Zouhaier Affi | ENIM : National Engineering School of Monastir - TUNISIE (original) (raw)

Papers by Zouhaier Affi

Research paper thumbnail of Precision comparison of two 3-DoF translational parallel manipulators based on the orientation errors due to joint clearances

Robotica

This paper presents a comparative study of two translational parallel manipulators (TPMs) with th... more This paper presents a comparative study of two translational parallel manipulators (TPMs) with three Degrees of Freedom (3-DOF) based on the orientation errors due to joint clearances. In fact, the kinematic and static models of the manipulators have been used to determine the analytical model of the orientation errors. Then, the maximum and the sensitivity of the orientation errors have been considered as criteria to compare the precision of the DELTA and the RAF manipulators. The maximum orientation error is determined by solving an optimization problem of the previous analytical model. The sensitivity of the orientation errors is divided into two types: one related to the sensitivity of the orientation errors to the geometric parameters and another one related to the sensitivity of the orientation error to the joint clearances. The results show that the RAF robot precision is more sensitive to the joint clearances than the DELTA one. However, this advantage of the DELTA is limite...

Research paper thumbnail of Multi-objective Design Optimization of the NBTTL Mechanism

Applied Condition Monitoring, 2016

This work deals with the multi-objective design optimization of NBTTL mechanism. The needle jerk ... more This work deals with the multi-objective design optimization of NBTTL mechanism. The needle jerk (NJ) and the maximum angular velocity ratio (MAVR) are minimized simultaneously. The goal is to minimize the machine input torque and vibration. The multi-objective imperialistic competitive algorithm (MOICA) is used to find the optimal link lengths of the NBTTL mechanism. Compared to Juki 8700, the obtained results show that the optimized mechanism can reduce the MAVR by 80 % and the NJ by 70 %.

Research paper thumbnail of Robust Multi-objective Design Optimization of the 3-UPU TPM Based on the GA-Krawczyk Method

Computational Kinematics, 2017

This paper deals with the robust design optimization of the 3-UPU translational parallel manipula... more This paper deals with the robust design optimization of the 3-UPU translational parallel manipulator. An approach, that regroups the genetic algorithm multi-objective optimization and the Krawczyk operator (GAMOK), is used to represent the optimal design vector of parameters and their uncertainties. This optimization leads to minimize the position error and relax the parameters intervals of tolerance. Based on this GAMOK algorithm, the designer can pick out the optimal design vector according to the desired accuracy in the workspace of the manipulator.

Research paper thumbnail of Prediction of the Position Error of the Uncertain 3-UPU TPM Using Interval Analysis

This paper deals with the prediction of the 3-UPU translational parallel manipulator position err... more This paper deals with the prediction of the 3-UPU translational parallel manipulator position error caused by the design parameter uncertainties. An algorithm, based on the interval analysis is developed and used to estimate the distribution of the position error within the robot workspace. As a result, we represented the distribution of the position error in different sections of the workspace and we showed that the minimum of the position error is located in the neighborhoods of base center. In general, the minimum position error is reached for higher sections of the workspace. Moreover, the effect of each design parameter uncertainty on the manipulator precision at different sections of the workspace is discussed. At the extreme points of the workspace, the most influent design parameters on the position error are the leg position angles and the radius of the base and the platform uncertainties. The actuator lengths uncertainties are supposed constant and have no effect on the pl...

Research paper thumbnail of Mechatronic Rail Vehicle Design Based on the Passenger Comfort

Journal of Engineering Science and Technology Review, 2016

This paper deals with the mechatronic design of the rail vehicle (MRV) in order to improve the pa... more This paper deals with the mechatronic design of the rail vehicle (MRV) in order to improve the passenger comfort. The quarter rail vehicle system dynamic model is presented. The real characteristic of the actuator are discussed and its controller is designed. A mechatronic model that expresses the controlled tracking error as function of the vehicle dynamics and the actuator characteristics is developed. This model is used by the LQR approach to identify the MRV controller gains. The MRV comfort is evaluated in terms of the passenger displacement, acceleration and frequency as a response of a rail discontinuity and rail leveling defaults. The obtained results prove that the MRV improve significantly the passenger comfort.

