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Measurement: Journal of the International Measurement Confederation (02632241) 224
The mesh stiffness is a necessary and influential parameter in system dynamics modeling and vibration analysis of straight bevel gear systems (SBG). A new experimental method, employing a laser extensometer (LE) and an innovative setup, is developed to calculate the mesh stiffness in both healthy and cracked systems. An analytical method based on potential energy and tooth root crack modeling is also proposed. Both methods were implemented on healthy and cracked gear systems with varying crack depths. The new LE experimental method's results are compared with those obtained from the proposed analytical method. The results showed good agreement between both methods, indicating that the newly proposed experimental method considers all parts of mesh stiffness and is suitable for measuring mesh stiffness in both healthy and cracked SBG systems. © 2023
Measurement: Journal of the International Measurement Confederation (02632241) 238
The mesh stiffness plays a crucial role in influencing the performance and behavior of straight bevel gear (SBG) systems. Precisely determining the mesh stiffness enables to assess the SBG system's dynamic behavior more accurately and anticipate potential concerns such as crack identification and noise reduction. A novel experimental method is developed, employing experimental modal analysis associated with metaheuristic algorithms and an innovative setup. This method effectively determines the mesh stiffness in healthy and cracked systems. Additionally, an analytical method based on the potential energy associated with crack modeling is proposed. Both methods are implemented on SBG systems with varying crack depths. The results obtained from the experimental method are compared with those from the analytical method, revealing good agreement between them. This demonstrates that the newly proposed experimental method effectively considers all parts of mesh stiffness and is appropriate for determining the mesh stiffness in healthy and cracked SBG systems. © 2024
Journal of Sound and Vibration (10958568) 570
Non-uniformity and damage are the two primary subjects in studying the vibrations of the beam-type elements. An exact closed-form explicit solution for the transverse displacement of a non-uniform multi-cracked beam with any type of boundary conditions is introduced. The generalized functions and the distributional derivative concepts are adopted. Four fundamental functions are introduced. These functions make the boundary conditions' process and compute the frequency equation more convenient. By introducing the non-dimensional parameters, the non-dimensional motion equation of the damaged beam with an arbitrary count of cracks is derived, and its exact closed-form explicit solution is obtained based on the four introduced fundamental functions. The standard method of computing these functions is presented, and the closed-form of these functions is determined for eight cases like uniform and conical beams. The closed-form of the frequency equation and mode shapes of the non-uniform multi-cracked beam are derived for several boundary conditions. The influence of the count of cracks, their location and intensity, and the boundary conditions on the natural frequency and mode shape are assessed by running a numerical study. The first and second frequencies of a conical beam are computed to verify the obtained results by applying this newly presented closed-form solution and the Differential Quadrature Element Method. A good agreement is evident when the obtained results are compared. © 2023
Nonlinear Dynamics (0924090X) 112(14)pp. 11945-11970
The tooth crack identification through the effect of the tooth root crack on nonlinear vibration behaviors in a straight bevel gear (SBG) system is sought. The mesh stiffness is evaluated through an analytical method based on the potential energy and Tredgold approximation associated with tooth root crack modeling. A 10-dof model is developed for the SBG system where the backlash nonlinearity is of concern. To assess the nonlinear vibration behaviors of the SBG system, first, the dynamic response is extracted analytically with the proposed dynamic model, and experimentally with a designed setup, then the extracted response is assessed based on the different crack identification statistical factors. Results indicate that the Skewness is the most effective factor in identifying the crack in the SBG system with backlash nonlinearity, compared to other investigated factors. The nonlinear vibration response as a time history, phase diagram, Poincaré map, modal analysis, and mesh stiffness FFT spectrum is analyzed and recommended as an appropriate indicator for tooth root cracks. The modeled mesh stiffness and simulated SBG system are verified by applying FEM and the experimental method. Graphical abstract: (Figure presented.) © The Author(s), under exclusive licence to Springer Nature B.V. 2024.
2025 29th International Computer Conference, Computer Society of Iran, CSICC 2025 pp. 539-545
In this article, a super-twisting algorithm-based ADRC structure is proposed. This structure contains three parts, a super twisting sliding mode controller, an extended state estimator, and an optimal tracking differentiator. This proposed ADRC is employed to control the Delta parallel robot both numerically, in MATLAB, and experimentally. In numerical simulations, the robustness of the proposed ADRC is verified by applying various external disturbances. Both the numerical and experimental results show the ability of the proposed ADRC structure in controlling the Delta robot in the presence of disturbances and uncertainties. © 2022 IEEE.
