A solution to SLAM problems by simultaneous estimation of kinematic parameters including sensor mounting offset with an augmented UKF

Accurate localization is required for autonomous robots to navigate in cluttered environments safely. Therefore, Extended Kalman Filter (EKF) and Unscented Kalman Filter (UKF), which incorporate probabilistic concepts as localization methods, have been researched up to now. It should be noted, however, that the errors of kinematic parameters such as wheel diameter, tread, and mounting sensor offset are not enough considered in conventional works. We propose an Augmented UKF-SLAM (AUKF-SLAM), which is an extension of the UKF-SLAM and can estimate the kinematic parameters including a sensor mounting offset together with the localization and mapping. The UKF-SLAM and the AUKF-SLAM are compared through some simulations to show that the proposed AUKF-SLAM is more accurate than the UKF-SLAM. Furthermore, localization experiments with only odometry are conducted using a real robot. The experimental results show to demonstrate that the localization using kinematic parameters estimated by the AUKF-SLAM is more accurate than that using values measured by hand in advance. Through some experimental verifications in an elevator hall, cluttered rooms, and a long distance corridor, it is confirmed that the proposed AUKF-SLAM which simultaneously estimates the effective kinematic parameters largely contributes to the total accuracy improvement of SLAM.     

Reinforcement of polypropylene by cellulose microfibers modified with polydopamine and octadecylamine

Cellulose microfibers (CMFs) having surfaces modified with polydopamine (PDPA) and octadecylamine (ODA) were prepared, and their reinforcing abilities for polypropylene (PP) were investigated. The PDPA coating was made via self-polymerization of dopamine (P-CMF), and subsequent alkylation was conducted by the reaction with ODA (OP-CMF). The modified CMFs exhibited improved dispersibility in the PP matrix due to the reduced hydrophilicity. The OP-CMF/PP composite prepared by batch mixing had a higher tensile modulus compared to that for the pure PP and composites with unmodified CMFs. However, excess alkylation lowered the tensile modulus, and the presence of an optimal degree of alkylation was demonstrated. The CMF/PP-IM composites fabricated by injection molding exhibited improved tensile properties compared to those prepared by batch mixing. Both the tensile modulus and yield stress were increased by increasing the CMF content and improved by the surface modification of the CMFs.     

Direct conversion mechanism of fluorine-GIC into poly(carbon monofluoride), (CF)n

The reaction mechanisms of a stage-1 fluorine-graphite intercalation compound (GIC), C_2.5F, with 0.10 MPa of fluorine gas have been studied at 573-773 K. The original stage-1 structure of C_2.5F with semi-ionic C-F bonds and planar sp² carbon sheets is maintained in most part of the compound after the reaction at 573 K, although a large number of covalent C-F bonds are formed on the surface. This compound is partially or completely converted to poly(carbon monofluoride), (CF)_n, with covalent C-F bonds and puckered sp³ carbon sheets at 673 or 773 K, respectively. Single-phase (CF)_n obtained at 773 K possesses remarkably small BET specific surface area, 61 m²/g carbon, almost unchanged from the value of the precursor C_2.5F (69 m²/g carbon). In this reaction, the accommodation of fluorine atoms supplied from the atmosphere into the galleries of C_2.5F is facilitated by the rearrangement of originally intercalated fluorine atoms in the GIC, forming (CF)_n with fewer defects compared to those by the conventional direct fluorination of graphite.     

Excess micromotion compensation of trapped ions in a linear Paul trap for trace isotope analysis

Excess micromotion of trapped calcium ions was detected and compensated in our linear Paul trap apparatus for trace isotope analysis. The micromotion was detected by Charge-coupled device (CCD). camera and radio frequency (rf) correlation method. We found that 230 and 2280 V of compensation voltages were needed for x- and y-axis compensation in our apparatus, respectively. The z-axis micromotion was confirmed by the experiment and its cause was investigated by finding a shape of z-axis confinement field. The confinement field was indeed distorted in our apparatus and it gave rise to the trapped ion to shift from potential center. And the micromotion of r-direction was transferred to the z-axis by the distorted confinement field. The z-axis micromotion was suppressed by increasing cap voltage of trap.     

