16 research outputs found
Friction modeling, identification and compensation
No full textHigh-precision tracking requires excellent control of slow motion and positioning. Recent advances have provided dynamic friction models that represent almost all experimentally observed properties of friction. The state space formulation of these new mathematical descriptions has the property that the state derivatives are continuous functions. This enables the application of established theories for nonlinear systems. The existence of locally stable fixed points does not imply for nonlinear systems the absence of limit cycles (periodic orbits) or unstable solutions. Therefore, global properties of PI velocity and PID position control are analyzed using a passivity and Lyapunov based approach. These linear control laws are then extended by nonlinear components based on the friction model considered. The applications presented in this work are in the domains of mechatronics and machine-tools.LAContact the author at the following address: friedhelm.altpeter(_AT_)ieee.or
The CDC Healthy Aging Research Network: advancing science toward action and policy for the evidence-based health promotion movement
No full textabstract: Despite recent progress in the uptake of evidence-based health promotion (EBHP) programs within communities, many factors contribute to the need to focus on dissemination. These include the growth in the aging population, health care resource limitations, and interests in preserving community-based opportunities for maintaining independence and maximizing quality of life. For these reasons, The Prevention Research Centers’ Healthy Aging Research Network (HAN), funded by the Centers for Disease Control and Prevention’s (CDC’s) Healthy Aging Program, has as its core mission, to translate effective healthy aging interventions into sustainable community-based programs. Researchers and community-based stakeholders collaborate across HAN’s seven member center and two affiliate universities (Figure 1) to develop and implement health promotion programs for older adults at individual, organizational, environmental, and policy levels (1–3). This commentary highlights selected HAN contributions to the EBHP movement from 2001 to 2014. These contributions serve as examples of potential models for future partnership efforts to enhance implementation, dissemination, and sustainability of EBHP programs.View the article as published at http://journal.frontiersin.org/article/10.3389/fpubh.2014.00261/ful
Single State Elasto-Plastic Friction Models
No full textFor control applications involving small displacements and velocities, friction modeling and compensation can be very important. In particular, the modeling of presliding displacement (motion prior to fully developed slip) can play a pivotal role. In this paper, it is shown that existing single-state friction models exhibit a nonphysical drift phenomenon which results from modeling presliding as a combination of elastic and plastic displacement. A new class of single state models is defined in which presliding is elasto-plastic: under loading, frictional displacement is first purely elastic and then transitions to plastic. The new model class is demonstrated to substantially reduce drift while preserving the favorable properties of existing models (e.g., dissipativity) and to provide a comparable match to experimental data
Motion stabilization in the presence of friction and backlash: a hybrid system approach
No full textIn this paper a hybrid system approach is considered to deal with backlash and
friction induced nonlinearities in mechanical control systems. To describe the low velocity
frictional behaviour a linearized friction model is proposed. The novelty of this study is that
based on the introduced friction model, the stability theorems developed for hybrid systems can
directly be applied for controller design of mechanical systems in the presence of Stribeck friction
and backlash. During the controller design it is assumed that the size of the backlash gap is
unknown and the load side position and velocity cannot be measured. For motion control an LQ
controller is applied. A condition is formulated for the control law parameters to guarantee the
asymptotic stability of the control system. Simulation measurements were performed to confirm
the theoretical results
Microbiome differences in sugarcane and metabolically engineered oilcane accessions and their implications for bioenergy production
No full textOilcane is a metabolically engineered sugarcane (Saccharum spp. hybrid) that hyper-accumulates lipids in its vegetable biomass to provide an advanced feedstock for biodiesel production. The potential impact of hyper-accumulation of lipids in vegetable biomass on microbiomes and the consequences of altered microbiomes on plant growth and lipid accumulation have not been explored so far. Here, we explore differences in the microbiome structure of different oilcane accessions and non-modified sugarcane. 16S SSU rRNA and ITS rRNA amplicon sequencing were performed to compare the characteristics of the microbiome structure from different plant compartments (leaf, stem, root, rhizosphere, and bulk soil) of four greenhouse-grown oilcane accessions and non-modified sugarcane. Significant differences were only observed in the bacterial microbiomes. In leaf and stem microbiomes, more than 90% of the entire microbiome of non-modified sugarcane and oilcane was dominated by similar core taxa. Taxa associated with Proteobacteria led to differences in the non-modified sugarcane and oilcane microbiome structure. While differences were observed between multiple accessions, accession 1566 was notable in that it was consistently observed to differ in its microbial membership than other accessions and had the lowest abundance of taxa associated with plant-growth-promoting bacteria. Accession 1566 is also unique among oilcane accessions in that it has the highest constitutive expression of the WRI1 transgene. The WRI1 transcription factor is known to contribute to significant changes in the global gene expression profile, impacting plant fatty acid biosynthesis and photomorphogenesis. This study reveals for the first time that genetically modified oilcanes associate with distinct microbiomes. Our findings suggest potential relationships between core taxa, biomass yield, and TAG in oilcane accessions and support further research on the relationship between plant genotypes and their microbiomes.This article is published as Yang, Jihoon, Thanwalee Sooksa-Nguan, Baskaran Kannan, Sofia Cano-Alfanar, Hui Liu, Angela Kent, John Shanklin, Fredy Altpeter, and Adina Howe. "Microbiome differences in sugarcane and metabolically engineered oilcane accessions and their implications for bioenergy production." Biotechnology for Biofuels and Bioproducts 16, no. 1 (2023): 1-14.
DOI: 10.1186/s13068-023-02302-6.
Copyright 2023 The Author(s).
Attribution 4.0 International (CC BY 4.0).
Posted with permission
