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A fresh insight into Kane's equations of motion
, Article Robotica ; 2015 ; 02635747 (ISSN) ; Yousefsani, S. A ; Gaskarimahalle, A. L ; Oskouei, S. B. G ; Sharif University of Technology
Cambridge University Press
2015
Abstract
With rapid development of methods for dynamic systems modeling, those with less computation effort are becoming increasingly attractive for different applications. This paper introduces a new form of Kane's equations expressed in the matrix notation. The proposed form can efficiently lead to equations of motion of multi-body dynamic systems particularly those exposed to large number of nonholonomic constraints. This approach can be used in a recursive manner resulting in governing equations with considerably less computational operations. In addition to classic equations of motion, an efficient matrix form of impulse Kane formulations is derived for systems exposed to impulsive forces....
Manipulation of multibody active objects using simple passive manipulators
, Article ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 12 November 2010 through 18 November 2010, Vancouver, BC ; Volume 8, Issue PARTS A AND B , 2010 , Pages 597-603 ; 9780791844458 (ISBN) ; Meghdari, A ; Sohrabpour, S ; Sharif University of Technology
2010
Abstract
In this paper, we study passivity in dynamic manipulation of active objects. Active object is a concept covering a variety of objects, which are not rigid and need to be controlled during manipulation process. In this work, we use multi-link mechanisms with sufficient actuators to be controlled as object and a series of simple 1-DoF passive manipulators to perform such a process. Control of the object, dynamic and motion planning of the system, and stability in presence of impact are significant issues in this study
Control and manipulation of multibody objects
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 3 , 2010 , Pages 579-584 ; 9780791849170 (ISBN) ; Meghdari, A ; Sohrabpour, S ; Sharif University of Technology
2010
Abstract
In this work, we study a kind of manipulation process during which we deal with active objects. An active object is a concept covering a variety of objects that are not rigid and need to be controlled during the manipulation process. Here, we use a multi-link mechanism with active motors (actuator) as the object and a series of simple planar manipulators to perform the manipulation process. Dynamic, control, motion planning, and stability at the presence of impact are the most important challenges in this work
Analysis of Autonomous Takeoff and Landing of a Tailsitter on Moving Platform
, M.Sc. Thesis Sharif University of Technology ; Banazadeh, Afshin (Supervisor)
Abstract
The purpose of this research is to add automatic landing and takeoff capability to the target drone. To design the automatic landing and takeoff algorithm and analyze and check its performance quality, the target drone must be modeled first. Since this drone has a relatively large blade, the dynamic effects of this large blade are included in the modeling. After modeling the drone, the controller has been designed for three phases of horizontal flight, vertical flight and the transition between these two flight phases. With the preparation of the controllers of different phases of flight, the automatic landing and takeoff algorithm of the flying drone is designed, implemented and its results...
On the identifiability of inertia parameters of planar multi-body space systems
, Article Acta Astronautica ; Volume 145 , April , 2018 , Pages 199-215 ; 00945765 (ISSN) ; Malaek, S. M. B ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
This work describes a new formulation to study the identifiability characteristics of Serially Linked Multi-body Space Systems (SLMBSS). The process exploits the so called “Lagrange Formulation” to develop a linear form of Equations of Motion w.r.t the system Inertia Parameters (IPs). Having developed a specific form of regressor matrix, we aim to expedite the identification process. The new approach allows analytical as well as numerical identification and identifiability analysis for different SLMBSSs' configurations. Moreover, the explicit forms of SLMBSSs identifiable parameters are derived by analyzing the identifiability characteristics of the robot. We further show that any SLMBSS...
Equilibrium analysis of multibody dynamic systems using genetic algorithm in comparison with constrained and unconstrained optimization techniques
, Article Structural and Multidisciplinary Optimization ; Volume 36, Issue 4 , 2008 , Pages 381-391 ; 1615147X (ISSN) ; Dehghani Firouz Abadi, R ; Fotouhi, M. M ; Sharif University of Technology
2008
Abstract
The present paper describes a set of procedures for the solution of nonlinear equilibrium problems in complex multibody systems. To find the equilibrium position of the system, six different optimization algorithms are used to minimize the total potential energy (TPE) of the system and compared with respect to accuracy and efficiency. A computer program is developed to evaluate the equality constraints and objective function of a general multibody dynamic system to find the equilibrium condition. It is seen that the indirect methods have better results and converge faster. Also it is shown that the genetic algorithm (GA) results in a global optimum while the other methods converge to a local...
