arXiv subjects

Yu Yao

Publications and source records attributed to Yu Yao.

98 records · Page 6Linked to original sources

arXiv2019

Game-Theoretic Modeling of Multi-Vehicle Interactions at Uncontrolled Intersections

Motivated by the need to develop simulation tools for verification and validation of autonomous driving systems operating in traffic consisting of both autonomous and human-driven vehicles, we propose a framework for modeling vehicle interactions at uncontrolled intersections. The proposed interaction modeling approach is based on game theory with multiple concurrent leader-follower pairs, and accounts for common traffic rules. We parameterize the intersection layouts and geometries to model uncontrolled intersections with various configurations, and apply the proposed approach to model the interactive behavior of vehicles at these intersections. Based on simulation results in various traffic scenarios, we show that the model exhibits reasonable behavior expected in traffic, including the capability of reproducing scenarios extracted from real-world traffic data and reasonable performance in resolving traffic conflicts. The model is further validated based on the level-of-service traffic quality rating system and demonstrates manageable computational complexity compared to traditional multi-player game-theoretic models.

eess.SY↗

arXiv2019

Constraints on the spacetime metric around seven "bare" AGNs using X-ray reflection spectroscopy

We present the study of a sample of seven "bare" active galactic nuclei (AGN) observed with Suzaku. We interpret the spectrum of these sources with a relativistic reflection component and we employ our model RELXILL_NK to test the Kerr nature of their supermassive black holes. We constrain the Johannsen deformation parameters $α_{13}$ and $α_{22}$, in which the Kerr metric is recovered when $α_{13} = α_{22} = 0$. All our measurements are consistent with the hypothesis that the spacetime geometry around these supermassive objects is described by the Kerr solution. For some sources, we obtain quite strong constraints on $α_{13}$ and $α_{22}$ when compared to those found in our previous studies. We discuss the systematic uncertainties in our tests and the implications of our results.

gr-qc↗

arXiv2019

Realtime Rooftop Landing Site Identification and Selection in Urban City Simulation

Safe autonomous landing in urban cities is a necessity for the growing Unmanned Aircraft Systems (UAS) industry. In urgent situations, building rooftops, particularly flat rooftops, can provide local safe landing zones for small UAS. This paper investigates the real-time identification and selection of safe landing zones on rooftops based on LiDAR and camera sensor feedback. A visual high fidelity simulated city is constructed in the Unreal game engine, with particular attention paid to accurately generating rooftops and the common obstructions found thereon, e.g., ac units, water towers, air vents. AirSim, a robotic simulator plugin for Unreal, offers drone simulation and control and is capable of outputting video and LiDAR sensor data streams from the simulated Unreal world. A neural network is trained on randomized simulated cities to provide a pixel classification model. A novel algorithm is presented which finds the optimum obstacle-free landing position on nearby rooftops by fusing LiDAR and vision data.

cs.RO↗

arXiv2019

The Smart Black Box: A Value-Driven High-Bandwidth Automotive Event Data Recorder

Autonomous vehicles require reliable and resilient sensor suites and ongoing validation through fleet-wide data collection. This paper proposes a Smart Black Box (SBB) to augment traditional low-bandwidth data logging with value-driven high-bandwidth data capture. The SBB caches short-term histories of data as buffers through a deterministic Mealy machine based on data value and similarity. Compression quality for each frame is determined by optimizing the trade-off between value and storage cost. With finite storage, prioritized data recording discards low-value buffers to make room for new data. This paper formulates SBB compression decision making as a constrained multi-objective optimization problem with novel value metrics and filtering. The SBB has been evaluated on a traffic simulator which generates trajectories containing events of interest (EOIs) and corresponding first-person view videos. SBB compression efficiency is assessed by comparing storage requirements with different compression quality levels and event capture ratios. Performance is evaluated by comparing results with a traditional first-in-first-out (FIFO) recording scheme. Deep learning performance on images recorded at different compression levels is evaluated to illustrate the reproducibility of SBB recorded data.

eess.SP↗

arXiv2019

Egocentric Vision-based Future Vehicle Localization for Intelligent Driving Assistance Systems

Predicting the future location of vehicles is essential for safety-critical applications such as advanced driver assistance systems (ADAS) and autonomous driving. This paper introduces a novel approach to simultaneously predict both the location and scale of target vehicles in the first-person (egocentric) view of an ego-vehicle. We present a multi-stream recurrent neural network (RNN) encoder-decoder model that separately captures both object location and scale and pixel-level observations for future vehicle localization. We show that incorporating dense optical flow improves prediction results significantly since it captures information about motion as well as appearance change. We also find that explicitly modeling future motion of the ego-vehicle improves the prediction accuracy, which could be especially beneficial in intelligent and automated vehicles that have motion planning capability. To evaluate the performance of our approach, we present a new dataset of first-person videos collected from a variety of scenarios at road intersections, which are particularly challenging moments for prediction because vehicle trajectories are diverse and dynamic.