Journal of Mechanical Science and Technology (1738494X) 34(6)pp. 2573-2583
A map-merging algorithm is proposed where reduced element maps are applied instead of grid maps and the maximal empty rectangles are applied as their features. Simultaneous localization and mapping (SLAM) refer to the process where a robot provides the environment map without any knowledge about its own position. Due to error accumulation, required time, saving lives and reasons alike, applying a single robot in the SLAM process is not justified. In such applications, many robots are to be applied in the SLAM process in a parallel sense. The map-merging process is one of the challenging topics in a multi-robot simultaneous localization and mapping process in producing a global map of the environment. In this study, a centralized algorithm is introduced for map-merging based on maximal empty rectangles as the features of local maps without any knowledge about robots’ initial or relative positions. Three examples and one experiment are applied in validating the performance of this newly proposed algorithm. The obtained results indicate that this algorithm can merge local maps with small overlapping areas in relation to the whole map, subject to multiple sources of error due to the difference in scales, diversity of agents applied and measurement noise. © 2020, The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany, part of Springer Nature.
Journal Of The Brazilian Society Of Mechanical Sciences And Engineering (16785878) 42(5)
In this article, the nonlinear transverse vibration of an elastically connected double microbeam system carrying a moving particle is assessed based on the modified couple stress and non-classical Timoshenko beam theories. Hamilton’s principle is applied to develop the motion equations and corresponding boundary conditions, and the Galerkin method is used to solve these equations. The numerical study reveals that the nonlinear and modified couple stress theories predict a stiffer system than the linear and classical theories do. A parametric study is run to determine the different parameters’ influence like the aspect ratio, the stiffness modulus of the elastic layer and the velocity of the moving particle, on the dynamic response of the system. The results show that the aspect ratio has a significant effect on the dynamic response of the system, indicating that the classical theory cannot predict the dynamic behavior of micro-size beam systems. The elastic layer stiffness modulus and the velocity of the moving particle have considerable effects on the dynamic deflections of the double-microbeam system. © 2020, The Brazilian Society of Mechanical Sciences and Engineering.
Archive of Applied Mechanics (14320681) 90(12)pp. 2739-2754
Based on the modified couple stress and non-classical Timoshenko beam theories, the nonlinear forced vibration of an elastically connected double nanobeam system subjected to a moving particle is assessed here. This system is assumed to be resting on an elastic medium. Hamilton’s principle and the Galerkin method are applied to govern the equations of system motion and corresponding boundary conditions and to solve these equations, respectively. The numerical study reveals that by applying the nonlinear and modified couple stress theories the system is predicted stiffer than what is obtained through linear and classical theories. To determine the effects of different parameters like the material length scale, the elastic stiffness modulus of the interlayer and medium, and the velocity of the moving particle on the system’s vibration, a parametric study is performed. The material length scale has a significant effect on the dynamic response of the system, indicating that the classical theory cannot predict the dynamic behavior of nanosize beam systems. The elastic stiffness modulus of both the interlayer and medium and the velocity of the moving particle have considerable effects on the dynamic deflections of the double nanobeam system. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature.
Journal Of Intelligent And Robotic Systems (15730409) 95(3-4)pp. 901-913
This paper presents kinematic control of surgical robotic systems subject to Remote Center of Motion (RCM) constraint in Minimally Invasive Robotic Surgeries (MIRS). A novel kinematic formulation for surgical systems is derived and the movement restriction in incision point, known as RCM constraint, is resolved by active control of the system through a so-called RCM-constrained Jacobian. The proposed minimal Jacobian matrix can realize fixed/moving trocar constraint effectively in comparison with the state-of-the-arts. In the following, an analysis related to the dexterity of the constrained system is introduced and an index for manipulability of the constrained system is introduced. The proposed approach is validated through several numerical simulations as well as experiments in a 7DoFs and 9DoFs MIRS scenarios. The results show the efficiency and the precision of the proposed method. © 2018, Springer Nature B.V.
International Journal of Engineering, Transactions A: Basics (17281431) 32(4)pp. 608-616
In this article, a fast and reliable map-merging algorithm is proposed to produce a global two dimensional map of an indoor environment in a multi-robot simultaneous localization and mapping (SLAM) process. In SLAM process, to find its way in this environment, a robot should be able to determine its position relative to a map formed from its observations. To solve this complex problem, simultaneous localization and mapping methods are required. In large and complex environments, using a single robot is not reasonable because of the error accumulation and the time required. This can explain the tendency to employ multiple robots in parallel for this task. One of the challenges in the multi-robot SLAM is the map-merging problem. A centralized algorithm for map-merging is introduced in this research based on the features of local maps and without any knowledge about robots initial or relative positions. In order to validate the proposed merging algorithm, a medium scale experiment has been set up consisting of two heterogeneous mobile robots in an indoor environment equipped with laser sensors. The results indicate that the introduced algorithm shows good performance both in accuracy and fast map-merging. © 2019 Materials and Energy Research Center. All rights reserved.
