An analysis is presented for two degree of freedom weakly nonlinear oscillators, with symmetric restoring force. Conditions of 1:3 internal resonance and subharmonic resonance of the lower linear natural mode are assumed to be satisfied... more
An analysis is presented for two degree of freedom weakly nonlinear oscillators, with symmetric restoring force. Conditions of 1:3 internal resonance and subharmonic resonance of the lower linear natural mode are assumed to be satisfied simultaneously. Initially, a set of slow-flow equations is derived, governing the amplitudes and phases of approximate response, by applying an asymptotic analytical method. Determination of approximate periodic steady-state motions of the system is then reduced to solution of sets of polynomial equations which is performed analytically. Then, a systematic search is performed based on this analysis, revealing effects of the system parameters on the existence and stability properties of periodic steady-state motions for an example mechanical system. The results are first presented in the form of frequency-response diagrams and attention is focused on understanding the evolution and interaction of the various solution branches as the internal resonance...
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One way to increase the durability of the machine is active surface coatings using new technological processes such as thermal spray coatings, especially the plasma jet. Was made by coating nickel plating process of the plasma jet knife... more
One way to increase the durability of the machine is active surface coatings using new technological processes such as thermal spray coatings, especially the plasma jet. Was made by coating nickel plating process of the plasma jet knife blade for removal of a group from the grower. In order to emphasize increasing the reliability of these knives by coating with nickel, they were mounted on a cultivator with a lot of knives witness, uncovered, and have been used extensively. Data on wear two groups of knives, coated with nickel and witness uncovered were recorded by photometric methods were processed and plotted statisitic. There was a significant decrease of 66.79% in average wear on the knife blades coated with nickel compared to the control, uncoated.
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In the present paper an optimization algorithm to find out the geometric design parameters of an open loop spatial robot with three revolute joints is described. The design variables include the base position, the geometry of the links... more
In the present paper an optimization algorithm to find out the geometric design parameters of an open loop spatial robot with three revolute joints is described. The design variables include the base position, the geometry of the links and the joint angles of the robot and are calculated so that the manipulator will be able to place its end-effector at prescribed poses, avoiding simultaneously singular configurations. The developed algorithm uses the Denavit-Hartenberg parameters and 4x4 homogeneous matrices to obtain the kinematic equations of the robot. The optimization problem is solved with a hybrid method that combines a genetic algorithm, a quasi-Newton algorithm and a constraints handling method. To examine the efficiency of the method, numerical examples for one, three and five prescribed poses of the end-effector are applied.
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In this paper we analyze the influence of cutting parameters on the surface quality, surface roughness respectively, processed by turning when heat treated bearing steel, also called hard turning, and processing by turning of bearing... more
In this paper we analyze the influence of cutting parameters on the surface quality, surface roughness respectively, processed by turning when heat treated bearing steel, also called hard turning, and processing by turning of bearing steel without heat treatment. We set parameters of the cutting regime influencing the achievement of roughness surfaces which must be within the predetermined requirements if bearing rings exceeding 500 mm in diameter. This analysis will be done by statistical methods using the software Minitab 14.
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In this paper a kinematic and dynamic model of the human upper extremity is developed for simulating movements and determination of the joints forces. These results can be used for the detection of dangerous movements of a patient having... more
In this paper a kinematic and dynamic model of the human upper extremity is developed for simulating movements and determination of the joints forces. These results can be used for the detection of dangerous movements of a patient having orthopaedic problems or for the design of prosthetic devices.
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ABSTRACT This paper presents some new results on the position analysis in polynomial form of the class-three Assur group. The aim of this position analysis is to determine all possible configurations of the Assur group, for a given... more
ABSTRACT This paper presents some new results on the position analysis in polynomial form of the class-three Assur group. The aim of this position analysis is to determine all possible configurations of the Assur group, for a given position of its external joints. Five new kinds of the class-three Assur group with two or three prismatic joints are investigated. The analysis leads to a non-linear system of equations. Using a successive elimination procedure, a final polynomial equation in one unknown is obtained. The real solutions of this polynomial equation correspond to assembly modes of the Assur group. Finally, five numerical applications of the proposed methods are presented.
