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2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006

作者： Ahmadian, M.T. Esmailzadeh, E. Asgari, M. Center of Excellence in Design Robotics and Automation Sharif University of Technology P.O. Box 11365-8639 Tehran Iran Faculty of Engineering and Applied Science University of Ontario Institute of Technology Oshawa Ont. Canada School of Mechanical Engineering Sharif University of Technology P.O. Box 11365-8639 Tehran Iran

ISBN: (纸本)0791837904

One of the engineers concern in designing bridges and structures under moving load is the uniformity of stress distribution. In this paper the analysis of a variable cross-section beam subjected to a moving concentrated force and mass is investigated. Finite element method with cubic Hermitian interpolation functions is used to model the structure based on Euler-Bernoulli beam and Wilson- direct integration method is implemented to solve time dependent equations. Effects of cross-section area variation, boundary conditions, and moving mass inertia on the deflection, natural frequencies and longitudinal stresses of beam are investigated. Results indicates using a beam of parabolically varying thickness with constant mass can decrease maximum deflection and stresses along the beam while increasing natural frequencies of the beam. The effect of moving mass inertia of moving load is found to be significant at high velocity. Copyright © 2006 by ASME.

关键词： Stress concentration

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Mechanism synthesis for path generation using the curvature based - Deflection based objective function

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WSEAS Transactions on Systems 2006年第12期5卷 2839-2843页

作者： Damangir, Soheil Jafarijashemi, Ghazaleh Mamduhi, Mohammadhossein Aghmioni, Alireza Nazemzadeh Zohoor, Hassan School of Mechanical Engineering Sharif University of Technology Tehran Iran Taylor's College Subang Jaya Kuala Lumpur Malaysia Academy of Sciences of I.R. Iran Center of Excellence in Design Robotics and Automation Sharif University of Technology Tehran Iran

This paper proposed a new curvature based path-description method for path-generation of planar mechanism, in which the position vector of a point on coupler, which follows most closely a predefined path, is directly calculated as a function of coupler motion properties. In addition this curvature based method makes it possible to define an objective function independent of rotation and translation transformations. Therefore, in this method, initial position, orientation, and coupler point vector parameters are not the optimization variable. These five parameters could be calculated as a function of other design parameters and they are found when these optimal values are obtained. Reducing five parameters of the optimal variables leads to a smaller design space and so less computation time to find the optimal result. Application of the method is also shown and its computation time and accuracy are compared with the result reported in the literature. It is found that this method is superior as it converges faster without loosing any accuracy.

关键词： Motion planning

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Modelling of a complex system using the dynamic rule prediction

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WSEAS Transactions on Systems 2006年第12期5卷 2833-2838页

作者： Damangir, Soheil Jafarijashemi, Ghazaleh Zohoor, Hassan School of Mechanical Engineering Sharif University of Technology Tehran Iran Taylor's College Subang Jaya Kuala Lumpur Malaysia Academy of Sciences of I.R. Iran Tehran Iran Center of Excellence in Design Robotics and Automation Sharif University of Technology Tehran Iran

Presented in this paper are a method, named the Dynamic Rule Prediction (DRP), which predicts the behavior of a system and its application in designing a controller. The aim of the study is to overcome some of the limitations and shortcoming of the other modeling methods. The effectiveness of this method is verified. The controller based on DRP possesses two main features. It can control the system without any prior knowledge of the controlled plant. It is, also, superior as its high-speed prediction. This paper focuses on the robot manipulator controllers and applications of this approach in it.

