scholarly journals Stable choice coding during changes of mind

2021 ◽  
Author(s):  
J Tyler Boyd-Meredith ◽  
Alex T Piet ◽  
Emily Jane Dennis ◽  
Ahmed El Hady ◽  
Carlos Brody
Keyword(s):  
Dynamic Environment ◽  
Behavioral Model ◽  
Dynamic Environments ◽  
Gain Modulation ◽  
Motor Execution ◽  
Uncertain Environments ◽  
Firing Rates ◽  
The World ◽  
State Changes ◽  
Old Evidence

How do we choose the best action in a constantly-changing environment? Many natural decisions unfold in dynamic environments where newer observations carry better information about the present state of the world. Recent work has shown that rats can learn to optimally discount old evidence, updating their provisional decision when the environmental state changes. Provisional decisions are thought to be represented in the Frontal Orienting Fields (FOF), but this has only been tested in static environments where the provisional and final decisions are not easily dissociated. Here, we characterize the representation of accumulated evidence in rat FOF during decision-making in a dynamic environment. We find that FOF encodes evidence throughout decision formation with a temporal gain modulation that rises until the period when the animal may need to act. Using a behavioral model to predict the timing of changes of mind revealed that FOF neurons respond rapidly to these events, representing the new provisional decisions in their firing rates. Our results suggest that the FOF represents provisional decisions even in dynamic, uncertain environments, allowing for rapid motor execution when it is time to act.

Real Time, Near-Optimal Trajectory Planning of an Omni-Directional Vehicle

2001 ◽  
Author(s):  
Tamás Kalmár-Nagy ◽  
Pritam Ganguly ◽  
Raffaello D’Andrea
Keyword(s):  
Real Time ◽  
Optimal Trajectory ◽  
Degrees Of Freedom ◽  
Dynamic Environments ◽  
Real Time Control ◽  
Uncertain Environments ◽  
Time Control ◽  
Innovative Method ◽  
Optimal Trajectory Planning ◽  
Three Degrees Of Freedom

Abstract In this paper, we discuss an innovative method of generating near-optimal trajectories for a robot with omni-directional drive capabilities, taking into account the dynamics of the actuators and the system. The relaxation of optimality results in immense computational savings, critical in dynamic environments. In particular, a decoupling strategy for each of the three degrees of freedom of the vehicle is presented, along with a method for coordinating the degrees of freedom. A nearly optimal trajectory for the vehicle can typically be calculated in less than 1000 floating point operations, which makes it attractive for real-time control in dynamic and uncertain environments.

Multi-Robot SLAM in Dynamic Environments with Parallel Maps

2021 ◽  
pp. 2150011
Author(s):  
Sajad Badalkhani ◽  
Ramazan Havangi ◽  
Mohsen Farshad
Keyword(s):  
Large Scale ◽  
Dynamic Environment ◽  
Dynamic Environments ◽  
Extensive Literature ◽  
Real World Data ◽  
Data Set ◽  
Cooperative Approach ◽  
Localization And Mapping ◽  
Multi Robot

There is an extensive literature regarding multi-robot simultaneous localization and mapping (MRSLAM). In most part of the research, the environment is assumed to be static, while the dynamic parts of the environment degrade the estimation quality of SLAM algorithms and lead to inherently fragile systems. To enhance the performance and robustness of the SLAM in dynamic environments (SLAMIDE), a novel cooperative approach named parallel-map (p-map) SLAM is introduced in this paper. The objective of the proposed method is to deal with the dynamics of the environment, by detecting dynamic parts and preventing the inclusion of them in SLAM estimations. In this approach, each robot builds a limited map in its own vicinity, while the global map is built through a hybrid centralized MRSLAM. The restricted size of the local maps, bounds computational complexity and resources needed to handle a large scale dynamic environment. Using a probabilistic index, the proposed method differentiates between stationary and moving landmarks, based on their relative positions with other parts of the environment. Stationary landmarks are then used to refine a consistent map. The proposed method is evaluated with different levels of dynamism and for each level, the performance is measured in terms of accuracy, robustness, and hardware resources needed to be implemented. The method is also evaluated with a publicly available real-world data-set. Experimental validation along with simulations indicate that the proposed method is able to perform consistent SLAM in a dynamic environment, suggesting its feasibility for MRSLAM applications.

