Fabrication and control of miniature McKibben actuators

This paper investigates the development of miniature McKibben actuators. Due to their compliancy, high actuation force, and precision, these actuators are on the one hand interesting for medical applications such as prostheses and instruments for surgery and on the other hand for industrial applications such as for assembly robots. During this research, pneumatic McKibben actuators have been miniaturized to an outside diameter of 1.5 mm and a length ranging from 22 mm to 62 mm. These actuators are able to achieve forces of 6 N and strains up to about 15% at a supply pressure of 1 MPa. The maximal actuation speed of the actuators measured during this research is more than 350 mm/s. Further, positioning experiments with a laser interferometer and a PI controller revealed that these actuators are able to achieve sub-micron positioning resolution. © 2010 Published by Elsevier B.V. All rights reserved.

Characterization and control of a pneumatic microactuator with an integrated inductive position sensor

As the intelligence and the functionality of microrobots increase, there is a growing need to incorporate sensors into these robots. In order to limit the outer dimensions of these microsystems, this research investigates sensors that can be integrated efficiently into microactuators. Here, a pneumatic piston-cylinder microactuator with an integrated inductive position sensor was developed. The main advantage of pneumatic actuators is their high force and power density at microscale. The outside diameter of the actuator is 1.3 mm and the length is 15 mm. The stroke of the actuator is 12 mm, and the actuation force is 1 N at a supply pressure of 1.5 MPa. The position sensor consists of two coils wound around the cylinder of the actuator. The measurement principle is based on the change in coupling factor between the coils as the piston moves in the actuator. The sensor is extremely small since one layer of 25 μm copper wire is sufficient to achieve an accuracy of 10 μm over the total stroke. Position tests with a PI controller and a sliding mode controller showed that the actuator is able to position with an accuracy up to 30 μm. Such positioning systems offer great opportunities for all devices that need to control a large number of degrees of freedom in a restricted volume. © 2007 Elsevier B.V. All rights reserved.

Selection and control of limb posture for stability.

Impedance control can be used to stabilize the limb against both instability and unpredictable perturbations. Limb posture influences motor noise, energy usage and limb impedance as well as their interaction. Here we examine whether subjects use limb posture as part of a mechanism to regulate limb stability. Subjects performed stabilization tasks while attached to a two dimensional robotic manipulandum which generated a virtual environment. Subjects were instructed that they could perform the stabilization task anywhere in the workspace, while the chosen postures were tracked as subjects repeated the task. In order to investigate the mechanisms behind the chosen limb postures, simulations of the neuro-mechanical system were performed. The results indicate that posture selection is performed to provide energy efficiency in the presence of force variability.

Control of lunar and martian dust - Experimental insights from artificial and natural cyanobacterial and algal crusts in the desert of Inner Mongolia, China

Studies on the colonization of environmentally extreme ground surfaces were conducted in a Mars-like desert area of Inner Mongolia, People's Republic of China, with microalgae and cyanobacteria. We collected and mass-cultured cyanobacterial strains from these regions and investigated their ability to form desert crusts artificially. These crusts had the capacity to resist sand wind erosion after just 15 days of growth. Similar to the surface of some Chinese deserts, the surface of Mars is characterized by a layer of fine dust, which will challenge future human exploration activities, particularly in confined spaces that will include greenhouses and habitats. We discuss the use of such crusts for the local control of desert sands in enclosed spaces on Mars. These experiments suggest innovative new directions in the applied use of microbe-mineral interactions to advance the human exploration and settlement of space.

