565 research outputs found
Design of generalized minimum variance controllers for nonlinear multivariable systems
The design and implementation of Generalized Minimum Variance control laws for nonlinear multivariable systems that can include severe nonlinearities is considered. The quadratic cost index minimised involves dynamically weighted error and nonlinear control signal costing terms. The aim here is to show the controller obtained is simple to design and implement. The features of the control law are explored. The controller obtained includes an internal model of the process and in one form is a nonlinear version of the Smith Predictor
Teleoperation of passivity-based model reference robust control over the internet
This dissertation offers a survey of a known theoretical approach and novel experimental results in establishing a live communication medium through the internet to host a virtual communication environment for use in Passivity-Based Model Reference Robust Control systems with delays. The controller which is used as a carrier to support a robust communication between input-to-state stability is designed as a control strategy that passively compensates for position errors that arise during contact tasks and strives to achieve delay-independent stability for controlling of aircrafts or other mobile objects. Furthermore the controller is used for nonlinear systems, coordination of multiple agents, bilateral teleoperation, and collision avoidance thus maintaining a communication link with an upper bound of constant delay is crucial for robustness and stability of the overall system. For utilizing such framework an elucidation can be formulated by preparing site survey for analyzing not only the geographical distances separating the nodes in which the teleoperation will occur but also the communication parameters that define the virtual topography that the data will travel through. This survey will first define the feasibility of the overall operation since the teleoperation will be used to sustain a delay based controller over the internet thus obtaining a hypothetical upper bound for the delay via site survey is crucial not only for the communication system but also the delay is required for the design of the passivity-based model reference robust control. Following delay calculation and measurement via site survey, bandwidth tests for unidirectional and bidirectional communication is inspected to ensure that the speed is viable to maintain a real-time connection. Furthermore from obtaining the results it becomes crucial to measure the consistency of the delay throughout a sampled period to guarantee that the upper bound is not breached at any point within the communication to jeopardize the robustness of the controller. Following delay analysis a geographical and topological overview of the communication is also briefly examined via a trace-route to understand the underlying nodes and their contribution to the delay and round-trip consistency. To accommodate the communication channel for the controller the input and output data from both nodes need to be encapsulated within a transmission control protocol via a multithreaded design of a robust program within the C language. The program will construct a multithreaded client-server relationship in which the control data is transmitted. For added stability and higher level of security the channel is then encapsulated via an internet protocol security by utilizing a protocol suite for protecting the communication by authentication and encrypting each packet of the session using negotiation of cryptographic keys during each session
Novel Haptic Cueing for UAV Tele-Operation.
The use of Unmanned Aerial Vehicles (UAVs) is continuously increasing both for military and civilian operations. The degree of automation inside an UAV has reached the capability of high levels of autonomy, increasing but human participation/action is still a requirement to ensure an ultimate level of safety for the mission. Direct remote piloting is often required for a board range of situations; this is true especially for larger UAVs, where a fault might be dangerous for the platform but even for the other entities of its environment (people, building etc.). Unfortunately the physical separation between pilot/operator and the UAV reduces greatly the situational awareness; this has a negative impact on system performance in the presence of remote and unforeseen environmental constraints and disturbances. This is why this thesis is dedicated to the study of means to increase the level of situational awareness of the UAV operator.
The sense of telepresence is very important in teleoperation, and it appears reasonable, and it has already been shown in the literature, that extending the visual feedback with force feedback is able to complement the visual information (when missing or limited). An artificially recreated sense of touch (haptic) may allow the operator to better perceive information from the remote aircraft state, the environment and its constraints, hopefully preventing dangerous situations. This thesis introdues first a novel classification for haptic aid systems in two large classes: Direct Haptic Aid (DHA) and Indirect Haptic Aid (IHA), then, after showing that almost all existing aid concepts belong to the first class, focuses on IHA and tries to show that classical applications (that used a DHA approach) can be revised in a IHA fashion. The novel IHA systems produce different sensations, which in most cases may appear as exactly "opposite in sign" from the corresponding DHA; these sensations can provide valuable cues for the pilot, both in terms of improvement of performance and "level of
appreciation". Furthermore, it will be shown that the novel cueing algorithms, which were designed just to appear "natural" to the operator, and not to directly help the pilot in his task (as in the DHA cases), can outperform the corresponding DHA systems.
Three case studies were selected: obstacle avoidance, wind gust rejection, and a combination of the two. For all the cases, DHA and IHA systems were designed and compared against baseline performance with no haptic aid. Test results show that a net improvement in terms of performance is provided by employing the IHA cuse instead of both the DHA cues or the visual cues only.
Both professional pilots and naïve subjects were used in some of the experiments. The perceived feelings transmitted by the haptic cues, strongly depend by the type of the experiment and the quality of the participants: the professional pilots, for instance, retained the DHA the most helpful force while they preferred IHA because they found it more natural and because they felt a better control authority on the aircraft; different results were obtained with naive participants.
In the end, this thesis aim is to show that the IHA philosophy is a valid and promising alternative to the other commonly used, and published in the scientific literature, approaches which fall in the DHA category.
Finally the haptic cueing for the obstacle avoidance task was tested in the presence of time delay in the communication link, as in a classical bilateral teleoperation scheme. The Master was provide with an admittance controller and an observer for force exerted by the human on the stick was developed. Experiments have shown that the proposed system is capable of standing substantial communication delays
Hardware-in-the-loop simulations and control design for a small vertical axis wind turbine
Control design plays an important role in wind energy conversion systems in achieving high efficiency and performance. In this study, hardware-in-the-loop (HIL) simulations are carried out to design a maximum power point tracking (MPPT) algorithm for small vertical axis wind turbines (VAWTs). Wind torque is calculated and applied to an electrical motor that drives the generator in the HIL simulator, which mimics the dynamics of the rotor. To deal with disturbance torques in the HIL system, a virtual plant is introduced to obtain an error between the speeds in the HIL system and virtual plant. This error is used by a proportional-integral (PI) controller to generate a disturbance torque compensation signal. The MPPT algorithm is tested in the HIL simulator under various wind conditions, and the results are compared with numerical simulations. The HIL simulator successfully mimics the dynamics of the VAWT under various wind conditions and provides a realistic framework for control designs
Design of a prototype personal static var compensator
The focus of this thesis is the design and implementation of a personal static var compensator (PSVC) for distributed var control through load power factor correction. The PSVC demonstrates the two key benefits of power factor correction, which include decreased power costs and increased system capacity. The PSVC prototype consists of two types of branches---a TSC branch and a TCR branch. A microprocessor is responsible for calculating the load displacement power factor (PFD) and for executing the fuzzy logic control scheme for the two branches. The PSVC was found to reduce the RMS current drawn by a 55-watt AC motor by 25% while raising its PFD by 40% to 0.99 lagging. The expected quick rate of return of installation costs is attributed to the PSVC\u27s low initial cost and its ability to reduce tariffs for reactive power consumption
Discrete methods for the implementation of control networks using integrated circuitry
Discrete methods for implementation of control networks using integrated circuitr
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