Research paper thumbnail of Modelling and analysis of the 3-UPU spherical manipulator

European Journal of Computational Mechanics, 2013

ABSTRACT In this paper, we present an analytical model of the kinematics of the spherical 3-UPU p... more ABSTRACT In this paper, we present an analytical model of the kinematics of the spherical 3-UPU parallel manipulator. This model was used to show that up to eight solutions can be found for the forward kinematic problem. The analytical expression of the Jacobean matrix is used to analyse the singularity of this manipulator. We show, in particular, that this manipulator does not have singular configurations within its workspace. Two case studies, one with three degrees of freedom and a second one with only two degrees of freedom, are chosen to illustrate the proposed analysis.

Research paper thumbnail of Genetic Algorithm Coupled with the Krawczyk Method for Multi-Objective Design Parameters Optimization of the 3-UPU Manipulator

Robotica, 2019

SUMMARYIn this paper, a multi-objective design optimization of the 3-UPU translational parallel m... more SUMMARYIn this paper, a multi-objective design optimization of the 3-UPU translational parallel manipulator is presented. Based on a new algorithm, which combines the genetic algorithms and the Krawczyk operator, the robot position error is minimized and the robot design parameters tolerances are maximized, simultaneously. The results show that the designer can maintain the manipulator accuracy by using a specific size of the base, and can restrict its tolerance even by enlarging the actuators’ tolerance intervals. This algorithm is also used to determine the maximum design parameters tolerances for an allowable robot position error. The proposed algorithm can be extended to optimize other types of robots.

Research paper thumbnail of Error estimation and sensitivity analysis of the 3-UPU translational parallel robot due to design parameter uncertainties

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2018

This work deals with the estimation and the sensitivity analysis of the 3-UPU parallel robot erro... more This work deals with the estimation and the sensitivity analysis of the 3-UPU parallel robot error. Based on the Newton–Euler formalism, the robot dynamic model is given in a closed form. This model is validated by the software ADAMS. Using the interval analysis method, a new algorithm is proposed, which estimates the errors in the motion of the end-effector and the errors in the actuator forces as a function of the design parameters uncertainties. The obtained results show that the kinematic errors are minimal at the workspace center. Moreover, these errors increase as the platform moves along the vertical axis. It is also shown that kinematic errors in the actuator joints are the most influential parameters on the manipulator accuracy. Therefore, using actuators with a higher accuracy can highly reduce the errors in motion of the platform.

Research paper thumbnail of Modeling and control of rail vehicle suspensions: A comparative study based on the passenger comfort

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2016

This paper deals with the modeling and control of rail vehicle suspensions. The analytical models... more This paper deals with the modeling and control of rail vehicle suspensions. The analytical models of the quarter rail vehicle with a passenger seat, describing the vertical dynamic, are presented for passive and active suspensions. Three controllers, i.e. PID-ZN, LQR and a PID-LQR are designed in order to improve the passenger comfort. This comfort is evaluated in terms of the passenger displacement, acceleration and frequency as a response of a two types of rail imperfection excitations. Results show that passenger comfort can be improved up to 98%. The obtained results prove that the active suspension with a PID- LQR controller yields the best results by regrouping the advantage of both PID and LQR controllers.

Research paper thumbnail of Mechatronic suspension design for full rail vehicle system

Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics, 2016

In this paper, an analytical mechatronic dynamic design model of a full rail vehicle system is de... more In this paper, an analytical mechatronic dynamic design model of a full rail vehicle system is developed. Based on the rail vehicle motion, its degree of freedom can be reduced to only 38. This reduction is necessary for the model simplicity. The developed model is validated with experimental result and compared with other one from literature. The real characteristics of the actuators are discussed, and its controller is designed. A mechatronic model that expresses the controlled tracking error as function of the vehicle dynamics and the actuator characteristics is developed. This model is used by the linear quadratic regulator approach to identify the mechatronic rail vehicle proportional–integral–derivative controller’s gains. The mechatronic rail vehicle comfort is evaluated in terms of the passenger displacement, acceleration and frequency as a response of a rail irregularities caused by a lateral and two vertical track irregularities. The simulations of vibration analysis are o...

