Learning how to do things with imitation

In this paper we discuss how agents can learn to do things by imitating other agents. Especially we look at how the use of different metrics and sub-goal granularity can affect the imitation results. We use a computer model of a chess world as a test-bed to also illustrate issues that arise when there is dissimilar embodiment between the demonstrator and the imitator agents

Achieving Corresponding Effects on Multiple Robotic Platforms: Imitating in Context Using Different Effect Metrics

Original paper can be found at: www.aisb.org.uk/publications/proceedings/aisb05/3_Imitation_Final.pdfOne of the fundamental problems in imitation is the correspondence problem, how to map between the actions, states and effects of the model and imitator agents, when the embodiment of the agents is dissimilar. In our approach, the matching is according to different metrics and granularity. This paper presents JABBERWOCKY, a system that uses captured data from a human demonstrator to generate appropriate action commands, addressing the correspondence problem in imitation. Towards a characterization of the space of effect metrics, we are exploring absolute/relative angle and displacement aspects and focus on the overall arrangement and trajectory of manipulated objects. Using as an example a captured demonstration from a human, the system produces a correspondence solution given a selection of effect metrics and starting from dissimilar initial object positions, producing action commands that are then executed by two imitator target platforms (in simulation) to successfully imitate

IRIS Observations of Spicules and Structures Near the Solar Limb

We have analyzed IRIS spectral and slit-jaw observations of a quiet region near the South Pole. In this article we present an overview of the observations, the corrections, and the absolute calibration of the intensity. We focus on the average profiles of strong (Mg ii h and k, C ii and Si iv), as well as of weak spectral lines in the near ultraviolet (NUV) and the far ultraviolet (FUV), including the Mg ii triplet, thus probing the solar atmosphere from the low chromosphere to the transition region. We give the radial variation of bulk spectral parameters as well as line ratios and turbulent velocities. We present measurements of the formation height in lines and in the NUV continuum, from which we find a linear relationship between the position of the limb and the intensity scale height. We also find that low forming lines, such as the Mg ii triplet, show no temporal variations above the limb associated with spicules, suggesting that such lines are formed in a homogeneous atmospheric layer and, possibly, that spicules are formed above the height of 2 arc sec. We discuss the spatio-temporal structure near the limb from images of intensity as a function of position and time. In these images, we identify p-mode oscillations in the cores of lines formed at low heights above the photosphere, slow moving bright features in O i and fast moving bright features in C ii. Finally, we compare the Mg ii k and h line profiles, together with intensity values of the Balmer lines from the literature, with computations from the PROM57Mg non-LTE model developed at the Institut d'Astrophysique Spatiale and estimated values of the physical parameters. We obtain electron temperatures in the range of $\sim8000$ K at small heights to $\sim20000$ K at large heights, electron densities from $1.1 \times 10^{11}$ to $4 \times 10^{10}$ cm$^{-3}$ and a turbulent velocity of $\sim24$km/s.Comment: Accepted for publication in Solar Physic