Preparation of oriented gold plate/cellulose nanofiber composite films by using TEMPO-oxidized cellulose nanofiber as a reducing agent

Microsystem Technologies - TEMPO-oxidized cellulose nanofiber (TOCN) has been drawing much attention as a useful material for preparation of transparent and stiff films or substrates. In this work,...     

Survey of actual viewing conditions at home and appropriate luminance of LCD‐TV screens

Abstract— To understand actual viewing conditions at home is important for TV design. And the preferred luminance level of LCD TVs under actual viewing conditions is also important in order to obtain both good picture quality and low power consumption. The actual viewing conditions of households and the preferred luminance levels was investigated. In a field test of 83 households, the display luminance, screen illuminance, and viewing locations were measured on site. In laboratory experiments, young and elderly subjects adjusted the luminance of an LCD‐TV screen to their preferred levels under different screen illuminance levels, angular screen sizes, and average luminance levels (ALL) of the images. As a result, two equations, which represent the preferred luminance level of LCD‐TV screens corresponding to different viewing conditions for young and elderly subjects were obtained. When the ALL of the images was 25% and the screen illuminance and angular screen size were set at 100 lx and 20°, respectively, the preferred luminance was 1 60 cd/m² for the young subjects and 248 cd/m² for the elderly subjects. By using the setting of the preferred luminance of an LCD TV under actual viewing conditions, it is possible to conserve energy consumption.     

Study on effects of solar radiation and rain on shrinkage, shrinkage cracking and creep of concrete

In this paper, the effects of actual environmental actions on shrinkage, creep and shrinkage cracking of concrete are studied comprehensively. Prismatic specimens of plain concrete were exposed to three sets of artificial outdoor conditions with or without solar radiation and rain to examine the shrinkage. For the purpose of studying shrinkage cracking behavior, prismatic concrete specimens with reinforcing steel were also subjected to the above conditions at the same time. The shrinkage behavior is described focusing on the effects of solar radiation and rain based on the moisture loss. The significant environment actions to induce shrinkage cracks are investigated from viewpoints of the amount of the shrinkage and the tensile strength. Finally, specific compressive creep behavior according to solar radiation and rainfall is discussed. It is found that rain can greatly inhibit the progresses of concrete shrinkage and creep while solar radiation is likely to promote shrinkage cracking and creep.     

Practical Continuous‐Flow Controlled/Living Anionic Polymerization

A continuous‐flow reaction system was developed, allowing flow conditions of the entire system to be maintained at a predetermined constant level, which is one of the most significant factors for successful industrial application. Controlled/living anionic polymerization was selected as a model reaction since the characteristics of its polymer products, molecular weights, and molecular weight distributions are highly susceptible to changes in the relative flow rates of a monomer and initiator solutions. In flow microreactors, controlled/living anionic polymerization of styrene in tetrahydrofuran (THF)/hexane initiated by THF‐diluted n‐butyllithium (n‐BuLi) was examined. Poly(styrenes) of larger molecule sizes such as Mn > 15 000 were successfully synthesized. After continuous operation for four hours, ca. 0.5 kg of the polymer was readily produced with narrow molecular weight distribution, demonstrating the applicability of this continuous‐flow system for controlled/living anionic polymerization on considerably large scale with a view to its industrial usage in the future.     

Synergetic improvement strategy on thermoelectric performance of CuAlO2 compacts

We fabricated Sr and Ca-doped CuAlO₂ compacts from the mixed powder of CuO, Cu₂O, Al₂O₃, and SrO or CaO by multi-pass hot pressing followed by spark plasma sintering (SPS). The XRD results showed the reaction of CuO, Cu₂O and Al₂O₃ was rather complete and only CuAlO₂ single phase was formed when the additive amount of SrO or CaO was appropriate. Multi-pass hot pressing increased the relative density and the usage of plate-like Al₂O₃ as reaction raw material enhanced the orientation degree. In spite of performance improvement conflicts through elemental doping, density increase and orientation improvement, the measurement on the thermoelectric performance indicated that the electrical resistivity, Seebeck coefficient, power factor, dimensionless figure of merit (ZT) were improved to varying degrees through the synergetic action of elemental doping, density increase, and orientation control. The highest power factor and ZT of the Ca-doped CuAlO₂ compacts reached 1.54?×?10^?4 W?m^?1 K^?2 and 0.015 at 973?K, respectively. The thermoelectric performance was higher than those of CuAlO₂ at the same temperature in published work before.