Dexterity analysis and robot hand design

Understanding about a dexterous robot hand's motion ranges is important to the precision grasping and precision manipulation. A planar robot hand is studied for object orientation, including ranges of motion, measures with respect to the palm, position reaching of a point in the grasped object, and rotation of the object about the reference point. The rotational dexterity index and dexterity chart are introduced and an analysis procedure is developed for calculating these quantities. A design procedure for determining the hand kinematic parameters based on a desired partial or complete dexterity chart is also developed. These procedures have been tested in detail for a planar robot hand with two 2- or 3-link fingers. The derived results are shown to be useful to performance evaluation, kinematic parameter design, and grasping motion planning for a planar robot hand

Intrathermocline eddies observed in the northwestern subtropical Pacific Ocean

Two anticyclonic intrathermocline eddies (ITEs) were detected by an underwater glider in the northwestern subtropical Pacific Ocean during August-October 2019. They both exhibited a lens-shaped vertical structure within the thermocline with their cores located at ~170 m. The North Pacific Subtropical Mode Water (STMW) was found within the cores of these two ITEs. The lens-shaped structure of ITE1 observed by the glider was very clear since the glider seemed to have moved into its core during the observation. Further analysis reveals that ITE1 displayed no signals at the sea surface and lasted for about 20 days (26 August-14 September 2019). ITE1 was locally formed and the water inside it was a mixture of local water and the water in the northern adjacent area. The low-salinity water at 0-50 m from the northern adjacent area extended southwestward and mixed with the local water. As a result, the local salinity-forced restratification caused a potential vorticity (PV) decrease in the subsurface and finally resulted in the generation of ITE1. The baroclinic instability at 50-170 m may be the main energy source for ITE1 generation. On the other hand, the lens-shaped structure of ITE2 observed by the glider was less prominent since the glider did not move into its core. Further analysis reveals that the lens-shaped structure of ITE2 was also very clear near its core and ITE2 displayed clear signals at the surface as an anticyclonic eddy (AE2). AE2/ITE2 was remotely generated within the main formation region of STMW and then moved southwestward. The low PV STMW was trapped in AE2 and a lens-shaped structure developed in the subsurface. Subduction of the STMW caused the generation of ITE2

A Fuzzy-based Collision Avoidance Approach for Multi-robot Systems

Multi-robot systems have been widely applied to various applications to perform a given task collaboratively and cooperatively. In a multi-robot environment, path-planning or collision avoidance is an imperative problem. For tackling this challenging problem, we mainly deal with the collision avoidance problem between robots and robots as well as between robots and obstacles in multi-robot systems. In this paper, the fuzzy reasoning based on a Step-Forward motion strategy is applied in making decision on motion of robots. The model of autonomous robot, the method of detecting dynamic speed of robot and the risk degree surrounding with a robot are discussed. The simulation results show that the fuzzy-based control strategies are effective and useful for making decisions on collision avoidance in multi-robot systems.Les syst\ue8mes multi-robots ont \ue9t\ue9 largement utilis\ue9s dans de nombreuses applications afin d'effectuer des t\ue2ches collaboratives en coop\ue9ration. Dans un environnement multi-robots, la planification des trajets ou l'\ue9vitement des collisions constituent un probl\ue8me imp\ue9ratif. Afin de r\ue9soudre ce probl\ue8me de taille, nous consid\ue9rons principalement le probl\ue8me de l'\ue9vitement des collisions entre robots ainsi que les collisions entre robots et obstacles dans les syst\ue8mes multi-robots. Le pr\ue9sent article pr\ue9sente l'application du raisonnement flou fond\ue9e sur une strat\ue9gie de d\ue9placement pas \ue0 pas \ue0 la prise de d\ue9cision relative au d\ue9placement de robots. On y discute aussi du mod\ue8le de robot autonome, de la m\ue9thode de d\ue9tection de la vitesse dynamique du robot et du degr\ue9 de risque environnant d'un robot. Les r\ue9sultats de la simulation indiquent que les strat\ue9gies de commande fond\ue9es sur le raisonnement flou sont efficaces et utiles pour effectuer la prise de d\ue9cision en vue de l'\ue9vitement de collisions dans des syst\ue8mes multi-robots.NRC publication: Ye

