Pedestrian-Robot Interactions on Autonomous Crowd Navigation: Reactive Control Methods and Evaluation Metrics

Autonomous navigation in highly populated areas remains a challenging task for robots because of the difficulty in guaranteeing safe interactions with pedestrians in unstructured situations. In this work, we present a crowd navigation control framework that delivers continuous obstacle avoidance and post-contact control evaluated on an autonomous personal mobility vehicle. We propose evaluation metrics for accounting efficiency, controller response and crowd interactions in natural crowds. We report the results of over 110 trials in different crowd types: sparse, flows, and mixed traffic, with low- (< 0.15 ppsm), mid- (< 0.65 ppsm), and high- (< 1 ppsm) pedestrian densities. We present comparative results between two low-level obstacle avoidance methods and a baseline of shared control. Results show a 10% drop in relative time to goal on the highest density tests, and no other efficiency metric decrease. Moreover, autonomous navigation showed to be comparable to shared-control navigation with a lower relative jerk and significantly higher fluency in commands indicating high compatibility with the crowd. We conclude that the reactive controller fulfils a necessary task of fast and continuous adaptation to crowd navigation, and it should be coupled with high-level planners for environmental and situational awareness.Comment: \c{opyright}IEEE All rights reserved. IEEE-IROS-2022, Oct.23-27. Kyoto, Japa

Durabilité des assemblages collés du génie civil (effets du vieillissement hygrothermique aux échelles micro- et macroscopiques)

La durabilité des assemblages collés du génie civil est abordée à travers deux approches complémentaires aux échelles micro et macroscopiques. La zone interfaciale pâte de ciment / adhésif époxy est d'abord caractérisée par micro-analyse thermique ( TA) et microscopie électronique, ce qui a permis de révéler l'existence d'une interphase polymère (gradient de TG dans l'adhésif à proximité du substrat) et d'une zone de transition (pénétration du polymère dans le substrat). Par ailleurs, l'effet du vieillissement hygrothermique se traduit par la plastification du réseau époxy à court terme et par une reprise du processus de réticulation à plus long terme. La résistance mécanique des assemblages collés est ensuite étudiée au moyen d'un test de clivage. Avant vieillissement, la rupture des assemblages est généralement cohésive dans le support cimentaire. Le vieillissement hygrothermique engendre un affaiblissement de l'interface et déplace le lieu de fissuration vers la zone de transitionCLERMONT FD-BCIU Sci.et Tech. (630142101) / SudocSudocFranceF

Robots' Motion Planning in Human Crowds by Acceleration Obstacles

We study the Acceleration Obstacle (AO) as a concept to enable a robot's navigation in human crowds. The AO's geometric properties are analyzed and a direct sampling-free algorithm is proposed to approximate its boundary by linear constraints. The resulting controller is formulated as a quadratic program and evaluated in interaction with simulated bi-directional crowd flow in a corridor. We compare it to alternative robotic controllers, considering the robot's and the crowd's performance and the robot's behavior with respect to emergent lanes. Our results indicate that the robot can achieve higher efficiency when being less integrated in lanes.ISSN:2377-376

Safe Self-collision Avoidance for Versatile Robots Based on Bounded Potentials

ISSN:2511-125

Why most biomedical findings echoed by newspapers turn out to be false: the case of attention deficit hyperactivity disorder.

CONTEXT: Because positive biomedical observations are more often published than those reporting no effect, initial observations are often refuted or attenuated by subsequent studies. OBJECTIVE: To determine whether newspapers preferentially report on initial findings and whether they also report on subsequent studies. METHODS: We focused on attention deficit hyperactivity disorder (ADHD). Using Factiva and PubMed databases, we identified 47 scientific publications on ADHD published in the 1990s and soon echoed by 347 newspapers articles. We selected the ten most echoed publications and collected all their relevant subsequent studies until 2011. We checked whether findings reported in each "top 10" publication were consistent with previous and subsequent observations. We also compared the newspaper coverage of the "top 10" publications to that of their related scientific studies. RESULTS: Seven of the "top 10" publications were initial studies and the conclusions in six of them were either refuted or strongly attenuated subsequently. The seventh was not confirmed or refuted, but its main conclusion appears unlikely. Among the three "top 10" that were not initial studies, two were confirmed subsequently and the third was attenuated. The newspaper coverage of the "top 10" publications (223 articles) was much larger than that of the 67 related studies (57 articles). Moreover, only one of the latter newspaper articles reported that the corresponding "top 10" finding had been attenuated. The average impact factor of the scientific journals publishing studies echoed by newspapers (17.1 n = 56) was higher (p<0.0001) than that corresponding to related publications that were not echoed (6.4 n = 56). CONCLUSION: Because newspapers preferentially echo initial ADHD findings appearing in prominent journals, they report on uncertain findings that are often refuted or attenuated by subsequent studies. If this media reporting bias generalizes to health sciences, it represents a major cause of distortion in health science communication

Reactive Navigation in Crowds for Non-holonomic Robots with Convex Bounding Shape

This paper describes a novel method for non-holonomic robots of convex shape to avoid imminent collisions with moving obstacles. The method's purpose is to assist navigation in crowds by correcting steering from the robot's path planner or driver. We evaluate its performance using a custom simulator which replicates real crowd movements and corresponding metrics which quantify the agent's efficiency and the robot's impact on the crowd and count collisions. We implement and evaluate the method on the standing wheelchair Qolo. In our experiments, it drives in autonomous mode using on-board sensing (LiDAR, RGB-D camera and a system to track pedestrians) and avoids collisions with up to five pedestrians and passes through a door

Existence and uniqueness results for time-inhomogeneous time-change equations and Fokker-Planck equations

We prove existence and uniqueness of solutions to Fokker-Planck equations associated to Markov operators multiplicatively perturbed by degenerate time-inhomogeneous coefficients. Precise conditions on the time-inhomogeneous coefficients are given. In particular, we do not necessarily require the coefficients to be neither globally bounded nor bounded away from zero. The approach is based on constructing random time-changes and studying related martingale problems for Markov processes with values in locally compact, complete and separable metric spaces

On Skorokhod embeddings and Poisson equations

The classical Skorokhod embedding problem for a Brownian motion $W$ asks to find a stopping time $\tau$ so that $W_\tau$ is distributed according to a prescribed probability distribution $\mu$. Many solutions have been proposed during the past 50 years and applications in different fields emerged. This article deals with a generalized Skorokhod embedding problem (SEP): Let $X$ be a Markov process with initial marginal distribution $\mu_0$ and let $\mu_1$ be a probability measure. The task is to find a stopping time $\tau$ such that $X_\tau$ is distributed according to $\mu_1$. More precisely, we study the question of deciding if a finite mean solution to the SEP can exist for given $\mu_0, \mu_1$ and the task of giving a solution which is as explicit as possible. If $\mu_0$ and $\mu_1$ have positive densities $h_0$ and $h_1$ and the generator $\mathcal A$ of $X$ has a formal adjoint operator $\mathcal A^*$, then we propose necessary and sufficient conditions for the existence of an embedding in terms of the Poisson equation $\mathcal A^* H=h_1-h_0$ and give a fairly explicit construction of the stopping time using the solution of the Poisson equation. For the class of L\'evy processes we carry out the procedure and extend a result of Bertoin and Le Jan to L\'evy processes without local times.Comment: Journal version available at http://projecteuclid.org/euclid.aoap/1563869044 Second part of the original manuscript can be found in arXiv:1812.0857