Intelligent Learning Control System Design Based on Adaptive Dynamic Programming

Adaptive dynamic programming (ADP) controller is a powerful neural network based control technique that has been investigated, designed, and tested in a wide range of applications for solving optimal control problems in complex systems. The performance of ADP controller is usually obtained by long training periods because the data usage efficiency is low as it discards the samples once used. Experience replay is a powerful technique showing potential to accelerate the training process of learning and control. However, its existing design can not be directly used for model-free ADP design, because it focuses on the forward temporal difference (TD) information (e.g., state-action pair) between the current time step and the future time step, and will need a model network for future information prediction. Uniform random sampling again used for experience replay, is not an efficient technique to learn. Prioritized experience replay (PER) presents important transitions more frequently and has proven to be efficient in the learning process. In order to solve long training periods of ADP controller, the first goal of this thesis is to avoid the usage of model network or identifier of the system. Specifically, the experience tuple is designed with one step backward state-action information and the TD can be achieved by a previous time step and a current time step. The proposed approach is tested for two case studies: cart-pole and triple-link pendulum balancing tasks. The proposed approach improved the required average trial to succeed by 26.5% for cart-pole and 43% for triple-link. The second goal of this thesis is to integrate the efficient learning capability of PER into ADP. The detailed theoretical analysis is presented in order to verify the stability of the proposed control technique. The proposed approach improved the required average trial to succeed compared to traditional ADP controller by 60.56% for cart-pole and 56.89% for triple-link balancing tasks. The final goal of this thesis is to validate ADP controller in smart grid to improve current control performance of virtual synchronous machine (VSM) at sudden load changes and a single line to ground fault and reduce harmonics in shunt active filters (SAF) during different loading conditions. The ADP controller produced the fastest response time, low overshoot and in general, the best performance in comparison to the traditional current controller. In SAF, ADP controller reduced total harmonic distortion (THD) of the source current by an average of 18.41% compared to a traditional current controller alone

Comprehensive Diagnosis and Tolerance Strategies for Electrical Faults and Sensor Faults in Dual Three-Phase PMSM Drives

IEEE In this paper, fault diagnosis and tolerant control strategies have been studied comprehensively for dual-three phase PMSM drives to improve the reliability. Based on direct torque control (DTC) with space vector modulation (SVM), a series of diagnostic and tolerant control methods have been proposed for five types of faults, namely speed-sensor fault, DC-link voltage-sensor fault, current-sensor fault, open-phase fault and open-switch fault. Firstly, diagnosis and tolerant schemes are proposed for speed-sensor fault by estimating the rotor angle speed with the rotating speed of stator flux. Secondly, diagnosis and tolerant schemes are proposed for DC-link voltage-sensor fault by combining the current model based stator flux observer with the voltage model based stator flux observer. Thirdly, a three-step method is designed to diagnose three types of faults related to current signals, namely current-sensor fault, open-phase fault and open-switch fault simultaneously. A vector space decomposition (VSD) based current estimation method is proposed to achieve fault-tolerant control for the current-sensor fault, and the voltage compensation based fault-tolerant control is presented for both open-phase fault and open-switch fault. The experiments have been taken on a laboratory prototype to verify the effectiveness of the proposed fault diagnosis and tolerance schemes

Measurements, Models, Systems and Design

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LASER RANGE IMAGING FOR ON-LINE MAPPING OF 3D IMAGES TO PSEUDO-X-RAY IMAGES FOR POULTRY BONE FRAGMENT DETECTION

A laser ranging image system was developed for on-line high-resolution 3D shape recovery of poultry fillets. The range imaging system in conjunction with X-ray imaging was used to provide synergistic imaging detection of bone fragments in poultry fillets. In this research, two 5 mW diode lasers coupled with two CCD cameras were used to produce 3D information based on structured lights and triangulation. A laser scattering phenomenon on meat tissues was studied when calculating the object thickness. To obtain the accurate 3D information, the cameras were calibrated to correct for camera distortions. For pixel registrations of the X-ray and laser 3D images, the range imaging system was calibrated, and noises and signal variations in the X-ray and laser 3D images were analyzed. Furthermore, the relationship between the X-ray absorption and 3D thickness of fillets was obtained, and a mapping function based on this relationship was applied to convert the fillet 3D images into the pseudo-X-ray images. For the on-line system implementation, the imaging hardware and software engineering issues, including the data flow optimization and the operating system task scheduling, were also studied. Based on the experimental on-line test, the range imaging system developed was able to scan poultry fillets at a speed of 0.2 m/sec at a resolution of 0.8(X) x 0.7(Y) x 0.7(Z) mm3. The results of this study have shown great potential for non-invasive detection of hazardous materials in boneless poultry meat with uneven thickness

Application of advanced technology to space automation

Automated operations in space provide the key to optimized mission design and data acquisition at minimum cost for the future. The results of this study strongly accentuate this statement and should provide further incentive for immediate development of specific automtion technology as defined herein. Essential automation technology requirements were identified for future programs. The study was undertaken to address the future role of automation in the space program, the potential benefits to be derived, and the technology efforts that should be directed toward obtaining these benefits

MEMS Accelerometers

Micro-electro-mechanical system (MEMS) devices are widely used for inertia, pressure, and ultrasound sensing applications. Research on integrated MEMS technology has undergone extensive development driven by the requirements of a compact footprint, low cost, and increased functionality. Accelerometers are among the most widely used sensors implemented in MEMS technology. MEMS accelerometers are showing a growing presence in almost all industries ranging from automotive to medical. A traditional MEMS accelerometer employs a proof mass suspended to springs, which displaces in response to an external acceleration. A single proof mass can be used for one- or multi-axis sensing. A variety of transduction mechanisms have been used to detect the displacement. They include capacitive, piezoelectric, thermal, tunneling, and optical mechanisms. Capacitive accelerometers are widely used due to their DC measurement interface, thermal stability, reliability, and low cost. However, they are sensitive to electromagnetic field interferences and have poor performance for high-end applications (e.g., precise attitude control for the satellite). Over the past three decades, steady progress has been made in the area of optical accelerometers for high-performance and high-sensitivity applications but several challenges are still to be tackled by researchers and engineers to fully realize opto-mechanical accelerometers, such as chip-scale integration, scaling, low bandwidth, etc

Recent Trends in Communication Networks

In recent years there has been many developments in communication technology. This has greatly enhanced the computing power of small handheld resource-constrained mobile devices. Different generations of communication technology have evolved. This had led to new research for communication of large volumes of data in different transmission media and the design of different communication protocols. Another direction of research concerns the secure and error-free communication between the sender and receiver despite the risk of the presence of an eavesdropper. For the communication requirement of a huge amount of multimedia streaming data, a lot of research has been carried out in the design of proper overlay networks. The book addresses new research techniques that have evolved to handle these challenges