关键词： Large scale systems

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Dynamics modeling of a humanoid robot

Dynamics modeling of a humanoid robot

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DETC2005: ASME International design Engineering Technical Conferences and Computers and Information in Engineering Conference

作者： Meghdari, Ali Sohrabpour, Saeed Nezamoddini, Seyed Ali Izadi, Ehsan Fakhar Tamaddoni, Seyed Hossein Basafa, Ehsan Center of Excellence in Design Robotics and Automation Mechanical Engineering Department Shanf University of Technology Tehran Iran

ISBN: (纸本)0791847411

This paper presents the overall dynamics analysis for humanoid robots and proposes a method to extend the dynamics equations to check the stability conditions and compute the maximum torques required at each joint. We consider a humanoid robotics system with various base conditions. As the robot walks, the robot will switch between single and double support conditions. The conventional works on dynamical stability of the robots mostly uses simple models with invariant bases. Our proposed method models a robot with various base conditions and describes the dynamics equations of humanoid robots in three dimensional space. Using this method, a straight walking was simulated as a sample gait during which joint torques was achieved and the stability condition was tested. Copyright © 2005 by ASME.

关键词： Robots

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Equations of Motion of a Single-Wheel Robot in a Rough Terrain

Equations of Motion of a Single-Wheel Robot in a Rough Terra...

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IEEE International Conference on robotics and automation (ICRA)

作者： A. Alasty H. Pendar Center of Excellence in Design Robotics and Automation Department of Mechanical Engineering Sharif University of technology Tehran Iran

In this article, dynamic equations of a single wheel robot, known as Gyrover, through Lagrange method applying a new approach will be addressed. There is no simplification on the dynamic analysis. Considering any possible differentiable function for the road’s curve, the effect of the road’s roughness is completely described in the dynamic equation evaluation. Although there are complicated relations between the wheel and rough terrain, due to the efficient generalized coordinate selection, closed form dynamic equation of the motion is derived. Because of the closed form formulation, required time for simulation will be reduced. From the proposed complete model a simplified model for the controller design could be extracted

关键词： Mobile robots Robot kinematics Wheels Stability robotics and automation Lagrangian functions Differential equations Robot control Motion control Gravity

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Adaptive inverse microstep tracking control of a hybrid stepper motor using RBF and MLP neural networks

Adaptive inverse microstep tracking control of a hybrid step...

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IEEE International Conference on Mechatronics and automation

作者： Y. Bastani G.R. Vossoughi Center of Excellence in Design Robotics and Automation Mechanical Engineering Department Sharif University of Technology Tehran Iran

In this paper, a radial basis function neural network-based (RBFNN) adaptive inverse controller for real-time position tracking control of a two phase hybrid stepper motor in microstep mode is presented. To ensure system's robustness and closed loop stability and to improve the performance of the controller, the RBF based adaptive inverse control is combined with a closed loop PID controller. Experimental results are provided for various types of trajectories, comparing the performance of the proposed controller to the same neuro-controller using feed forward back-propagation neural networks (FFBP) proposed previously by the authors. The results show the superior performance of RBFNN over FFBP neural networks. Also the comparison of neuro controllers with a conventional fixed gain stand-alone PID controller show the improvement of the controller performance from 80% up to 99.7% decrease in the mean squared error (MSE) for different trajectories. Trajectories were tracked with the maximum error of 0.02 up to 0.06 degrees. Also the robustness of the method is confirmed through experimental results comparing neuro-controllers and the conventional PID controller by varying the load's inertia and disturbance torques. For this purpose two methods were examined. First using the same neuro-controllers trained by the initial training data and in the second method, neuro-controllers were adapted by new training data according to the new working conditions.

关键词： Programmable control Adaptive control Micromotors Neural networks Control systems Three-term control Robust control Robust stability Training data Adaptive systems

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PID neural network control of SUT building energy management system

PID neural network control of SUT building energy management...

