Control of Underactuated Manipulators using Fuzzy Logic Based Switching Controller

This paper introduces a new concept for designing a fuzzy logic based switching controller in order to control underactuated manipulators. The proposed controller employs elemental controllers, which are designed in advance. Parameters of both antecedent and consequent parts of a fuzzy indexer are optimized by using evolutionary computation, which is performed off-line. Design parameters of the fuzzy indexer are encoded into chromosomes, i.e., the shapes of the Gaussian membership functions and corresponding switching indices of the consequent part are evolved to minimize the angular position errors. Such parameters are trained for different initial configurations of the manipulator and the common rule base is extracted. Then, these trained fuzzy rules can be brought into the online operations of underactuated manipulators. 2-DOF underactuated manipulator is taken into consideration so as to illustrate the design procedure. Computer simulation results show that the new methodology is effective in designing controllers for underactuated robot manipulators.     

Mode partition noise in 850 nm VCSELs

In high-speed 850 nm vertical cavity surface emitting lasers designed for 10 G Ethernet over 300 m of multimode fibre, mode partition noise (MPN) can impair the performance of the transmission link where the power budget is limited. A simple and practical method to evaluate the Ogawa k-factor from the power penalty is presented due to MPN using free space optical filters to vary the laser root mean square spectral width. k values that varied from 0.3 to 0.45 is reported. In addition, the previously reported improvement in power penalty is confirmed in the presence of polarisation mode selective filtering     

Effect of carbon nanotube (CNT) content on the mechanical properties of CNT-reinforced aluminium composites

The interest in carbon nanotubes (CNTs) as reinforcements for aluminium (Al) has been growing considerably. Efforts have been largely focused on investigating their contribution to the enhancement of the mechanical performance of the composites. The uniform dispersion of CNTs in the Al matrix has been identified as being critical to the pursuit of enhanced properties. Ball milling as a mechanical dispersion technique has proved its potential. In this work, we use ball milling to disperse up to 5 wt.% CNT in an Al matrix. The effect of CNT content on the mechanical properties of the composites was investigated. Cold compaction and hot extrusion were used to consolidate the ball-milled Al–CNT mixtures. Enhancements of up to 50% in tensile strength and 23% in stiffness compared to pure aluminium were observed. Some carbide formation was observed in the composite containing 5 wt.% CNT. In spite of the observed overall reinforcing effect, the large aspect ratio CNTs used in the present study were difficult to disperse at CNT wt.% greater than 2, and thus the expected improvements in mechanical properties with increase in CNT weight content were not fully realized.     

Control of three degrees-of-freedom underactuated manipulator using fuzzy based switching

A novel concept for designing a fuzzy logic-based switching controller to control underactuated manipulators is presented. The proposed controller employs elemental controllers, which are designed in advance. Parameters of both antecedent and consequent parts of a fuzzy indexer are optimized by using evolutionary computation. Design parameters of the fuzzy indexer are encoded into chromosomes, i.e., the shapes of the Gaussian membership functions and corresponding switching laws of the consequent part are evolved to minimize the angular position errors. Then, these trained fuzzy rules can be brought into the online operation of underactuated manipulators. Simulation results show that the new methodology is effective in designing controllers for underactuated robot manipulators.This work was presented, in part, at the 8th International Symposium on Artificial Life and Robotics, Oita, Japan, January 24–26, 2003     

Assembly of a functional phage PRD1 receptor depends on 11 genes of the IncP plasmid mating pair formation complex

PRD1, a lipid-containing double-stranded DNA bacteriophage, uses the mating pair formation (Mpf) complex encoded by conjugative IncP plasmids as a receptor. Functions responsible for conjugative transfer of IncP plasmids are encoded by two distinct regions, Tra1 and Tra2. Ten Tra2 region gene products (TrbB to TrbL) and one from the Tra1 region (TraF) form the Mpf complex. We carried out a mutational analysis of the PRD1 receptor complex proteins by isolating spontaneous PRD1-resistant mutants. The mutations were distributed among the trb genes in the Tra2 region and accumulated predominantly in three genes, trbC, trbE, and trbL. Three of 307 phage-resistant mutants were weakly transfer proficient. Mutations causing a phage adsorption-deficient, transfer-positive phenotype were analyzed by sequencing.     

