Tom Creemers

Box Approximations of Planar Linkage Configuration Spaces

This paper presents a numerical method able to compute all possible configurations of planar linkages. The procedure is applicable to rigid linkages (i.e., those that can only adopt a finite number of configurations) and to mobile ones (i.e., those that exhibit a continuum of possible configurations). The method is based on the fact that this problem can be reduced to finding the roots of a polynomial system of linear, quadratic, and hyperbolic equations, which is here tackled with a new strategy exploiting its structure. The method is conceptually simple and easy to implement, yet it provides solutions of the desired accuracy in short computation times. Experiments are included that show its performance on the double butterfly linkage and on larger linkages formed by the concatenation of basic patterns.

Smart schedules streamline distributions maintenance

The scheduling and coordination of maintenance tasks and resource dispatching, with the aim of guaranteeing service to all customers, forms an essential part of the planning engineers tasks. Least cost solutions are key. This article features a novel application called PLANETS, based on a constraint-logic programming paradigm, for scheduling maintenance activities on large distribution networks. Examples are included from system tests performed on subsets of the distribution network of Empresa Nacional Hidroelectrica del Ribagorzana (ENHER), a Spanish electric company.

Fast multiresolutive approximations of planar linkage configuration spaces

This paper presents a numerical method able to compute all possible configurations of a planar linkage. The procedure is applicable to rigid linkages (i.e., those that can only adopt a finite number of isolated configurations) and to mobile ones (i.e., those that have internal degrees of freedom). The method is based on the fact that this analysis always reduces to finding the roots of a polynomial system of linear, quadratic, and hyperbolic equations, which is here tackled with a new strategy exploiting its structure. The method is conceptually simple, geometric in nature, and easy to implement, yet it provides solutions of the desired accuracy in short computation times. Experiments are included which show its performance on the double butterfly linkage, for which an accurate an complete discretization of its configuration space is obtained

A General Platform for Robot Navigation in Natural Environments

A user interface for the remote control of vision-based robot navigation in previously unknown, indoor or outdoor environments has been developed. Visual feedback from the camera(s) of the robot is provided to the user, allowing him to select a visual target to be reached by the robot and launch an autonomous navigation process. Manual control can be taken back by the user at any time. The interface is built as a modular platform, capable of accommodating different types of robots and different algorithms for vision and navigation. There are hardware-dependent modules, whose purpose is to isolate the particularities of each robot from the rest of the control system, and must be implemented for each different robot to be used with the platform. Other modules are hardware-independent, and they implement generic tasks like landmark detection or path planning. Alternative versions of these modules can co-exist in the system, so that the user may select the preferred combination of them for each navigation task.