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IEEE/ASME (AIM) International Conference on Advanced Intelligent Mechatronics

作者： M. Fardadi A.S. Ghafari S.K. Hannani Center of Excellence in Energy Conversion School of Mechanical Engineering Sharif University of Technology Tehran Iran Center of Excellence in Design Robotics and Automation School of Mechanical Engineering Sharif University of Technology Tehran Iran

PID neural network controller design for Sharif University of Technology (SUT) building energy management system (BEMS) is addressed in this paper. The most important characteristics of process systems are time delay with model uncertainties. Artificial neural networks can perform adaptive controller properties through learning processes. PID neural network has the advantage of both conventional PID controllers and the neural structure. Simulation results using modified Hooke-Jeeves optimization method show that this controller has short convergence time and quick learning speed and the performance of the closed loop system is very good

关键词： Three-term control Neural networks Control systems Energy management Artificial neural networks Buildings Delay effects Uncertainty Adaptive systems Programmable control

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Dynamics modeling of "Cedra" rescue robot on uneven terrains

Dynamics modeling of "Cedra" rescue robot on uneven terrains

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2004 ASME International Mechanical Engineering Congress and Exposition, IMECE

作者： Meghdari, A. Mahboobi, S.H. Gaskarimahalle, A.L. Center of Excellence in Design Robotics and Automation School of Mechanical Engineering Sharif University of Technology Tehran Iran

In this paper an effective approach for kinematic and dynamic modeling of high mobility wheeled mobile robots (WMR) has been presented. As an example of these robots, the method has been applied on CEDRA rescue robot which is a complex, multibody mechanism. The model is derived for 6-DOF motions enabling movement in x, y, z directions, as well as pitch, roll and yaw rotations. Forward kinematics equations are derived using Denavit-Hartenberg method and the wheels Jacobian matrices. Moreover the inverse kinematics of the robot is obtained and solved for the wheel velocities and steering commands in terms of desired velocity, heading and measured link angles. Finally dynamical analysis of the rover has been thoroughly studied. Due to the complexity of this multi-body system especially on rough terrain, Kane's method of dynamics has been used to model this problem. The approach has been developed in such a way that it can easily be extended to other mechanisms and rovers. Copyright © 2004 by ASME.

关键词： Mobile robots

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An upper bound approach for analysis of hydroforming of sheet metals

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International Journal of Engineering, Transactions B: Applications 2004年第4期17卷 389-398页

作者： Assempour, A. Bagherzadeh, M. Emami, M.R. Center of Excellence in Design Robotics and Automation Department of Mechanical Engineering Sharif University of Technology Tehran Iran

Considering a kinematical velocity admissible field, the upper bound method has been used for predicting the amount of pressure in hydroforming of sheet metals. The effects of work hardening, friction and blank size have been considered in pressure prediction. Also the effect of sheet thickness variation has been considered in the present work formulations. The relation between pressure and punch stroke has been obtained and optimized by changing the selective parameters in the velocity components. The results for cylindrical and hemispheric parts have been obtained and compared with the published experimental results. The effects of work hardening, friction and blank size on hydroforming pressure have been examined on an elliptical part. Good agreement was found between the experimental and numerical results.

关键词： Sheet metal

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Investigation of train dynamics in passing through curves using a full model

Investigation of train dynamics in passing through curves us...

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ASME/IEEE Joint Conference on Rail

作者： M. Durali M.M.J. Bahabadi Robotics and Automation Mechanical Engineering Center of excellence for Design Tehran Iran Center of excellence for Design Robotics & Autom. Dept. of Mechanical Eng. Tehran Iran

In this article a train model is developed for studying train derailment in passing through bends. The model is three dimensional, nonlinear, and considers 43 degrees of freedom for each wagon. All nonlinear characteristics of suspension elements as well as flexibilities of wagon body and bogie frame, and the effect of coupler forces are included in the model. The equations of motion for the train arc solved numerically for different train conditions. A neural network was constructed as an element in solution loop for determination of wheel-rail contact geometry. Derailment factor was calculated for each case. The results are presented and show the major role of coupler forces on possible train derailment.

关键词： Railway accidents Rail transportation Wheels Mechanical engineering Friction Couplings Differential equations Nonlinear equations Neural networks Geometry

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