Search for: mass-spring-models
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    Guiding medical needles using single-point tissue manipulation

    , Article Proceedings - IEEE International Conference on Robotics and Automation, 12 May 2009 through 17 May 2009, Kobe ; 2009 , Pages 2705-2710 ; 10504729 (ISSN); 9781424427895 (ISBN) Torabi, M ; Hauser, K ; Alterovitz, R ; Duindam, V ; Goldberg, K ; Sharif University of Technology
    This paper addresses the use of robotic tissue manipulation in medical needle insertion procedures to improve targeting accuracy and to help avoid damaging sensitive tissues. To control these multiple, potentially competing objectives, we present a phased controller that operates one manipulator at a time using closed-loop imaging feedback. We present an automated procedure planning technique that uses tissue geometry to select the needle insertion location, manipulation locations, and controller parameters. The planner uses a stochastic optimization of a cost function that includes tissue stress and robustness to disturbances. We demonstrate the system on 2D tissues simulated with a... 

    Real-time simulation of the nonlinear visco-elastic deformations of soft tissues

    , Article International Journal of Computer Assisted Radiology and Surgery ; Volume 6, Issue 3 , 2011 , Pages 297-307 ; 18616410 (ISSN) Basafa, E ; Farahmand, F ; Sharif University of Technology
    Purpose: Mass-spring-damper (MSD) models are often used for real-time surgery simulation due to their fast response and fairly realistic deformation replication. An improved real time simulation model of soft tissue deformation due to a laparoscopic surgical indenter was developed and tested. Method: The mechanical realization of conventional MSD models was improved using nonlinear springs and nodal dampers, while their high computational efficiency was maintained using an adapted implicit integration algorithm. New practical algorithms for model parameter tuning, collision detection, and simulation were incorporated. Results: The model was able to replicate complex biological soft tissue... 

    Biped hopping control bazsed on spring loaded inverted pendulum model

    , Article International Journal of Humanoid Robotics ; Volume 7, Issue 2 , 2010 , Pages 263-280 ; 02198436 (ISSN) Tamaddoni, S. H ; Jafari, F ; Meghdari, A ; Sohrabpour, S ; Sharif University of Technology
    Human running can be stabilized in a wide range of speeds by automatically adjusting muscular properties of leg and torso. It is known that fast locomotion dynamics can be approximated by a spring loaded inverted pendulum (SLIP) system, in which leg is replaced by a single spring connecting body mass to ground. Taking advantage of the inherent stability of SLIP model, a hybrid control strategy is developed that guarantees a stable biped locomotion in sagittal plane. In the presented approach, nonlinear control methods are applied to synchronize the biped dynamics and the spring-mass dynamics. As the biped center of mass follows the mass of the mass-spring model, the whole biped performs a... 

    Dynamic modeling of a piezo-driven compliant mechanism using modal analysis

    , Article ASME 2009 International Mechanical Engineering Congress and Exposition, 13 November 2009 through 19 November 2009 ; Volume 10, Issue PART B , 2010 , Pages 715-720 ; 9780791843833 (ISBN) Darki, A. A ; Shahidi, A. R ; Zohoor, H ; Sanikhani, H ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME) 
    Dynamic modeling of piezo-driven compliant mechanisms is necessary to predict dynamic behavior of nanopositioning systems, and also to optimize their controlling methods. Dynamic tests on a real system or dynamic analyses on a FEM model is very time consuming when they must be carried out iteratively. According to previous works, obtaining static specifications of model is possible within a reasonable error margin. But all geometric dimensions and mass distribution details of the whole moving parts should be considered to calculate dynamic specifications of the model. In this paper, a functional method is described to obtain dynamic specifications of an planar compliant mechanism, by means... 

    A novel method of gait synthesis for bipedal fast locomotion

    , Article Journal of Intelligent and Robotic Systems: Theory and Applications ; Volume 53, Issue 2 , 2008 , Pages 101-118 ; 09210296 (ISSN) Meghdari, A ; Sohrabpour, S ; Naderi, D ; Tamaddoni, S. H ; Jafari, F ; Salarieh, H ; Sharif University of Technology
    Common methods of gait generation of bipedal locomotion based on experimental results, can successfully synthesize biped joints' profiles for a simple walking. However, most of these methods lack sufficient physical backgrounds which can cause major problems for bipeds when performing fast locomotion such as running and jumping. In order to develop a more accurate gait generation method, a thorough study of human running and jumping seems to be necessary. Most biomechanics researchers observed that human dynamics, during fast locomotion, can be modeled by a simple spring loaded inverted pendulum system. Considering this observation, a simple approach for bipedal gait generation in fast... 

    A non-linear mass-spring model for more realistic and efficient simulation of soft tissues surgery

    , Article Medicine Meets Virtual Reality 16 - Parallel, Combinatorial, Convergent: NextMed by Design, MMVR 2008, Long Beach, CA, 30 January 2008 through 1 February 2008 ; Volume 132 , 2008 , Pages 23-25 ; 09269630 (ISSN); 9781586038229 (ISBN) Basafa, E ; Farahmand, F ; Vossoughi, G ; Sharif University of Technology
    IOS Press  2008
    An extension to the classical mass-spring model for more realistic simulation of soft tissues for surgery simulation was proposed. The conventional equations of mass-spring model were generalized for non-linear springs, and model parameters were tuned using experimental data. Results show that the proposed model is fast and interactive, and also demonstrate the typical nonlinear and visco-elastic behaviors of soft tissues well. © 2008 The authors. All rights reserved  

    Semi active vibration control of a passenger car using magnetorheological shock absorber

    , Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, Istanbul, 12 July 2010 through 14 July 2010 ; Volume 3 , 2010 , Pages 21-27 ; 9780791849170 (ISBN) Fellah Jahromi, A ; Zabihollah, A ; Sharif University of Technology
    A novel semi-active control system for suspension systems of passenger car using Magnetorheological (MR) damper is introduced. The suspension system is considered as a mass-spring model with an eight-degrees-of-freedom, a passive damper and an active damper. The semi-active vibration control is designed to reduce the amplitude of automotive vibration caused by the alteration of road profile. The control mechanism is designed based on the optimal control algorithm, Linear Quadratic Regulator (LQR). In this system, the damping coefficient of the shock absorber changes actively trough inducing magnetic field. It is observed that utilizing the present control algorithm may significantly reduce...