scholarly journals Simultaneous task allocation and planning for temporal logic goals in heterogeneous multi-robot systems

2018 ◽  
Vol 37 (7) ◽  
pp. 818-838 ◽  
Author(s):  
Philipp Schillinger ◽  
Mathias Bürger ◽  
Dimos V. Dimarogonas
Keyword(s):  
Temporal Logic ◽  
Resource Constraints ◽  
A Priori ◽  
Planning Problem ◽  
Execution Costs ◽  
Robot Systems ◽  
Optimal Action ◽  
Mission Specification ◽  
Complex Planning

This paper describes a framework for automatically generating optimal action-level behavior for a team of robots based on temporal logic mission specifications under resource constraints. The proposed approach optimally allocates separable tasks to available robots, without requiring a priori an explicit representation of the tasks or the computation of all task execution costs. Instead, we propose an approach for identifying sub-tasks in an automaton representation of the mission specification and for simultaneously allocating the tasks and planning their execution. The proposed framework avoids the need to compute a combinatorial number of possible assignment costs, where each computation itself requires solving a complex planning problem. This can improve computational efficiency compared with classical assignment solutions, in particular for on-demand missions where task costs are unknown in advance. We demonstrate the applicability of the approach with multiple robots in an existing office environment and evaluate its performance in several case study scenarios.

scholarly journals A Constraint-based Mission Planning Approach for Reconfigurable Multi-Robot Systems

2018 ◽  
Vol 21 (62) ◽  
pp. 25
Author(s):  
Thomas M Roehr
Keyword(s):  
Degrees Of Freedom ◽  
Resource Constraints ◽  
Mission Planning ◽  
General Nature ◽  
Planning Problem ◽  
Modular Systems ◽  
Planning Approach ◽  
Robot Systems ◽  
Revised Definitions ◽  
Multi Robot

The application of reconfigurable multi-robot systems introduces additional degrees of freedom to design robotic missions compared to classical multi-robot systems. To allow for autonomous operation of such systems, planning approaches have to be investigated that cannot only cope with the combinatorial challenge arising from the increased flexibility of modular systems, but also exploit this flexibility to improve for example the safety of operation. While the problem originates from the domain of robotics it is of general nature and significantly intersects with operations research. This paper suggests a constraint-based mission planning approach, and presents a set of revised definitions for reconfigurable multi-robot systems including the representation of the planning problem using spatially and temporally qualified resource constraints. Planning is performed using a multi-stage approach and a combined use of knowledge-based reasoning, constraint-based programming and integer linear programming. The paper concludes with the illustration of the solution of a planned example mission.

scholarly journals Normal form approach in the motion planning of space robots: a case study

2021 ◽  
Author(s):  
Krzysztof Tchoń ◽  
Katarzyna Zadarnowska
Keyword(s):  
Normal Form ◽  
Motion Planning ◽  
Normal Forms ◽  
Inverse Dynamics ◽  
Planning Problem ◽  
Inverse Dynamics Problem ◽  
Velocity Level ◽  
Form Approach ◽  
Space Approach

AbstractWe examine applicability of normal forms of non-holonomic robotic systems to the problem of motion planning. A case study is analyzed of a planar, free-floating space robot consisting of a mobile base equipped with an on-board manipulator. It is assumed that during the robot’s motion its conserved angular momentum is zero. The motion planning problem is first solved at velocity level, and then torques at the joints are found as a solution of an inverse dynamics problem. A novelty of this paper lies in using the chained normal form of the robot’s dynamics and corresponding feedback transformations for motion planning at the velocity level. Two basic cases are studied, depending on the position of mounting point of the on-board manipulator. Comprehensive computational results are presented, and compared with the results provided by the Endogenous Configuration Space Approach. Advantages and limitations of applying normal forms for robot motion planning are discussed.

Magnetotelluric static shift: Estimation and removal using the cokriging method

Geophysics ◽  
2007 ◽  
Vol 72 (1) ◽  
pp. F25-F34 ◽  
Author(s):  
Benoit Tournerie ◽  
Michel Chouteau ◽  
Denis Marcotte
Keyword(s):  
Apparent Resistivity ◽  
A Priori ◽  
Shift Factor ◽  
Static Shift ◽  
Geostatistical Model ◽  
Data Set ◽  
Resistivity Sounding ◽  
The Difference ◽  
Cross Variogram

