Search for: motion-control
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    On self-similar behaviour of the hysteresis loops in pitching motions

    , Article Aeronautical Journal ; Volume 108, Issue 1086 , 2004 , Pages 427-434 ; 00019240 (ISSN) Soltani, M. R ; Davari, A. R ; Sharif University of Technology
    Royal Aeronautical Society  2004
    A new similarity parameter has been used for analyzing the unsteady aerodynamic, behaviour of vehicles undergoing sinusoidal pitching motion. If this parameter is identical for two unsteady manoeuvres with different reduced frequencies and oscillation amplitudes, the corresponding hysteresis loops of the force and moment collapse on each other, To support and verify this, extensive unsteady wind tunnel tests have been conducted on a standard model, which is a well known fighter type configuration. The acquired data were used to train a certain type of neural network, called the Generalised Regression Neural Network (GRNN), to reduce the number of wind tunnel runs. The scheme, once proved to... 

    A robotic model of transfemoral amputee locomotion for design optimization of knee controllers

    , Article International Journal of Advanced Robotic Systems ; Volume 10 , 2013 ; 17298806 (ISSN) Shandiz, M. A ; Farahmand, F ; Osman, N. A. A ; Zohoor, H ; Sharif University of Technology
    A two-dimensional, seven link, nine degrees of freedom biped model was developed to investigate the dynamic characteristics of normal and transfemoral amputee locomotion during the entire gait cycle. The equations of motion were derived using the Lagrange method and the stance foot-ground contact was simulated using a five-point penetration model. The joint driving torques were obtained using forward dynamic optimization of the normal human gait and applied to the intact joints of the amputee. Three types of motion controllers; frictional, elastic and hydraulic were considered for the prosthetic joints of the amputee and their design parameters were optimized to achieve the closest... 

    The influence of different configurations on position error of linear variable reluctance resolvers

    , Article 2017 25th Iranian Conference on Electrical Engineering, ICEE 2017, 2 May 2017 through 4 May 2017 ; 2017 , Pages 955-960 ; 9781509059638 (ISBN) Daniar, A ; Nasiri Gheidari, Z ; Sharif University of Technology
    In this study a new linear variable reluctance (LVR) resolver is proposed for linear motion control systems. The proposed resolver works based on the sinusoidal variation of air-gap length. Both signal and excitation windings are wound on primary teeth while the secondary has no winding. Two different configurations are examined for the sensor: long, stationary primary with short, moving secondary and long, stationary secondary with short, moving primary. The effect of secondary's number/shape of saliencies and primary's winding configuration on the accuracy of detected position is discussed. 2-D and 3-D time stepping finite element method (FEM) are used for analysis. By comparing the... 

    The influence of winding's pole pairs on position error of linear resolvers

    , Article 2017 25th Iranian Conference on Electrical Engineering, ICEE 2017, 2 May 2017 through 4 May 2017 ; 2017 , Pages 949-954 ; 9781509059638 (ISBN) Saneie, H ; Nasiri Gheidari, Z ; Tootoonchian, F ; Sharif University of Technology
    Using linear position sensors is necessary in linear motion control systems. In this paper the influence of winding's pole pairs on the accuracy of linear resolver is studied. 2-D and 3-D time stepping finite element method (FEM) is used to calculate the performance characteristics of the resolver. The effect of finite mover's length, transverse edge effect and the end windings length are discussed in detail. Then a prototype of the studied resolver along with its experimental test setup is built. Good correlation between simulation and experimental results verified the simulation process. © 2017 IEEE  

    Subdomain model for predicting the performance of linear resolver considering end effect and slotting effect

    , Article IEEE Sensors Journal ; Volume 20, Issue 24 , 2020 , Pages 14747-14755 Paymozd, A ; Saneie, H ; Nasiri Gheidari, Z ; Tootoonchian, F ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2020
    Linear position sensors are essential parts of linear motion control systems. Among different linear sensors, linear resolvers are an appropriate choice for harsh environments. Design optimization of linear resolvers needs an accurate, but computationally fast model for their performance prediction. Slotting effect of the cores and end effect are two important phenomena that must be accurately involved in the model to ensure its reliable results. Therefore, in this paper a semi-analytical model based on subdomain modeling technique is proposed for linear resolvers. Then, according to the developed model, the induced voltages in the signal windings of the resolver are calculated and... 