Research paper thumbnail of A hybrid multi-objective imperialist competitive algorithm and Monte Carlo method for robust safety design of a rail vehicle

Comptes Rendus Mécanique, 2017

This paper deals with the robust safety design optimization of a rail vehicle system moving in sh... more This paper deals with the robust safety design optimization of a rail vehicle system moving in short radius curved tracks. A combined multi-objective imperialist competitive algorithm and Monte Carlo method is developed and used for the robust multi-objective optimization of the rail vehicle system. This robust optimization of rail vehicle safety considers simultaneously the derailment angle and its standard deviation where the design parameters uncertainties are considered. The obtained results showed that the robust design reduces significantly the sensitivity of the rail vehicle safety to the design parameters uncertainties compared to the determinist one and to the literature results.

Research paper thumbnail of Control and vibration of rail vehicle semi-active suspensions with comfort evaluation

International Journal of Vehicle Noise and Vibration, 2017

This paper deals with the modelling and control of rail vehicle semi-active suspensions. The anal... more This paper deals with the modelling and control of rail vehicle semi-active suspensions. The analytical models of the quarter rail vehicle with a passenger seat, describing the vertical motion, are presented for semi-active and passive suspensions. Two controllers, i.e., PID-ZN and LQR are designed in order to improve the passenger comfort. This comfort is evaluated in terms of the passenger displacement and vibration. These comfort criteria are evaluated as a response of a rail imperfection excitation. The obtained results prove that the semi-active suspension with a LQR controller yields the best results compared to PID controller.

Research paper thumbnail of Sensitivity analysis and prediction of the orientation error of a three translational parallel manipulator

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2016

This paper deals with the sensitivity analysis and the prediction of the orientation error limits... more This paper deals with the sensitivity analysis and the prediction of the orientation error limits of a three-DoF translational parallel manipulator (3-TPM). An analytical model relating the robot accuracy to the design parameters uncertainties, the joints clearances, the nominal pose, and the external load is developed. Based on this model, an analytical sensitivity analysis is performed to show the influence of each parameter on the orientation error. An algorithm based on the interval analysis is used to predict the bounds of the translator orientation error. Using the RAF robot as an example, it is shown that the pin length of the revolute joint, the width of the parallelogram structure and the radial clearance in the revolute joints are the most influential parameters on the orientation error of the manipulator. Moreover, one of the main results of this analysis is that an increase of the tolerances on certain parameters does not necessarily lead to an increase of the orientatio...

Research paper thumbnail of Modeling and Control for Lateral Rail Vehicle Dynamic Vibration with Comfort Evaluation

Applied Condition Monitoring, 2016

Investigation of control vibration is an important topic for the purposes of ride comfort in rail... more Investigation of control vibration is an important topic for the purposes of ride comfort in railway engineering. The vibration of rail vehicles becomes very complex because it is affected by the condition of vehicles, including suspensions and wheel profile, condition of track sections, including rail profile, rail irregularities, cant and curvature. The present study deals with the modeling and control for vertical active suspension rail vehicle by PID-ZN controller. A model of 17 degrees of freedom is adopted which consists of one car body 2 bogies and 4 wheel-sets. A Sperling ride index (ISO2631) is calculated using filtered RMS accelerations in order to evaluate the ride comfort. It should be noticed that the control model was carried out to improve Wz index about 41% at speed of 60 m/s.

Research paper thumbnail of Development of a reduced dynamic model for comfort evaluation of rail vehicle systems

Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics, 2016

In this paper, an analytical reduced dynamic model of a rail vehicle system is developed. This mo... more In this paper, an analytical reduced dynamic model of a rail vehicle system is developed. This model considers only 38 degrees of freedom of the rail vehicle system. This reduced model can predict the dynamic behaviour of the rail vehicle while being simpler than existing dynamic models. The developed model is validated using experimental results found in the bibliography and its results are compared with existing more complex models from the literature. The developed model is used for the passenger comfort evaluation, which is based on the value of the weighted root mean square acceleration according to the ISO 2631 standard. Several parameters of the system, i.e., passenger position, loading of the railway vehicle and its speed, and their effect on the passenger comfort are investigated. It was shown that the level of comfort is mostly affected by the speed of the railway vehicle and the position of the seat. The load, however, did not have a significant effect on the level of com...

