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Article
Design Interval Type-2 Fuzzy Like (PID) Controller for Trajectory Tracking of Mobile Robot

Authors: Mustafa Y. Abbas --- Mohamed J. Mohamed
Journal: IRAQI JOURNAL OF COMPUTERS,COMMUNICATION AND CONTROL & SYSTEMS ENGINEERING المجلة العراقية لهندسة الحاسبات والاتصالات والسيطرة والنظم ISSN: 18119212 Year: 2019 Volume: 19 Issue: 3 Pages: 1-15
Publisher: University of Technology الجامعة التكنولوجية

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Abstract

One of the major problems in the field of mobile robots is the trajectory tracking problem. There are a big number of investigations for different control strategies that have been used to control the motion of the mobile robot when the nonlinear kinematic model of mobile robots was considered. The trajectory tracking control of autonomous wheeled mobile robot in a changing unstructured environment needs to take into account different types of uncertainties. Type-1 fuzzy logic sets present limitations in handling those uncertainties while type-2 fuzzy logic sets can manage these uncertainties to give a superior performance. This paper focuses on the design of interval type-2 fuzzy like proportional-integral-derivative (PID) controller for the kinematic model of mobile robot. The firefly optimization algorithm has been used to find the best values of controller’s parameters. The aim of this controller is trying to force the mobile robot tracking a pre-defined continuous path with minimum tracking error. The Matlab simulation results demonstrate the good performance and robustness of this controller. These were confirmed by the obtained values of the position tracking errors and a very smooth velocity, especially with regards to the presence of external disturbance or change in the initial position of mobile robot. Finally, in comparison with other proposed controllers, the results of nonlinear IT2FLC PID controller outperform the nonlinear PID neural controller in minimizing the MSE for all control variables and in the robustness measure.


Article
Motion Control of Three Links Robot Manipulator (Open Chain) with Spherical Wrist

Authors: Hassan Mohammad Alwan حسن محمد علوان --- Zaid Hikmat Rashid زيد حكمت رشيد
Journal: Al-Khwarizmi Engineering Journal مجلة الخوارزمي الهندسية ISSN: 18181171 23120789 Year: 2019 Volume: 15 Issue: 2 Pages: 13-23
Publisher: Baghdad University جامعة بغداد

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Abstract

Robot manipulator is a multi-input multi-output system with high complex nonlinear dynamics, requiring an advanced controller in order to track a specific trajectory. In this work, forward and inverse kinematics are presented based on Denavit Hartenberg notation to convert the end effector planned path from cartesian space to joint space and vice versa where a cubic spline interpolation is used for trajectory segments to ensure the continuity in velocity and acceleration. Also, the derived mathematical dynamic model is based on Eular Lagrange energy method to contain the effect of friction and disturbance torques beside the inertia and Coriolis effect. Two types of controller are applied ; the nonlinear computed torque control (CTC) and the simpler form of its Proportional Derivative plus Gravity (PD+G) where they are designed to reduce the tracking trajectory errors which tend to zero where the used Kp and Kv gains are 900,60. Also, the RMS errors for tracking a step input of CTC were equal to [2.5E-14, 4.4E-14, 5.0E-14, -4.7E-14, -3.9E-14, -4.6E-14] (deg) and of PD+G were equal to [-1.77E-5, -1.22E-6, -4.28E-6, -8.97E-6, -1.32E-5, 1.05E-5] (deg) for joints one to six, respectively. The results show that CTC is more accurate but requires additional acceleration input and is more computationally extensive and PD+G controller is performed with acceptable tracking errors in manipulator position control applications.

الاذرع المناورة هي نظام متعدد المدخلات و المخرجات ذو دينامية غير خطية معقدة يحتاج الى مسيطر متقدم من اجل تعقب مسار محدد. في هذا البحث, الكينماتك الامامي و العكسي تم حسابه بالاعتماد على طريقة دانفينت – هارتنبيرغ من اجل تحويل احداثيات النهايه المؤثرة لمسار مخطط من الفضاء الكارتيزي الى فضاء المفاصل و العكس صحيح حيث تم استخدام الاستكمال المكعب لاجزاء المسار لضمان الاستمرارية في السرعة و التعجيل. كذلك الموديل الديناميكي المشتق يعتمد على طريقة الطاقة اويلر – لاكرانج لتتضمن تاثير عزوم الاحتكاك و الاضطراب بجانب تأثير الزخم و الكوريوليس. و تم تطبيق نوعين من المسيطر: المسيطر ذي العزم المحسوب غير الخطي و المسيطر الابسط له نسبي مشتق زائد الجاذبية لتقليل اخطاء التعقب للمسار الى الصفر حيث كانت قيم Kpو Kv هي 900 و 60 و معدل الجذر التربيعي للاخطاء لمدخل الخطوة نوع المسيطر الاول ( 2.5e-14 و 4.4e-14 و 5.0e-14 و -4.7e-14 و -3.9e-14 و-4.6e-14 ) درجة و للمسيطر الثاني (-1.77e-5 و -1.22e-6 و-4.28e-6 و -8.97e-6 و -1.32e-5 و1.05e-5 ) درجة للمفاصل من واحد الى سته تعاقبياً. أظهرت النتائج ان المسيطر الاول اكثر دقة و لكن يتطلب مدخلات اكثر و عمليات حسابية اكثر بينما المسيطر الثاني يؤدي بقيم تعقب مقبولة للخطأ لا سيَما للتطبيقات التي تهتم بالموقع.

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