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

    , Article WSEAS Transactions on Systems ; Volume 5, Issue 12 , 2006 , Pages 2839-2843 ; 11092777 (ISSN) Damangir, S ; Jafarijashemi, G ; Mamduhi, M ; Aghmioni, A. N ; Zohoor, H ; Sharif University of Technology
    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... 

    Modeling, control and islanding detection of microgrids with passive loads

    , Article Proceedings of EPE-PEMC 2010 - 14th International Power Electronics and Motion Control Conference, 6 September 2010 through 8 September 2010 ; September , 2010 , Pages T11107-T11112 ; 9781424478545 (ISBN) Popov, M ; Karimi, H ; Nikkhajoei, H ; Terzija, V ; Sharif University of Technology
    This paper presents a control scheme for microgrids with passive loads. The existing control techniques for distributed generation systems are designed to operate either in the grid-connected or in the islanded mode. In the grid-connected mode of operation, a currentcontrolled scheme based on d-q variables is used for the regulation of real and reactive powers of the converter. In the islanded mode of operation, the converter is controlled in the voltage-controlled mode. This paper deals with the modeling of both control schemes. Furthermore, reconnection from the islanded mode to the grid-connected mode based on the use of adequate Phase-Locked Loops (PLLs) has been demonstrated  

    Position error calculation of linear resolver under mechanical fault conditions

    , Article IET Science, Measurement and Technology ; Volume 11, Issue 7 , 2017 , Pages 948-954 ; 17518822 (ISSN) Daniar, A ; Nasiri-Gheidari, Z ; Tootoonchian, F ; Sharif University of Technology
    Position sensors are inseparable part of motion control systems. Linear resolvers (LRs) are electromagnetic position sensors that are suitable for high vibration, polluted environments. The accuracy of their detected position can be affected by different mechanical faults. In this study, variety of possible mechanical faults along with their mathematical index in LRs is introduced. Static eccentricity, dynamic eccentricity, inclined mover and run out error are the presented mechanical faults that are discussed independently and simultaneously. Then, three-dimensional non-linear, time-stepping finite element method is employed to investigate the performance of the studied resolver under... 

    Overtaking stationary and moving obstacles for autonomous ground vehicles

    , Article 8th Biennial ASME Conference on Engineering Systems Design and Analysis, ESDA2006, Torino, 4 July 2006 through 7 July 2006 ; Volume 2006 , 2006 ; 0791837793 (ISBN); 9780791837795 (ISBN) Amini Javid, G ; Durali, M ; Kasaaizadeh, A ; Sharif University of Technology
    American Society of Mechanical Engineers  2006
    In this paper, a method for overtaking stationary and moving obstacles will be introduced. The method consists of designing a desired trajectory for lateral motion of the vehicle and then using a lateral motion controller for tracking this desired trajectory. The desired trajectory is a sigmoid exponential function of relative distance between the vehicle and the obstacle and guarantees overtaking the obstacle, if tracked exactly, despite of lateral and longitudinal motions of the obstacle. Lateral acceleration of the vehicle should not exceed safety limits during tracking desired trajectory. This matter has been used as a decision criterion for determining feasible and unfeasible desired... 

    Dynamic modeling and optimal control of a novel microswimmer with gimbal based disks

    , Article Robotica ; Volume 39, Issue 8 , 2021 , Pages 1468-1484 ; 02635747 (ISSN) Nickandish, A ; Pishkenari, H. N ; Sharif University of Technology
    Cambridge University Press  2021
    We have introduced a new low-Reynolds-number microrobot with high 3D maneuverability. Our novel proposed microrobot has a higher rank of the controllability matrix with respect to the previous microswimmers which makes it capable of performing complex motions in space. In this study, governing equations of the microswimmer's motion have been derived and simulated. Subsequently, we have proposed a cascade optimal control technique to control the swimmer trajectory. In the proposed control scheme, the actuation is provided in a way that an exponential stability on the system trajectory error as well as minimum fluctuations of control signals are achieved. © The Author(s), 2021. Published by... 

