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From crystals to lattice robots

Nicolas Brener, Faiz Ben Amar, Philippe Bidaud
2008 2008 IEEE International Conference on Robotics and Automation  
We identify three fundamental properties of lattice robots such as (1) discreteness (2) translational symmetry and (3) composition, and explain the analogy of lattice robots kinematics and crystal symmetry described by space groups. Then we give the possible connectors symmetries and orientations compatible with space groups, and the possible sliding and hinge joints locations and orientations compatible with the displacements in such groups. We present a framework for the design of lattice
more » ... ts by assembling compatible joints and connectors into a space group and give a 3D example. Point group Order Chiral space groups 1 1 P1 2 2
doi:10.1109/robot.2008.4543748 dblp:conf/icra/BrenerAB08 fatcat:augk3td4zjgtnkvndgyio3wtsi

Experimental Evaluation of Obstacle Clearance by a Hybrid Wheel-Legged Robot [chapter]

Christophe Grand, Pierre Jarrault, Faiz Ben Amar, Philippe Bidaud
2015 Springer Tracts in Advanced Robotics  
This paper deals with the problem of frontal obstacle crossing by a poly-articulated wheeled robot. We focus on the particular architecture of hybrid wheel-legged robots that are redundantly actuated systems. In this paper, experimental results that show the climbing capabilities of such system when crossing large obstacle are presented. We focus on the case of a step like obstacle whose height is superior to the diameter of the wheels. In this case, the adhesion properties have a large impact
more » ... n the crossing capabilities. First, the control methodology based on both the optimization of the system posture and the distribution of internal forces is introduced. The optimization criterion represents the maximum allowable force disturbance that the system can support before violating the frictional contact constraint. Then, our experimental prototype, the robot Hylos2 and the experimental setup are presented. As our approach is based on the control of the contact forces, experiments used to quantify the level of friction in the mechanical transmissions are first reported. Then a step-crossing trial on the real system is presented.
doi:10.1007/978-3-319-23778-7_4 fatcat:7drfyzatwbh2fhg4gjuuu5lyii

Designing Modular Lattice Systems with Chiral Space Groups

Nicolas Brener, Faiz Ben Amar, Philippe Bidaud
2008 The international journal of robotics research  
We propose to use the concept of chiral space groups used by the crystallography science to define and design lattice robots. Chiral space groups are of great interest because they give all possible sets of discrete displacements having a group structure and a translational symmetry. We explain the analogy between lattice robot kinematics and crystal symmetry, and identify three fundamental properties of lattice robots such as (1) discreteness (2) translational symmetry and (3) composition.
more » ... we give the possible connectors symmetries and orientations into a chiral space group, and the possible sliding and hinge joints locations and orientations compatible with the displacements in chiral space groups. We present a framework for the design of lattice robots by assembling compatible joints and connectors into a chiral space group. Several 2D and 3D examples of design are given to illustrate the framework. Moreover, we list the symmetries of the two chiral space groups P432 and P622 because they contain the symmetries of all the 65 chiral space groups and allow to design any lattice system.
doi:10.1177/0278364908089349 fatcat:e4vtp2igprgl3hdwy3v5wviwmm

Routing and course control of an autonomous sailboat

Hadi Saoud, Minh-Duc Hua, Frederic Plumet, Faiz Ben Amar
2015 2015 European Conference on Mobile Robots (ECMR)  
In this paper, we present a layered control scheme for an autonomous sailboat. The high level control uses an adjusted PRM-Dijkstra algorithm for the routing (global path planning) of autonomous sailboat. This algorithm exploits the sailboat kinematics and wind distribution on the map. For the low level control, we design a new nonlinear course (direction of the velocity vector) controller that exhibits superior performance compared to conventionally used heading controller. A smoothing
more » ... is also introduced in the design of the controller to switch easily from course control to heading control, especially when course measurements are noisy at low speed.
doi:10.1109/ecmr.2015.7324218 dblp:conf/ecmr/SaoudHPA15 fatcat:sabrmop7q5fyfie4maqpzxm7si

Optimal sail angle computation for an autonomous sailboat robot

Hadi Saoud, Minh-Duc Hua, Frederic Plumet, Faiz Ben Amar
2015 2015 54th IEEE Conference on Decision and Control (CDC)  
A method to compute the optimal sail angle for an autonomous sailboat is proposed, which allows for maximizing the longitudinal velocity while maintaining safe sailing conditions by limiting the roll angle. A simplified 4-DOF dynamic model of the sailboat is used to obtain the roll dynamics and longitudinal sail force. From these expressions, we derive a cost function which depends on the thrust force. The cost needs to be minimized under stability constraint in roll motion while the system is
more » ... ubject to a bound on the roll angle. Numerical simulations, using a full nonlinear dynamic model of the sailboat, show the improved performance of the proposed method, compared to traditional solutions that can be found in the literature.
doi:10.1109/cdc.2015.7402329 dblp:conf/cdc/SaoudHPA15 fatcat:xyni7nycqbhczpf47tq45vtosu

