Novel Voltage-Based Weighted Hybrid Force/Position Control for Redundant Robot Manipulators

Existing hybrid force/position control algorithms mostly explicitly contain a dynamic model. Moreover, force and position controllers will be switched frequently. To solve the above problems, a novel voltage-based weighted hybrid force/position control algorithm is proposed for redundant robot manipulators. Firstly, mapping between voltage and terminal position and orientation is established so that the designed controller can be simplified by adopting the motor current as the feedback to replace the tedious calculation of the dynamic model. Secondly, a voltage-based weighted hybrid force/position control algorithm is proposed to eliminate the selection matrix. Force and position control laws are summed directly through a weighted way to avoid the problems of space decomposition and switching. Thirdly, the stability is proven using Lyapunov stability theory, then the selection method for weighted coefficient is provided. Fourthly, comparative simulations are performed. Results show that the proposed algorithm is suitable for impedance control and hybrid force/position control and can compensate for their deficiencies. Lastly, the transport experiment in the YZ plane is conducted. Results show that position and force accuracies in the Y- and Z-axis directions are 3.489 × 10−4 and 7.313 × 10−4 m and 1.238 × 10−1 and 1.997 × 10−1 N, respectively. Accordingly, it can effectively improve the operation capability and control accuracy.

Observation of spin-space quantum transport induced by an atomic quantum point contact

Quantum transport is ubiquitous in physics. So far, quantum transport between terminals has been extensively studied in solid state systems from the fundamental point of views such as the quantized conductance to the applications to quantum devices. Recent works have demonstrated a cold-atom analog of a mesoscopic conductor by engineering a narrow conducting channel with optical potentials, which opens the door for a wealth of research of atomtronics emulating mesoscopic electronic devices and beyond. Here we realize an alternative scheme of the quantum transport experiment with ytterbium atoms in a two-orbital optical lattice system. Our system consists of a multi-component Fermi gas and a localized impurity, where the current can be created in the spin space by introducing the spin-dependent interaction with the impurity. We demonstrate a rich variety of localized-impurity-induced quantum transports, which paves the way for atomtronics exploiting spin degrees of freedom.

Low-symmetry nonlocal transport in microstructured squares of delafossite metals

Intense work studying the ballistic regime of electron transport in two-dimensional systems based on semiconductors and graphene had been thought to have established most of the key experimental facts of the field. In recent years, however, additional forms of ballistic transport have become accessible in the quasi–two-dimensional delafossite metals, whose Fermi wavelength is a factor of 100 shorter than those typically studied in the previous work and whose Fermi surfaces are nearly hexagonal in shape and therefore strongly faceted. This has some profound consequences for results obtained from the classic ballistic transport experiment of studying bend and Hall resistances in mesoscopic squares fabricated from delafossite single crystals. We observe pronounced anisotropies in bend resistances and even a Hall voltage that is strongly asymmetric in magnetic field. Although some of our observations are nonintuitive at first sight, we show that they can be understood within a nonlocal Landauer-Büttiker analysis tailored to the symmetries of the square/hexagonal geometries of our combined device/Fermi surface system. Signatures of nonlocal transport can be resolved for squares of linear dimension of nearly 100 µm, approximately a factor of 15 larger than the bulk mean free path of the crystal from which the device was fabricated.

Application of rosemary essential oil (Rosmarinus officinalis Linnaeus, 1753) for anesthesia and transport of bighead carp (Hypophthalmichthys nobilis Richardson, 1845) fingerlings

The aim of the present research is to study the efficacy of rosemary oil as an anesthetic for bighead carp (Hypophthalmichthys nobilis Richardson, 1845) and as an anesthetic used for transport of fingerlings. The fish used in the experiment have an average body weight (BW, g) of 42.13±17.90 and an average total length (TL, cm) of 16.54±2.32. Five treatments are conducted with five experimental concentrations: 0.20 ml.l-1, 0.30 ml.l-1, 0.40 ml.l-1, 0.50 ml.l-1 and 0.60 ml.l-1. For each concentration 10 fish are used or a total of 50 fish. For the transport experiment, 3 concentrations are used: 0.06 ml.l-1, 0.08 ml.l-1 and 0.10 ml.l-1. The applied stocking density is 3 fish/l. A total of 60 fish are used for each concentration or a total of 180 fish. The established results, for the first experiment, show that at concentration of 0.60 ml.l-1 the induction of anesthesia is the fastest (3.46 min). From all tested concentrations the recovery time is the shortest at the lowest concentration – 2.16 min (p≤0.001). The concentration of 0.10 ml.l-1 of rosemary oil can be used for transport of bighead carp fingerlings for a period from 1 to 2 hours. The concentration of 0.08 ml.l-1 can be applied when the duration of the transport is from 1 to 3 hours.

Nonlinear Sorption of Organic Contaminant during Two-Dimensional Transport in Saturated Sand

Multi-dimensional transport studies are necessary in order to better explain the fate of contaminants in groundwater. In this study, a two-dimensional transport experiment with organic contaminants in saturated sand was conducted to investigate the migration of the organic contaminant plume in multi-dimensional flow conditions. The transport test was conducted using toluene as a model organic contaminant in a saturated sand box under steady flow conditions. The initial plume was generated via injection at a point source. After 24 h, the plume distribution was delineated by interpolating toluene concentrations in the porewater samples. The mass centers of the toluene and the conservative tracer were almost coincident, but the size of the toluene plume was significantly reduced in longitudinal as well as transversal directions. The appropriateness of several types of sorption models were compared to describe the toluene sorption in two-dimensional transport system using numerical modeling. Among the sorption models, the Langmuir model was found to be the most appropriate to describe the sorption of toluene during two-dimensional transport. The results showed that two-dimensional experiments are better than one-dimensional column experiments in identifying the adsorption characteristics that occur during transport in saturated aquifers.

Improvement of Road Safety through Appropriate Cargo Securing Using Outliers

The article focuses on evaluating a transportation experiment that intends to improve road safety by analyzing transport shocks that significantly affect the system of securing the load, vehicle, driver, and other aspects. Within Europe, improper or insufficient securing of loads causes up to 25% of all cargo vehicle accidents. Our transport experiment consists of eight rides of a Tatra truck. The measured values of shocks (acceleration coefficients) are statistically evaluated. Three hypotheses are established for these purposes. First, it is proven that the probability distributions of the shocks values differ statistically significantly among individual rides, namely in their shape and median value. Thus further statistical analyses are performed separately for the individual rides, axes, and the accelerometer locations. These analyses prove significant exceedances of the normatively set limits given by the EN 12195-1:2010 standard, which is potentially risky. Especially for the z axis and y axis, the set 20% limit was exceeded in 75.0% and 56.3% of cases, respectively. In the case of the x axis, the established 20% limit was practically not exceeded at all. The analysis of exceeding the permitted limits (the statistical evaluation of the second and third established hypothesis) is based on boxplots that graphically describe the individual rides, as well as on the found contaminated log-normal distribution of the values of the acceleration coefficients in the individual rides. The last hypothesis regarding exceeding the double value of the permitted limit is rejected. Methods of statistical comparison are used during data analysis. The probability distribution of acceleration coefficients is modeled using a contaminated log-normal distribution.