Smart materials have been widely used for control actuation. A robotic hand can be equipped with artificial tendons and sensors for the operation of its various joints mimicking human-hand motions. The motors in the robotic hand could be replaced with novel electroactive-polymer (EAP) actuators. In the three-finger gripper proposed in this paper, each finger can be actuated individually so that dexterous handling is possible, allowing precise manipulation. In this dissertation, a microscale position-control system using a novel EAP is presented. A third-order model was developed based on the system identification of the EAP actuator with an AutoRegresive Moving Average with eXogenous input (ARMAX) method using a chirp signal input from 0.01 Hz to 1 Hz limited to 7 ± V. With the developed plant model, a digital PID (proportional-integral-derivative) controller was designed with an integrator anti-windup scheme. Test results on macro (0.8-mm) and micro (50-μm) step responses of the EAP actuator are provided in this dissertation and its position tracking capability is demonstrated. The overshoot decreased from 79.7% to 37.1%, and the control effort decreased by 16.3%. The settling time decreased from 1.79 s to 1.61 s. The controller with the anti-windup scheme effectively reduced the degradation in the system performance due to actuator saturation. EAP microgrippers based on the control scheme presented in this paper will have significant applications including picking-and-placing micro-sized objects or as medical instruments. To develop model-based control laws, we introduced an approximated linear model that represents the electromechanical behavior of the gripper fingers. Several chirp voltage signal inputs were applied to excite the IPMC (ionic polymer metal composite) fingers in the interesting frequency range of [0.01 Hz, 5 Hz] for 40 s at a sampling frequency of 250 Hz. The approximated linear Box-Jenkins (BJ) model was well matched with the model obtained using a stochastic power-spectral method. With feedback control, the large overshoot, rise time, and settling time associated with the inherent material properties were reduced. The motions of the IPMC fingers in the microgripper were coordinated to pick, move, and release a macro- or micro-part. The precise manipulation of this three-finger gripper was successfully demonstrated with experimental closed-loop responses.

No description available.

In this thesis, a grid-connected wind-energy converter system including a matrix converter is proposed. The matrix converter, as a power electronic converter, is used to interface the induction generator with the grid and control the wind turbine shaft speed. At a given wind velocity, the mechanical power available from a wind turbine is a function of its shaft speed. Through the matrix converter, the terminal voltage and frequency of the induction generator is controlled, based on a constant V/f strategy, to adjust the turbine shaft speed and accordingly, control the active power injected into the grid to track maximum power for all wind velocities. The power factor at the interface with the grid is also controlled by the matrix converter to either ensure purely active power injection into the grid for optimal utilization of the installed wind turbine capacity or assist in regulation of voltage at the point of connection. Furthermore, the reactive power requirements of the induction generator are satisfied by the matrix converter to avoid use of self-excitation capacitors. The thesis addresses two dynamic models: a comprehensive dynamic model for a matrix converter and an overall dynamical model for the proposed wind turbine system. The developed matrix converter dynamic model is valid for both steady-state and transient analyses, and includes all required functions, i.e., control of the output voltage, output frequency, and input displacement power factor. The model is in the qdo reference frame for the matrix converter input and output voltage and current fundamental components. The validity of this model is confirmed by comparing the results obtained from the developed model and a simplified fundamental-frequency equivalent circuit-based model. In developing the overall dynamic model of the proposed wind turbine system, individual models of the mechanical aerodynamic conversion, drive train, matrix converter, and squirrel-cage induction generator are developed and combined to enable steady-state and transient simulations of the overall system. In addition, the constraint constant V/f strategy is included in the final dynamic model. The model is intended to be useful for controller design purposes. The dynamic behavior of the model is investigated by simulating the response of the overall model to step changes in selected input variables. Moreover, a linearized model of the system is developed at a typical operating point, and stability, controllability, and observability of the system are investigated. Two control design methods are adopted for the design of the closed-loop controller: a state-feedback controller and an output feedback controller. The state-feedback controller is designed based on the Linear Quadratic method. An observer block is used to estimate the states in the state-feedback controller. Two other controllers based on transfer-function techniques and output feedback are developed for the wind turbine system. Finally, a maximum power point tracking method, referred to as mechanical speed-sensorless power signal feedback, is developed for the wind turbine system under study to control the matrix converter control variables in order to capture the maximum wind energy without measuring the wind velocity or the turbine shaft speed.

