Analisis dan penilaian prestasi lengah lepas tangan menggunakan protokol pencetusan sesi (SIP) bagi sistem terintegrasi UMTS-WLAN

Teknologi rangkaian tanpa vvayar 4G merupakan penggabungan beberapa teknologi rangkaian capaian yang berbeza seperti rangkaian Universal Mobile Telecommunication System (UMTS) dan Rangkaian Kawasan Setempat Tanpa Wayar (WLAN). Rangkaian 4G menyokong mobiliti tanpa kelim {seamless) dalam menjanjikan perhubungan dan perkhidmatan yang terbaik kepada pelanggan. Protokol Pencetusan Sesi (SIP) yang berada pada lapisan aplikasi telah diramalkan sebagai calon terbaik bagi menguruskan mobiliti di dalam rangkaian 4G. Rangkaian 4G yang menawarkan aplikasi multimedia dalam perkhidmatannya mesti mempunyai lengah lepas tangan yang rendah bagi mencapai objektif penubuhannya. Tujuan utama disertasi ini adalah untuk menilai lengah lepas tangan bagi sistem terintegrasi UMTSWLAN yang menggunakan SIP sebagai protokol pengisyaratan. Model simulasi menggunakan MATLAB dibangunkan untuk menilai prestasi lengah lepas tangan tersebut. Model simulasi menggambarkan pergerakan hos mobil ke rangkaian UMTS dan WLAN. Lengah lepas tangan yang berlaku diukur berdasarkan model analitik. Prestasi lengah lepas tangan dinilai berdasarkan perubahan kadar ralat kerangka (FER), kadar ketibaan sesi SIP dan halaju hos mobil (MIT) semasa MH bergerak ke rangkaian UMTS dan WLAN. Keputusan simulasi menunjukkan bahawa lengah lepas tangan meningkat dengan penambahan FER dan kadar ketibaan sesi SIP. Halaju kebolehgerakan pengguna memberi kesan terhadap nilai lengah lepas tangan. Keputusan juga menunjukkan lengah lepas tangan minimum yang berlaku sewaktu MH bergerak ke rangkaian UMTS adalah 1.9565 saat dengan lebar jalur saluran 128kbps dan ke rangkaian WLAN adalah sekitar 0.8651 saat dengan lebar jalur saluran 11 Mbps. Berdasarkan nilai ini, lengah lepas tangan semasa MH bergerak ke rangkaian UMTS atau WLAN adalah tidak boleh diterima untuk penjurusan multimedia. Di dalam kajian ini didapati capaian tanpa wayar GPRS menyumbang lengah terbesar daripada keseluruhan lengah lepas tangan ke rangkaian UMTS

Measurements, Models, Systems and Design

531 s.

Terminal sliding mode control strategy design for second-order nonlinear system

This study mainly focuses on the terminal sliding mode control (TSMC) strategy design, including an adaptive terminal sliding mode control (ATSMC) and an exact-estimator-based terminal sliding mode control (ETSMC) for second-order nonlinear dynamical systems. In the ATSMC system, an adaptive bound estimation for the lump uncertainty is proposed to ensure the system stability. On the other hand, an exact estimator is designed for exact estimating system uncertainties to solve the trouble of chattering phenomena caused by a sign function in ATSMC law in despite of the utilization of a fixed value or an adaptive tuning algorithm for the lumped uncertainty bound. The effectiveness of the proposed control schemes can be verified in numerical simulations.<br /

Data-driven online temperature compensation for robust field-oriented torque-controlled induction machines

Squirrel-cage induction machines (IMs) with indirect field-oriented control are widely used in industry and are frequently chosen for their accurate and dynamic torque control. During operation, however, temperature rises leading to changes in machine parameters. The rotor resistance, in particular, alters, affecting the accuracy of the torque control. The authors investigated the effect of a rotor resistance parameter mismatch in the control algorithm on the angular rotor flux misalignment and the subsequent deviation of stator currents and motor torque from their setpoints. Hence, an online, data-driven torque compensation to eliminate the temperature effect is proposed to enable robust torque-controlled IMs. A model-based analysis and experimental mapping of the temperature effect on motor torque is presented. A temperature-torque lookup-table is subsequently implemented within the control algorithm demonstrating the ability to reduce the detrimental effect of temperature on torque control. Experimental results on a 5.5 kW squirrel-cage induction motor show that the proposed data-driven online temperature compensation method is able to reduce torque mismatch when compared to having no temperature compensation. Up to 17% torque mismatch is reduced at nominal torque and even up to 23% at torque setpoints that are lower than 20% of the nominal torque. A limited torque error of <1% remains in a broad operating range

Model-Based Fault Detection and Identification for Prognostics of Electromechanical Actuators Using Genetic Algorithms

Traditional hydraulic servomechanisms for aircraft control surfaces are being gradually replaced by newer technologies, such as Electro-Mechanical Actuators (EMAs). Since field data about reliability of EMAs are not available due to their recent adoption, their failure modes are not fully understood yet; therefore, an effective prognostic tool could help detect incipient failures of the flight control system, in order to properly schedule maintenance interventions and replacement of the actuators. A twofold benefit would be achieved: Safety would be improved by avoiding the aircraft to fly with damaged components, and replacement of still functional components would be prevented, reducing maintenance costs. However, EMA prognostic presents a challenge due to the complexity and to the multi-disciplinary nature of the monitored systems. We propose a model-based fault detection and isolation (FDI) method, employing a Genetic Algorithm (GA) to identify failure precursors before the performance of the system starts being compromised. Four different failure modes are considered: dry friction, backlash, partial coil short circuit, and controller gain drift. The method presented in this work is able to deal with the challenge leveraging the system design knowledge in a more effective way than data-driven strategies, and requires less experimental data. To test the proposed tool, a simulated test rig was developed. Two numerical models of the EMA were implemented with different level of detail: A high fidelity model provided the data of the faulty actuator to be analyzed, while a simpler one, computationally lighter but accurate enough to simulate the considered fault modes, was executed iteratively by the GA. The results showed good robustness and precision, allowing the early identification of a system malfunctioning with few false positives or missed failures.https://susy.mdpi

Inverted Pendulum Human Transporter Balance Control System Based on Proportional Integral Derivative – Active Force Control

Many research for the balancing of inverted pendulum control system to develop the performance. This paper will simulate a Proportional Integral Derivative – Active Force Control (PID-ACF) methods to swing a pendulum attached to a cart from an initial downwards position to an upright position and keep that condition stable and implemented to the segway chair human transporter. The combined control between PID and AFC system is used to maintain the actual acceleration is affected by disruption of the references given, because external disturbance can affect the system. For the experimental it will compare the performance between using a classical control PID and PID-AFC

Inverted Pendulum Human Transporter Balance Control System Based on Proportional Integral Derivative – Active Force Control

Many research for the balancing of inverted pendulum control system to develop the performance. This paper will simulate a Proportional Integral Derivative – Active Force Control (PID-ACF) methods to swing a pendulum attached to a cart from an initial downwards position to an upright position and keep that condition stable and implemented to the segway chair human transporter. The combined control between PID and AFC system is used to maintain the actual acceleration is affected by disruption of the references given, because external disturbance can affect the system. For the experimental it will compare the performance between using a classical control PID and PID-AFC. Keywords: inverted pendulum, Active Force Control, segway