Comparison of evolutionary rates in the mitochondrial DNA cytochrome b gene and control region and their implications for phylogeny of the Cobitoidea (Teleostei : Cypriniformes)

It is widely accepted that mitochondrial DNA (mtDNA) control region evolves faster than protein encoding genes with few exceptions. In the present study, we sequenced the mitochondrial cytochrome b gene (cyt b) and control region (CR) and compared their rates in 93 specimens representing 67 species of loaches and some related taxa in the Cobitoidea (Order Cypriniformes). The results showed that sequence divergences of the CR were broadly higher than those of the cyt b (about 1.83 times). However, in considering only closely related species, CR sequence evolution was slower than that of cyt b gene (ratio of CR/cyt b is 0.78), a pattern that is found to be very common in Cypriniformes. Combined data of the cyt b and CR were used to estimate the phylogenetic relationship of the Cobitoidea by maximum parsimony, neighbor-joining, and Bayesian methods. With Cyprinus carpio and Danio rerio as outgroups, three analyses identified the same four lineages representing four subfamilies of loaches, with Botiinae on the basal-most clade. The phylogenctic relationship of the Cobitoidea was ((Catostomidae + Gyrinocheilidae) + (Botiinae + (Balitorinae + (Cobitinae + Nemacheilinae)))), which indicated that Sawada's Cobitidae (including Cobitinae and Botiinae) was not monophyletic. Our molecular phylogenetic analyses are in very close agreement with the phylogenetic results based on the morphological data proposed by Nalbant and Bianco, wherein these four subfamilies were elevated to the family level as Botiidae, Balitoridae, Cobitidae, and Nemacheilidae. (c) 2005 Elsevier Inc. All rights reserved.

Molecular phylogeny of three subspecies of common carp Cyprinus carpio, based on sequence analysis of cytochrome b and control region of mtDNA

The complete cytochrome b and the control region of mtDNA (about 2070 bp in total) of 10 strains belonging to three subspecies of the common carp, including three wild subspecies (the Yangtze River wild common carp - Cyprinus carpio haematopterus, Yuanjiang River wild common carp Cyprinus carpio rubrofuscus and Volga River wild common carp - Cyprinus carpio carpio) and seven domestic strains (Xingguo red carp, Russian scattered scaled mirror carp, Qingtian carp, Japanese Koi carp, purse red carp, Big-belly carp, German mirror carp) were sequenced. Phylogenetic analysis indicated that the 10 strains form three distinct clades, corresponding to C. c. haematopterus, C. c. rubrofuscus and C. c. carpio respectively. Purse red carp, an endemic domestic strain in Jiangxi province of China, showed a higher evolution rate in comparison with the other strains of C. c. haematopterus, most probably because of intensive selection and a long history of domestication. Base variation ratios among the three subspecies varied from 0.78% (between C. c. haematopterus and C. c. rubrofuscus) to 1.47%(between C. c. carpio and C. c. rubrofuscus). The topography of the phylogenetic tree and the geographic distribution of three subspecies closely resemble each other. The divergence time between C. c. carpio and the other two subspecies was estimated to be about 0.9 Myr and about 0.5 Myr between C. c. haematopterus and C. c. rubrofuscus. Based on phylogenetic analysis, C. c. rubrofuscus might have diverged from C. c. haematopterus.

Design and control of a climbing robot based on hot melt adhesion

Robust climbing in unstructured environments has been one of the long-standing challenges in robotics research. Among others, the control of large adhesion forces is still an important problem that significantly restricts the locomotion performance of climbing robots. The main contribution of this paper is to propose a novel approach to autonomous robot climbing which makes use of hot melt adhesion (HMA). The HMA material is known as an economical solution to achieve large adhesion forces, which can be varied by controlling the material temperature. For locomotion on both inclined and vertical walls, this paper investigates the basic characteristics of HMA material, and proposes a design and control of a climbing robot that uses the HMA material for attaching and detaching its body to the environment. The robot is equipped with servomotors and thermal control units to actively vary the temperature of the material, and the coordination of these components enables the robot to walk against the gravitational forces even with a relatively large body weight. A real-world platform is used to demonstrate locomotion on a vertical wall, and the experimental result shows the feasibility and overall performances of this approach. © 2013 Elsevier B.V. All rights reserved.