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This paper presents some performances of a modified orthoglide parallel mechanism build for integration in a CNC milling machine. The parallel mechanism is driven and controlled by a vertical CN C milling machine. The designed mechanism... more
This paper presents some performances of a modified orthoglide parallel mechanism build for integration in a CNC milling machine. The parallel mechanism is driven and controlled by a vertical CN C milling machine. The designed mechanism is modeled with the finite elements method (FEM) in order to a nalyze the static behavior inside the workspace. The FEM m odel is validated by comparing the theoretical values of the natural frequencies with the experimental ones of t he prototype mechanism. Furthermore various tests are performed in order to investigate the position prec ision of the designed mechanism.
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In this paper a kinematic and dynamic model of the human upper extremity is developed for simulating movements and determination of the joints forces. These results can be used for the detection of dangerous movements of a patient having... more
In this paper a kinematic and dynamic model of the human upper extremity is developed for simulating movements and determination of the joints forces. These results can be used for the detection of dangerous movements of a patient having orthopaedic problems or for the design of prosthetic devices.
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In this paper an algorithm for the optimum collision-free path planning of a spatial robot, using multiple optimization criteria is developed, in the frame of a total inquire of optimum serial robots manipulation. The interface platform... more
In this paper an algorithm for the optimum collision-free path planning of a spatial robot, using multiple optimization criteria is developed, in the frame of a total inquire of optimum serial robots manipulation. The interface platform is an offline control system that exploits graphical data of the robot parts and workspace obstacles in order to import them in the optimization algorithm. The main optimization criteria are the total travel time from an initial known to a final known configuration through a user-defined amount of intermediate calculated poses, the avoidance of singular configurations and the path smoothness, taking into account the collision avoidance of all robot parts and obstacles, as well as the joint angles limits. The optimization problem is solved through a hybrid method that combines a genetic algorithm, a quasi-Newton algorithm and a constraints handling method, using a multi-objective function and various constraints. The feasibility of the proposed algori...
Research Interests: Engineering, Genetic Algorithm, Path planning, Control system, Optimization, and 15 moreOptimization Problem, Collision Avoidance, Travel Time, Hybrid Algorithm, Constraint Handling, Robot Design, Search Space, Fitness Function, Path Planning, Hill Climbing, Robot Manipulator, Hybrid Method, Optimal Solution, Objective function, and optimal algorithm
The optimum design of a cam mechanism is a time consuming task, due to the numerous alternatives considerations. In the present work, the problem of design parameters optimization of a cam mechanism with translating flat‐ face follower is... more
The optimum design of a cam mechanism is a time consuming task, due to the numerous alternatives considerations. In the present work, the problem of design parameters optimization of a cam mechanism with translating flat‐ face follower is investigated from a multi‐objective point of view. The design parameters, just like the cam base circle radius, the follower face width and the follower offset can be determined considering as optimization criteria the minimization of the cam size, of the input torque and of the contact stress. During the optimization procedure, a number of constraints regarding the pressure angle, the contact stress, etcare taken into account. The optimization approach, based on genetic algorithm, is applied to find the optimal solutions with respect to the afore‐mentioned objective function and to ensure the kinematic requirements. Finally, the dynamic behaviour of the designed cam mechanism is investigated considering the frictional forces. © 2013 Published by F...
