Models are derived for the dynamics of a one link flexible manipulator in contact with a stiff su... more Models are derived for the dynamics of a one link flexible manipulator in contact with a stiff surface, and unconstrained. A means of accomodating the transition between contact and non contact is presented. The effect of joint stiction on tip force is demonstrated through simulation and experiment A combination of tip force (noncollocated) and hub velocity (col1ocated) feedback is implemented to address the difficulties presented by what is an inherently nonminimum phase system. Feedforward and integral control scheme are compared with respect to reduction of steady state error in the face of friction and other uncertainties.
The International Journal of Advanced Manufacturing Technology, 2016
One of the major issues related to parallel kinematic machine tools (PKMs) is their structural de... more One of the major issues related to parallel kinematic machine tools (PKMs) is their structural dependency on their configuration. In this paper, the machine configuration effect on its stability is investigated for the case of a Hexaglide machine tool. An FEM model of the Hexaglide machine tool is developed. The frequency response function (FRF) at the tool tip is obtained by a modal analysis. The numerical results are validated through comparison with those of an experimental modal test. The pose dependency of the PKM stability over its workspace is investigated. It is shown that the machine stability over the workspace is dependent on the spindle/tool/ holder system characteristic. For spindle/tool/holder systems with higher stiffness and lower natural frequency, the stability variation is higher. Moreover, it is found that the stability contours can be affected by the entrance and exit cutting angle.
Industrial press units are divided into two primary groups, single-action and double-action. A si... more Industrial press units are divided into two primary groups, single-action and double-action. A single-action press unit has a mechanism that guides drawing slide. A double-action press unit has a blank holder mechanism as well. A double-action press die has more weight and is more expensive than a single-action one. For the following reasons, single action die, uses for double action press that blank holder mechanism is not in use in this situation and unit changes to single action. The conclusion of this work is the dynamics and stress analysis of of the later state. In this work, for a kinematics analysis, a mathematical model of the mechanism is presented. Later, a dynamics analysis of the double-action mechanism with a standard die and with a small die of a single-action state is provided. This work is concluded by the stress analysis of the two states. Conclusions yield that the use of a single-action die for a double-action press increases the force and stress in the ram mecha...
This paper studies the chaotic behavior of a doubly clamped Euler-Bernoulli beam under magnetic e... more This paper studies the chaotic behavior of a doubly clamped Euler-Bernoulli beam under magnetic excitation via an experimental approach. The Responses of vibrations of the beam under different magnetic excitations are being investigated. The setup includes a doubly-clamped beam which is installed on two static bases and it is excited in the middle by an electromagnetic exciter. The excitation frequency varies from 1 to 50 Hz with different bias and amplitude voltages. Using various numerical methods such as Fast Fourier Transformation, Phase diagrams and Maximum Lyapunov Exponents, the experimental results are examined to find regular and irregular responses. The experimental results show that there exists some harmonic and super harmonic and in some cases chaotic responses in this system.
Journal of Mechanics in Medicine and Biology, 2015
This paper deals with growth control of cancer cells population using type-1 and interval type-2 ... more This paper deals with growth control of cancer cells population using type-1 and interval type-2 fuzzy logic. A type-1 fuzzy controller is designed in order to reduce the population of cancer cells, adjust the drug dosage in a manner that allows normal cells re-grow in treatment period and maintain the maximum drug delivery rate and plasma concentration of drug in an appropriate range. Two different approaches are studied. One deals with reducing the number of cancer cells without any concern about the rate of decreasing, and the other takes the rate of malignant cells damage into consideration. Due to the fact that uncertainty is an inherent part of real systems and affects controller efficacy, employing new methods of design such as interval type-2 fuzzy logic systems for handling uncertainties may be efficacious. Influence of noise on the system is investigated and the effect of altering free parameters of design is studied. Using an interval type-2 controller can diminish the ef...