Design and control of a pendulum driven hopping robot

In this paper a new kind of hopping robot has been designed which uses inverse pendulum dynamics to induce bipedal hopping gaits. Its mechanical structure consists of a rigid inverted T-shape mounted on four compliant feet. An upright "T" structure is connected to this by a rotary joint. The horizontal beam of the upright "T" is connected to the vertical beam by a second rotary joint. Using this two degree of freedom mechanical structure, with simple reactive control, the robot is able to perform hopping, walking and running gaits. During walking, it is experimentally shown that the robot can move in a straight line, reverse direction and control its turning radius. The results show that such a simple but versatile robot displays stable locomotion and can be viable for practical applications on uneven terrain.

基于CPLD和ATMEGAL128的数字电源系统的设计；Design of Digital Power Control System Based on CPLD and ATMEGAL128

介绍了一种基于CPLD设计的电源控制模块,并且利用Atmegal128单片机和RTL8019S实现逻辑功能和远程控制功能。该电源系统主要用于重离子加速器注入器(SFC)中,具有很好的灵活性、可远程控制、性能稳定等特点。

A new route to control product selectivity in the oxidative dehydrogenation of cyclohexane and cyclohexene

The product selectivity can be controlled by adding acetic acid in feed over vanadium phosphate (VPO) in gas phase oxidative dehydrogenation (ODH), in which cyclohexane and cyclohexene are oxidized to cyclohexene and 1,3-cyclohexadiene (1,3-CHD), respectively, at almost 100% selectivity. This approach is also an efficient method to capture the very unstable intermediates in the mechanism study.

Construction and control of plasmid DNA network

The influences of different cations on plasmid DNA network structures on a mica substrate were investigated by atomic force microscopy (AFM). Interactions between the DNA strands and mica substrate, and between the DNA strands themselves were more strongly influenced by the complex cations (Fe(phen)(3)(2+), Ni(phen)(3)(2+), and Co(phen)(3)(3+)) than by the simple cations (Mg2+, Mn2+, Ni2+, Ca2+, Co3+). The mesh height of the plasmid DNA network was higher when the complex cations were added to DNA samples. The mesh size decreased with increasing DNA concentration and increased with decreasing DNA concentration in the same cation solution sample. Hence, plasmid DNA network height can be controlled by selecting different cations, and the mesh size can be controlled by adjusting plasmid DNA concentration.

Photoperiodic long-day control of sporophyll and hair formation in the brown alga Undaria pinnatifida

Two photoperiodic responses, the development of sporophylls and hairs, have been quantified in sporophytes of the brown alga Undaria pinnatifida. In a final experiment, the algae were cultivated in outdoor, 2000-L seawater tanks in a greenhouse for up to 12 weeks, and daylength was regulated by automatic blinds mounted on top of the tanks. Vegetative young sporophytes were treated under short-day (SD; 8 h light per day) or long-day conditions (LD; 16 h light per day), at 12 h light per day or in a night-break regime (NB; 8 h light per day, 7.5 h dark, 1 h light, 7.5 h dark). The earliest sporophyll development was observed 6, 7 or 9 weeks under LD, NB or SD conditions, respectively. After 12 weeks the sporophylls were significantly longer and wider under LD or NB conditions than in the SD regime, and only half of the experimental algae had formed sporophylls under SD conditions, but all algae under LD or NB conditions. In a foregoing 7-week culture experiment performed in 300-L indoor tanks, enhanced sporophyll formation had also been observed under LD and not under SD conditions (NB omitted). In both experiments, blade elongation rates remained high until the end of the experiments in SD, but declined during sporophyll initiation in LD, NB or at 12 h light per day. Another difference caused by photoperiod was observed in regard to the development of surface hair spots which occurred in both experiments on the blades in LD, NB or at 12 h light per day with identical densities, but were completely lacking under SD conditions. It is concluded that U. pinnatifida is a facultatative long-day plant in regard to reproduction forming vigorously sporophylls in long days, and an obligate long-day plant in regard to hair formation.