Research paper thumbnail of Optimal design of the needle bar and thread take up lever mechanism using a multi-objective imperialist competitive algorithm

2015 10th International Symposium on Mechatronics and its Applications (ISMA), 2015

This work deals with the multi-objective design optimization of a needle-bar-and-thread-take-up-l... more This work deals with the multi-objective design optimization of a needle-bar-and-thread-take-up-lever (NBTTL) mechanism used in sewing machines. Two criteria are considered simultaneously, i.e., vibration (evaluated through the needle jerk) and the quality of the stitch formation given by the coupler tracking error. Indeed, the needle jerk and the coupler tracking error are minimized in order to reduce the sewing machine vibration and ensure a proper stitch formation. For this purpose, the multi-objective imperialistic competitive algorithm (MOICA) is used to find the optimal link lengths of the NBTTL mechanism. The obtained results show that the optimized mechanism has 73% less needle Jerk than the one for the Juki 8700, while keeping a low coupler tracking error (less than 7%).

Research paper thumbnail of Reduced Inverse Dynamic Model of Parallel Manipulators Based on the Lagrangian Formalism

Lecture Notes in Mechanical Engineering, 2015

This paper deals with the dynamic modeling of the 3-UPU parallel robot based on the Lagrangian fo... more This paper deals with the dynamic modeling of the 3-UPU parallel robot based on the Lagrangian formalism. The reduced inverse dynamic model gives the actuators forces as function of only the active variables and the manipulator load. The closed loops equations are used in order to eliminate the passive coordinates from the equations of motion as well as the Lagrange multipliers. This type of model can be useful for the control of parallel robots.

Research paper thumbnail of Modeling and Simulation for Lateral Rail Vehicle Dynamic Vibration with Comfort Evaluation

Lecture Notes in Mechanical Engineering, 2015

Research paper thumbnail of Computer Aided Design for Dynamic Modeling and Control of Closed Loop Mechanisms

ABSTRACT In this work, computer aided method for dynamics modeling and control of closed loop mec... more ABSTRACT In this work, computer aided method for dynamics modeling and control of closed loop mechanisms is presented. A crank slider mechanism is used to illustrate our approach. The proposed method allows us to analyze the dynamic behavior of the mechanism in a simple and rapid way. This tool allowed us to show that for a mechanism with general inertia characteristics, the PD controller does not yield an acceptable behavior, i.e., a non zero steady state error, and it is necessary to have a PID controller to eliminate this error. Then the crank slider mechanism is redesigned by applying a negative mass distribution approach to obtain a statically balanced mechanism, which exhibits a simpler dynamic behavior. We showed that in this case the PD controller is sufficient to eliminate the steady error. Hence, the mechanical design of parallel robots can be improved in order to simplify the control strategy. This goal presents the main advantage of the proposed approach. A sensitivity analysis, using the Taguchi method, is then presented to analyze the effect of some physical parameters on the dynamic behavior of the system. We show, for instance, that the steady state error is very sensitive to the location of the center of gravity of the crank.

Research paper thumbnail of ADAMS/Simulink interface for dynamic modeling and control of closed loop mechanisms

In this work, computer aided methods for dynamics modeling and control of a closed loop mechanism... more In this work, computer aided methods for dynamics modeling and control of a closed loop mechanisms are presented. The software, ADAMS, was used to generate automatically the dynamic model. This model was then used under the Matlab/Simulink environment to control the mechanism. Simulation results are presented to illustrate the behavior of the whole mechatronic system under different control strategies. The crank slider mechanism was chosen to illustrate our approach. In particular, it is shown that simple PD controller is sufficient to yield acceptable dynamic behavior of a statically balanced mechanism even when gravity was taken into account. Mechatronic systems-Dynamic modeling-Control-Closed loop mechanisms.

