6,047 research outputs found
Distributed importance-based fuzzy logic controllers for flexible link manipulators
This research studies the design and tuning of the distributed importance-based fuzzy logic controllers (FLCs) for two dynamic systems: a single-link flexible manipulator and a two-link rigid-flexible manipulator. The importance analysis algorithm is introduced in the structure design of a FLC. The fuzzy rules for the former system are written based on observing the system behaviors. The fuzzy rules for the latter are selected to mimic the performance of the comparable linear controllers. A Modified Nelder and Mead Simplex Algorithm is used to tune the parameters of the membership functions in the distributed importance-based FLC. The tuned distributed importance-based FLC for the single-link flexible manipulator is compared with a linear quadratic regulator and the tuned distributed PD-like FLC. Similarly, the tuned distributed importance-based FLC for the two-link rigid-flexible manipulator is compared with the tuned importance-based linear controller and the tuned distributed PD-like FLC. The robustness of each tuned controller is tested under different conditions
Fuzzy Logic for Digital Phase-Locked Loop Filter Design
The problem of robust phase-locked loop design has attracted attention for many years, particularly since the advent of the global positioning system. This paper proposes and demonstrates the use of a fuzzy PLL to estimate the time-varying phase of a sinusoidal signal. It is shown via simulation results that fuzzy PLL\u27s offer performance comparable to analytically derived PLL\u27s (e.g. Kalman filters and H∞ estimators) when the phase exhibits high dynamics and high noise. The fuzzy PLL rules are optimized using a gradient descent method and a genetic algorith
Influence of material composition on flame spread behavior over combustible solid of paper/bagasse
Fire Safety Engineering is an application of science to improve the safety from the destructive effect of the fire. Paper is one of sources that easily catch fire, however, research on flame spread towards paper is still not enough to describe about the phenomenon. Inspiration from this, the behavior of downward flame spread over paper/bagasse is experimentally investigated. Composition of 0%, 30%, 50%, 70% and 100% bagasse is chosen for this research. Flame spread behavior for each composition is analyzed from the observation. Results show for each composition, the flame spreads with “U” shape at the beginning of combustion until the whole specimen. The result shows that the flame spread rate decreases as bagasse composition increases. The highest flame spread is 0.813 mm/s for pure paper and the lowest one is 0.481 mm/s for pure bagasse. Not only that, it also shows the flame spread rate decreases as the density increases. It is clarified that density for bagasse is higher than paper. Result infers that the flame spread shape and rate are not only influenced by the bagasse composition but also by the densit
Experimental and theoretical control of a smart projectile fin using piezoelectric bimorph actuator
The goal of this work is to develop efficient control algorithms for the control of a smart projectile fin. Smart fins are deployed as soon as the projectile reaches the apogee and are used to steer the projectile towards its target by controlling the rotation angle of the fin. The fin is actuated using the piezoelectric macro-fiber composite (MFC) bimorph actuator which is completely enclosed within the aero-shell. The actuator is composed of two Macro Fiber Composites (MFC\u27s), manufactured by Smart Material Co. The presented smart fin design minimizes the volume and weight of the unit; Two different models of the smart fin are developed. One is mathematical model that uses finite element approach to describe dynamics of the smart fin system. This model includes the aerodynamic moment which is a function of the angle of attack of the projectile. Second model is based on system identification approach. A linear model of the actuator and fin is identified experimentally by exciting the system using a chirp signal. Comparison is done between these two models based on open-loop step response of the smart fin system; In this dissertation, five kinds of control systems based on fuzzy logic, inverse dynamics and adaptive structure theory are developed. The aerodynamic disturbances and parameter uncertainties are considered in these controllers. The simulation results illustrate that asymptotic trajectory tracking of the fin angle is achieved, in spite of uncertainties in the system parameters and presence of aerodynamic disturbance. A prototype model of the projectile fin is developed in the laboratory for real-time control. The designed controllers are validated using the subsonic wind tunnel at University of Nevada, Las Vegas (UNLV) for various wind speeds. Experimental results show that the designed controllers accomplish fin angle control
Guidance and control of an autonomous underwater vehicle
Merged with duplicate record 10026.1/856 on 07.03.2017 by CS (TIS)A cooperative project between the Universities of Plymouth and Cranfield was aimed
at designing and developing an autonomous underwater vehicle named Hammerhead.
The work presented herein is to formulate an advance guidance and control system
and to implement it in the Hammerhead. This involves the description of Hammerhead
hardware from a control system perspective. In addition to the control system,
an intelligent navigation scheme and a state of the art vision system is also developed.
However, the development of these submodules is out of the scope of this thesis.
To model an underwater vehicle, the traditional way is to acquire painstaking mathematical
models based on laws of physics and then simplify and linearise the models to
some operating point. One of the principal novelties of this research is the use of system
identification techniques on actual vehicle data obtained from full scale in water
experiments. Two new guidance mechanisms have also been formulated for cruising
type vehicles. The first is a modification of the proportional navigation guidance for
missiles whilst the other is a hybrid law which is a combination of several guidance
strategies employed during different phases of the Right.
