The paper addresses the problem of autonomous underwater vehicle (AUV) modeling and parameter estimation as a means to predict the expected dynamic performance of underwater vehicles and thus provide solid guidelines ...
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The paper addresses the problem of autonomous underwater vehicle (AUV) modeling and parameter estimation as a means to predict the expected dynamic performance of underwater vehicles and thus provide solid guidelines during their design phase. The use of analytical and semi-empirical (ASE) methods to predict the hydrodynamic derivatives of a large class of AUVs with conventional, streamlined bodies is discussed. An application is made to the estimation of the hydrodynamic derivatives of the MAYA AUV, an autonomous vehicle that is being developed under a joint Indian-Portuguese project. The estimates are used to predict the behavior of the vehicle in the vertical plane and to assess the impact of stern plane size on its expected performance.
This paper deals with the design of complex dynamic model of quadruped walking mobil robot. There is described the method of building of the numerical computational model and its simulating. Complex model consist of s...
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This paper deals with the design of complex dynamic model of quadruped walking mobil robot. There is described the method of building of the numerical computational model and its simulating. Complex model consist of submodels of robotic mechanism, DC motor, gearbox model and thermal model of electrical motor. Control algorithms are also considered in model. In the paper is also discussed application of computational model directly for control of robot and also as a data generator for global and local approximation method, mainly artificial neural networks.
This project is concerned with computational simulation of air flow in the individual parts of a synchronous machine. FLUENT6 software was used for computational modeling. A model of a machine fan was built, which was...
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This project is concerned with computational simulation of air flow in the individual parts of a synchronous machine. FLUENT6 software was used for computational modeling. A model of a machine fan was built, which was used for calculation of ventilation characteristics. Ventilation characteristics were calculated for three ventilator diameters. The aim was to find the operating point for each fan. A model of the asymmetrical inlet to the machine and the distribution of airflow to the stator and rotor was built, which consisted of inlet to machine, axial stator and rotor channels and ten radial channels in the stator packet. A parametric computational model was developed with three main parameters - size of axial stator and rotor channels and size of radial channels. The results of the computer simulation were compared with experimental measurements, which were accomplished on the synchronous generator using a Pitot tube and digital micro manometer.
The atomic force microscope (AFM) system has evolved into a useful tool for direct measurements of intermolecular forces with atomic-resolution characterization that can be employed in a broad spectrum of applications...
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The atomic force microscope (AFM) system has evolved into a useful tool for direct measurements of intermolecular forces with atomic-resolution characterization that can be employed in a broad spectrum of applications such as electronics, semi-conductors, materials, manufacturing, polymers, biological analysis, and biomaterials. The non-contact AFM offers unique advantages over other contemporary scanning probe techniques such as contact AFM and scanning tunneling microscopy. Current AFM imaging techniques are often based on a lumped-parameters model and ordinary differential equation (ODE) representation of the micro-cantilevers coupled with an ad-hoc method for atomic interaction force estimation (especially in non-contact mode). Since the magnitude of the interaction force lies within the range of nano-Newtons to pica-Newtons, precise estimation of the atomic force is crucial for accurate topographical imaging. In contrast to the previously utilized lumped modeling methods, this paper aims at improving current AFM measurement technique through developing a general distributed-parameters base modeling approach that reveals greater insight into the fundamental characteristics of the microcantilever-sample interaction. For this, the governing equations of motion are derived in the global coordinates via the Hamilton's Extended Principle. By properly selecting a set of general coordinates, the resulting non-homogenous boundary value problem is then converted to a homogenous one, and hence, analytically solvable. The AFM controller can then be designed based on the original infinite dimensional distributed-parameters system which, in turn, removes some of the disadvantages associated with the truncated-model base controllers such as control spillovers, residual oscillations and increased order of the control. Numerical simulations are provided to support these claims.
A translational cantilevered Euler-Bernoulli beam with tip mass dynamics at its free end is used to study the effect of several damping mechanisms on the stabilization of the beam displacement. Specifically, a Lyapuno...
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A translational cantilevered Euler-Bernoulli beam with tip mass dynamics at its free end is used to study the effect of several damping mechanisms on the stabilization of the beam displacement. Specifically, a Lyapunov-based controller utilizing a partial differential equation model of the translational beam is developed to exponentially stabilize the beam displacement while the beam support is regulated to a desired set-point position. Depending on the composition of the tip mass dynamics assumption (i.e. body-mass, point-mass, or massless), it is shown that proper combination of different damping mechanisms (i.e., strain-rate, structural, or viscous damping) guarantees exponential stability of the beam displacement. This novel Lyapunov-based approach, which is based on the energy dissipation mechanism in the beam, brings new dimensions to the stabilization problem of translational beams with tip mass dynamics. The stability analysis utilizes relatively simple mathematical tools to illustrate the exponential and asymptotic stability results. The numerical results are presented to show the effectiveness of the controller.
