Optimal path planning for nonholonomic robotics systems via parametric optimisation

Abstract. Motivated by the path planning problem for robotic systems this paper considers nonholonomic path planning on the Euclidean group of motions SE(n) which describes a rigid bodies path in n-dimensional Euclidean space. The problem is formulated as a constrained optimal kinematic control problem where the cost function to be minimised is a quadratic function of translational and angular velocity inputs. An application of the Maximum Principle of optimal control leads to a set of Hamiltonian vector field that define the necessary conditions for optimality and consequently the optimal velocity history of the trajectory. It is illustrated that the systems are always integrable when n = 2 and in some cases when n = 3. However, if they are not integrable in the most general form of the cost function they can be rendered integrable by considering special cases. This implies that it is possible to reduce the kinematic system to a class of curves defined analytically. If the optimal motions can be expressed analytically in closed form then the path planning problem is reduced to one of parameter optimisation where the parameters are optimised to match prescribed boundary conditions.This reduction procedure is illustrated for a simple wheeled robot with a sliding constraint and a conventional slender underwater vehicle whose velocity in the lateral directions are constrained due to viscous damping

Superconducting Integrated Receiver development for TELIS

TELIS (TErahertz and submm LImb Sounder) is a cooperation between European institutes, DLR, RAL, and SRON, to build a three-channel balloon-borne heterodyne spectrometer for atmospheric research. Many atmospheric trace gases have their rotational transitions in the sub millimeter and THz range, yielding a very rich spectrum. Limb sounding results in very accurate vertical profiles. All three TELIS receivers will operate simultaneously. The 500 GHz channel is developed by RAL and will produce vertical profiles of BrO, ClO, O3, and N2O. The 1.8 THz channel is developed by DLR and will mainly target the OH radical, and will also measure HO2, HCl, NO, NO2, O3, H2O, O2, and HOCl. Finally the 550 - 650 GHz channel is developed by SRON and IREE and will measure profiles of ClO, BrO, O3, HCl, HOCl, H2O, and its 3 isotopologues, HO2, NO, N2O, HNO3, CH3Cl, and HCN. TELIS will fly on the MIPAS-B2 gondola. The two instruments together will yield the most complete set of stratospheric constituents. The qualification flight is foreseen in the winter of 2006/2007. The TELIS instrument serves as a test bed for many novel cryogenic heterodyne technology: novel low-noise cryogenic heterodyne mixer detectors, novel low-noise cryogenic intermediate-frequency amplifiers, novel back-end spectrometer. In the presentation these technologies will be discussed and compared with ‘standard’ technology as applied in the Microwave Limb Sounder (MLS) on EOS-Aura, launched in 2004. Emphasis will be on the science and technology of the channel developed by SRON. It contains a Superconducting Integrated Receiver (SIR), which combines on a 4x4 mm2 chip the low-noise Superconductor-isolator-Superconductor (SIS) mixer and its quasi-optical antenna, a superconducting phase-locked Flux Flow Oscillator (FFO) acting as Local Oscillator (LO) and SIS Harmonic Mixer (HM) for FFO phase locking. Latest test results and retrieval simulations will be presented

Autohydrolysis of Annona cherimola Mill. seeds: optimization, modeling and products characterization

Annona cherimola Mill. seeds are a residue of the industrial processing of this fruit, for which, presently, there is no industrial application. They have a considerable amount of oil, which can be converted into biodiesel, but the remaining lignocellulosic fraction still needs relevant added-value valorization routes. Inthis work,the selectivehemicelluloses removal by autohydrolysis was optimizedaiming tomaximize the yield of oligosaccharides with potential applications in food, pharmaceutical and cosmetic industries. A maximum of 10.4 g L−1 of oligosaccharides was obtained, for a severity factor of 3.6, where 74.5% of the original hemicellulose was solubilized. The process kinetics is presented, modeled (based on the Arrhenius equation) and its scale-up is dis cussed. The hydrolyzate shelf-life was evaluated and the produced oligosaccharides are stable at room temperature for, at least, 3 weeks. Furthermore, all oligosaccharides are also stable at 100 ◦C for 1 h, in pH values between 1 and 11, enabling their industrial processing, and at 37 ◦C for 3 h, in pH values between 1 and 3, thus indicating its potential classification as non-digestible oligosaccharides. The remaining cel lulose enriched solids presented an increased enzymatic digestibility (as a function of the autohydrolysis severity) that assures its efficient use in subsequent processes (e.g., bioethanol production). The upgrade route developed in this work in combination to the previously reported use of A. cherimola seed oil for biodiesel production can lead to an integrated zero-waste valorization strategy within the biorefinery framework.info:eu-repo/semantics/publishedVersio