We present and test a new method to correct for the static shift affecting magnetotelluric (MT) apparent resistivity sounding curves. We use geostatistical analysis of apparent resistivity and phase data for selected periods. For each period, we first estimate and model the experimental variograms and cross variogram between phase and apparent resistivity. We then use the geostatistical model to estimate, by cokriging, the corrected apparent resistivities using the measured phases and apparent resistivities. The static shift factor is obtained as the difference between the logarithm of the corrected and measured apparent resistivities. We retain as final static shift estimates the ones for the period displaying the best correlation with the estimates at all periods. We present a 3D synthetic case study showing that the static shift is retrieved quite precisely when the static shift factors are uniformly distributed around zero. If the static shift distribution has a nonzero mean, we obtained best results when an apparent resistivity data subset can be identified a priori as unaffected by static shift and cokriging is done using only this subset. The method has been successfully tested on the synthetic COPROD-2S2 2D MT data set and on a 3D-survey data set from Las Cañadas Caldera (Tenerife, Canary Islands) severely affected by static shift.

scholarly journals Modeling the bioconversion of polysaccharides in a continuous reactor: A case study of the production of oligogalacturonates by Dickeya dadantii

2018 ◽  
Vol 294 (5) ◽  
pp. 1753-1762 ◽  
Author(s):  
Jacques-Alexandre Sepulchre ◽  
Sylvie Reverchon ◽  
Jean-Luc Gouzé ◽  
William Nasser
Keyword(s):  
A Priori ◽  
Pectate Lyase ◽  
Degradation Process ◽  
Continuous Reactor ◽  
Practical Implementation ◽  
Dickeya Dadantii ◽  
Pectate Lyases ◽  
Upper Limit ◽  
Promising Avenue

In the quest for a sustainable economy of the Earth's resources and for renewable sources of energy, a promising avenue is to exploit the vast quantity of polysaccharide molecules contained in green wastes. To that end, the decomposition of pectin appears to be an interesting target because this polymeric carbohydrate is abundant in many fruit pulps and soft vegetables. To quantitatively study this degradation process, here we designed a bioreactor that is continuously fed with de-esterified pectin (PGA). Thanks to the pectate lyases produced by bacteria cultivated in the vessel, the PGA is depolymerized into oligogalacturonates (UGA), which are continuously extracted from the tank. A mathematical model of our system predicted that the conversion efficiency of PGA into UGA increases in a range of coefficients of dilution until reaching an upper limit where the fraction of UGA that is extracted from the bioreactor is maximized. Results from experiments with a continuous reactor hosting a strain of the plant pathogenic bacterium Dickeya dadantii and in which the dilution coefficients were varied quantitatively validated the predictions of our model. A further theoretical analysis of the system enabled an a priori comparison of the efficiency of eight other pectate lyase–producing microorganisms with that of D. dadantii. Our findings suggest that D. dadantii is the most efficient microorganism and therefore the best candidate for a practical implementation of our scheme for the bioproduction of UGA from PGA.

scholarly journals SIMULATION OF BRIDGE CONSTRUCTION WORKS: AN EXPLORATORY STUDY

2014 ◽  
Vol 1 (1) ◽  
Author(s):  
Fahimeh Zaeri ◽  
James Olabode Bamidele Rotimi
Keyword(s):  
Exploratory Study ◽  
Construction Projects ◽  
Resource Constraints ◽  
Discrete Elements ◽  
Bridge Construction ◽  
Complex Interactions ◽  
Simulation Based ◽  
Construction Operation ◽  
Construction Works

Bridge construction projects are associated with uncertainties partly due to sequencing issues, logistics, interactions, and resource constraints. Their construction is mostly cyclic and repetitive, yet complex, requiring innovative approaches to cope with its management. Construction projects planners seek methods to enable them to schedule bridge construction projects in consideration of these constraining factors. The main objective of this research is to develop a concept of a simulation-based modeling approach. It aimed to decide which data in real systems are important for the modeling of an operation, and in which way they must be gathered to help planners approach a proper simulation-based schedule. A case study project based in New Zealand was selected for this paper. It focuses on developing a resource-based model of bridge construction using a launching-girder construction method, taking into account the complex interactions among the project’s components. The discrete elements within the project and steps taken to develop a model are described in this paper. The study enhances knowledge on the applicability of simulation in repetitive construction operation, which in turn can provide more realistic models for scheduling progress.

scholarly journals Robust Bayesian Joint Inversion of Gravimetric and Muographic Data for the Density Imaging of the Puy de Dôme Volcano (France)

2021 ◽  
Vol 8 ◽  
Author(s):  
Anne Barnoud ◽  
Valérie Cayol ◽  
Peter G. Lelièvre ◽  
Angélie Portal ◽  
Philippe Labazuy ◽  
...  
Keyword(s):  
Joint Inversion ◽  
A Priori ◽  
Constant Density ◽  
Acquisition Duration ◽  
Regularization Parameters ◽  
Absolute Density ◽  
Gravimetric Data ◽  
Ill Posed ◽  
Leave One Out