A switch-shunt stiffness method for vibration attenuation of flexible beams undergoing translational base motion with a laminated piezoelectric patch attachment is presented. The piezoelectric actuator, bonded on the ...
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A switch-shunt stiffness method for vibration attenuation of flexible beams undergoing translational base motion with a laminated piezoelectric patch attachment is presented. The piezoelectric actuator, bonded on the top surface of the flexible beam, is switched between open and short circuit configurations. This results in a variable equivalent stiffness which, in turn, can remove energy from the overall system by directly affecting the stored potential energy in the flexible beam. Initially, a single degree of freedom system is considered for validation of the switched stiffness method. The method is then applied to a flexible beam with moving base, representing a Cartesian-type one-link robot manipulator. Simulation results demonstrate favorable vibration attenuation in both cases;the single degree of freedom oscillator and the cantilever flexible beam. Several variations of the switching mechanisms are explored in an effort to achieve optimal vibration characteristics. Experimental testing is currently under investigation for validation of the simulation results presented here.
This paper Proportional-Integra1 tracking problem of presents the development of a sliding mode controller for robot manitsulators. A robust sliding mode controller is deriveh so that the actual trajectory tracks the ...
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With the widespread application of mechatronic concepts to dynamic systems in recent years, interest has been focused on the substitution of piezoelectric ceramic (PZT) fibers for conventional electrical motors and ac...
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With the widespread application of mechatronic concepts to dynamic systems in recent years, interest has been focused on the substitution of piezoelectric ceramic (PZT) fibers for conventional electrical motors and actuators. Piezoelectricity effects in elongated and poled PVDF as well as the ferroelectric properties have been observed for a number of decades. Although PVDF copolymers have found diverse uses in industrial applications, such as ultrasonic transducers and vibration damping, their low stiffness and electromechanical coupling coefficients have limited their use. To improve the performance and capability of future automated systems, the development of next generation actuator subsystems utilizing nanotubes is presented. Specifically, the actuation mechanism associated with carbon and boron nitride (BN) nanotube-based actuators, and ultimately manufacturing macro-level actuators compromised of functional nanotubes are discussed in this paper. This exciting area of research is motivated by discovery of bond extension in charged nanotubes. Termed "artificial muscles", such actuators provide wonderful opportunities in MEMS due to their incredible strength and stiffness, with relatively low (∼10 V) driving voltage. The proposed nanotube-based actuator configuration could be utilized for many applications such as miniature motors, vibration control of flexible structures, micro scale robotic systems, biomedical (drug delivery and tumor removal), and power generation applications.
This paper presents the development of a Proportional-Integral sliding mode controller for tracking problem of robot manipulators. A robust sliding mode controller is derived so that the actual trajectory tracks the d...
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This paper presents the development of a Proportional-Integral sliding mode controller for tracking problem of robot manipulators. A robust sliding mode controller is derived so that the actual trajectory tracks the desired trajectory as closely as possible despite the highly non-linear and coupled dynamics. The proposed controller is designed using the centralized and decentralized approaches. The Proportional-Integral sliding mode is chosen to ensure the stability of overall dynamics during the entire period i.e. the reaching phase and the sliding phase. Application to a two-link planar robot manipulator is considered.
The atomic force microscope (AFM) system has evolved into a useful tool for direct measurements of microstructural parameters and intermolecular forces at nanoscale level with atomic-resolution characterization. Typic...
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The atomic force microscope (AFM) system has evolved into a useful tool for direct measurements of microstructural parameters and intermolecular forces at nanoscale level with atomic-resolution characterization. Typically, these micro-cantilever systems are operated in three open-loop modes;non-contact mode, contact mode, and tapping mode. In order to probe electric, magnetic, and/or atomic forces of a selected sample, the non-contact mode is utilized by moving the cantilever slightly away from the sample surface and oscillating the cantilever at or near its natural resonance frequency. Alternatively, the contact mode acquires sample attributes by monitoring interaction forces while the cantilever tip remains in contact with the target sample. The tapping mode of operation combines qualities of both the contact and non-contact modes by gleaning sample data and oscillating the cantilever tip at or near its natural resonance frequency while allowing the cantilever tip to impact the target sample for a minimal amount of time. Recent research on AFM systems has focused on many fabrication and manufacturing processes at molecular levels due to its tremendous surface microscopic capabilities. This paper provides a review of such recent developments in AFM imaging systems with emphasis on operational modes, microcantilever dynamic modeling and control. Due to the important contributions of AFM systems to manufacturing, this paper also provides a comprehensive review of recent applications of different AFM systems in these important areas.
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