In addition to the modelling process and guidance systems, a number of robust control
methodologies have been conceived for Hammerhead. A discrete time linear
quadratic Gaussian with loop transfer recovery based autopilot is formulated and integrated
with the conventional and more advance guidance laws proposed. A model
predictive controller (MPC) has also been devised which is constructed using artificial
intelligence techniques such as genetic algorithms (GA) and fuzzy logic. A GA
is employed as an online optimization routine whilst fuzzy logic has been exploited
as an objective function in an MPC framework. The GA-MPC autopilot has been
implemented in Hammerhead in real time and results demonstrate excellent robustness
despite the presence of disturbances and ever present modelling uncertainty. To
the author's knowledge, this is the first successful application of a GA in real time
optimization for controller tuning in the marine sector and thus the thesis makes an
extremely novel and useful contribution to control system design in general. The
controllers are also integrated with the proposed guidance laws and is also considered
to be an invaluable contribution to knowledge. Moreover, the autopilots are used in
conjunction with a vision based altitude information sensor and simulation results
demonstrate the efficacy of the controllers to cope with uncertain altitude demands.J&S MARINE LTD., QINETIQ,
SUBSEA 7 AND SOUTH WEST WATER PL
Revolusi Industri
Terhasilnya buku ini adalah atas hasrat untuk berkongsi sedikit pengetahuan mengenai
revolusi industri terkini yang pesat berkembang mengikut peredaran masa. Sejajar dengan
kehendak pendidikan abad 21, atas kesedaran bahawa masih ramai lagi antara kita masih
kurang cakna tentang proses yang sedang pesat berlangsung ini. Dengan adanya
transformasi sebegini, proses pertumbuhan ekonomi menjadi lebih kuat dan menghasilkan
tahap produksi lebih tinggi.
Penggunaan teknologi yang semakin berkembang pesat ke serata dunia termasuklah
di Malaysia dan telah mempengaruhi manusia setiap hari hingga tidak boleh dibayangkan
bagaimana dunia hari ini tanpa penggunaan teknologi dalam kehidupan seharian. Dalam
melahirkan modal insan yang berdaya saing menghadapi revolusi industri, pihak universiti
dan syarikat antarabangsa sentiasa menjalin kerjasama yang baik. Dengan adanya platform
yang canggih sebagai contoh dalam teknologi IoT ini, keupayaan berkomunikasi dengan
efisyen secara lisan dan bertulis menjadi sangat kritikal pada masa kini. Pada hari ini, sesi
perbincangan boleh dilakukan di mana-mana sahaja tanpa mengira sempadan. Oleh itu, jika
bahasa dan seni komunikasi tidak dijaga dengan baik, ia boleh menimbulkan konflik antara
komunikasi, salah faham dan kerja berpasukan yang kurang berkesan.
Penggunaan teknologi-teknologi yang canggih menjadi semakin meluas mengikut
peredaran zaman. Setiap individu perlulah meningkatkan potensi diri selaras dengan
pembangunan negara agar kita tidak jauh ketinggalan. Dengan berkembangnya
pembangunan negara yang begitu pesat ini juga, setiap individu perlu memberi sokongan
yang padu agar negara kita menjadi negara yang setanding dengan negara maju yang lain
serta menjadi negara yang kompetitif. Ternyata revolusi industri ini mempunyai banyak
kesan baik dan memberi manfaatnya kepada orang ramai tetapi jika ia tidak ditangani
dengan baik akan menyebabkan kesan buruk kepada negara
Genetic Algorithms Based Approach for Designing Spring Brake Orthosis – Part Ii: Control of FES Induced Movement
Spring brake orthotic swing phase for paraplegic gait is initiated through releasing the brake on the knee mounted with a torsion spring. The stored potential energy in the spring, gained from the previous swing phase, is solely responsible for swing phase knee flexion. Hence the later part of the SBO operation, functional electrical stimulation (FES) assisted extension movement of the knee has to serve an additional purpose of restoring the spring potential energy on the fly. While control of FES induced movement as such is often a challenging task, a torsion spring, being antagonistically paired up with the muscle actuator, as in spring brake orthosis (SBO), only adds to the challenge. Two new schemes are proposed for the control of FES induced knee extension movement in SBO assisted swing phase. Even though the control schemes are closed-loop in nature, special attention is paid to accommodate the natural dynamics of the mechanical combination being controlled (the leg segment) as a major role playing feature. The schemes are thus found to be immune from some drawbacks associated with both closed-loop tracking as well as open-loop control of FES induced movement. A leg model including the FES knee joint model of the knee extensor muscle vasti along with the passive properties is used in the simulation. The optimized parameters for the SBO spring are obtained from the earlier part of this work. Genetic algorithm (GA) and multi-objective GA (MOGA) are used to optimize the parameters associated with the control schemes with minimum fatigue as one of the control objectives. The control schemes are evaluated in terms of three criteria based on their ability to cope with muscle fatigue
Discussion on Different Controllers Used for the Navigation of Mobile Robot
Robots that can comprehend and navigate their surroundings independently on their own are considered intelligent mobile robots (MR). Using a sophisticated set of controllers, artificial intelligence (AI), deep learning (DL), machine learning (ML), sensors, and computation for navigation, MR\u27s can understand and navigate around their environments without even being connected to a cabled source of power. Mobility and intelligence are fundamental drivers of autonomous robots that are intended for their planned operations. They are becoming popular in a variety of fields, including business, industry, healthcare, education, government, agriculture, military operations, and even domestic settings, to optimize everyday activities. We describe different controllers, including proportional integral derivative (PID) controllers, model predictive controllers (MPCs), fuzzy logic controllers (FLCs), and reinforcement learning controllers used in robotics science. The main objective of this article is to demonstrate a comprehensive idea and basic working principle of controllers utilized by mobile robots (MR) for navigation. This work thoroughly investigates several available books and literature to provide a better understanding of the navigation strategies taken by MR. Future research trends and possible challenges to optimizing the MR navigation system are also discussed
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