Volume 1: 20th Biennial Conference on Mechanical Vibration and Noise, Parts A, B, and C, 2005
The atomic force microscope (AFM) system has evolved into a useful tool for direct measurements o... more 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. In this paper, the nonlinear dynamical behavior of the AFM is ...
The Ionic polymer-metal composites (IPMCs) form an important category of electroactive polymers w... more The Ionic polymer-metal composites (IPMCs) form an important category of electroactive polymers which generate large deformation under a low driving voltage. In this paper an empirical model of IPMC is developed by measuring the step response of a 23 mm×3.6 mm×0.16 mm IPMC strip in a cantilever configuration. Moreover, a model-based precision position control of an IPMC base on the fuzzy logic is presented. Open-loop position responses of an IPMC are not repeatable, and hence closed-loop precision control is of critical importance to ensure proper functioning, repeatability and reliability. A CCD camera was used to observe the closed loop response of the IPMC strip in order to control this electro-mechanical actuator experimentally. The IPMC actuator could follow various commanded position trajectories such as sinusoidal and square position profiles. The control architecture presented includes a fuzzy system whose structure and parameters were designed by trail-and-error beside a ga...
Chaos: An Interdisciplinary Journal of Nonlinear Science, 2010
In this paper, a novel robust adaptive control method is proposed for controlling the Lorenz chao... more In this paper, a novel robust adaptive control method is proposed for controlling the Lorenz chaotic attractor. A new backstepping controller for the Lorenz system based on the Lyapunov stability theorem is proposed to overcome the singularity problem that appeared in using the typical backstepping control method. By exploiting the property of the system, the resulting controller is shown to be singularity free and the closed loop system is globally stable. Due to unavailability of system states measurement in practice, the controller is selected such that only one system state is needed. To overcome the problem of parameter uncertainty, an additional term to Lyapunov function is added and an identification scheme is adopted to have a negative definite Lyapunov function derivative. The simulation results demonstrate the effectiveness of the proposed controllers and approaches.
Models are derived for the dynamics of a one link flexible manipulator in contact with a stiff su... more Models are derived for the dynamics of a one link flexible manipulator in contact with a stiff surface, and unconstrained. A means of accomodating the transition between contact and non contact is presented. The effect of joint stiction on tip force is demonstrated through simulation and experiment A combination of tip force (noncollocated) and hub velocity (col1ocated) feedback is implemented to address the difficulties presented by what is an inherently nonminimum phase system. Feedforward and integral control scheme are compared with respect to reduction of steady state error in the face of friction and other uncertainties.
The International Journal of Advanced Manufacturing Technology, 2016
One of the major issues related to parallel kinematic machine tools (PKMs) is their structural de... more One of the major issues related to parallel kinematic machine tools (PKMs) is their structural dependency on their configuration. In this paper, the machine configuration effect on its stability is investigated for the case of a Hexaglide machine tool. An FEM model of the Hexaglide machine tool is developed. The frequency response function (FRF) at the tool tip is obtained by a modal analysis. The numerical results are validated through comparison with those of an experimental modal test. The pose dependency of the PKM stability over its workspace is investigated. It is shown that the machine stability over the workspace is dependent on the spindle/tool/ holder system characteristic. For spindle/tool/holder systems with higher stiffness and lower natural frequency, the stability variation is higher. Moreover, it is found that the stability contours can be affected by the entrance and exit cutting angle.
Industrial press units are divided into two primary groups, single-action and double-action. A si... more Industrial press units are divided into two primary groups, single-action and double-action. A single-action press unit has a mechanism that guides drawing slide. A double-action press unit has a blank holder mechanism as well. A double-action press die has more weight and is more expensive than a single-action one. For the following reasons, single action die, uses for double action press that blank holder mechanism is not in use in this situation and unit changes to single action. The conclusion of this work is the dynamics and stress analysis of of the later state. In this work, for a kinematics analysis, a mathematical model of the mechanism is presented. Later, a dynamics analysis of the double-action mechanism with a standard die and with a small die of a single-action state is provided. This work is concluded by the stress analysis of the two states. Conclusions yield that the use of a single-action die for a double-action press increases the force and stress in the ram mecha...