Journal of Mechanical Science and Technology (1738494X) 33(3)pp. 1115-1121
Gear systems are used to transmit power in the industry when accuracy and synchrony are needed and helical gear systems are used in more accurate and high-speed industries. It is important to ensure that these systems work faultlessly, therefore the detection of the crack location and situation is very efficient in the gear systems. In this research, a new approach is proposed to detect the multi crack location and length in the helical gear teeth. To this end, after giving an explanation of helical gear mesh stiffness and demonstrating the helical gear pair dynamic modeling, the transmission error ratio method is used to detect the cracks locations and lengths. Then, according to solved examples, when the cracks locations are far enough that their effects on the transmission error are completely separated, the cracked teeth and the lengths of cracks can be detected exactly, and when the cracks are in adjacent teeth, according to the cracks lengths and depths and their effects overlap, the number of cracks and their lengths can be detected exactly, approximately or absolutely undetectable. © 2019, KSME & Springer.
Journal of Mechanical Science and Technology (1738494X) 32(8)pp. 3537-3545
Time-dependent mesh stiffness is a most important reason of vibration and dynamic excitation in gear sets. In this research, analytical formulas of the helical gear set and the planetary gear system are combined to calculate the time-dependent mesh stiffness of the helical planetary gear system. For this purpose, at the first step, the analytical equations are derived for the spur gear pair. Then by dividing a helical tooth into the several independent thin spur tooth slices, the helical gear pair mesh stiffness is extracted. Finally, these equations are extended to the helical planetary gear system. The suggested analytical results and those which obtained by the finite element method (FEM) are compared and are in good agreement when the helix angle is less than 15 degrees. Also, the helical planetary gear system mesh stiffness in different cases such as fixed carrier, fixed sun gear and fixed ring gears is calculated. These results show that the value of mesh frequency ratio in each case scales the mesh stiffness shapes in the rotation angle direction. In other words, mesh frequency ratio parameter determines the number of meshing period in each rotation of planets. © 2018, The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany, part of Springer Nature.
International Journal of Engineering, Transactions A: Basics (17281431) 30(1)pp. 134-142
Cooperative arms are two or more arms in series which assume the structure of a parallel robot on account of gripping an intermediary object, and are commonly used in accurate assembly industries, coaxialization, movement of object, etc. Gripping an intermediary object is one of the complicated subjects in analysis of cooperative arms, whose analysis is mostly dependent upon the manner the object is gripped by the arms fingertips. In the case of griping objects in frictional manner, the elimination of unwanted slippage of fingertips on the object due to the environmental factors, and also the effect of the fingertips geometry on the movement equations are among the major topics in such arms analysis. The dynamic analysis and control synthesis of the undesired slippage between an object and robot fingertips in object manipulation and the effects of finger radius or geometry of the fingertip on the function dynamics and slippage control is studied in this article. The slip/roll contact model is applied in the dynamic formulation and analysis of the finger geometry the effects of which are studied using numerical simulation.
Advanced Robotics (01691864) 30(2)pp. 97-108
Handling objects with robotic soft fingers without considering the odds of slippage are not realistic. Grasping and manipulation algorithms have to be tested under such conditions for evaluating their robustness. In this paper, a dynamic analysis of rigid object manipulation with slippage control is studied using a two-link finger with soft hemispherical tip. Dependency on contact forces applied by a soft finger while grasping a rigid object is examined experimentally. A power-law model combined with a linear viscous damper is used to model the elastic behavior and damping effect of the soft tip, respectively. In order to obtain precise dynamic equations governing the system, two second-order differential equations with variable coefficients have been designed to describe the different possible states of the contact forces accordingly. A controller is designed based on the rigid fingertip model using the concept of feedback linearization for each phase of the system dynamics. Numerical simulations are used to evaluate the performance of the controller. The results reveal that the designed controller shows acceptable performance for both soft and rigid finger manipulation in reducing and canceling slippage. Furthermore, simulations indicate that the applied force in the soft finger manipulation is considerably less than the rigid "one.". © 2015 Taylor and Francis and The Robotics Society of Japan.
Hadian jazi, S. ,
Keshmiri m., M. ,
Sheikholeslam, F. ,
Shahreza, M.G. ,
Keshmiri, M. Robotica (02635747) 32(5)pp. 783-802
Considering undesired slippage between manipulated object and finger tips of a multi-robot system, adaptive control synthesis of the object grasping and manipulation is addressed in this paper. Although many studies can be found in the literature dealing with grasp analysis and grasp synthesis, most assume no slippage between the finger tips and the object. Slippage can occur for many reasons such as disturbances, uncertainties in parameters, and dynamics of the system. In this paper, system dynamics is analyzed using a new presentation of friction and slippage dynamics. Then an adaptive control law is proposed for trajectory tracking and slippage control of the object as well as compensation for parameter uncertainties of the system, such as mass properties and coefficients of friction. Stability of the proposed adaptive controller is studied analytically and the performance of the system is studied numerically. Copyright © Cambridge University Press 2013.