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This paper presents the position analysis in polynomial form of the Assur groups of class 3 and order 3 including two or three prismatic joints (triad). The aim of this position analysis is to determine all possible configurations of the... more
This paper presents the position analysis in polynomial form of the Assur groups of class 3 and order 3 including two or three prismatic joints (triad). The aim of this position analysis is to determine all possible configurations of the Assur group, for a given position of its external joints. Two kinds of the Assur group of class 3, with two and three prismatic joints are investigated. The position analysis leads to a non-linear system of three equations with three unknown parameters. Using a successive elimination procedure, a final polynomial equation in one unknown is obtained. The real solutions of the polynomial equation correspond to assembly modes of the Assur group. The smaller upper-bound of the real solutions is established for the investigated triads. Two numerical applications of the proposed methods are presented. The position analysis for an Assur group is to find all possible configurations, when the position of the external joints and dimensions of the links are gi...
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An important area in Reverse Engineering applications is the combination of multiple scans o f a 3D product to model the object. Moreover the registrat ion refinement of multiple range images is a crucial st ep in multi-view 3D modeling.... more
An important area in Reverse Engineering applications is the combination of multiple scans o f a 3D product to model the object. Moreover the registrat ion refinement of multiple range images is a crucial st ep in multi-view 3D modeling. In the present paper a hybr id optimization method is developed to align point clo uds, without any user-applied initial alignment. The pro osed method combines a genetic algorithm with a quasi-Ne wton algorithm and furthermore a constraints handling me thod is involved. Several free-form point clouds are used t o verify the accuracy and the reliability of the proposed me thod and two characteristic examples are presented. The appl ied examples point clouds are retrieved using a Coordin ate Measuring Machine (CMM), which is not restrictive f or the developed optimizing methodology.
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The mechanical strength properties of lumbar spine vertebrae are of great importance in a wide range of applications. Herein, through nanoindentations and appropriate evaluation of the corresponding results, trabecular bone struts... more
The mechanical strength properties of lumbar spine vertebrae are of great importance in a wide range of applications. Herein, through nanoindentations and appropriate evaluation of the corresponding results, trabecular bone struts stress-strain characteristics can be determined. In the frame of the present paper, an L2 fresh cadaveric vertebra, from which posterior elements were removed, was subjected to compression. With the aid of developed finite elements method based algorithms, the cortical shell and the cancellous core bulk elasticity moduli and stresses were determined, whereas the tested vertebra geometrical model used in these algorithms was considered as having a compound structure, consisting of the cancellous bone surrounded by the cortical shell. Moreover nanoindentations were conducted and an appropriate evaluation method of the obtained results was applied to extract stress-strain curves of individual lumbar spine vertebra trabecular bone struts. These data were used ...
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The mechanical strength properties of lumbar spine vertebrae are of great importance in a wide range of applications. Herein, through nanoindentations and appropriate evaluation of the corresponding results, trabecular bone struts... more
The mechanical strength properties of lumbar spine vertebrae are of great importance in a wide range of applications. Herein, through nanoindentations and appropriate evaluation of the corresponding results, trabecular bone struts stress-strain characteristics can be determined. In the frame of the present paper, an L2 fresh cadaveric vertebra, from which posterior elements were removed, was subjected to compression. With the aid of developed finite elements method based algorithms, the cortical shell and the cancellous core bulk elasticity moduli and stresses were determined, whereas the tested vertebra geometrical model used in these algorithms was considered as having a compound structure, consisting of the cancellous bone surrounded by the cortical shell. Moreover nanoindentations were conducted and an appropriate evaluation method of the obtained results was applied to extract stress-strain curves of individual lumbar spine vertebra trabecular bone struts. These data were used ...
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ABSTRACT
ABSTRACT
A procedure for the automatic generation of the robot programming used in welding operations is introduced in the present paper. The developed off-line programming system includes graphical simulation of the robot and its workcell,... more
A procedure for the automatic generation of the robot programming used in welding operations is introduced in the present paper. The developed off-line programming system includes graphical simulation of the robot and its workcell, kinematic model of the robot, motion planning and creation of the NC code for welding. The proposed system is applied in a case of a robot with six revolute joints for welding operations.