Research paper thumbnail of Precision comparison of two 3-DoF translational parallel manipulators based on the orientation errors due to joint clearances

Robotica

This paper presents a comparative study of two translational parallel manipulators (TPMs) with th... more This paper presents a comparative study of two translational parallel manipulators (TPMs) with three Degrees of Freedom (3-DOF) based on the orientation errors due to joint clearances. In fact, the kinematic and static models of the manipulators have been used to determine the analytical model of the orientation errors. Then, the maximum and the sensitivity of the orientation errors have been considered as criteria to compare the precision of the DELTA and the RAF manipulators. The maximum orientation error is determined by solving an optimization problem of the previous analytical model. The sensitivity of the orientation errors is divided into two types: one related to the sensitivity of the orientation errors to the geometric parameters and another one related to the sensitivity of the orientation error to the joint clearances. The results show that the RAF robot precision is more sensitive to the joint clearances than the DELTA one. However, this advantage of the DELTA is limite...

Research paper thumbnail of Multi-objective Design Optimization of the NBTTL Mechanism

Applied Condition Monitoring, 2016

This work deals with the multi-objective design optimization of NBTTL mechanism. The needle jerk ... more This work deals with the multi-objective design optimization of NBTTL mechanism. The needle jerk (NJ) and the maximum angular velocity ratio (MAVR) are minimized simultaneously. The goal is to minimize the machine input torque and vibration. The multi-objective imperialistic competitive algorithm (MOICA) is used to find the optimal link lengths of the NBTTL mechanism. Compared to Juki 8700, the obtained results show that the optimized mechanism can reduce the MAVR by 80 % and the NJ by 70 %.

Research paper thumbnail of Robust Multi-objective Design Optimization of the 3-UPU TPM Based on the GA-Krawczyk Method

Computational Kinematics, 2017

This paper deals with the robust design optimization of the 3-UPU translational parallel manipula... more This paper deals with the robust design optimization of the 3-UPU translational parallel manipulator. An approach, that regroups the genetic algorithm multi-objective optimization and the Krawczyk operator (GAMOK), is used to represent the optimal design vector of parameters and their uncertainties. This optimization leads to minimize the position error and relax the parameters intervals of tolerance. Based on this GAMOK algorithm, the designer can pick out the optimal design vector according to the desired accuracy in the workspace of the manipulator.

Research paper thumbnail of Prediction of the Position Error of the Uncertain 3-UPU TPM Using Interval Analysis

This paper deals with the prediction of the 3-UPU translational parallel manipulator position err... more This paper deals with the prediction of the 3-UPU translational parallel manipulator position error caused by the design parameter uncertainties. An algorithm, based on the interval analysis is developed and used to estimate the distribution of the position error within the robot workspace. As a result, we represented the distribution of the position error in different sections of the workspace and we showed that the minimum of the position error is located in the neighborhoods of base center. In general, the minimum position error is reached for higher sections of the workspace. Moreover, the effect of each design parameter uncertainty on the manipulator precision at different sections of the workspace is discussed. At the extreme points of the workspace, the most influent design parameters on the position error are the leg position angles and the radius of the base and the platform uncertainties. The actuator lengths uncertainties are supposed constant and have no effect on the pl...

Research paper thumbnail of Mechatronic Rail Vehicle Design Based on the Passenger Comfort

Journal of Engineering Science and Technology Review, 2016

This paper deals with the mechatronic design of the rail vehicle (MRV) in order to improve the pa... more This paper deals with the mechatronic design of the rail vehicle (MRV) in order to improve the passenger comfort. The quarter rail vehicle system dynamic model is presented. The real characteristic of the actuator are discussed and its controller is designed. A mechatronic model that expresses the controlled tracking error as function of the vehicle dynamics and the actuator characteristics is developed. This model is used by the LQR approach to identify the MRV controller gains. The MRV comfort is evaluated in terms of the passenger displacement, acceleration and frequency as a response of a rail discontinuity and rail leveling defaults. The obtained results prove that the MRV improve significantly the passenger comfort.