Imaging the internal structure of volcanoes helps highlighting magma pathways and monitoring potential structural weaknesses. We jointly invert gravimetric and muographic data to determine the most precise image of the 3D density structure of the Puy de Dôme volcano (Chaîne des Puys, France) ever obtained. With rock thickness of up to 1,600 m along the muon lines of sight, it is, to our knowledge, the largest volcano ever imaged by combining muography and gravimetry. The inversion of gravimetric data is an ill-posed problem with a non-unique solution and a sensitivity rapidly decreasing with depth. Muography has the potential to constrain the absolute density of the studied structures but the use of the method is limited by the possible number of acquisition view points, by the long acquisition duration and by the noise contained in the data. To take advantage of both types of data in a joint inversion scheme, we develop a robust method adapted to the specificities of both the gravimetric and muographic data. Our method is based on a Bayesian formalism. It includes a smoothing relying on two regularization parameters (an a priori density standard deviation and an isotropic correlation length) which are automatically determined using a leave one out criterion. This smoothing overcomes artifacts linked to the data acquisition geometry of each dataset. A possible constant density offset between both datasets is also determined by least-squares. The potential of the method is shown using the Puy de Dôme volcano as case study as high quality gravimetric and muographic data are both available. Our results show that the dome is dry and permeable. Thanks to the muographic data, we better delineate a trachytic dense core surrounded by a less dense talus.

Commercial microwave links instead of rain gauges: fiction or reality?

2014 ◽  
Vol 71 (1) ◽  
pp. 31-37 ◽  
Author(s):  
Martin Fencl ◽  
Jörg Rieckermann ◽  
Petr Sýkora ◽  
David Stránský ◽  
Vojtěch Bareš
Keyword(s):  
Rainfall Variability ◽  
A Priori ◽  
Rain Gauges ◽  
Precipitation Estimates ◽  
Spatio Temporal ◽  
Areal Rainfall ◽  
Quantitative Precipitation Estimates ◽  
Commercial Microwave Links ◽  
Unique Dataset

Commercial microwave links (MWLs) were suggested about a decade ago as a new source for quantitative precipitation estimates (QPEs). Meanwhile, the theory is well understood and rainfall monitoring with MWLs is on its way to being a mature technology, with several well-documented case studies, which investigate QPEs from multiple MWLs on the mesoscale. However, the potential of MWLs to observe microscale rainfall variability, which is important for urban hydrology, has not been investigated yet. In this paper, we assess the potential of MWLs to capture the spatio-temporal rainfall dynamics over small catchments of a few square kilometres. Specifically, we investigate the influence of different MWL topologies on areal rainfall estimation, which is important for experimental design or to a priori check the feasibility of using MWLs. In a dedicated case study in Prague, Czech Republic, we collected a unique dataset of 14 MWL signals with a temporal resolution of a few seconds and compared the QPEs from the MWLs to reference rainfall from multiple rain gauges. Our results show that, although QPEs from most MWLs are probably positively biased, they capture spatio-temporal rainfall variability on the microscale very well. Thus, they have great potential to improve runoff predictions. This is especially beneficial for heavy rainfall, which is usually decisive for urban drainage design.

A semi-active milling procedure in view of preparing implantation beds in robot-assisted orthopaedic surgery

2005 ◽  
Vol 219 (3) ◽  
pp. 163-174 ◽  
Author(s):  
G Van Ham ◽  
K Denis ◽  
J Vander Sloten ◽  
R Van Audekercke ◽  
G Van der Perre ◽  
...  
Keyword(s):  
Robot Motion ◽  
Robot Assisted ◽  
Cavity Preparation ◽  
Feed Force ◽  
Robot Systems ◽  
Surface Irregularities ◽  
Robot Assistance ◽  
Set Up ◽  
Tool Motion

Bone cutting in total joint reconstructions requires a high accuracy to obtain a well-functioning and long-lasting prosthesis. Hence robot assistance can be useful to increase the precision of the surgical actions. A drawback of current robot systems is that they autonomously machine the bone, in that way ignoring the surgeon's experience and introducing a safety risk. This paper presents a semi-active milling procedure to overcome that drawback. In this procedure the surgeon controls robot motion by exerting forces on a force-controlled lever that is attached to the robot end effector. Meanwhile the robot constrains tool motion to the planned motion and generates a tool feed determined by the feed force that the surgeon executes. As a case study the presented milling procedure has been implemented on a laboratory set-up for robot-assisted preparation of the acetabulum in total hip arthroplasty. Two machining methods have been considered. In the first method the surgeon determines both milling trajectory and feed by the forces that he/she executes on the force-controlled lever. In the second method the cavity is machined contour by contour, and the surgeon only provides the feed. Machining experiments have shown that the first method results in large surface irregularities and is not useful. The second method, however, results in accurate cavity preparation and has therefore potential to be implemented in future robot systems.

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