Modeling and Controller Design of a Single Bladed Aerial Vehicle
, M.Sc. Thesis Sharif University of Technology ; Banazadeh, Afshin (Supervisor) ; Saghafi, Fariborz (Supervisor)
Abstract
In this thesis, multi-body modeling of a monocopter air vehicle is developed based on the Newton-Euler approach along with nonlinear simulation in vertical flight phases consist of climb, hover and descent. Aerodynamic and thrust forces and moments are modeled utilizing blade element momentum theory. The sole control surface is modeled like a conventional flap on a wing. Free flight simulation is implemented in MATLAB Simulink environment to appraise the behavior of the monocopter dynamic and to show the efficiency and productivity of the suggested model. Simulation results present harmonic oscillations in Euler angles, linear and angular velocities that are compatible with the physics and...
Stability Analysis and Control of Periodic Nonlinear Micro Air Vehicles
, M.Sc. Thesis Sharif University of Technology ; Banazadeh, Afshin (Supervisor)
Abstract
This research aims to identify dynamic behavior, determine stability properties, and choose an appropriate control method for nonlinear time-periodic (NLTP) systems by using the optimal design approach. The primary objective is to address the challenges associated with these systems, particularly in making them smarter and more autonomous, while acquiring the knowledge needed to overcome these challenges. In this respect, multi-body modeling and nonlinear simulation of a mono-wing, as a modern NLTP micro air vehicle, are initially developed. A trade study is performed in free-flight conditions based on sensitivity analysis of parameters such as initial conditions, geometry, and mass...
A novel computer-oriented dynamical approach with efficient formulations for multibody systems including ignorable coordinates
, Article Applied Mathematical Modelling ; Volume 62 , 2018 , Pages 461-475 ; 0307904X (ISSN) ; Heidarzadeh, S ; Sharif University of Technology
Elsevier Inc
2018
Abstract
Based on Lagrangian mechanics, we present a novel and computationally efficient set of equations of motion in the matrix notation, for unconstrained or constrained mechanical systems including ignorable coordinates. The equations are applicable to multibody systems including holonomic or nonholonomic constraints. It is shown that by appropriate selection of generalized speeds as a new set of motion variables, the constraint reaction forces can be automatically eliminated from the set of developed reduced dynamical equations in a straightforward manner, resulting in a minimal set of dynamic equations. We present simulation results on one constrained and one unconstrained system to demonstrate...
Workspace analysis of a three dof cable-driven mechanism
, Article Journal of Mechanisms and Robotics ; Volume 1, Issue 4 , 2009 , Pages 1-7 ; 19424302 (ISSN) ; Behzadipour, S ; Sadough Vanini, A ; Alasty, A ; Sharif University of Technology
2009
Abstract
A cable-driven mechanism based on the idea of BetaBot (2005, "A New Cable-Based Parallel Robot With Three Degrees of Freedom, " Multibody Syst. Dyn., 13, pp. 371-383) is analyzed and geometrical description of its workspace boundary is found. In this mechanism, the cable arrangement eliminates the rotational motions leaving the moving platform with three translational motions. The mechanism has potentials for large scale manipulation and robotics in harsh environments. A detailed analysis of the tensionable workspace of the mechanism is presented. The mechanism, in a tensionable position, can develop tensile forces in all cables to maintain its rigidity under arbitrary external loading. A...
Investigation of dynamics and vibration of a three unit pig in oil and gas pipelines
, Article 2008 ASME International Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 31 October 2008 through 6 November 2008 ; Volume 11 , 2009 , Pages 265-275 ; 9780791848722 (ISBN) ; Fazeli, A ; Azimi, M ; Sharif University of Technology
2009
Abstract
In this paper, the transient motion of a three unit intelligent Pipe Inspection Gauge (PIG) while moving across anomalies and bends inside gas/oil pipeline has been investigated. The pipeline fluid has been considered as isothermal and compressible. In addition, the pipeline itself has also been considered to be flexible. The fluid continuity and momentum equations along with the 3D multi body dynamic equations of motion of the pig comprise a system of coupled dynamic differential equations which have been solved numerically. Pig's position and velocity profiles as well as upstream and downstream fluid's pressure waves are presented as simulation results which provide a better understanding...