A Fuzzy-based Collision Avoidance Approach for Multi-robot Systems

Multi-robot systems have been widely applied to various applications to perform a given task collaboratively and cooperatively. In a multi-robot environment, path-planning or collision avoidance is an imperative problem. For tackling this challenging problem, we mainly deal with the collision avoidance problem between robots and robots as well as between robots and obstacles in multi-robot systems. In this paper, the fuzzy reasoning based on a Step-Forward motion strategy is applied in making decision on motion of robots. The model of autonomous robot, the method of detecting dynamic speed of robot and the risk degree surrounding with a robot are discussed. The simulation results show that the fuzzy-based control strategies are effective and useful for making decisions on collision avoidance in multi-robot systems.Les syst\ue8mes multi-robots ont \ue9t\ue9 largement utilis\ue9s dans de nombreuses applications afin d'effectuer des t\ue2ches collaboratives en coop\ue9ration. Dans un environnement multi-robots, la planification des trajets ou l'\ue9vitement des collisions constituent un probl\ue8me imp\ue9ratif. Afin de r\ue9soudre ce probl\ue8me de taille, nous consid\ue9rons principalement le probl\ue8me de l'\ue9vitement des collisions entre robots ainsi que les collisions entre robots et obstacles dans les syst\ue8mes multi-robots. Le pr\ue9sent article pr\ue9sente l'application du raisonnement flou fond\ue9e sur une strat\ue9gie de d\ue9placement pas \ue0 pas \ue0 la prise de d\ue9cision relative au d\ue9placement de robots. On y discute aussi du mod\ue8le de robot autonome, de la m\ue9thode de d\ue9tection de la vitesse dynamique du robot et du degr\ue9 de risque environnant d'un robot. Les r\ue9sultats de la simulation indiquent que les strat\ue9gies de commande fond\ue9es sur le raisonnement flou sont efficaces et utiles pour effectuer la prise de d\ue9cision en vue de l'\ue9vitement de collisions dans des syst\ue8mes multi-robots.NRC publication: Ye

Collision Avoidance in Multi-Robot Systems

Multi-robot systems have been widely applied to various applications to perform a given task collaboratively and cooperatively. In a multi-robot environment, path-planning or collision avoidance is an important problem. This paper tackles this important but challenging problem. We developed a step-forward approach for collision avoidance in multi-robot systems, building on the established techniques from omni-directional vision systems, automatic control, and dynamic programming. The developed collision avoidance algorithms can help avoid the collision from any static obstacles and any dynamic objects such as a moving robot. In this paper, we report the developed collision avoidance algorithms, along with simulation-based experimental results. The results show that the collision avoidance strategies are effective and useful for making decisions on collision avoidance in multi-robot systems.Les syst\ue8mes multi-robots ont \ue9t\ue9 largement utilis\ue9s dans diverses applications pour ex\ue9cuter une t\ue2che donn\ue9e, de mani\ue8re collaborative et coop\ue9rative. Dans un environnement multi-robots, la planification des parcours et la pr\ue9vention des collisions constituent un probl\ue8me important. Cet article s'attaque \ue0 ce probl\ue8me important, mais stimulant. Nous avons d\ue9velopp\ue9 une approche progressiste \ue0 la pr\ue9vention des collisions dans les syst\ue8mes multi-robots, en misant sur des techniques \ue9tablies, allant des syst\ue8mes de vision omnidirectionnelle au contr\uf4le automatique, en passant par la programmation dynamique. Les algorithmes de pr\ue9vention de collisions d\ue9velopp\ue9s peuvent aider \ue0 \ue9viter les collisions avec des obstacles statiques et des objets dynamiques, comme un robot en mouvement. Dans cet article, nous d\ue9crivons les algorithmes de pr\ue9vention de collision que nous avons d\ue9velopp\ue9s, ainsi que des r\ue9sultats exp\ue9rimentaux bas\ue9s sur des simulations. Ces r\ue9sultats indiquent que les strat\ue9gies de pr\ue9vention de collisions sont efficaces et utiles pour la prise de d\ue9cisions en mati\ue8re de pr\ue9vention de collisions dans les syst\ue8mes multi-robots.NRC publication: Ye

Multi-Scale Numerical Assessments of Urban Wind Resource Using Coupled WRF-BEP and RANS Simulation: A Case Study

Urban wind resource assessments (WRAs) contribute to the effective exploitation of wind energy and thus are of significant importance to the sustainable development of cities. To improve the simulation accuracy of urban wind flow with high spatial resolution, this study implemented a multi-scale numerical assessment of the wind power potential in a highly-urbanized region with realistic terrain conditions by integrating the Reynolds-averaged Navier-Stokes (RANS) equations into the Weather Research and Forecasting (WRF) model with Building Effect Parameterization (WRF-BEP). The sensitivity analyses are first conducted to obtain an appropriate combination of physical parameterization schemes in the WRF-BEP model. Then, the wind tunnel tests are performed to validate the computational accuracy of urban wind flow using the RANS equations. Based on a close examination of the urban wind flow resulting from the coupled WRF-BEP and RANS simulations, the integration of micro-wind turbines into the building skin is not recommended in the highly-urbanized region. Furthermore, five optimum roof installation locations with low turbulence intensities (smaller than 18%) and high wind power densities (approximately 220 W/m2, 260 W/m2, 270 W/m2, 300 W/m2 and 400 W/m2, respectively) are identified. Finally, the important effects of the terrain conditions, planetary boundary layer (PBL) parameterization schemes and turbulence models on WRAs are discussed. The results of WRAs in this multi-scale numerical case study presented a systemic approach to effectively determine the installation locations of micro-wind turbines that possess the greatest potential to harness wind energy in a realistic highly-urbanized area