Hadian jazi, S. ,
Keshmiri m., M. ,
Sheikholeslam, F. ,
Shahreza, M.G. ,
Keshmiri, M. Advanced Robotics (01691864) 26(15)pp. 1693-1726
This paper addresses dynamic analysis and control synthesis of object grasping in a cooperative multirobot system with n-serial manipulators from an undesired slippage point of view. Two control approaches are presented in this article; a modified version of a conventional method in grasp synthesis and a new method based on a new modeling of system dynamics. A new formulation for frictional contact is used in dynamical modeling, where equality and inequality equations of the standard Coulomb friction model are all converted to a single second-order differential equation. A multiphase controller is utilized to control the object trajectory tracking as well as object slippage in the new control approach. Performance and robustness of both approaches are studied numerically. The results show superiority of the new method and its desirable and excellent performance. © 2012 Taylor & Francis and The Robotics Society of Japan.
Considering slippage between finger tips and an object, adaptive control synthesis of grasping and manipulating an object by a multi-fingered system is addressed in this paper. Slippage can occur due to many reasons such as disturbances, uncertainties in parameters and dynamics. In this paper, using a novel representation of friction and slippage dynamics, a new approach is introduced to analyze the system dynamics. Then an adaptive controller with a simple update rule is proposed to ensure the bounded trajectory tracking and slippage control, and at the same time to compensate for parameter uncertainties including coefficients of friction. The performance of the proposed adaptive controller is shown analytically and studied numerically. Copyright © 2008 by ASME.
Considering slippage in the end-effectors of a set of two cooperating manipulators grasping an object, this paper presents a new dynamic modeling and control synthesis of grasping phenomenon. This dynamic modeling is based on a new formulation for frictional contact where equality and inequality equations in the standard Coulomb Friction model are converted all to a single second order differential equation with switching coefficients. Accuracy of the friction model is verified by comparing its results with those of SimMech. Then equations of motion are reduced to conventional form for nonconstrained system. Assuming the new reduced order system to be BIBO, internal stability of the whole system is analyzed. In the control synthesis of the system a multi phase controller is utilized to control the trajectory tracking of the object as well as slippage control of the end-effectors on the object surfaces. For the proposed controller, a proof is given for system stability and its performance and robustness are shown numerically. The results show superiority of the method and its desirable and excellent performance. Copyright © 2007 by ASME.
2(PARTS A AND B)pp. 1047-1055
Considering slippage between finger tips and an object, adaptive control synthesis of grasping and manipulating an object by a multi-fingered system is addressed in this paper. Slippage can occur due to many reasons such as disturbances, uncertainties in parameters and dynamics. In this paper, using a novel representation of friction and slippage dynamics, a new approach is introduced to analyze the system dynamics. Then an adaptive controller with a simple update rule is proposed to ensure the bounded trajectory tracking and slippage control, and at the same time to compensate for parameter uncertainties including coefficients of friction. The performance of the proposed adaptive controller is shown analytically and studied numerically. © 2008 by ASME.
Advanced Robotics (01691864) 22(13-14)pp. 1559-1584
Grasping an object by a cooperating system such as multi-fingered hands and multi-manipulator robotic system has received much attention. Research has focused on analysis of force-closure grasps and the synthesis of optimal grasping, when there is no slipping condition. Although the control system is designed to keep the contact force in the friction cone and avoid the slipping condition, slippage can occur for many reasons. In this research, dynamics analysis and control synthesis of a manipulator moving an object on a horizontal surface using the contact force of an end-effector are performed considering the slipping condition. Equality and inequality equations of frictional contact conditions are replaced by a single second-order differential equation with switching coefficients in order to facilitate the dynamic modeling. Accuracy of this modeling is verified by comparing the results of the model with those of SimMech. Using this modeling of friction, a set of reduced order form is obtained for equations of motion of the system. A new method is proposed to control the object motion and the end-effector undesired slippage based on the reduced form. Finally, performance of the method is evaluated both numerically and experimentally. © 2008 VSP.
Proceedings of the IASTED International Conference on Modelling and Simulation (10218181) pp. 149-154
Almost all of the researches on object grasping by manipulators and cooperating robots consider no slippage between end-effectors and object, however it can occur. This paper presents dynamics analysis and control synthesis of a manipulator moving an object on a horizontal surface using contact force of end-effector considering slipping condition. Equality and inequality equations of frictional contact conditions are replaced by a single second order differential equation with switching coefficients in order to facilitate the dynamical modeling. Using this modeling of friction, a set of reduced order form is obtained for equations of motion of the system and a new method is proposed to control end-effector slippage on the object.