Research paper thumbnail of Modelling and analysis of the 3-UPU spherical manipulator

European Journal of Computational Mechanics, 2013

ABSTRACT In this paper, we present an analytical model of the kinematics of the spherical 3-UPU p... more ABSTRACT In this paper, we present an analytical model of the kinematics of the spherical 3-UPU parallel manipulator. This model was used to show that up to eight solutions can be found for the forward kinematic problem. The analytical expression of the Jacobean matrix is used to analyse the singularity of this manipulator. We show, in particular, that this manipulator does not have singular configurations within its workspace. Two case studies, one with three degrees of freedom and a second one with only two degrees of freedom, are chosen to illustrate the proposed analysis.

Research paper thumbnail of Genetic Algorithm Coupled with the Krawczyk Method for Multi-Objective Design Parameters Optimization of the 3-UPU Manipulator

Robotica, 2019

SUMMARYIn this paper, a multi-objective design optimization of the 3-UPU translational parallel m... more SUMMARYIn this paper, a multi-objective design optimization of the 3-UPU translational parallel manipulator is presented. Based on a new algorithm, which combines the genetic algorithms and the Krawczyk operator, the robot position error is minimized and the robot design parameters tolerances are maximized, simultaneously. The results show that the designer can maintain the manipulator accuracy by using a specific size of the base, and can restrict its tolerance even by enlarging the actuators’ tolerance intervals. This algorithm is also used to determine the maximum design parameters tolerances for an allowable robot position error. The proposed algorithm can be extended to optimize other types of robots.

Research paper thumbnail of Error estimation and sensitivity analysis of the 3-UPU translational parallel robot due to design parameter uncertainties

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2018

This work deals with the estimation and the sensitivity analysis of the 3-UPU parallel robot erro... more This work deals with the estimation and the sensitivity analysis of the 3-UPU parallel robot error. Based on the Newton–Euler formalism, the robot dynamic model is given in a closed form. This model is validated by the software ADAMS. Using the interval analysis method, a new algorithm is proposed, which estimates the errors in the motion of the end-effector and the errors in the actuator forces as a function of the design parameters uncertainties. The obtained results show that the kinematic errors are minimal at the workspace center. Moreover, these errors increase as the platform moves along the vertical axis. It is also shown that kinematic errors in the actuator joints are the most influential parameters on the manipulator accuracy. Therefore, using actuators with a higher accuracy can highly reduce the errors in motion of the platform.

Research paper thumbnail of Modeling and control of rail vehicle suspensions: A comparative study based on the passenger comfort

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2016

This paper deals with the modeling and control of rail vehicle suspensions. The analytical models... more This paper deals with the modeling and control of rail vehicle suspensions. The analytical models of the quarter rail vehicle with a passenger seat, describing the vertical dynamic, are presented for passive and active suspensions. Three controllers, i.e. PID-ZN, LQR and a PID-LQR are designed in order to improve the passenger comfort. This comfort is evaluated in terms of the passenger displacement, acceleration and frequency as a response of a two types of rail imperfection excitations. Results show that passenger comfort can be improved up to 98%. The obtained results prove that the active suspension with a PID- LQR controller yields the best results by regrouping the advantage of both PID and LQR controllers.

Research paper thumbnail of Mechatronic suspension design for full rail vehicle system

Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics, 2016

In this paper, an analytical mechatronic dynamic design model of a full rail vehicle system is de... more In this paper, an analytical mechatronic dynamic design model of a full rail vehicle system is developed. Based on the rail vehicle motion, its degree of freedom can be reduced to only 38. This reduction is necessary for the model simplicity. The developed model is validated with experimental result and compared with other one from literature. The real characteristics of the actuators are discussed, and its controller is designed. A mechatronic model that expresses the controlled tracking error as function of the vehicle dynamics and the actuator characteristics is developed. This model is used by the linear quadratic regulator approach to identify the mechatronic rail vehicle proportional–integral–derivative controller’s gains. The mechatronic rail vehicle comfort is evaluated in terms of the passenger displacement, acceleration and frequency as a response of a rail irregularities caused by a lateral and two vertical track irregularities. The simulations of vibration analysis are o...