Characterization of lattice modular robots by discrete displacement groups

N Brener, Faiz Ben Amar, P Bidaud
2010 2010 IEEE/RSJ International Conference on Intelligent Robots and Systems  
The paper provides a method to determine and compare the reconfigurability of lattice systems. First it shows the difference that exists between the reconfigurability and self-reconfigurability features of a lattice system. Then a method using displacement groups is introduced to characterize these features. Based on this method, these features are then compared for some existing lattice systems.
doi:10.1109/iros.2010.5649934 dblp:conf/iros/BrenerAB10 fatcat:bjqttoexf5dtzajz3mqngui3j4

Évaluation des modes de déplacement d'un robot à locomotion hybride roue-patte évoluant en milieux naturels

Christophe Grand, Faïz Ben Amar, Frédéric Plumet, Philippe Bidaud
2005 Mécanique & industries  
Reçu le 25 février 2005, accepté le 21 mars 2005 Résumé -Cet article s'intéresse au problème de l'évaluation des modes de déplacement d'un robotà locomotion hybride roue-patte. Après une brève description du système mécatronique, nous présentons sa modélisation cinémato-statique dont l'originalité repose sur l'intégration des interactions roue-sol en terrains naturels. Les modèles d'interaction sont validés expérimentalementà l'aide d'un banc d'essai spécifique. Les modèles analytiques sont
more » ... ite exploités pour réaliser une analyse comparative des performances de locomotion pour chacun des modes de déplacement sur différents terrains. Les critères considérés sont la marge de stabilité, la gradabilité et la consommation d'énergie. Mots clés : Robot mobile / hybride / roue-patte / locomotion / modélisation / performances / terrains naturels / terra-mécanique / expérimental Abstract -Evaluation of the locomotion modes for an hybrid wheel-legged robot evolving in outdoor environment. This article deals with the problem of locomotion modes evaluation of an hybrid wheel-legged robot. After a brief mechatronic description of the system, we present its kinetostatic modeling whose originality is the integration of the wheel-ground interaction models on natural terrains. These interaction models are experimentally validated on a specific test-bed. Then, the analytical models are exploited to carry out a comparative analysis of the performances of locomotion for each mode on different terrains. The considered criteria are the stability margin, the gradability and the energy consumption.
doi:10.1051/meca:2005041 fatcat:6klb5wd6ozbt5piqlblbmzhic4

Analysis and optimization of obstacle clearance of articulated rovers

Faiz Ben Amar, Pierre Jarrault, Philippe Bidaud, Christophe Grand
2009 2009 IEEE/RSJ International Conference on Intelligent Robots and Systems  
The paper develops a method for analyzing and improving by control obstacle clearance capacities of articulated multi-wheeled rovers. On uneven ground surface, load and traction force distributions through the wheel/ground contact system are highly coupled. They are both conditioned by the global equilibrium of the mechanical system and the contact stability constraints. The optimal traction force distribution problem is formulated here as a convex optimization problem using Linear Matrix
more » ... lities (LMIs). Velocity and force transmissions in articulated multi-wheeled mobile robots are introduced under a generic form decomposed in task, joint and contact levels. A tyre-model is used for the evaluation of the robustness of the solution with respect to slippage phenomena. Simulation results show that the traction distribution forces which is so determined lead to a significant increase in obstacle clearance capacities compared to an usual velocity control technique.
doi:10.1109/iros.2009.5354379 dblp:conf/iros/AmarJBG09 fatcat:d5qbze5csjdqdgqfqthvb7nm2e

Kinematic analysis and stability optimization of a reconfigurable legged-wheeled mini-rover

Christophe Grand, Faiz Ben Amar, Philippe Bidaud, Grant R. Gerhart, Chuck M. Shoemaker, Douglas W. Gage
2002 Unmanned Ground Vehicle Technology IV  
A PC-104 is used for the * correspondance: {grand, amar, bidaud} high-level control such as attitude control, load and traction force balance, generation of different locomotion mode (rolling  ... 
doi:10.1117/12.474461 fatcat:zea65lziubcjpj2yaprvscnk3u