In this thesis, a grid-connected wind-energy converter system including a matrix converter is proposed. The matrix converter, as a power electronic converter, is used to interface the induction generator with the grid and control the wind turbine shaft speed. At a given wind velocity, the mechanical power available from a wind turbine is a function of its shaft speed. Through the matrix converter, the terminal voltage and frequency of the induction generator is controlled, based on a constant V/f strategy, to adjust the turbine shaft speed and accordingly, control the active power injected into the grid to track maximum power for all wind velocities. The power factor at the interface with the grid is also controlled by the matrix converter to either ensure purely active power injection into the grid for optimal utilization of the installed wind turbine capacity or assist in regulation of voltage at the point of connection. Furthermore, the reactive power requirements of the induction generator are satisfied by the matrix converter to avoid use of self-excitation capacitors. The thesis addresses two dynamic models: a comprehensive dynamic model for a matrix converter and an overall dynamical model for the proposed wind turbine system. The developed matrix converter dynamic model is valid for both steady-state and transient analyses, and includes all required functions, i.e., control of the output voltage, output frequency, and input displacement power factor. The model is in the qdo reference frame for the matrix converter input and output voltage and current fundamental components. The validity of this model is confirmed by comparing the results obtained from the developed model and a simplified fundamental-frequency equivalent circuit-based model. In developing the overall dynamic model of the proposed wind turbine system, individual models of the mechanical aerodynamic conversion, drive train, matrix converter, and squirrel-cage induction generator are developed and combined to enable steady-state and transient simulations of the overall system. In addition, the constraint constant V/f strategy is included in the final dynamic model. The model is intended to be useful for controller design purposes. The dynamic behavior of the model is investigated by simulating the response of the overall model to step changes in selected input variables. Moreover, a linearized model of the system is developed at a typical operating point, and stability, controllability, and observability of the system are investigated. Two control design methods are adopted for the design of the closed-loop controller: a state-feedback controller and an output feedback controller. The state-feedback controller is designed based on the Linear Quadratic method. An observer block is used to estimate the states in the state-feedback controller. Two other controllers based on transfer-function techniques and output feedback are developed for the wind turbine system. Finally, a maximum power point tracking method, referred to as mechanical speed-sensorless power signal feedback, is developed for the wind turbine system under study to control the matrix converter control variables in order to capture the maximum wind energy without measuring the wind velocity or the turbine shaft speed.

This thesis presents a feedback design for an active noise cancellation (ANC) headphone. The designed ANC headphone consists of an analog controller, an audio power amplifier, a headphone speaker, a mini microphone, and a microphone amplifier, which constitute a feedback loop. The controller design follows the method of feedback sensitivity shaping with degree constraint introduced by R. Nagamune and A. Blomqvist in 2005. The advantage of this method is that it eliminates the needs for choosing an analytic weighting function and performing model reduction to yield a lower-order controller, as commonly required in conventional H2/H¡Û optimizations. A fifth-order analog controller for the ANC headphone is designed. The experimental result shows a maximum acoustic noise reduction of 19.7 dB near 200 Hz and an overall noise reduction of more than 10 dB in the control frequency band from 107 Hz to 523 Hz. Moreover, the out-of-band noise amplification is limited to a barely noticeable level of 4.26 dB.

The U.S. transportation sector represented about 28% of all energy consumption in 2018. Petroleum products accounted for 92% of this total energy. Light-duty vehicles are the largest energy consumers in the transportation sector. The high amount of petroleum used by light-duty vehicles creates significant economic and environmental challenges. Electric Vehicles (EVs) have a higher fuel economy and can be emission-free; they are therefore an alternative solution for minimizing the negative environmental impact of internal combustion engine vehicles. However, the adoption of EVs has been limited by their limited driving range, long recharging time, and comparatively higher price. Dynamic wireless charging technology allows for charging the EV battery in motion. Charging pads are embedded in the road and the EV battery is charged while the vehicle is passing over them. This technology not only extends the EV range but also results in a considerable reduction in battery size and capacity. Therefore, dynamic wireless charging solves one of the major issues of EVs, leading to their large-scale adoption. In the first part of this dissertation, a pad optimization methodology is presented to minimize system cost and losses. Using this method, two pads are optimized, built and tested for charging the EV. In the next section, two methods are presented to estimate how much the EV is laterally misaligned with respect to the center of the charging pads. This helps to increase system efficiency and power transfer capability. Finally, new concrete-based material is presented and studied to reduce the charging pad cost and increase their durability.