Research paper thumbnail of A hybrid multi-objective imperialist competitive algorithm and Monte Carlo method for robust safety design of a rail vehicle

Comptes Rendus Mécanique, 2017

This paper deals with the robust safety design optimization of a rail vehicle system moving in sh... more This paper deals with the robust safety design optimization of a rail vehicle system moving in short radius curved tracks. A combined multi-objective imperialist competitive algorithm and Monte Carlo method is developed and used for the robust multi-objective optimization of the rail vehicle system. This robust optimization of rail vehicle safety considers simultaneously the derailment angle and its standard deviation where the design parameters uncertainties are considered. The obtained results showed that the robust design reduces significantly the sensitivity of the rail vehicle safety to the design parameters uncertainties compared to the determinist one and to the literature results.

Research paper thumbnail of Control and vibration of rail vehicle semi-active suspensions with comfort evaluation

International Journal of Vehicle Noise and Vibration, 2017

This paper deals with the modelling and control of rail vehicle semi-active suspensions. The anal... more This paper deals with the modelling and control of rail vehicle semi-active suspensions. The analytical models of the quarter rail vehicle with a passenger seat, describing the vertical motion, are presented for semi-active and passive suspensions. Two controllers, i.e., PID-ZN and LQR are designed in order to improve the passenger comfort. This comfort is evaluated in terms of the passenger displacement and vibration. These comfort criteria are evaluated as a response of a rail imperfection excitation. The obtained results prove that the semi-active suspension with a LQR controller yields the best results compared to PID controller.

Research paper thumbnail of Sensitivity analysis and prediction of the orientation error of a three translational parallel manipulator

Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 2016

This paper deals with the sensitivity analysis and the prediction of the orientation error limits... more This paper deals with the sensitivity analysis and the prediction of the orientation error limits of a three-DoF translational parallel manipulator (3-TPM). An analytical model relating the robot accuracy to the design parameters uncertainties, the joints clearances, the nominal pose, and the external load is developed. Based on this model, an analytical sensitivity analysis is performed to show the influence of each parameter on the orientation error. An algorithm based on the interval analysis is used to predict the bounds of the translator orientation error. Using the RAF robot as an example, it is shown that the pin length of the revolute joint, the width of the parallelogram structure and the radial clearance in the revolute joints are the most influential parameters on the orientation error of the manipulator. Moreover, one of the main results of this analysis is that an increase of the tolerances on certain parameters does not necessarily lead to an increase of the orientatio...

Research paper thumbnail of Modeling and Control for Lateral Rail Vehicle Dynamic Vibration with Comfort Evaluation

Applied Condition Monitoring, 2016

Investigation of control vibration is an important topic for the purposes of ride comfort in rail... more Investigation of control vibration is an important topic for the purposes of ride comfort in railway engineering. The vibration of rail vehicles becomes very complex because it is affected by the condition of vehicles, including suspensions and wheel profile, condition of track sections, including rail profile, rail irregularities, cant and curvature. The present study deals with the modeling and control for vertical active suspension rail vehicle by PID-ZN controller. A model of 17 degrees of freedom is adopted which consists of one car body 2 bogies and 4 wheel-sets. A Sperling ride index (ISO2631) is calculated using filtered RMS accelerations in order to evaluate the ride comfort. It should be noticed that the control model was carried out to improve Wz index about 41% at speed of 60 m/s.

Research paper thumbnail of Development of a reduced dynamic model for comfort evaluation of rail vehicle systems

Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics, 2016

In this paper, an analytical reduced dynamic model of a rail vehicle system is developed. This mo... more In this paper, an analytical reduced dynamic model of a rail vehicle system is developed. This model considers only 38 degrees of freedom of the rail vehicle system. This reduced model can predict the dynamic behaviour of the rail vehicle while being simpler than existing dynamic models. The developed model is validated using experimental results found in the bibliography and its results are compared with existing more complex models from the literature. The developed model is used for the passenger comfort evaluation, which is based on the value of the weighted root mean square acceleration according to the ISO 2631 standard. Several parameters of the system, i.e., passenger position, loading of the railway vehicle and its speed, and their effect on the passenger comfort are investigated. It was shown that the level of comfort is mostly affected by the speed of the railway vehicle and the position of the seat. The load, however, did not have a significant effect on the level of com...