Determination of mechanical properties of FCC nano-beams based on molecular dynamics simulations
, Article 5th International Symposium on Mechatronics and its Applications, ISMA 2008, Amman, 27 May 2008 through 29 May 2008 ; October , 2008 ; 9781424420346 (ISBN) ; Meghdari, A ; Hosseini, A. E ; Sharif University of Technology
2008
Abstract
In this research, we have modeled nano-Beams using molecular dynamics. The scope of our study is FCC metals, therefore an appropriate inter-atomic potential for this kind of materials must be chosen. A multi-body long-range potential proposed by Sutton-Chen, which has been used in many physical investigations of FCC metals is applied in our study. Using conducted simulations, the different mechanical properties of material such as elastic modulus, shear modulus and poison's ratio are calculated. The results show that the elastic properties decrease with increase in nano cantilever size. ©2008 IEEE
Investigation of the effect of the added mass fluctuation and lateral vibration absorbers on the vertical nonlinear vibrations of the offshore wind turbine
, Article Nonlinear Dynamics ; Volume 103, Issue 2 , 2021 , Pages 1499-1515 ; 0924090X (ISSN) ; Moradi, H ; Vossoughi, G ; Sharif University of Technology
Springer Science and Business Media B.V
2021
Abstract
In this article, the effects of the changes in the mass of the floating wind turbine (as a multi-body system) on its nonlinear vertical vibrations are investigated. The fluctuations of the hydrodynamic added mass of the floating platform and the mass of the vibration absorbers, which added to the structure to mitigate the lateral vibrations, change the mass and consequently the dynamics of the vertical vibrations. In this regard, first, the governing equations of the vertical vibrations of the floating wind turbine are derived. The FAST code is used to validate the proposed model of the dynamics of the vertical vibrations through numerical simulations. Then, derived equations are solved...
Quasi-velocities definition in Lagrangian multibody dynamics
, Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 235, Issue 20 , 2021 , Pages 4679-4691 ; 09544062 (ISSN) ; Zohoor, H ; Sharif University of Technology
SAGE Publications Ltd
2021
Abstract
Based on Lagrangian mechanics, use of velocity constraints as a special set of quasi-velocities helps derive explicit equations of motion. The equations are applicable to holonomic and nonholonomic constrained multibody systems. It is proved that in proposed quasi-spaces, the Lagrange multipliers are eliminated from equations of motion; however, it is possible to compute these multipliers once the equations of motion have been solved. The novelty of this research is employing block matrix inversion to find the analytical relations between the parameters of quasi-velocities and equations of motion. In other words, this research identifies arbitrary submatrices and their effects on equations...
Aeroelastic behavior of a slender body considering free fittings
, Article Journal of Mechanical Science and Technology ; Volume 24, Issue 9 , 2010 , Pages 1755-1762 ; 1738494X (ISSN) ; Haddadpour, H ; Ahmadian, M. T ; Sharif University of Technology
2010
Abstract
This paper presents dynamic and vibration analysis of a flight vehicle with consideration of the free fitting between its two sections. Using the Lagrangian approach, a general analytical model is developed for a non-spinning elastic vehicle in planar motion. The model contains rigid body motions and bending deformations of two sections of the flight vehicle and a nonlinear rotational spring that models the freeplay between the two sections. To express bending deformation, the mode summation method is applied. It is shown that freeplay in the joints significantly affects the trajectory of the flight vehicle. Numerical examples reveal the effect of a joint's nonlinearity on the trajectory and...
Simulation of vehicle body spot weld failures due to fatigue by considering road roughness and vehicle velocity
, Article Simulation Modelling Practice and Theory ; Volume 105 , 2020 ; Ahmadi, A ; Reza Kasyzadeh, K ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Durability of the vehicle components needs special attention in the design step due to this fact that the loads on a vehicle are dynamic by their nature. Also, fatigue resistance of the vehicle body is quite important as it is the main load-bearing component among others. The main purpose of the present research is to simulate the spot weld failures of the vehicle body structure due to fatigue damage induced on the body during standardized maneuvers. This was accomplished by using a combination of multi-body dynamics and finite element analyses. To enhance the precision of the analysis, a thickness-dependent nugget diameter was utilized to model the spot welds. To validate the finite element...
Design optimization of an above-knee prosthesis based on the kinematics of gait
, Article 30th Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS'08, Vancouver, BC, 20 August 2008 through 25 August 2008 ; 2008 , Pages 4274-4277 ; 9781424418152 (ISBN) ; Farahmand, F ; Parnianpour, M ; Sharif University of Technology
2008
Abstract
A dynamic model of an above-knee prosthesis during the complete gait cycle was developed. The model was based on a two-dimensional multi-body mechanical system and included a hydraulic and an elastic controller for the knee and a kinematical driver controller for the prosthetic ankle. The equations of motion were driven using Lagrange method. Simulation of the foot contact was conducted using a two-point penetration contact model. The knee elastic and hydraulic controller units, the knee extension stop, and the kinematical driver controller of the ankle were represented by a spring and a dashpot, a nonlinear spring, and a torsional spring-damper within a standard prosthetic configuration....