Showing 5 results for Fesharakifard
Vahid Aberoomand, Rasul Fesharakifard, Ali Kamal Eigoli,
Volume 16, Issue 12 (2-2017)
Abstract
In electromagnetic motors, increase in output torque leads to increase in rotor inertia. Various robotics applications, especially haptic interfaces, oblige convenient dynamic performances of electromagnetic motors which are strongly in turn influenced by the rotor’s inertia. In the present paper, a robust control method for a viscous hybrid actuator is developed which supplies a desired varying torque while maintaining a constant low inertia. This hybrid actuator includes two dc motors with the shafts coupled through a rotational damper using a viscous non-contact coupler. This coupling method is based on Eddy current to provide the required performances. The large far motor eliminates or reduces the inertial forces and external dynamics effects on the actuator. The small near motor provides the desired output torque. Since the system is essentially linear, the applied robust control method is based on Hꝏ and parametric uncertainties and physical constraints including motors’ voltages saturation, rotary damper’s speed saturation, fastest user’s speed and acceleration applied to the actuator and force sensor noise are considered in its design. Also the robust method of µ-synthesis for the system in presence of parameteric uncertainties and other physical constraints are studied. The implementation of the controller on a 1 dof haptic interface model validate the achievement of the desired performances.
Ramin Afhami, Rasul Fesharakifard, Mohammad Azam Khosravi,
Volume 18, Issue 3 (5-2018)
Abstract
This paper focuses on the dynamic modeling of quadrotor with respect to changes in operating conditions. The main objective of this investigation is to provide complete governing quadrotor dynamic equations using the Euler-Lagrange method considering all aerodynamic forces which affect it's motion. In previous papers, dynamical equations are never considered comprehensively. The study of quadrotor's dynamics permits to understand it's physics and behavior and provides a precise model of the system. Once such a model is obtained, the control of quadrotor turns much simpler than current inaccurate models. In order to take into account, the set of forces and torques involved in quadrotor dynamics, the previous studies are used and after describing each of the forces and their precise terms, the complete dynamic quadrature model is presented. At the end, the system's performance is simulated in two different operating conditions, one regardless of the external object coupled with quadrotor, and the other in the coupled condition with a camera, and by this means, the achieved dynamic model is validated. In the first operating conditions in two different tests, the dynamic equations of the present work will be compared against the previous ones. In the second operating conditions, the quadrotor performance under influence of a connected camera whose motion changes continuously the system dynamic equations is studied.
Z. Naseriasl , R. Fesharakifard, H. Ghafarirad ,
Volume 19, Issue 4 (April 2019)
Abstract
Nowadays, the need of welding industry's to improve weld quality has led to the consideration of robotic welding. The use of articulated industrial robots for welding has many challenges. Because some robots do not have the capability of online error compensating of the seam track. Therefore, in order to remove the welding seam tracking error, the use of an auxiliary mechanism is proposed in this article. This mechanism is a table with 1-degree of freedom (dof), which produces a continuous motion in workpiece under the welding torch. The rotational motion of the motor is transformed into a translational motion of the workpiece by a ball-screw system, where this linear motion compensates the tracking error. Since in the welding process, relative motion accuracy of the workpiece and the welding torch is crucial, proper control of the interface table ensures the weld quality. In this paper, two different methods for controlling the table with 1-dof are studied. In the first method, due to the complexity of friction model of the ball-screw mechanism and the presence of nonlinear terms, this part of the model is considered as an external disturbance, and, then, a PID controller for the linear part is designed. In the second method, known as feedback linearization, a control law is designed for that the tracking error tends to zero by passing time. Throught a comparison between the simulation results, the second control method demonstrates better precision relating the first controller. While the error of PID controller equals to 3 mm and the second controller’s error does not go beyond 0.5 mm. At last, the experimental cell used for the robotic welding is introduced to evaluate the mentioned results.
Farnoud Norouzi Niyaee, Kamran Taheri Sartang, Mohammad Mahan Taheri Sartangtaghavi Farahi, Rasoul Taheri Sartangtaghavi FarahiFesharakifard, ,
Volume 22, Issue 10 (October 2022)
Abstract
Choosing the right equipment in terms of price, performance and reliability, is one of the main challenges in the automation industry. Among these equipments, electric motors are the most important elements which are widely used in the industries. Electro motors selection is made according to certain rules and principles, and it is very important to know the governing conditions. Using amotor with less power than required will lead to system failure and a motor with much more power will result in extra costs. In this article, scientific selection of an electric motor for the bending process in an automation system has been discussed. Using real conditions of a manufacturer and available data in articles and books, the necessary relationships were extracted. 28 number of motors (among the available ones) were nominated in the first stage of preliminary monitoring. Then, by applying other prevailing conditions and characteristics, 3 motors with different powers selected for final investigations. Eventually, after using Simscape simulations & exerting less energy consumption criteria, the 5RK90GE-CW2ML2 motor (manufactured by Oriental Motor Company) was selected and was approved after satisfying the power, quality and safety conditions.
Nasser Malboubi, Mohammad Reza Razfar, Rasul Fesharakifard,
Volume 23, Issue 1 (January 2022)
Abstract
در این مقاله به جبران خطای ناشی از خیز ابزار در جهت عمود بر پیشروی حین برادهبرداری در فرزکاری پرداخته شدهاست. هنگام فرزکاری، بدلیل وجود نیروی مزاحم عمود بر پیشروی در ابزار، انحرافی رخ میدهد که دقت ماشینکاری را کاهش میدهد. با نیروی جبرانکننده در میانه ابزار این خیز کاهش مییابد و برای ایجاد این نیرو میتوان عملگر هیدرولیکی تعبیه کرد. بنابراین همزمان با ماشینکاری، نیرویی متناسب اما بر خلاف نیروی مزاحم اعمال خواهد شد تا این خطا کاهش یابد. بدین منظور نیروهای مزاحم در طول ماشینکاری و خیز ناشی از آن باید بدست آید و سپس نیروی متناسب به ابزار اعمال شود. قدم اول در سالیدورک فرز انگشتی مدلسازی و بعد به روش عددی، عملیات ماشینکاری برای محاسبه نیروی ایجاد کننده خطا (پارامتر خروجی) شبیهسازی میشود که در آن تیغه فرز و قطعهکار هر دو بصورت انعطافپذیر سهبعدی میباشد. با یافتن نتایج نیرویی ابزار تحت حالات مختلف ماشینکاری (با سرعت پیشروی، دور و عمق و تعداد لبه متفاوت بعنوان پارامتر های کنترلی) از آباکوس، مدل نیمهتحلیلی ماشینکاری در ماژول Simscape Multibodyمتلب، ایجاد میشود. با مقایسه نتایج با آباکوس پارامترهای مدل تودهای متلب تنظیم میگردد. با استخراج نیرو بصورت جدولی از آباکوس و اعمال آن در متلب خیز سریع تر از مدل عددی بدست میآید. جهت یافتن نیروی جبرانکننده(پارامتر خروجی)، از تئوری تیرها ضریب 3.2 برابر نیروی ماشینکاری برای اعمال به وسط ابزار حاصل میشود. این نیرو بصورت حلقه باز در مدل متلب وارد و نتیجه آن کاهش خطا درحدود 70 درصد در میزان خیز جانبی نوک ابزار میشود.
