Ashraf Hatwesh - Academia.edu (original) (raw)
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Jawaharlal Nehru Technological University
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Papers by Ashraf Hatwesh
On machine tools, precise control of the position of the tool tip relative to the workpiece is re... more On machine tools, precise control of the position of the tool tip relative to the workpiece is required to follow the desired path where quality of producing parts is significantly dependent on dynamic performance. The design of such a controller that can perform with all plant uncertainties is a major challenge. It is therefore the aim of this paper to assess the performance of a new design methodology that may enhance the performance of machine tool feed drives. The controller in general has a form of P/PI/PID (Proportional/ Integral/Derivative) compensators that is easy to implement in practice and does not require additional hardware. In addition to a simple structure, the design applies the principles of a phase margin approach to allow the self-tuning controller to automatically update the controller settings. This ability is required to optimise control when the position and the mass of the fixture and/or workpiece change. Effectiveness of the proposed methodology is demonstr...
2017 23rd International Conference on Automation and Computing (ICAC), 2017
Knowledge of machine tool drive dynamics is imperative to achieve optimal, robust performance wit... more Knowledge of machine tool drive dynamics is imperative to achieve optimal, robust performance with precision and productivity. Modelling ball-screw drives is vital in order to have a feasible insight into the structural vibration modes of the mechanical assembly, which typically limits the bandwidth of developed controllers. In this paper, an output-only modal identification, Operational Modal Analysis (OMA), is used to validate a ball-screw feed drive model while running without cutting. The experimental results indicate that the identified parameters on the running state are different from those of static state and mathematical modelling. Furthermore, it is possible to validate and calibrate dynamic models using OMA by measuring the table structure responses without knowing the excitation input.
One of the most significant drawbacks of modelling complex machine structures and drives using nu... more One of the most significant drawbacks of modelling complex machine structures and drives using numerical models (discreet or hybrid Finite Element Analysis (FEAs)) is the difficulty of obtaining accurate modal parameters, such as stiffness and damping values of the mechanical parts as well as the accuracy of the models. Although the FEA is one of the numerical methods that are used to speed up the simulation/calculations, the dynamics of the machine tool/drives are expected to change under machining conditions, which makes numerical models inconvenient. Using Operational Modal Analysis (OMA), on-line parameters identification, can overcome the static state deviations and give more accurate results to represent the mechanical system. Thus, the project will introduce a new systematic procedure to carry out OMA on ball-screw drives. Firstly, the identification techniques are evaluated by means of simulated models and applied to identify the dynamics of the ball-screw drive using two di...
On machine tools, precise control of the position of the tool tip relative to the workpiece is re... more On machine tools, precise control of the position of the tool tip relative to the workpiece is required to follow the desired path where quality of producing parts is significantly dependent on dynamic performance. The design of such a controller that can perform with all plant uncertainties is a major challenge. It is therefore the aim of this paper to assess the performance of a new design methodology that may enhance the performance of machine tool feed drives. The controller in general has a form of P/PI/PID (Proportional/ Integral/Derivative) compensators that is easy to implement in practice and does not require additional hardware. In addition to a simple structure, the design applies the principles of a phase margin approach to allow the self-tuning controller to automatically update the controller settings. This ability is required to optimise control when the position and the mass of the fixture and/or workpiece change. Effectiveness of the proposed methodology is demonstr...
2017 23rd International Conference on Automation and Computing (ICAC), 2017
Knowledge of machine tool drive dynamics is imperative to achieve optimal, robust performance wit... more Knowledge of machine tool drive dynamics is imperative to achieve optimal, robust performance with precision and productivity. Modelling ball-screw drives is vital in order to have a feasible insight into the structural vibration modes of the mechanical assembly, which typically limits the bandwidth of developed controllers. In this paper, an output-only modal identification, Operational Modal Analysis (OMA), is used to validate a ball-screw feed drive model while running without cutting. The experimental results indicate that the identified parameters on the running state are different from those of static state and mathematical modelling. Furthermore, it is possible to validate and calibrate dynamic models using OMA by measuring the table structure responses without knowing the excitation input.
One of the most significant drawbacks of modelling complex machine structures and drives using nu... more One of the most significant drawbacks of modelling complex machine structures and drives using numerical models (discreet or hybrid Finite Element Analysis (FEAs)) is the difficulty of obtaining accurate modal parameters, such as stiffness and damping values of the mechanical parts as well as the accuracy of the models. Although the FEA is one of the numerical methods that are used to speed up the simulation/calculations, the dynamics of the machine tool/drives are expected to change under machining conditions, which makes numerical models inconvenient. Using Operational Modal Analysis (OMA), on-line parameters identification, can overcome the static state deviations and give more accurate results to represent the mechanical system. Thus, the project will introduce a new systematic procedure to carry out OMA on ball-screw drives. Firstly, the identification techniques are evaluated by means of simulated models and applied to identify the dynamics of the ball-screw drive using two di...