    Robust backstepping control of robotic nurse unit to assist paraplegic patient

    , Article 2005 ASME International Mechanical Engineering Congress and Exposition, IMECE 2005, Orlando, FL, 5 November 2005 through 11 November 2005 ; Volume 74 DSC, Issue 1 PART A , 2005 , Pages 641-646 ; 0791842169 (ISBN); 9780791842164 (ISBN) Ghafari, A. S ; Meghdari, A ; Sharif University of Technology
    A robust motion controller based on backstepping technique for a robotic nurse unit to assist paraplegic patients is addressed in this paper. A backstepping controller is proposed for tracking a desired trajectory in hospital environment. Simulation results are provided to validate the proposed controller. The results show satisfactory performance of the designed controller in tracking problem. Copyright © 2005 by ASME  

    Anti-sway control of a gantry crane with flexible rope

    , Article 3rd International Conference on Advances in Vehicle Control and Safety 2007, AVCS 2007 and 3rd International Conference on Integrated Modeling and Analysis in Applied Control and Automation ; 2007 , Pages 23-28 ; ISSN: 23052139 Radparvar, Y ; Alasti, A ; Sharif University of Technology
    In this paper, a new approach for controlling the sway angle of the load in trolley cranes is presented which is based on the flexibility of the cable and variation of its length by the time. The crane dynamics has been described by hybrid PDE and ODE equations which uses the PDE as the equations of motion for the flexible cable and ODE for those of the trolley and the load. The purpose of the controller is to transport the load to the desired position and to eliminate its sway angle at the destination. The control law is based on the Lyapunov's second method. The efficiency of the proposed controller is demonstrated via various simulations  

    Design and performance analysis of a transparent force control strategy for an exoskeleton

    , Article International Conference on Robotics and Mechatronics, ICROM 2015, 7 October 2015 through 9 October 2015 ; 2015 , Pages 563-568 ; 9781467372343 (ISBN) Rashidi, A ; Zibafar, A ; Khezrian, R ; Vossoughi, G ; Sharif University of Technology
    Exoskeleton robots are developed for human rehabilitation and power augmentation. Human and robot interaction is an important issue involved with these robots. In this paper, the interaction force reduction is considered leading to the transparency of a lower limb exoskeleton during swing phase of walking. Achieving this goal, a robust Lyapunov based motion control method has been developed. The desired reference signals for motion control are generated using a direct force control approach. Robot accelerations are estimated by an observer to be employed in the control loop. An adaptation procedure has been proposed for the bound estimation of uncertainties. As part of assumptions, the... 

    Achievable performance region for a fractional-order proportional and derivative motion controller

    , Article IEEE Transactions on Industrial Electronics ; Volume 62, Issue 11 , June , 2015 , Pages 7171-7180 ; 02780046 (ISSN) Badri, V ; Tavazoei, M. S ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2015
    In recent years, design and tuning of fractional-order controllers for use in motion control have attracted much attention. This paper deals with one of the interesting methods that have been recently proposed for tuning fractional-order proportional and derivative (FOPD) motion controllers. The FOPD controller tuned based on the considered method results in simultaneously meeting the desired phase margin, the desired gain crossover frequency, and the flatness of the phase Bode plot at such a frequency. Since, in this tuning method, the derivative parameter and order are determined in a graphical way, in the first view, it is not clear for which pairs of phase margin and gain crossover... 

    Performance verification of saturated IPM bearingless motors considering magnetic pull variation

    , Article Proceedings - 2016 IEEE International Power Electronics and Motion Control Conference, PEMC 2016, 25 September 2016 through 28 September 2016 ; 2016 , Pages 643-649 ; 9781509017980 (ISBN) Faiz, J ; Nasiri Gheidari, Z ; Rahman, A ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc  2016
    Interior permanent magnet (IPM) bearingless motors are becoming a good choice for high-speed applications. In these motors, reducing the thickness of the PM leads to the increase of the radial forces which affects the demagnetizing fields. Various types of PM motors have so far been recommended for enhancement of the radial forces and torque. In the proposed IPM motor the d-axis flux-linkage and the q-axis torque component are raised due to the armature reaction and this saturates the stator teeth. In addition, the magnetic attraction force generated by displacement force depends on the armature reaction. The mathematical model of IPM bearingless motor based on the dq transformation,... 