A survey on discrete space and continuous space facility layout problems

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Irappa Basappa Hunagund ◽  
V. Madhusudanan Pillai ◽  
Kempaiah U.N.
Keyword(s):  
Literature Review ◽  
Facility Layout ◽  
Dynamic Environment ◽  
Dynamic Environments ◽  
Structure Design ◽  
Discrete Space ◽  
Content Type ◽  
Continuous Space ◽  
Complete Problems ◽  
Flexible Bay Structure

Purpose The purpose of this paper is to review, evaluate and classify the academic research that has been published in facility layout problems (FLPs) and to analyse how researches and practices on FLPs are. Design/methodology/approach The review is based on 166 papers published from 1953 to 2021 in international peer-reviewed journals. The literature review on FLPs is presented under broader headings of discrete space and continuous space FLPs. The important formulations of FLPs under static and dynamic environments represented in the discrete and continuous space are presented. The articles reported in the literature on various representations of facilities for the continuous space Unequal Area Facility Layout Problems (UA-FLPs) are summarized. Discussed and commented on adaptive and robust approaches for dynamic environment FLPs. Highlighted the application of meta-heuristic solution methods for FLPs of a larger size. Findings It is found that most of the earlier research adopted the discrete space for the formulation of FLPs. This type of space representation for FLPs mostly assumes an equal area for all facilities. UA-FLPs represented in discrete space yield irregular shape facilities. It is also observed that the recent works consider the UA-FLPs in continuous space. The solution of continuous space UA-FLPs is more accurate and realistic. Some of the recent works on UA-FLPs consider the flexible bay structure (FBS) due to its advantages over the other representations. FBS helps the proper design of aisle structure in the detailed layout plan. Further, the recent articles reported in the literature consider the dynamic environment for both equal and unequal area FLPs to cope with the changing market environment. It is also found that FLPs are Non-deterministic Polynomial-complete problems, and hence, they set the challenges to researchers to develop efficient meta-heuristic methods to solve the bigger size FLPs in a reasonable time. Research limitations/implications Due to the extremely large number of papers on FLPs, a few papers may have inadvertently been missed. The facility layout design research domain is extremely vast which covers other areas such as cellular layouts, pick and drop points and aisle structure design. This research review on FLPs did not consider the papers published on cellular layouts, pick and drop points and aisle structure design. Despite the possibility of not being all-inclusive, the authors firmly believe that most of the papers published on FLPs are covered and the general picture presented on various approaches and parameters of FLPs in this paper are precise and trustworthy. Originality/value To the best of the authors’ knowledge, this paper reviews and classifies the literature on FLPs for the first time under the broader headings of discrete space and continuous space representations. Many important formulations of FLPs under static and dynamic environments represented in the discrete and continuous space are presented. This paper also provides the observations from the literature review and identifies the prospective future directions.

The categorization of geometric objects in 3D and 2D contexts depends on invariant referents

2021 ◽  
Author(s):  
Simon Stephan ◽  
Sarah Placì ◽  
Michael R. Waldmann ◽  
Giorgio Vallortigara
Keyword(s):  
Cognitive Abilities ◽  
Intelligent Systems ◽  
Dynamic Environments ◽  
Object Categorization ◽  
Geometrical Configuration ◽  
Geometrical Features ◽  
Geometric Objects ◽  
The World ◽  
Treat All

The categorization of geometric objects is one of the most fundamental problems all intelligent systems have to deal with in dynamic environments in which objects' geometrical configuration constantly changes. Animals, including humans, do not treat all geometrical differences equally: they ignore some geometrical features when it comes to generalization but not others. So far, no theory has been presented that explains this cognitive phenomenon. We here propose and empirically test such a theory. The theory identifies and relies on the invariant referents existing in 3D (i.e., gravity) and 2D (e.g., any 2D frame) environments to predict the geometrical differences reasoners consider as important or irrelevant for object categorization. We test and confirm a novel central prediction of the theory, namely that human reasoners categorize objects differently in 3D and 2D environments. These findings cast new light on core cognitive abilities that minds use to make sense of the world.

