106 research outputs found
Design Optimization for High Throughput Recursive Systematic Convolutional Encoders
No full textRecursive Systematic Convolutional (RSC) codes are the building blocks of the modern communication systems. In this paper we propose a new analytical model to manipulate the modulo-2 algebraic operations and a finite state machine model describing the single-cycle RSC architecture to design high throughput RSC code with special emphasis for parallel implementation and a puncturing scheme embedded in the design. The new design approach is suitable for any RSC code and for almost any degree of parallelism implementations. We also present some case studies about the RSC code architecture and some simulation results for the Bit Error Rate, to compare commonly used RSC codes with different constraints on the length, and redesigned with the proposed methodology
Sliding mode control applied in trajectory-tracking of WMRs and autonomous vehicles
No full textTese de doutoramento apresentada à Fac. de Ciências e Tecnologia da Universidade de CoimbraThe thesis is structured as follows:
• Chapter 2: Trajectory tracking problems are summarized.
• Chapter 3: Kinematic and dynamic modeling of theWMRs and car-like robots are presented.
• Chapter 4: The concept of sliding mode are first introduced. Then the fundamentals of SMC are summarized, including basic definitions, methods of sliding surface and control law design, robustness properties and the methods on handling chattering problems. New sliding-mode trajectory-tracking and slidingmode path-following controllers for WMRs and car-like vehicles, are also proposed in this chapter.
• Chapter 5: The trajectory/path planning are developed, including the velocity profile.
• Chapter 6: A model with two freedom degrees is considered for the HNC model. The user comfort is examined not only in the time domain, but also in the frequency domain.
• Chapter 7: Experimental results obtained with the implementation of the proposed controllers in RobChair are summarized and discussed.
• Chapter 8: Finally, conclusions are drawn and some suggestions for future work are provided
Investigating an A-star algorithm-based fitness function for mobile robot evolution
No full textOne of the factors that affect the success of Evolutionary Robotics (ER) is the way fitness functions are designed to operate. While needs-based custom fitness functions have been developed, most of the time they have been defined in simpler mathematical functions to reduce the computation time. In this paper, we hypothesize that an incremental fitness function based on established techniques in specific task domains in robotics will aid the evolution process. An A-star algorithm-based fitness function for path planning is designed and implemented for evolving the body plans and controllers of robots for navigation and obstacle avoidance tasks. It has been shown that using this concept, fitter robots have evolved in most cases when compared to simple distance-only based fitness functions. However, due to variable performance of the evolver with the A-star fitness function, the results are inconclusive. We also identify problems associated with the fitness function and make recommendations for designing future fitness functions based on observations of the experiments
Multiple-lane vehicle platooning based on a multi-agent distributed model predictive control strategy
No full textVehicle platooning became an interesting topic in the last years, many researchers and practitioners from the academia and industry trying to develop new theories and design appropriate control methods and communication methodologies in order to bring this concept as fast as possible on the roads. Since vehicles drive on multi-lane roads and highways, the subsequent paradigm was to treat vehicles as swarms, i. e., groups of vehicles that travel closely together on different lanes and are electronically connected. A step forward towards this new concept would be the design of multiple-lane platoons. As such, this paper proposes a multi-agent distributed model predictive control strategy for the longitudinal coordination of the vehicles in individual platoons and a classical PI control algorithm for the lateral control of each vehicle in the platoon w. r. t. its neighbors. The simulation results obtained in Matlab/Simulink and the performance analysis prove that the concept is viable
Two New Nonlinear Modified Adjustment Laws for Variable Structure and Compound Robust Adaptive Control. Higher Relative Degree Case
No full textNew Modified Update Laws in Robust Variable Structure and Compound Adaptive Control for Plant Model with Higher Relative Degree
No full textRobustness in Variable Structure and Compound Adaptive Control by Two New Modified Update Laws
No full textSecuring the Network for a Smart Bracelet System
No full textDigital instruments play a vital role in our daily life. It is a routine to produce business papers, watch the news program, write articles and blogs, manage healthcare systems, to purchase online, to send messages and all this is processed by making observations and then manipulating, receiving and availing the diverse data. This electronic data provides the foundation of real time data. All this transmission of data needs to be secured. Security is essential for healthcare systems as the present one where the blood pressure recordings provided by the smart bracelet are sent to the user's mobile phone via Bluetooth. The bracelet monitors the pregnant women, but also other users who wish to have their blood pressure under control. The system's server analyses the recordings and announces the user, as well as the associated persons to the user in case of an emergency. The doctors, the medical staff, user and user's family and caregivers have access to the health recordings belonging to the monitored user. Security is a main feature of the electronic healthcare system based on the smart bracelet.</p
Hybrid system control of an assembly/disassembly mechatronic line using robotic manipulator mounted on mobile platform
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