A new hand finger movements’ classification system based on bicoherence analysis of two-channel surface EMG signals

Neural Computing and Applications - In this study, two-channel surface electromyography (sEMG) signals were used to classify hand finger movements. Bicoherence analysis of the sEMG signal recorded...     

Person tracking and reidentification: Introducing Panoramic Appearance Map (PAM) for feature representation

This paper develops a concept of Panoramic Appearance Map (PAM) for performing person reidentification in a multi-camera setup. Each person is tracked in multiple cameras and the position on the floor plan is determined using triangulation. Using the geometry of the cameras and the person location, a panoramic map centered at the person’s location is created with the horizontal axis representing the azimuth angle and vertical axis representing the height. Each pixel in the map image gets color information from the cameras which can observe it. The maps between different tracks are compared using a distance measure based on weighted SSD in order to select the best match. Temporalintegration by registering multiple maps over the tracking period improves the matching performance. Experimental results of matching persons between two camera sets show the effectiveness of the approach. This work has been sponsored by the Technical Support Working Group (TSWG) of US Department of Defence (DoD).     

Adaptive motion/force control of uncertain nonholonomic mobile manipulator with estimation of unknown external force

This paper describes a stable adaptive motion/force control of uncertain nonholonomic mobile manipulator with the consideration of external force. As it is well known, unexpected external force makes the motion of the system unstable since there are no fixed points in the stationary coordinate. Here, a novel adaptive control scheme is utilized to estimate and compensate the unknown external force exerted to the end-effector even if the parameters of the system are uncertain. The important advantages of this approach are to achieve estimation without the requirement of force-sensing feedback and the knowledge of the system dynamic model. The update laws for the force and the parameters are derived from a Lyapunov function to guarantee the control system stability. Furthermore, a unified operational space dynamic formulation is presented to solve the problem of redundancy. As a result, the desired end-effector and platform trajectories are simultaneously tracked with a perfect coordination between the two subsystems. Therefore, the proposed controller proves that it can not only guarantee the stability, but also the tracking performance of the system in the task space. The effectiveness of the proposed algorithm is evaluated through extensive simulations and they demonstrate the stability, tracking trajectories and feasibility in estimating the external force and the dynamic uncertainties.     

Influence of Growth Rate on Eutectic Spacing,Microhardness, and Ultimate Tensile Strength in the Directionally Solidified Al-Cu-Ni Eutectic Alloy

Metallurgical and Materials Transactions B - In this work, the mechanical properties of the Al-Cu-Ni eutectic alloy, Al-32.5 wt pct Cu-1 wt pct Ni, were investigated in terms of...     

Measurements of Thermal Conductivity Variations with Temperature for the Organic Analog of the Nonmetal–Nonmetal System: Urea–4-Bromo-2-Nitroaniline

Thermal conductivity variations with temperature for solid phases in the Urea (U)–[X] mol pct 4-bromo-2-nitroaniline (BNA) system (X = 0, 2, 45, 89.9, and 100) were measured using the radial heat flow method. From graphs of thermal conductivity variations with temperature, the thermal conductivities of the solid phases at their melting temperature and temperature coefficients for the U–[X] mol pct BNA system (X  =  0, 2, 45, 89.9, and 100) were found to be 0.26, 0.55, 0.46, 0.38, and 0.23 W/Km and 0.007781, 0.005552, 0.002058, 0.002188, and 0.002811 K^?1, respectively. The ratios of thermal conductivity of the liquid phase to thermal conductivity of the solid phase in the U–[X] mol pct BNA system (X  =  0, 2, 45, 89.9, and 100) were also measured to be 0.30, 0.44, 0.46, 0.49, and 0.51, respectively, with a Bridgman-type directional solidification apparatus at their melting temperature.     

Solid–Liquid Interfacial Energy of Solid Neopentylglycol Solution in Equilibrium with Neopentylglycol–Aminomethylpropanediol Eutectic Liquid

The grain boundary groove shapes for solid neopentylglycol solution (NPG-40 mol pct AMPD) in equilibrium with the neopentylglycol (NPG)–aminomethylpropanediol (AMPD) eutectic liquid (NPG-42.2 mol pct AMPD) have been directly observed using a horizontal linear temperature gradient apparatus. From the observed grain boundary groove shapes, the Gibbs–Thomson coefficient (Г) and solid–liquid interfacial energy (σ _SL) of solid NPG solution have been determined to be (7.4 ± 0.7) × 10^?8 K m and (6.4 ± 1.0) × 10^?3 J m^?2, respectively. The grain boundary energy of solid NPG solution has been determined to be (12.5 ± 1.0) × 10^?3 J m^?2 from the observed grain boundary groove shapes. The ratio of thermal conductivity of equilibrated eutectic liquid to thermal conductivity of solid NPG solution has also been determined to be 0.48.     

Productivity and costs in the course of timber transportation with the Koller K300 cable system in Turkey

This study was carried out on very steep and difficult terrain. Whole trees were logged uphill to the forest road by a Koller K300 cable crane. Investigations were carried out by time studies for which the repetition time measurement method was selected. Through time studies, the productivity and cost of the Koller cable system were evaluated.     

Ensuring functional reliability of molded micro components

Microsystems technology is an emerging technology that is used in ever more technical systems, such as inkjet nozzles or accelerometers. 3D micromechanical structures became feasible by miniaturizing macromechanical elements. One big challenge in downsizing mechanical elements is to adapt conventional manufacturing technologies to the conditions of microtechnology. Integrated design and production processes must be suited to the new requirements, in-depth knowledge of production technology is required to design micromechanical components. Since 2000, the Collaborative Research Center 499 “Design, Production and Quality Assurance of Molded Microcomponents made of Metallic and Ceramic Materials” has been focusing on a continuous and stable process chain for molded micro components (Albers et al. 2005, Microsyst Technol). The aim of prior funding periods was to develop the knowledge about how components, such as gearwheels, and systems, such as micro gears, can be designed. Present research is focused on how to design functional elements, i.e. shaft-hub joints to transmit torque. This paper will introduce an approach that generates know-how via testing several plain bearings and shaft-hub joints in order to derive the necessary know-how to develop simulation tools later on.     

On trajectory tracking control for nonholonomic mobile manipulators with dynamic uncertainties and external torque disturbances

This paper studies the trajectory tracking control problem of mobile manipulators subject to nonholonomic constraints, operating in task space, with the presence of external torque disturbances and dynamic uncertainties. The proposed controls are robust to external torque disturbances and can overcome the effects of the unknown dynamic parameters. The stability of the closed-loop system and the asymptotic convergences of tracking errors are proved using Lyapunov synthesis. The proposed control strategies have been designed to drive the system motion converges to the desired manifold and, at the same time, guarantees the boundedness of all the closed-loop signals. Simulation results validate that the system trajectory converge to the desired one.