Collaboration Intricacies of Web 2.0 for Training Human Resource Managers

2009 ◽  
pp. 131-135
Author(s):  
Jacqueline A. Gilbert
Keyword(s):  
World Wide Web ◽  
Sense Of Community ◽  
Virtual Worlds ◽  
World Wide ◽  
Dynamic Environment ◽  
Cognitive Presence ◽  
Human Resource Managers ◽  
Resource Managers ◽  
The People ◽  
The World

The World Wide Web (WWW) was initially written as a “point and click hypertext editor” (Berners-Lee, 1998, para. 2). Used as a search device by academia and industry, it has over the years experienced both rapid and explosive growth. Earlier incarnations of the World Wide Web were known as “Web 1.0.” Since its inception however the internet has undergone a rapid transformation into what is now considered a sense of community, a reciprocal sharing among users, and a sense of “cognitive presence” (Garrison, Anderson, & Archer, 2000), which has been facilitated by a plethora of software tools that allowed users to widely share their work, in thought (e.g., blogs), in creative endeavors, and in collaborative projects. Siemens’ (2005) theory of “connectivism” encompasses the feeling that sharing promotes and encourages a sense of community that is continually being recreated by its audience. The newest forms of interaction are in the form of virtual worlds, in which avatars can attend class, build their own edifices, sell objects, and meet with other individuals in a global virtual exchange. What was once considered static computing has been transformed into a rich, dynamic environment that is defined by the people who peruse it, as evidenced in the following quotation: “The breaking down of barriers has led to many of the movements and issues we see on today’s internet. File-sharing, for example, evolves not of a sudden criminality among today’s youth, but rather in their pervasive belief that information is something meant to be shared” (Downes, 2006, para. 15). As of 2006, the Web had a billion users worldwide (Williams, 2007). Today’s Web users for the most part are not simply information seekers, but co-creators who wish to collaborate and share information in an electronic environment.

Does the preoptic anterior hypothalamus receive thermoafferent information?

1998 ◽  
Vol 274 (1) ◽  
pp. R9-R18 ◽  
Author(s):  
Nancy J. Berner ◽  
H. Craig Heller
Keyword(s):  
Brain Regions ◽  
Anterior Hypothalamus ◽  
Mammalian Brain ◽  
Eeg Activity ◽  
Arousal State ◽  
Firing Rates ◽  
State Changes ◽  
Unanesthetized Animals ◽  
Peripheral Temperature ◽  
State Selectivity

The preoptic anterior hypothalamus (POAH) is considered the thermointegrative center of the mammalian brain. Studies on anesthetized and unanesthetized animals have demonstrated neurons in the POAH that respond to changes in both POAH temperature (TPOAH) and skin temperature (Ts). In these studies, however, electroencephalographic (EEG) activity was not monitored. Recent work has revealed the potential for arousal state selectivity of neurons combined with thermal influences on arousal state to create the appearance that cells are thermosensitive or thermoresponsive when in fact they may not be responding directly to temperature or to thermoafferent input. It is therefore necessary to reexamine the influence of central and peripheral temperature on POAH cells. In the present study, 66 POAH cells were recorded from urethan-anesthetized rats while EEG, TPOAH, and Ts were monitored. Seventy-five percent (41 of 55) of the cells were EEG state responsive; 22% (6 of 27) were TPOAH sensitive; and 33% (19 of 58) appeared to be Tsresponsive. However, when EEG state changes were taken into account, none of the cells that appeared to be Ts responsive were responding to Ts within any uniform EEG state. All changes in their firing rates were associated with EEG state changes. This study raises a question as to whether or not peripheral temperature information is integrated in the POAH. Consideration should be given to the possibility that Ts information is integrated lower in the neuroaxis. Monitoring EEG is essential in studies attempting to characterize the integrative properties of POAH neurons of anesthetized or unanesthetized animals. This caveat applies not just to thermoregulatory studies but to investigations of other integrative functions of the hypothalamus and many other brain regions as well.

scholarly journals Evolution of simple multicellular life cycles in dynamic environments

2019 ◽  
Vol 16 (154) ◽  
pp. 20190054 ◽  
Author(s):  
Yuriy Pichugin ◽  
Hye Jin Park ◽  
Arne Traulsen
Keyword(s):  
Natural Selection ◽  
Reproductive Strategies ◽  
Population Growth Rate ◽  
Dynamic Environment ◽  
Dynamic Environments ◽  
Life Cycles ◽  
Matrix Population Model ◽  
Bet Hedging ◽  
Reproduction Mode ◽  
Natural Response

The mode of reproduction is a critical characteristic of any species, as it has a strong effect on its evolution. As any other trait, the reproduction mode is subject to natural selection and may adapt to the environment. When the environment varies over time, different reproduction modes could be optimal at different times. The natural response to a dynamic environment seems to be bet hedging, where multiple reproductive strategies are stochastically executed. Here, we develop a framework for the evolution of simple multicellular life cycles in a dynamic environment. We use a matrix population model of undifferentiated multicellular groups undergoing fragmentation and ask which mode maximizes the population growth rate. Counterintuitively, we find that natural selection in dynamic environments generally tends to promote deterministic, not stochastic, reproduction modes.

