invariant constraint violations while maximizing the probability of satisfying the arbitrary LTL constraint. We characterize the optimality condition for the desired control policy. A policy iteration based algorithm is proposed to compute the control policy. We illustrate the proposed approaches using two numerical case studies. Copyright © 2019, The Authors. All rights reserved.

关键词： Game theory

Real-world snapshots vs. theory: Questioning the t-probing security model

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arXiv 2020年

作者： Krachenfels, Thilo Ganji, Fatemeh Moradi, Amir Tajik, Shahin Seifert, Jean-Pierre Technische Universität Berlin Security in Telecommunications Germany Worcester Polytechnic Institute Department of Electrical and Computer Engineering United States Ruhr-Universität Bochum Horst Görtz Institute for IT-Security Germany

Due to its sound theoretical basis and practical efficiency, masking has become the most prominent countermeasure to protect cryptographic implementations against physical side-channel attacks (SCAs). The core idea of masking is to randomly split every sensitive intermediate variable during computation into at least t+1 shares, where t denotes the maximum number of shares that are allowed to be observed by an adversary without learning any sensitive information. In other words, it is assumed that the adversary is bounded either by the possessed number of probes (e.g., microprobe needles) or by the order of statistical analyses while conducting higher-order SCA attacks (e.g., differential power analysis). Such bounded models are employed to prove the SCA security of the corresponding implementations. Consequently, it is believed that given a sufficiently large number of shares, the vast majority of known SCA attacks are mitigated. In this work, we present a novel laser-assisted SCA technique, called Laser Logic State Imaging (LLSI), which offers an unlimited number of contactless probes, and therefore, violates the probing security model assumption. This technique enables us to take snapshots of hardware implementations, i.e., extract the logical state of all registers at any arbitrary clock cycle with a single measurement. To validate this, we mount our attack on masked AES hardware implementations and practically demonstrate the extraction of the full-length key in two different scenarios. First, we assume that the location of the registers (key and/or state) is known, and hence, their content can be directly read by a single snapshot. Second, we consider an implementation with unknown register locations, where we make use of multiple snapshots and a SAT solver to reveal the secrets. Copyright © 2020, The Authors. All rights reserved.

关键词： Side channel attack

A differentially private incentive design for traffic offload to public transportation

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arXiv 2019年

作者： Niu, Luyao Clark, Andrew Department of Electrical and Computer Engineering Worcester Polytechnic Institute WorcesterMA01609 United States

—Increasingly large trip demands have strained urban transportation capacity, which consequently leads to traffic congestion. In this work, we focus on mitigating traffic congestion by incentivizing passengers to switch from private to public transit services. We address the following challenges. First, the passengers incur inconvenience costs when participating in traffic offload due to delay and discomfort, and thus need to be reimbursed. The inconvenience cost, however, is unknown to the government when choosing the incentives. Furthermore, participating in traffic offload raises privacy concerns from passengers. An adversary could infer personal information, (e.g., daily routine, region of interest, and wealth), by observing the decisions made by the government, which are known to the public. We adopt the concept of differential privacy and propose privacy-preserving incentive designs under two settings, denoted as two-way communication and one-way communication. Under two-way communication, we focus on how the government should reveal passengers’ inconvenience costs to properly incentivize them while preserving differential privacy. We formulate the problem as a mixed integer linear program, and propose a polynomial-time approximation algorithm. We show the proposed approach achieves truthfulness, individual rationality, social optimality, and differential privacy. Under one-way communication, we focus on how the government should design the incentives without revealing passengers’ inconvenience costs while still preserving differential privacy. We formulate the problem as a convex program, and propose a differentially private and near-optimal solution algorithm. A numerical case study using Caltrans Performance Measurement System (PeMS) data source is presented as evaluation. Copyright © 2019, The Authors. All rights reserved.

关键词： Urban transportation

Haptic display for virtual reality: progress and challenges

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Virtual Reality & Intelligent Hardware 2019年第2期1卷 136-162页

作者： Dangxiao WANG Yuan GUO Shiyi LIU Yuru ZHANG Weiliang XU Jing XIAO State Key Laboratory of Virtual Reality Technology and Systems Beihang UniversityBeijing 100083China Beijing Advanced Innovation Center for Biomedical Engineering Beihang UniversityBeijing 100083China Peng Cheng Laboratory Shenzhen 518055China Department of Mechanical Engineering University of AucklandAuckland 1142New Zealand School of Computer Science and the Robotics Engineering Program Worcester Polytechnic InstituteWorcesterMA 01609-2280USA

Immersion, interaction, and imagination are three features of virtual reality (VR). Existing VR systems possess fairly realistic visual and auditory feedbacks, and however, are poor with haptic feedback, by means of which human can perceive the physical world via abundant haptic properties. Haptic display is an interface aiming to enable bilateral signal communications between human and computer, and thus to greatly enhance the immersion and interaction of VR systems. This paper surveys the paradigm shift of haptic display occurred in the past 30 years, which is classified into three stages, including desktop haptics, surface haptics, and wearable haptics. The driving forces, key technologies and typical applications in each stage are critically reviewed. Toward the future high-fidelity VR interaction, research challenges are highlighted concerning handheld haptic device, multimodal haptic device, and high fidelity haptic rendering. In the end, the importance of understanding human haptic perception for designing effective haptic devices is addressed.

关键词： Haptic display Virtual reality Desktop haptics Surface haptics Wearable haptics Multimodal haptics