Navigation without localisation: reliable teach and repeat based on the convergence theorem

We present a novel concept for teach-and-repeat visual navigation. The proposed concept is based on a mathematical model, which indicates that in teach-and-repeat navigation scenarios, mobile robots do not need to perform explicit localisation. Rather than that, a mobile robot which repeats a previously taught path can simply `replay' the learned velocities, while using its camera information only to correct its heading relative to the intended path. To support our claim, we establish a position error model of a robot, which traverses a taught path by only correcting its heading. Then, we outline a mathematical proof which shows that this position error does not diverge over time. Based on the insights from the model, we present a simple monocular teach-and-repeat navigation method. The method is computationally efficient, it does not require camera calibration, and it can learn and autonomously traverse arbitrarily-shaped paths. In a series of experiments, we demonstrate that the method can reliably guide mobile robots in realistic indoor and outdoor conditions, and can cope with imperfect odometry, landmark deficiency, illumination variations and naturally-occurring environment changes. Furthermore, we provide the navigation system and the datasets gathered at http://www.github.com/gestom/stroll_bearnav.Comment: The paper will be presented at IROS 2018 in Madri

Overview Chapter 1: Fertility in Europe

Early in the 21st century, three-quarters of Europe’s population lived in countries with fertility considerably below replacement. This general conclusion is arrived at irrespective of whether period or cohort fertility measures are used. In Western and Northern Europe, fertility quantum was slightly below replacement. In Southern, Central and Eastern Europe, fertility quantum as measured by the period total fertility rate (TFR) and its tempo-adjusted version was markedly below replacement; in many countries it was around 1.5, and in some populations it was as low as 1.3 to 1.4 births per woman. Throughout Europe, a historic transformation of childbearing patterns characterised by a pronounced delay of entry into parenthood has been taking place. This secular trend towards later childbearing has greatly contributed to the decline and fluctuations in period fertility rates. Delayed births were being recuperated, especially among childless women, but the extent of recuperation differs by country and region. All in all, despite a recent upward trend in the period TFR, European fertility early in the 21st century was at its lowest point since the Second World War.childbearing, Europe, fertility

Only All Naturalists Should Worry About Only One Evolutionary Debunking Argument

Do the facts of evolution generate an epistemic challenge to moral realism? Some think so, and many “evolutionary debunking arguments” have been discussed in the recent literature. But they are all murky right where it counts most: exactly which epistemic principle is meant to take us from evolutionary considerations to the skeptical conclusion? Here, I will identify several distinct species of evolutionary debunking argument in the literature, each one of which relies on a distinct epistemic principle. Drawing on recent work in epistemology, I will show that most of these initially plausible principles are false, spoiling the arguments that rely on them. And we will see that each argument threatens only one popular view of moral psychology: a “Representationalist” view on which our moral judgments rely crucially on a mental intermediary—e.g. a sentiment, gut reaction, or affect-laden intuition—delivered by our evolved moral faculty. In the end, only one evolutionary debunking argument remains a menace: an “ Argument from Symmetry ” that I will introduce to the literature. But we will see that it should worry only all naturalists, pressuring them into a trilemma: give up moral realism, accept a rationalism that is incongruous with naturalism, or give up naturalism. Non-naturalists are free and clear

2003 Multilingual Survey of California Voters

Provides an analysis of the views of California's major racial and ethnic groups on the gubernatorial recall, Governor Gray Davis' performance in office, the candidates seeking to replace him, and the racial classification initiative