Modified Newton's method applied to potential field based navigation for nonholonomic robots in dynamic environments

Robotica ◽  
2008 ◽  
Vol 26 (3) ◽  
pp. 285-294 ◽  
Author(s):  
Jing Ren ◽  
Kenneth A. McIsaac ◽  
Rajni V. Patel
Keyword(s):  
Newton’S Method ◽  
Potential Field ◽  
Newton's Method ◽  
Dynamic Environment ◽  
Dynamic Environments ◽  
Field Methods ◽  
Control Laws ◽  
Nonholonomic Robots ◽  
Modified Newton’S Method ◽  
Speed Up

SUMMARYThis paper is to investigate inherent oscillations problems of Potential Field Methods (PFMs) for nonholonomic robots in dynamic environments. In prior work, we proposed a modification of Newton's method to eliminate oscillations for omnidirectional robots in static environment. In this paper, we develop control laws for nonholonomic robots in dynamic environment using modifications of Newton's method. We have validated this technique in a multirobot search-and-forage task. We found that the use of the modifications of Newton's method, which applies anywhere C2 continuous navigation functions are defined, can greatly reduce oscillations and speed up robot's movement, when compared to the standard gradient approaches.

scholarly journals Navigation in Unknown Dynamic Environments Based on Deep Reinforcement Learning

Sensors ◽  
2019 ◽  
Vol 19 (18) ◽  
pp. 3837 ◽  
Author(s):  
Junjie Zeng ◽  
Rusheng Ju ◽  
Long Qin ◽  
Yue Hu ◽  
Quanjun Yin ◽  
...  
Keyword(s):  
Reinforcement Learning ◽  
Domain Knowledge ◽  
Moving Objects ◽  
Dynamic Environment ◽  
Dynamic Environments ◽  
Continuous Control ◽  
Complex Environments ◽  
Reward Function ◽  
Knowledge Based ◽  
Task Architecture

In this paper, we propose a novel Deep Reinforcement Learning (DRL) algorithm which can navigate non-holonomic robots with continuous control in an unknown dynamic environment with moving obstacles. We call the approach MK-A3C (Memory and Knowledge-based Asynchronous Advantage Actor-Critic) for short. As its first component, MK-A3C builds a GRU-based memory neural network to enhance the robot’s capability for temporal reasoning. Robots without it tend to suffer from a lack of rationality in face of incomplete and noisy estimations for complex environments. Additionally, robots with certain memory ability endowed by MK-A3C can avoid local minima traps by estimating the environmental model. Secondly, MK-A3C combines the domain knowledge-based reward function and the transfer learning-based training task architecture, which can solve the non-convergence policies problems caused by sparse reward. These improvements of MK-A3C can efficiently navigate robots in unknown dynamic environments, and satisfy kinetic constraints while handling moving objects. Simulation experiments show that compared with existing methods, MK-A3C can realize successful robotic navigation in unknown and challenging environments by outputting continuous acceleration commands.

Research on Mobile Robot SLAM in Dynamic Environment

2011 ◽  
Vol 130-134 ◽  
pp. 232-238
Author(s):  
Bai Fan Chen ◽  
Zi Xing Cai
Keyword(s):  
Mobile Robot ◽  
Experimental Test ◽  
Data Association ◽  
Dynamic Environment ◽  
Dynamic Environments ◽  
Target Model ◽  
Dynamic Objects ◽  
Objects Detection

A SLAMiDE（SLAM in Dynamic Environments) system is designed and realized in the paper, which supplies a holistic framework and a series of implementation methods for mobile robot SLAM in dynamic environments. A uniform target model is proposed in SLAMiDE system. The dynamic targets and static targets and the mobile robot pose are estimated simultaneously, by synthesized the research of the data association and dynamic targets detection and static SLAM based on local maps. Finally, the results of the experimental test prove that the SLAMiDE system can realize dynamic objects detection and mapping and location correctly.

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