Keep it Upright: Model Predictive Control for Nonprehensile Object Transportation with Obstacle Avoidance on a Mobile Manipulator

We consider a nonprehensile manipulation task in which a mobile manipulator must balance objects on its end effector without grasping them -- known as the waiter's problem -- and move to a desired location while avoiding static and dynamic obstacles. In constrast to existing approaches, our focus is on fast online planning in response to new and changing environments. Our main contribution is a whole-body constrained model predictive controller (MPC) for a mobile manipulator that balances objects and avoids collisions. Furthermore, we propose planning using the minimum statically-feasible friction coefficients, which provides robustness to frictional uncertainty and other force disturbances while also substantially reducing the compute time required to update the MPC policy. Simulations and hardware experiments on a velocity-controlled mobile manipulator with up to seven balanced objects, stacked objects, and various obstacles show that our approach can handle a variety of conditions that have not been previously demonstrated, with end effector speeds and accelerations up to 2.0 m/s and 7.9 m/s$^2$, respectively. Notably, we demonstrate a projectile avoidance task in which the robot avoids a thrown ball while balancing a tall bottle.Comment: 8 pages, 14 figures; submitted to Robotics and Automation Letters (RA-L

Languages and Learning at Key Stage 2: A Longitudinal Study Final Report

In 2006, The Open University, the University of Southampton and Canterbury Christ Church University were commissioned by the then Department for Education and Skills (DfES), now Department for Children, Schools and Families (DCSF) to conduct a three-year longitudinal study of languages learning at Key Stage 2 (KS2). The qualitative study was designed to explore provision, practice and developments over three school years between 2006/07 and 2008/09 in a sample of primary schools and explore children’s achievement in oracy and literacy, as well as the possible broader cross-curricular impact of languages learning

Reconstruction using local sparsity:a novel regularization technique and an asymptotic analysis of spatial sparsity priors

Das Gebiet der inversen Probleme, wobei die Unbekannte neben ihrer örtlichen Dimension mindestens noch eine zusätzliche Dimension enthält, ist bedeutend für viele Anwendungen wie z.B. Bildgebung, Naturwissenschaften und Medizin. Es hat sich durchgesetzt dünnbesetzte Matrizen (Sparsity) als Lösungen zu fördern. Diese Arbeit beschäftigt sich mit einer speziellen Art der Dünnbesetztheit, welche eine gewisse Struktur in der Lösungsmatrix favorisiert. Wir präsentieren und analysieren eine neue Regularisierung, welche lokale Dünnbesetztheit fördert, indem die l^{1,inf}-Norm in einem Variationsansatz minimiert wird. Zusätzlich analysieren wir die Asymptotik verschiedener Regularisierungsfunktionale, welche Dünngesetztheit fördern. Wir betrachten diskrete Funktionale, welche dünnbesetzte Lösungen bevorzugen, und analysieren ihr Verhalten für feiner werdende Diskretisierungen. Hierbei erhalten wir einige Gamma-Grenzwerte. Wir betrachten nicht nur l^p-Normen für p ≥ 1 sondern auch die l^0-“Norm”.The specific field of inverse problems, where the unknown obtains apart from its spatial dimensions at least one additional dimension, is of major interest for many applications in imaging, natural sciences and medicine. Enforcing certain sparsity priors on such unknowns, which can be written as a matrix, has thus become current state of research. This thesis deals with a special type of sparsity prior, which enforces a certain structure on the unknown matrix. We present and analyze a novel regularization technique promoting so-called local sparsity by minimizing the l^{1,inf}-norm as a regularization functional in a variational approach. Furthermore, we theoretically analyze the asymptotics of spatial sparsity priors. We consider discrete sparsity promoting functionals and analyze their behavior as the discretization becomes finer. In so doing, we are able to compute some gamma-limits. We not only consider usual l^p-norms for p ≥ 1, but also analyze the asymptotics of the l^0-“norm”

Applications of aerospace technology in industry, a technology transfer profile: Fire safety

The fire safety field is considered as being composed of three parts: an industry, a technology base, and a user base. An overview of the field is presented, including a perspective on the magnitude of the national fire safety problem. Selected NASA contributions to the technology of fire safety are considered. Communication mechanisms, particularly conferences and publications, used by NASA to alert the community to new developments in the fire safety field, are reviewed. Several examples of nonaerospace applications of NASA-generated fire safety technology are also presented. Issues associated with attempts to transfer this technology from the space program to other sectors of the American economy are outlined

Applications of aerospace technology in industry, a technology transfer profile: Lubrication

Technology transfer in the lubrication field is discussed in terms of the movement of NASA-generated lubrication technology into the private sector as affected by evolving industrial requirements. An overview of the field is presented, and NASA technical contributions to lubrication technology are described. Specific examples in which these technologies have been used in the private sector are summarized

Asymptotic behaviour of multiple scattering on infinite number of parallel demi-planes

The exact solution for the scattering of electromagnetic waves on an infinite number of parallel demi-planes has been obtained by J.F. Carlson and A.E. Heins in 1947 using the Wiener-Hopf method. We analyze their solution in the semiclassical limit of small wavelength and find the asymptotic behaviour of the reflection and transmission coefficients. The results are compared with the ones obtained within the Kirchhoff approximation