Dynamics, Robotics and Control

Dynamics, Robotics and Control

Research in dynamics and control focuses on pattern formation and investigation of the dynamics of a range of complex systems. These systems include unmanned aerial vehicles, spacecraft, unmanned underwater vehicles, robotic systems, flow control, and smart indoor environments. Theoretical, numerical and experimental investigations are aimed at modeling the dynamics to understand basic underlying phenomena, and using these models for estimation and control of such systems.

Dynamics

Dynamics is an old science that describes the time evolution of the states of a system, which could be a mechanical or aerospace system. A good understanding of the dynamics of a system helps to identify phenomena and create mathematical models that capture these phenomena. The dynamics may be represented by ordinary or partial differential equations with time as an independent variable, and these differential equations may be linear or nonlinear. Study of phenomena like critical points, equilibria and relative equilibria, limit cycles, stability, bifurcation and chaos help in understanding the global behavior of a system over time, when system states, parameters and initial conditions change. Mathematical models that describe these phenomena could be used, in turn, for feedback control of these systems.

Control Systems

A control system is usually understood to mean a feedback control system, where information on some or all state(s) of a dynamical system is used to control the system to a desired operating point or trajectory. Describing system properties, including stability, controllability and observability, are important aspects of control theory and practice. Controllability is a system property that defines whether the system can be controlled from a given state to another state. Observability is a system property that defines whether the system states can be reconstructed from observed (measured) variables. Both these properties are defined, in general, for a local neighborhood of a given state of a nonlinear system. For linear systems and in special cases for certain nonlinear systems, these properties can be defined globally over the entire state space. However, for the vast majority of mechanical and aerospace systems, these notions can only be defined globally

Nonlinear control and nonlinear estimation, using the framework of geometric mechanics, is an active research topic in this area. This framework describes the dynamics of maneuverable robotic systems and unmanned vehicles without using local representations of the motion. Recent studies have looked at design of continuous-time nonlinear control and estimation schemes that have guaranteed stability properties and are robust to measurement noise and disturbances. These continuous-time schemes are then discretized for computer implementation, such that these stability and robustness properties are retained in discrete time.

Applied Control

  • Unmanned and robotic systems
  • Spacecraft dynamics and control
  • Noise control in high speed flows
  • Intelligent indoor environments – control of parameters aimed at realizing human comfort

Nanotechnology

In nanoscale science and engineering research one seeks novel and robust ways for the manipulation of biological or synthetic matter with at least one of the dimensions smaller than typically 100 nm. Examples include synthesis of novel materials via molecular self-assembly and fabrication of devices by nanolithography. Technological impact of such research ranges from medicine and sustainable production of chemicals/fuels to THz information processing and renewable energy harvesting. At Syracuse University, BMCE faculty research in this area focuses on the synthesis and characterization of nanostructured materials for biomedical, optoelectronic, catalytic and renewable energy harvesting applications, developing computational and experimental approaches to explore the mechanisms of molecular self-assembly and investigations of the environmental impacts of nanotechnology. Specific examples of current research projects are:

Nanostructured Interfaces

Scanning electron microscope (SEM) images of nanoscale patterns generated by pulsed laser melting of a 4 nm thick Co film deposited on a glass substrate via e-beam evaporation. The patterns result from hydrodynamic instabilities in the molten metal film. A variety of metals can be patterned by using this technique. Such nanostructured interfaces have unique optical and magnetic properties which can be tuned by their size, shape and length scale (collaboration with Dr. Kalyanaraman, University of Tennessee, Knoxville).

For further details, see:

  1. Trice, C. Favazza, D.G. Thomas, H.G. Garcia, R. Kalyanaraman, R. Sureshkumar, A novel self-organization mechanism in ultrathin liquid films: theory and experiment, Phys. Rev. Lett., 101, 017802 (2008)

Environmental Impact of Nano ZnO

ZnO NPs (20 nm diameter) in presence of bacterial cells: in aqueous solution (C) where the nanoparticles agglomerate and do not impact the cell wall appreciably and after electrospray (D) where the individual NPs attack the cell. The latter scenario would correspond to aerosol mode of exposure (collaboration with Dr. Yinjie Tang, Washington University in Saint Louis).

ZnO nanoparticles (NPs) are widely used as pigments, semiconductors, sunscreens, and food additives. To determine the potential eco-toxicity of ZnO NPs, researchers have investigated their toxicological properties, fate, and transport in the environment. Injurious effects of ZnO NPs upon a variety of organisms in aquatic environments have recently been reported. Several studies indicated that the dissolved Zn2+ from ZnO NPs in the aquatic environment causes these eco-toxicities. Other studies have shown that metal NPs may be more toxic than either their ionic forms or their parent compounds. NPs tend to aggregate in aquatic environments to form micrometer-sized particles, and this state of dispersion reduces the influences of particle size, particle shape, and surface charge on the NPs’ eco-toxicity: see figure below. Further, many microorganisms such as Shewanella oneidensis MR-1 and Escherichia coli secrete extracellular polymeric substrates (EPS) which can inhibit the binding of NPs onto the cell. The focus is the study is to understand the effect of different modes of exposure (aqueous medium, aerosol) on the eco-toxicity of NPs.

For more details, see:

  1. Wu, Y. Wang, Y. Lee, A. Horst, Z. Wang, D. Chen, R. Sureshkumar & Y. Tang, Comparative Eco-toxicities of Nano-ZnO Particles under Aquatic and Aerosol Exposure Modes, Environmental Science and Technology

Nanotoxicity

Concerns of nanotoxicity caused by nanoparticle-cell interactions are becoming increasingly important as the applications of nanoparticles continue to grow. There is significant interest in correlating the properties of nanoparticles such as size, shape, surface charge, and chemical functionality to their toxicity to biological systems. A recent study by Nangia and Sureshkumar showed that simple shape and charge modifications of chemically functionalized gold nanoparticles can cause tremendous change in their uptake by the cell. Using high-performance molecular dynamics simulations, interactions of charged nanoparticles of six distinct shapes (cone, cube, rod, rice, pyramid, and sphere) were performed with a model cell membrane. The results indicated that depending on nanoparticle shape and surface functionalization charge, the translocation rates can span over 60 orders of magnitude.

Figure: The translocation of nanoparticles is highly shape-dependent with rice-shaped particle that penetrates on microsecond time-scale, versus other shapes like sphere, pyramid, cone, rod, and cube that occur on much longer scales.

Faculty