This paper studies the chaotic behavior of a doubly clamped Euler-Bernoulli beam under magnetic e... more This paper studies the chaotic behavior of a doubly clamped Euler-Bernoulli beam under magnetic excitation via an experimental approach. The Responses of vibrations of the beam under different magnetic excitations are being investigated. The setup includes a doubly-clamped beam which is installed on two static bases and it is excited in the middle by an electromagnetic exciter. The excitation frequency varies from 1 to 50 Hz with different bias and amplitude voltages. Using various numerical methods such as Fast Fourier Transformation, Phase diagrams and Maximum Lyapunov Exponents, the experimental results are examined to find regular and irregular responses. The experimental results show that there exists some harmonic and super harmonic and in some cases chaotic responses in this system.
Journal of Mechanics in Medicine and Biology, 2015
This paper deals with growth control of cancer cells population using type-1 and interval type-2 ... more This paper deals with growth control of cancer cells population using type-1 and interval type-2 fuzzy logic. A type-1 fuzzy controller is designed in order to reduce the population of cancer cells, adjust the drug dosage in a manner that allows normal cells re-grow in treatment period and maintain the maximum drug delivery rate and plasma concentration of drug in an appropriate range. Two different approaches are studied. One deals with reducing the number of cancer cells without any concern about the rate of decreasing, and the other takes the rate of malignant cells damage into consideration. Due to the fact that uncertainty is an inherent part of real systems and affects controller efficacy, employing new methods of design such as interval type-2 fuzzy logic systems for handling uncertainties may be efficacious. Influence of noise on the system is investigated and the effect of altering free parameters of design is studied. Using an interval type-2 controller can diminish the ef...
Volume 1: 20th Biennial Conference on Mechanical Vibration and Noise, Parts A, B, and C, 2005
The atomic force microscope (AFM) system has evolved into a useful tool for direct measurements o... more 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. In this paper, the nonlinear dynamical behavior of the AFM is ...
The Ionic polymer-metal composites (IPMCs) form an important category of electroactive polymers w... more The Ionic polymer-metal composites (IPMCs) form an important category of electroactive polymers which generate large deformation under a low driving voltage. In this paper an empirical model of IPMC is developed by measuring the step response of a 23 mm×3.6 mm×0.16 mm IPMC strip in a cantilever configuration. Moreover, a model-based precision position control of an IPMC base on the fuzzy logic is presented. Open-loop position responses of an IPMC are not repeatable, and hence closed-loop precision control is of critical importance to ensure proper functioning, repeatability and reliability. A CCD camera was used to observe the closed loop response of the IPMC strip in order to control this electro-mechanical actuator experimentally. The IPMC actuator could follow various commanded position trajectories such as sinusoidal and square position profiles. The control architecture presented includes a fuzzy system whose structure and parameters were designed by trail-and-error beside a ga...
Chaos: An Interdisciplinary Journal of Nonlinear Science, 2010
In this paper, a novel robust adaptive control method is proposed for controlling the Lorenz chao... more In this paper, a novel robust adaptive control method is proposed for controlling the Lorenz chaotic attractor. A new backstepping controller for the Lorenz system based on the Lyapunov stability theorem is proposed to overcome the singularity problem that appeared in using the typical backstepping control method. By exploiting the property of the system, the resulting controller is shown to be singularity free and the closed loop system is globally stable. Due to unavailability of system states measurement in practice, the controller is selected such that only one system state is needed. To overcome the problem of parameter uncertainty, an additional term to Lyapunov function is added and an identification scheme is adopted to have a negative definite Lyapunov function derivative. The simulation results demonstrate the effectiveness of the proposed controllers and approaches.
Uploads
Papers by Aria Alasty