Research paper thumbnail of Optimal design of the needle bar and thread take up lever mechanism using a multi-objective imperialist competitive algorithm

2015 10th International Symposium on Mechatronics and its Applications (ISMA), 2015

This work deals with the multi-objective design optimization of a needle-bar-and-thread-take-up-l... more This work deals with the multi-objective design optimization of a needle-bar-and-thread-take-up-lever (NBTTL) mechanism used in sewing machines. Two criteria are considered simultaneously, i.e., vibration (evaluated through the needle jerk) and the quality of the stitch formation given by the coupler tracking error. Indeed, the needle jerk and the coupler tracking error are minimized in order to reduce the sewing machine vibration and ensure a proper stitch formation. For this purpose, the multi-objective imperialistic competitive algorithm (MOICA) is used to find the optimal link lengths of the NBTTL mechanism. The obtained results show that the optimized mechanism has 73% less needle Jerk than the one for the Juki 8700, while keeping a low coupler tracking error (less than 7%).

Research paper thumbnail of Reduced Inverse Dynamic Model of Parallel Manipulators Based on the Lagrangian Formalism

Lecture Notes in Mechanical Engineering, 2015

This paper deals with the dynamic modeling of the 3-UPU parallel robot based on the Lagrangian fo... more This paper deals with the dynamic modeling of the 3-UPU parallel robot based on the Lagrangian formalism. The reduced inverse dynamic model gives the actuators forces as function of only the active variables and the manipulator load. The closed loops equations are used in order to eliminate the passive coordinates from the equations of motion as well as the Lagrange multipliers. This type of model can be useful for the control of parallel robots.

Research paper thumbnail of Modeling and Simulation for Lateral Rail Vehicle Dynamic Vibration with Comfort Evaluation

Lecture Notes in Mechanical Engineering, 2015

Research paper thumbnail of Computer Aided Design for Dynamic Modeling and Control of Closed Loop Mechanisms

ABSTRACT In this work, computer aided method for dynamics modeling and control of closed loop mec... more ABSTRACT In this work, computer aided method for dynamics modeling and control of closed loop mechanisms is presented. A crank slider mechanism is used to illustrate our approach. The proposed method allows us to analyze the dynamic behavior of the mechanism in a simple and rapid way. This tool allowed us to show that for a mechanism with general inertia characteristics, the PD controller does not yield an acceptable behavior, i.e., a non zero steady state error, and it is necessary to have a PID controller to eliminate this error. Then the crank slider mechanism is redesigned by applying a negative mass distribution approach to obtain a statically balanced mechanism, which exhibits a simpler dynamic behavior. We showed that in this case the PD controller is sufficient to eliminate the steady error. Hence, the mechanical design of parallel robots can be improved in order to simplify the control strategy. This goal presents the main advantage of the proposed approach. A sensitivity analysis, using the Taguchi method, is then presented to analyze the effect of some physical parameters on the dynamic behavior of the system. We show, for instance, that the steady state error is very sensitive to the location of the center of gravity of the crank.

Research paper thumbnail of ADAMS/Simulink interface for dynamic modeling and control of closed loop mechanisms

In this work, computer aided methods for dynamics modeling and control of a closed loop mechanism... more In this work, computer aided methods for dynamics modeling and control of a closed loop mechanisms are presented. The software, ADAMS, was used to generate automatically the dynamic model. This model was then used under the Matlab/Simulink environment to control the mechanism. Simulation results are presented to illustrate the behavior of the whole mechatronic system under different control strategies. The crank slider mechanism was chosen to illustrate our approach. In particular, it is shown that simple PD controller is sufficient to yield acceptable dynamic behavior of a statically balanced mechanism even when gravity was taken into account. Mechatronic systems-Dynamic modeling-Control-Closed loop mechanisms.