cs.CV↗

arXiv2019

Two-body charmed baryon decays involving vector meson with $SU(3)$ flavor symmetry

We study the two-body anti-triplet charmed baryon decays of ${\bf B}_c\to {\bf B}_n V$, with ${\bf B}_c=(Ξ_c^{0},-Ξ_c^{+},Λ_c^+)$ and ${\bf B}_n(V)$ the baryon (vector meson) states. Based on the $SU(3)$ flavor symmetry, we predict that ${\cal B}(Λ^{+}_{c}\to Σ^{+}ρ^{0},Λ^0 ρ^+)=(0.61\pm 0.46,0.74\pm 0.34)\%$, in agreement with the experimental upper bounds of $(1.7,6)\%$, respectively. We also find ${\cal B}(Λ^+_c \to Ξ^0 K^{*+},Σ^0 K^{*+},Λ^0 K^{*+}) =(8.7 \pm 2.7,1.2\pm 0.3,2.0\pm 0.5)\times 10^{-3}$ to be compatible with the pseudoscalar counterparts. For the doubly Cabibbo-suppressed decay $Ξ^+_c \to pϕ$, measured for the first time, we predict its branching ratio to be $(1.5\pm 0.7)\times 10^{-4}$, together with ${\cal B}(Ξ^+_c \to p \bar K^{*0},Σ^+ ϕ) =(7.8 \pm 2.2,1.9\pm0.9)\times 10^{-3}$. The ${\bf B}_c\to{\bf B}_n V$ decays with ${\cal B}\simeq {\cal O}(10^{-4}-10^{-3})$ are accessible to the BESIII, BELLEII and LHCb experiments.

hep-ph↗

arXiv2018

Continuous-Time Inverse Quadratic Optimal Control Problem

In this paper, the problem of finite horizon inverse optimal control (IOC) is investigated, where the quadratic cost function of a dynamic process is required to be recovered based on the observation of optimal control sequences. We propose the first complete result of the necessary and sufficient condition for the existence of corresponding LQ cost functions. Under feasible cases, the analytic expression of the whole solution space is derived and the equivalence of weighting matrices in LQ problems is discussed. For infeasible problems, an infinite dimensional convex problem is formulated to obtain a best-fit approximate solution with minimal control residual. And the optimality condition is solved under a static quadratic programming framework to facilitate the computation. Finally, numerical simulations are used to demonstrate the effectiveness and feasibility of the proposed methods.

math.OC↗

arXiv2017

Charmless two-body anti-triplet $b$-baryon decays

We study the charmless two-body decays of $b$-baryons $(Λ_b$, $Ξ_b^-$, $Ξ_b^0)$. We find that ${\cal B}(Ξ_b^-\to Λρ^-)=(2.08^{+0.69}_{-0.51})\times 10^{-6}$ and ${\cal B}(Ξ_b^0\to Σ^+ M^-)=(4.45^{+1.46}_{-1.09},11.49^{+3.8}_{-2.9},4.69^{+1.11}_{-0.79},2.98^{+0.76}_{-0.51})\times 10^{-6}$ for $M^-=(π^-,ρ^-,K^-,K^{*-})$, which are compatible to ${\cal B}(Λ_b\to p π^-,p K^-)$. We also obtain that ${\cal B}(Λ_b\to Λω)=(2.30\pm0.10)\times 10^{-6}$, ${\cal B}(Ξ_b^-\toΞ^- ϕ,Ξ^- ω)\simeq {\cal B}(Ξ_b^0\toΞ^0 ϕ,Ξ^0 ω)=(5.35\pm0.41,3.65\pm0.16)\times 10^{-6}$ and ${\cal B}(Ξ^-_b\toΞ^{-} η^{(\prime)})\simeq {\cal B}(Ξ^0_b\to Ξ^0 η^{(\prime)})=(2.51^{+0.70}_{-0.46},2.99^{+1.16}_{-0.57})\times 10^{-6}$. For the CP violating asymmetries, we show that ${\cal A}_{CP}(Λ_b\to p K^{*-})={\cal A}_{CP}(Ξ_b^-\to Σ^0(Λ)K^{*-})={\cal A}_{CP}(Ξ_b^0\to Σ^+K^{*-})=(19.7\pm 1.4)\%$. Similar to the charmless two-body $Λ_b$ decays, the $Ξ_b$ decays are accessible to the LHCb detector.

hep-ph↗