Dynamic Coupling Map: Acceleration Space Analysis for Underactuated Robots

Ziad Zamzami, Faïz Ben Amar
2016 Proceedings of the 13th International Conference on Informatics in Control, Automation and Robotics  
Swing-up and throwing tasks for underactuated manipulators are examples of dynamic motions that exhibit highly nonlinear coupling dynamics. One of the key ingredients for such complex behaviors is motion coordination to exploit their passive dynamics. Despite the existence of powerful tools such as nonlinear trajectory optimization, they are usually treated as blackboxes that provide local optimal trajectories. We introduce the Dynamical Coupling Map (DCM), a novel graphical technique, to help
more » ... ain insight into the output trajectory of the optimization and analyze the capability of underactuated robots. The DCM analysis is demonstrated on the swing up motion of a simplified model of a gymnast on high bar. The DCM shows in a graphical and intuitive way the pivotal role of exploiting the nonlinear inertial forces to reach the unstable equilibrium configuration while taking into account the torque bounds constraints. In this paper, we present the DCM as a posteriori analysis of a local optimal trajectory, found by employing the direct collocation trajectory optimization framework.
doi:10.5220/0006012405480557 dblp:conf/icinco/ZamzamiA16 fatcat:w7vjjbeiwvgkjn45eqqvm4qenm

Trajectory planning of unmanned ground vehicles evolving on an uneven terrain with vertical dynamic consideration

B. Menkouz, A. Bouzar Essaidi, M. Haddad, T. Chettibi, Faiz Ben Amar
2015 2015 4th International Conference on Electrical Engineering (ICEE)  
In this paper, we treat the problem of trajectory planning of an unmanned ground vehicle evolving on an uneven terrain. In such environment, the role of the suspension system cannot be neglected and a vehicle vertical model has to be taken into account. In the present work, we present three reduced models with different level of complexity. These models make possible to handle the constraints inherent to stability, embedded equipment safety and suspension mechanical integrity.An optimization
more » ... blem is also formulated in order to define the optimal speed profile for a safety behaviour of the mobile robot.
doi:10.1109/intee.2015.7416800 fatcat:ld4lqbkhvvedzm33i7ubka52iu

Whole-body Motion Tracking for a Quadruped-on-wheel Robot via a Compact-form Controller with Improved Prioritized Optimization

Wenqian Du, Mohamed Fnadi, Faiz Ben Amar
2020 IEEE Robotics and Automation Letters  
Whole-body motion tracking for a quadruped-onwheel robot via a compact-form controller with improved prioritized optimization. Abstract-This paper develops a more general dynamics controller to generate whole-body behaviors for a quadrupedon-wheel robot. To track the quadruped centroidal motion, the wheeled motion is achieved by combining the wheel contact constraints and the centroidal momentum/dynamics model. The dynamics controller is based on a new hybrid hierarchical and prioritized
more » ... d optimization framework. We propose one concept of a recursively updated dynamics model and this model enables to integrate the new prioritized weighted scheme in the hierarchical framework. In contrast with the conventional weighted scheme, we propose to use null-space projections among its sub-tasks. Then the prioritized impedance controller is proposed and integrated in our dynamics model, which enables to influence the hierarchical and prioritized weighted tasks in a decoupled way. The task accelerations in the two schemes are extracted with quadratic forms depending on the actuated torque and the prioritized impedance force using null-space based inverse dynamics. The inequality constraints are modified to ensure the compatibility with the hybrid convex optimization. This dynamics controller is more general and its algorithm is given completely which enables our robot to track the centroidal motion on rough terrain and handle other missions in three simulation scenarios.
doi:10.1109/lra.2019.2963822 fatcat:wmkqzi5a5bfzthvn3hzcegxmpm

Accurate and stable mobile robot path tracking: An integrated solution for off-road and high speed context

R Lenain, E Lucet, C Grand, B Thuilot, Faiz Ben Amar
2010 2010 IEEE/RSJ International Conference on Intelligent Robots and Systems  
This paper is focused on the problem of accurate and reliable path tracking control of a 4-wheels carlike mobile robot moving off-road at high speed. Dynamic and extended kinematic models that take into account the effects of wheel skidding are presented. Based on the extended kinematic model, an adaptive and predictive controller for path tracking is derived. This control law is combined to a stabilization algorithm of yaw motion, based on the dynamic model and the modulation of driven wheel
more » ... rces. The overall control architecture is experimentally evaluated on a slipping terrain. Results demonstrate enhanced performances as the robot succeed in following the path at high speed, accurately and without loss of control.
doi:10.1109/iros.2010.5650213 dblp:conf/iros/LenainLGTA10 fatcat:4xpc3o2rhfapnl3lqnfikaajwm