No description available.

This thesis entails the stability analysis of the Multiple Input Single Output (MISO) DC-DC converter developed for the DC House Project at Cal Poly. A frequency domain control system model of the MISO converter was designed and constructed using MATLAB Simulink. Transfer functions were derived and modeled for each stage of the converter to best fit the converter circuit system used in the original MISO circuit. Stability metrics such as overshoot, undershoot, rise time, phase margin and gain margin were measured to evaluate and analyze the stability of the converter. These metrics were measured with the original model including the current sharing network that allows load sharing between multiple MISO modules. The simulation results demonstrate that based on the existing model, the system is stable with a gain margin of infinity and phase margin of around 40 degrees at crossover frequency of 47kHz with nominal input voltage of 24V. Another compensator was proposed to overcome the shortcomings of the original compensator model with respect to the overshoot and phase margin. The new compensator model improved the phase margin at the same crossover frequency with a higher rise time and lowered percent overshoot. Additional improvements and tradeoffs are further discussed to help with the decision when designing a compensator for DC-DC converter that uses the current mode control technique.

No description available.

Electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) are gaining popularity because they are more environmentally friendly, less noisy and more efficient. These vehicles have batteries can be charged by on-board battery chargers that can be conductive or inductive. In conductive chargers, the charger is physically connected to the grid by a connector. With the inductive chargers, energy can be transferred wirelessly over a large air-gap through inductive coupling, eliminating the physical connection between the charger and the grid. A typical on-board battery charger consists of a boost power factor correction (PFC) converter followed by a dc-dc converter. This dissertation focuses on the design, modeling and control of a bidirectional dc-dc converter for conductive battery charging application. In this dissertation, a detailed design procedure is presented for a bidirectional CLLLC-type resonant converter for a battery charging application. This converter is similar to an LLC-type resonant converter with an extra inductor and capacitor in the secondary side. Soft-switching can be ensured in all switches without additional snubber or clamp circuitry. Because of soft-switching in all switches, very high-frequency operation is possible, thus the size of the magnetics and the filter capacitors can be made small. To further reduce the size and cost of the converter, a CLLC-type resonant network with fewer magnetics is derived from the original CLLLC-type resonant network. First, an equivalent model for the bidirectional converter is derived for the steady-state analysis. Then, the design methodology is presented for the CLLLC-type resonant converter. Design of this converter includes determining the transformer turns ratio, design of the magnetizing inductance based on ZVS condition, design of the resonant inductances and capacitances. Then, the CLLC-type resonant network is derived from the CLLLC-type resonant network. To validate the proposed design procedure, a 3.5 kW converter was designed following the guidelines in the proposed methodology. A prototype was built and tested in the lab. Experimental results verified the design procedure presented. The dynamics analysis of any converter is necessary to design the control loop. The bandwidth, phase margin and gain margin of the control loops should be properly designed to guarantee a robust system. The dynamic analysis of the resonant converters have not been extensively studied, with the previous work mainly concentrated on the steady-state models. In this dissertation, the continuous-time large-signal model, the steady-state operating point, and the small-signal model are derived in an analytical closed-form. This model includes both the frequency and the phase-shift control. Simulation and experimental verification of the derived models are presented to validate the presented analysis. A detailed controller design methodology is proposed in this dissertation for the bidirectional CLLLC-type resonant converter for battery charging application. The dynamic characteristics of this converter change significantly as the battery charges or discharges. And, at some operating points, there is a high-Q resonant peaking in the open-loop bode-plot for any transfer functions in this converter. So, if the controller is not properly designed, the closed-loop system might become unstable at some operating points. In this paper, a controller design methodology is proposed that will guarantee a stable operation during the entire operating frequency range in both battery charging mode (BCM) and regeneration mode (RM). To validate the proposed controller design methodology, the output current and voltage loop controllers are designed for a 3.5 kW converter. The step response showed a stable system with good transient performance thus validating the proposed controller design methodology. / Ph. D.