Internal corrosion of tinplate container in canned mango (Mangifera indica) L. Nectar

Mango nectar prepared from Banganapalli variety caused less corrosion than nectar prepared from Badami or Raspuri variety. Degree of corrosion was inversely proportional to the viscosity of nectar. Among different fractions of mango pulp, only organic acid fractions were responsible for corrosion. β-carotene did not contribute to corrosion. Corrosion was more in pulp and nectar prepared from unpeeled mangoes. The peel contains gallic acid and ellagic acid of which the former acts as accelerator of corrosion. Rutin, catechin and pyracatechol acted as accelerators of corrosion but not quercetin. Leucopetunidin and leucopelargonidin have been tentatively identified in the mango peel and they did not affect the process of corrosion.     

Spark plasma extrusion (SPE) of ball-milled aluminum and carbon nanotube reinforced aluminum composite powders

Ball-milled aluminum (Al) and Al–carbon nanotube (CNT) composite (2.5 wt.% CNT loading) powders have been consolidated using a spark plasma extrusion (SPE) process. Compared with spark plasma sintering (SPS), SPE has the added advantages of allowing the production of powder-based materials of extended geometries and bulk deformation under the influence of electric current which may yield materials with unique properties. The process is discussed in this short communication together with resulting microstructures and properties for the investigated materials.     

Control of underactuated robot manipulators using switching computed torque method: GA based approach

A new concept for controlling of underactuated robot manipulators is presented by using switching computed torque method. One fundamental feature of the present approach is to use the partly stable controllers (PSCs) in order to fulfill the ultimate control objective. Dynamic model of an underactuated robot system is directly analyzed to synthesize partly stable, computed torque controllers without performing rigorous linearizations or any other deformation methods to the original nonlinear system. Here, we use genetic algorithms (GAs) to employ the optimum control action for a given time frame with the available set of elemental controllers, depending on which links or state variables are controlled, i.e. the selection of optimum switching sequence of the control actions. Two underactuated robot manipulators are taken into consideration so as to illustrate the design procedure. Simulation results show the effectiveness of the proposed method. This basic concept has led authors to explore a vast research area on controlling underactuated manipulators.     

Intelligent vision system for dynamic environments

This article describes an intelligent vision system that absorbs useful information from its environment and draws useful conclusions. This system can give instructions to locate vacant seats that are currently occupied in a theater. The extraction of useful information without viewing or exposing the inside details of an environment through an active vision system is proposed. Reasoning-based conclusions are drawn for optimum searching. The effectiveness of the proposed method is demonstrated using an experiment. This work was presented in part at the 10th International Symposium on Artificial Life and Robotics, Oita, Japan, February 4–6, 2005     

Microfluidic paper microbial fuel cell powered by Shewanella putrefaciens in IoT cloud framework

The present work demonstrates a miniaturized, easily fabricated, environment-friendly, and cost-effective Microfluidic Paper-based Microbial Fuel Cell (MPMFC) as a potential Energy Harvesting Device. The device consists of a microchannel with a reductant (Shewanella putrefaciens exoelectrogen bacterium with L.B Broth) and oxidant (aerated tap water) flowing over Carbon electrode (anode) and Silver electrode (cathode) using co-laminar flow with the self-capillary phenomenon. The electrochemical analysis like Polarization, Open Circuit Voltage (OCV) was evaluated using a potentiostat, and conductivity and sheet resistance were evaluated using a four-point probe instrument. Various bacterial studies, like growth curve study (Optical Density), volumetric concentrations, and incubation time, were carried out to find out the best suitable optimal bacterial conditions. Lastly, detailed element composition study and morphology of the surface of the electrode with biofouling was carried out using Energy Dispersive Spectroscopy (EDS) and Scanning Electron Microscopy (SEM) techniques, respectively. The portable MPMFC yields a maximum power density of 15.4 μW/cm² (1340 nA/cm²) at 390 mV over 90 μL of culture. Also, An Internet of Things (IoT)/cloud-based hardware has been developed and integrated with MPMFC platform to observe the real-time device performance leading to its long-lasting potential to operate miniaturized microelectronics sensors and portable devices.