Genetic surveillance in the Greater Mekong Subregion and South Asia to support malaria control and elimination [article]

Christopher Jacob, Nguyen Thuy-Nhien, Mayfong Mayxay, Richard Maude, Huynh Hong Quang, Bouasy Hongvanthong, Viengxay Viengxay, Thang Ngo Duc, Huy Rekol, Rob van der Pluijm, Lorenz Von Seidlein, Rick Fairhurst (+84 others)
2020 medRxiv   pre-print
The use of parasite genetic data by National Malaria Control Programmes (NMCPs) is currently limited, and typically focused on specific genetic features or a small number of study sites. We have developed GenRe-Mekong, a platform for genetic surveillance of malaria in the Greater Mekong Subregion (GMS). By integrating simple sample collection procedures in the routine operations of public health facilities, GenRe-Mekong enables NMCPs to conduct large-scale surveillance project in endemic
more » ... . Samples are processed by the SpotMalaria platform, which uses high-throughput technologies to produce a broad set of genotypes, including most known drug resistance markers, species markers and a genomic barcode. Through the application of heuristics based on published evidence, GenRe-Mekong delivers Genetic Report Cards, a compendium of genotypes and phenotype predictions that are used to map prevalence of resistance to multiple drugs. To date, GenRe-Mekong has worked with NMCPs in five countries, and with several large-scale research projects, processing 9,645 samples from clinical cases. The monitoring of resistance markers has been especially valuable for NMCPs tracking the recent rapid spread of DHA-piperaquine resistant parasites across the region. In Vietnam and Laos, data from GenRe-Mekong have provided novel knowledge about the spread of these resistant strains in provinces previously thought to be unaffected. GenRe-Mekong facilitates data sharing by aggregating at regional level results from different countries, providing cross-border views of the spread of resistant strains.
doi:10.1101/2020.07.23.20159624 fatcat:mg7tube4yvblhdttrbsfaglaw4

Genetic surveillance in the Greater Mekong subregion and South Asia to support malaria control and elimination

Christopher G Jacob, Nguyen Thuy-Nhien, Mayfong Mayxay, Richard J Maude, Huynh Hong Quang, Bouasy Hongvanthong, Viengxay Vanisaveth, Thang Ngo Duc, Huy Rekol, Rob van der Pluijm, Lorenz von Seidlein, Rick Fairhurst (+86 others)
2021 eLife  
Background:National Malaria Control Programmes (NMCPs) currently make limited use of parasite genetic data. We have developed GenRe-Mekong, a platform for genetic surveillance of malaria in the Greater Mekong Subregion (GMS) that enables NMCPs to implement large-scale surveillance projects by integrating simple sample collection procedures in routine public health procedures.Methods:Samples from symptomatic patients are processed by SpotMalaria, a high-throughput system that produces a
more » ... sive set of genotypes comprising several drug resistance markers, species markers and a genomic barcode. GenRe-Mekong delivers Genetic Report Cards, a compendium of genotypes and phenotype predictions used to map prevalence of resistance to multiple drugs.Results:GenRe-Mekong has worked with NMCPs and research projects in eight countries, processing 9623 samples from clinical cases. Monitoring resistance markers has been valuable for tracking the rapid spread of parasites resistant to the dihydroartemisinin-piperaquine combination therapy. In Vietnam and Laos, GenRe-Mekong data have provided novel knowledge about the spread of these resistant strains into previously unaffected provinces, informing decision-making by NMCPs.Conclusions:GenRe-Mekong provides detailed knowledge about drug resistance at a local level, and facilitates data sharing at a regional level, enabling cross-border resistance monitoring and providing the public health community with valuable insights. The project provides a rich open data resource to benefit the entire malaria community.Funding:The GenRe-Mekong project is funded by the Bill and Melinda Gates Foundation (OPP11188166, OPP1204268). Genotyping and sequencing were funded by the Wellcome Trust (098051, 206194, 203141, 090770, 204911, 106698/B/14/Z) and Medical Research Council (G0600718). A proportion of samples were collected with the support of the UK Department for International Development (201900, M006212), and Intramural Research Program of the National Institute of Allergy and Infectious Diseases.
doi:10.7554/elife.62997 pmid:34372970 pmcid:PMC8354633 fatcat:bibo2sty35d43pqkjxwfktufqu
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