    Stability analysis of robotic swarm with limited field of view

    , Article ASME 2007 International Mechanical Engineering Congress and Exposition, IMECE 2007, 11 November 2007 through 15 November 2007 ; Volume 9 , 2007 , Pages 175-184 ; 0791843033 (ISBN) Etemadi, Sh ; Alasty, A ; Vossoughi, G. R ; Sharif University of Technology
    American Society of Mechanical Engineers (ASME)  2007
    This paper presents an analytical study of swarm motion in static environments, in which, motion of the swarm is modeled as a quasi static model. Motion of each member is being affected by interactive forces and environmental effects. Interactive effects on each member could be attractive or repulsive due to being far from or close to other members respectively. Environmental effects also could be attractive or repulsive or a combination of both. The method is based on Lyapunov analysis. Two objectives are investigated through the analysis; one is to preserve the unity of swarm i.e. not losing any member through motion, and the other is to move toward attractant areas and away from repellant... 

    Dynamics and control of a novel microrobot with high maneuverability

    , Article Robotica ; Volume 39, Issue 10 , 2021 , Pages 1729-1738 ; 02635747 (ISSN) Esfandbod, A ; Nejat Pishkenari, H ; Meghdari, A ; Sharif University of Technology
    Cambridge University Press  2021
    In this study, we introduce a novel three-dimensional micro-scale robot capable of swimming in low Reynolds number. The proposed robot consists of three rotating disks linked via three perpendicular adjustable rods, actuated by three rotary and three linear motors, respectively. The robot mechanism has an important property which makes it superior to the previously designed micro swimmers. In fact, our goal is designing a micro swimmer which its controllability matrix has full rank and hence it will be capable to perform any desired maneuver in space. After introducing the mechanism and derivation of the dynamical equations of motion, we propose a control method to steer the robot to the... 

    A method for real-time safe navigation in noisy environments

    , Article 2013 18th International Conference on Methods and Models in Automation and Robotics, MMAR 2013, Miedzyzdroje ; 2013 , Pages 329-333 ; 9781467355063 (ISBN) Neyshabouri, S. A. S ; Kamali, E ; Niknezhad, M. R ; Monfared, S. S. M. S ; Sharif University of Technology
    The challenge of finding an optimized and reliable path dates back to emersion of mobile robots. Several approaches have been developed that have partially answered this need. Satisfying results in previous implementations has led to an increased utilization of sampling-based motion planning algorithms in recent years, especially in high degrees of freedom (DOF), fast evolving environments. Another advantage of these algorithms is their probabilistic completeness that guarantees delivery of a path in sufficient time, if one exists. On the other hand, sampling based motion planners leave no comment on safety of the planned path. This paper suggests biasing the Rapidly-exploring Random Trees... 

    A fuzzy modeling and control method for PWM converters

    , Article Proceedings of EPE-PEMC 2010 - 14th International Power Electronics and Motion Control Conference, 6 September 2010 through 8 September 2010 ; September , 2010 , Pages T3186-T3190 ; 9781424478545 (ISBN) Tahami, F ; Nejadpak, A ; Sharif University of Technology
    The state-space averaging applied to switched networks generally results in nonlinear systems. It is common to perform a small signal linearization about an operating point to obtain a linear system. When the variations in signals are large, e.g., in PFC rectifiers, the small signal approximation produces results that are susceptible to instability problems. In this paper a class of piecewise linear models merged by fuzzy system are introduced for PWM converters. The necessary and sufficient and conditions for stability of fuzzy models using fuzzy state-feedback controllers are given. The results obtained are illustrated with a buck-boost converter. The simulation and experimental results... 

    Control of lumbar spine flexion-extension movement by PD controller and feedback linearization method

    , Article ICCAS 2010 - International Conference on Control, Automation and Systems, 27 October 2010 through 30 October 2010 ; 2010 , Pages 2024-2029 ; 9781424474530 (ISBN) Abedi, M ; Vossughi, G. R ; Parnianpour, M ; Sharif University of Technology
    The role of motor control in development of low back pain is subject of many researches both in theoretical and experimental fields. In this work flexion-extension movement of lumbar spine have been controlled by three different methods, including feedback linearization (FBL), PD control and their combinations. The model involves 7 links: 1 link for pelvis, 5 links for lumbar vertebrae and 1 link for trunk. Torque actuators have been used on each joint to make them follow desired trajectory. In linear control method, equations of motion have been linearized with respect to upright position and then control signals have been applied in the direction of eigenvectors. Robustness of each method...