An important area in Reverse Engineering applications is the combination of multiple scans of a 3D product to model the object. Moreover the registration refinement of multiple range images is a crucial step in multi- view 3D modeling. In... more
An important area in Reverse Engineering applications is the combination of multiple scans of a 3D product to model the object. Moreover the registration refinement of multiple range images is a crucial step in multi- view 3D modeling. In the present paper a hybrid optimization method is developed to align point clouds, without any user-applied initial alignment. The proposed method combines a genetic algorithm with a quasi-Newton algorithm and furthermore a constraints handling method is involved. Several free-form point clouds are used to verify the accuracy and the reliability of the proposed method and two characteristic examples are presented.
In this paper an algorithm for the optimum collision-free path planning of a spatial robot, using multiple optimization criteria is developed, in the frame of a total inquire of optimum serial robots manipulation. The interface platform... more
In this paper an algorithm for the optimum collision-free path planning of a spatial robot, using multiple optimization criteria is developed, in the frame of a total inquire of optimum serial robots manipulation. The interface platform is an offline control system that exploits graphical data of the robot parts and workspace obstacles in order to import them in the optimization algorithm. The main optimization criteria are the total travel time from an initial known to a final known configuration through a user-defined amount of intermediate calculated poses, the avoidance of singular configurations and the path smoothness, taking into account the collision avoidance of all robot parts and obstacles, as well as the joint angles limits. The optimization problem is solved through a hybrid method that combines a genetic algorithm, a quasi-Newton algorithm and a constraints handling method, using a multi-objective function and various constraints. The feasibility of the proposed algori...
Research Interests: Genetic Algorithm, Path planning, Control system, Optimization Problem, Collision Avoidance, and 12 moreTravel Time, Hybrid Algorithm, Constraint Handling, Robot Design, Search Space, Fitness Function, Path Planning, Hill Climbing, Robot Manipulator, Hybrid Method, Optimal Solution, and Objective function
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ABSTRACT The performance of a robot manipulator during a process depends on its position relative to the corresponding path. An ill-placed manipulator risks inefficient operation as well as blocks due to singularities. The paper deals... more
ABSTRACT The performance of a robot manipulator during a process depends on its position relative to the corresponding path. An ill-placed manipulator risks inefficient operation as well as blocks due to singularities. The paper deals with an optimization algorithm to determine the base position and the joint angles of a spatial robot, when the end-effector poses are prescribed, avoiding the singular configurations. The optimization problem is solved through a hybrid heuristic method that combines the advantages of a genetic algorithm, a quasi-Newton algorithm and a constraints handling method. Six cases of a 6-DOF manipulator are studied to verify the feasibility of the proposed algorithm.
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In this paper a kinematic and dynamic model of the human upper extremity is developed for simulating movements and determination of the joints forces. These results can be used for the detection of dangerous movements of a patient having... more
In this paper a kinematic and dynamic model of the human upper extremity is developed for simulating movements and determination of the joints forces. These results can be used for the detection of dangerous movements of a patient having orthopaedic problems or for the design of prosthetic devices.
Research Interests:
... Implementation of low temperature-deposited coating fatigue parameters in commercial roller bearings catalogues. K. -D. Bouzakis Corresponding Author Contact Information , E-mail The Corresponding Author , N. Vidakis, A. Lontos, S.... more
... Implementation of low temperature-deposited coating fatigue parameters in commercial roller bearings catalogues. K. -D. Bouzakis Corresponding Author Contact Information , E-mail The Corresponding Author , N. Vidakis, A. Lontos, S. Mitsi and K. David. ...
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This paper presents the solution in polynomial form to the position analysis of the Assur group of class 4 (tetrad) with four links, one prismatic and five revolute joints. The aim of this position analysis is to determine all possible... more
This paper presents the solution in polynomial form to the position analysis of the Assur group of class 4 (tetrad) with four links, one prismatic and five revolute joints. The aim of this position analysis is to determine all possible configurations of the Assur group, for a given ...