A passivity approach to controller-observer design for robots

Passivity-based control methods for robots, which achieve the control objective by reshaping the robot system's natural energy via state feedback, have, from a practical point of view, some very attractive properties. However, the poor quality of velocity measurements may significantly deteriorate the control performance of these methods. In this paper the authors propose a design strategy that utilizes the passivity concept in order to develop combined controller-observer systems for robot motion control using position measurements only. To this end, first a desired energy function for the closed-loop system is introduced, and next the controller-observer combination is constructed such that the closed-loop system matches this energy function, whereas damping is included in the controller- observer system to assure asymptotic stability of the closed-loop system. A key point in this design strategy is a fine tuning of the controller and observer structure to each other, which provides solutions to the output-feedback robot control problem that are conceptually simple and easily implementable in industrial robot applications. Experimental tests on a two-DOF manipulator system illustrate that the proposed controller-observer systems enable the achievement of higher performance levels compared to the frequently used practice of numerical position differentiation for obtaining a velocity estimat

L\u27Egal Franglais

The following list of words that look the same in French and English is a modified form of one made for the members of the Ouvroir de Literature Potentielle (OuLiPo), a group of eighteen writers and mathematicians based in Paris whose raison d\u27etre is the literary use of constructive form. Specifically, it was generated to provide material for the composition of heteronymic, ambivalent Anglo-French texts. The list, which is not meant to be exhaustive, has been drawn up according to three principles

The geography of rural settlement in the Durham region

No abstract availabl

Time-varying network models

We introduce the exchangeable rewiring process for modeling time-varying networks. The process fulfills fundamental mathematical and statistical properties and can be easily constructed from the novel operation of random rewiring. We derive basic properties of the model, including consistency under subsampling, exchangeability, and the Feller property. A reversible sub-family related to the Erd\H{o}s-R\'{e}nyi model arises as a special case.Comment: Published at http://dx.doi.org/10.3150/14-BEJ617 in the Bernoulli (http://isi.cbs.nl/bernoulli/) by the International Statistical Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm