The use of lightweight, thin flexible structures creates a dilemma in the aerospace and robotic industries. While increased operating efficiency and mobility can be achieved by employing such structures, these benefits are compromised by significant structural vibrations due to the increased flexibility. To address this problem, extensive research in the area of vibration control of flexible structures has been performed over the last two decades. The majority of the research has been based on the use of discrete piezoceramic actuators (PZTs) as active dampers, as they are commercial availability and have high force and bandwidth capabilities. Many different active vibration control strategies have previously been proposed, in order to effectively suppress vibrations. The synthesized vibration controllers will be less effective or even make the system to become unstable if the actuator locations and control gains are not chosen properly. However, there is currently no quantitative procedure that deals with these procedures simultaneously. This thesis presents a theoretical and numerical study of vibration control of a singlelink flexible manipulator attached to a rotating hub, with PZTs bonded to the surface of the link. A commercially available fibre optic sensor called ShapeTapeTM is introduced as a new feedback sensing technique, which is complemented by a quantitative and definitive model based procedure for selecting the individual PZT locations and gains. Based on Euler-Bernoulli beam theory, discrete finite element equations are obtained using Lagrange’s equations for a PZT-mounted beam element. Slewing of the flexible link by a rotating hub induces vibrations in the link that persist long after the hub stops rotating. These vibrations are suppressed through a combined scheme of PD-based hub motion control and proposed PZT actuator control, which is a composite linear (L-type) and angular (A-type) velocity feedback controller. A Lyapunov approach was used to synthesize the PZT controller. The feedback sensing of linear and angular velocities is realized by using the ShapeTapeTM, which measures the bend and twist of the flexible link’s centerline. Both simulation and experimental results show that tip vibrations are most effectively suppressed using the proposed composite controller. Its performance advantage over the individual linear or angular velocity feedback controllers confirms theoretical predictions made based on a non-proportional damping model of the PZT effects. Furthermore, it is demonstrated that the non-proportional nature of the PZT damping effect must be considered in order to bound the range of allowable controller gain values.

The purpose of this research work is to propose an improved method for real-time sensitivity analysis (SA) applicable to large-scale complex systems. Borrowed from the EventTracker principle of the interrelation of causal events, it deploys the Rank Order Clustering (ROC) method to automatically group every relevant system input to parameters that represent the system state (i.e. output). The fundamental principle of event modelling is that the state of a given system is a function of every acquirable piece of knowledge or data (input) of events that occur within the system and its wider operational environment unless proven otherwise. It therefore strives to build the theoretical and practical foundation for the engineering of input data. The event modelling platform proposed attempts to filter unwanted data, and more importantly, include information that was thought to be irrelevant at the outset of the design process. The underpinning logic of the proposed Event Clustering technique (EventiC) is to build causal relationship between the events that trigger the inputs and outputs of the system. EventiC groups inputs with relevant corresponding outputs and measures the impact of each input variable on the output variables in short spans of time (relative real-time). It is believed that this grouping of relevant input-output event data by order of its importance in real-time is the key contribution to knowledge in this subject area. Our motivation is that components of current complex and organised systems are capable of generating and sharing information within their network of interrelated devices and systems. In addition to being an intelligent recorder of events, EventiC could also be a platform for preliminary data and knowledge construction. This improvement in the quality, and at times the quantity of input data, may lead to improved higher level mathematical formalism. It is hoped that better models will translate into superior controls and decision making. It is therefore believed that the projected outcome of this research work can be used to predict, stabilize (control), and optimize (operational research) the work of complex systems in the shortest possible time. For proof of concept, EventiC was designed using the MATLAB package and implemented using real-time data from the monitoring and control system of a typical cement manufacturing plant. The purpose for this deployment was to test and validate the concept, and to demonstrate whether the clusters of input data and their levels of importance against system performance indicators could be approved by industry experts. EventiC was used as an input variable selection tool for improving the existing fuzzy controller of the plant. Finally, EventiC was compared with its predecessor EventTracker using the same case study. The results revealed improvements in both computational efficiency and the quality of input variable selection.

Plasma actuators are devices which function by creating a discharge in air at atmospheric conditions. These devices have been demonstrated to effectively delay flow separation and enhance the lift- drag characteristics of wing sections. They have also been shown to have potential applications in controlling dynamic stall, flow separation control over turbine blades, flow vectoring, boundary layer manipulation and bluff body flow control. This study examines the characteristics of the plasma actuator, its working and the optimization of its configuration for its use as a lift enhancing device. A single actuator connected to a high-voltage, high-frequency power supply was studied in quiescent conditions. It was demonstrated by means of flow visualization experiments and hot-wire anemometry that the plasma actuator functions by inducing a flow, thus behaving as a source of momentum flux in any system that it is introduced into. Further, it was inferred that the flow induced is a wall jet and that the magnitude of the velocity achieved is maximum within a few millimeters of the surface of the actuator. A parametric investigation of the actuator was conducted next. The variation of the peak velocity induced in quiescent conditions with the variation of configuration parameters was studied by means of photographic studies and hot-wire anemometry. These experiments indicated that there is a strong correlation between the visible extent of the plasma along the direction of the induced _ow (plasma width) and the peak velocity achieved. The peak velocity achieved is found to increase with the increase in the plasma width as long as the discharge created is in the uniform glow discharge regime. The development of localized high intensity streamers, which destroy the uniformity of the plasma, lead to a loss in the peak velocity. Hot-wire tests indicated that the peak velocity increases with a decrease in the spanwise overlap of the electrodes, with the other parameters kept constant. Also, in the uniform glow discharge regime, the velocity increases with the increase in the thickness of the dielectric placed between the two electrodes. After a particular optimum thickness, further increase of the thickness leads to formation of streamers. The velocity increased with a decrease in streamwise overlap, with the maximum being reached for a overlap of approximately 2mm, after which it remained a constant. It was observed that the absence of overlap leads to a loss of uniformity of the discharge created. The velocity was found to be independent of the variations in the electrode widths. Particle Image Velocimetry (PIV) was conducted to study the characteristics of the jet produced. It was observed that when the actuator is switched on, a low pressure region is created near the surface of the actuator, vertically above it, leading to a flow towards this region from above the actuator. Furthermore, a vortex is shed, which is convected downstream, after which a wall jet is established close to the dielectric surface.

A Stewart Platform robot was designed, constructed, and programmed for use in Cal Poly’s ME 423 Robotics: Fundamentals and Applications laboratory section. A Stewart Platform is a parallel manipulator robot with six prismatic joints that has six degrees of freedom, able to be defined in both position and orientation. Its purpose is to supplement parallel robot material covered in lecture. Learning objectives include applying and verifying the Stewart Platform inverse kinematics and investigating the Stewart Platform’s operation, range of motion, and limitations. The Stewart Platform geometry and inverse kinematics were modeled and animated using MATLAB. The platform was then built using linear actuators, magnetic spherical bearings, and acrylic plates. Control of the Stewart Platform is achieved using an Arduino Due and a custom HexaMoto shield. Users interact with the system using a GUI created with MATLAB’s App Designer.

Pneumatic drives are an integral part of many machinery, with high demands on their reliability. Unfortunately, they sometimes fail, either due to improper production or assembly at the factory or by gradual degradation of moving parts and sealing elements during operation. Current diagnostic methods do not allow localization or identification of the type of damage and do not allow the operator to make a qualified decision. This work deals with the use of acoustic emission for these purposes. On PB type cylinders manufactured by Poličské strojírny a.s., a methodology is introduced which leads to the direct identification or at least localization of selected defects. By implementing this methodology in the final inspection of the production plant, the percentage of exposed pieces of waste will be increased, thus preventing accidents of these faulty pieces during operation.

This thesis is focused on detecting air leakage in serial production of pneumatic linear actuators. Testing for air leakage is an important part of the production process in which the manufacturer ensures that the product satisfies quality requirements and works correctly. The thesis was created in collaboration with the Czech manufacturing plant of SMC Industrial Automation CZ s.r.o., which produces pneumatic actuators. Goal of the design part of the thesis is to select the most effective method for testing and finding universal principle for testing in specified conditions. The principle is then applied to design a testing device for the CQ2 cylinders. The testing device consists of three parts - pneumatic circuit, control circuit and electric circuit. Thesis conclusion contains comparison of the newly designed testing device with the device currently in use.

The subject of this diploma thesis is designing a way of substituting pneumatic drives with electrical actuators for mechanical movements in a headlights tester. The thesis also contains a theoretical introduction to the issue in the first part. Substitution variants are assessed considering chosen parameters and evaluated using multi-criteria evaluation method. Two final designs are compiled based on the evaluation results and processed into the 3D model of the tester. Drawings are produced for these solutions. In conclusion, a recommendation derived from achieved results is given to the tester manufacturer, ELCOM a.s.

In der vorliegenden Dissertationsschrift wird ein thermo-elektro-mechanisches Modell zur Simulation des Verhaltens von dielektrischen Elastomeraktoren vorgestellt. Zur Beschreibung der elektrischen und thermischen Eigenschaften werden lineare Modelle verwendet. Ein isotropes viskohyperelastisches mechanisches Materialmodell wird auf Grundlage der Hyperelastizität nach Ogden und der Beschreibung viskosen Verhaltens mittels Prony-Reihen eingesetzt. Die elektromechanische Kopplung ist durch die elektrostatische Anziehungskraft geladener Elektroden begründet. Die verlustbehafteten Prozesse der elektromechanischen Energieumwandlung bzw. des Ladungstransports führen zu einer Verlustleistung, welche in Wärme umgewandelt wird. Auf diese Weise wird eine unidirektionale Kopplung zwischen dem elektromechanischen und dem thermischen Feld erreicht. Die entsprechenden Materialparameter wurden der Literatur entnommen oder von Daten experimenteller Untersuchungen abgeleitet, welche am Institut für Elektromechanische Konstruktion (EMK) der Technischen Universität Darmstadt durchgeführt wurden. Mittels der Finite-Elemente-Methode wurde das thermo-elektro-mechanischen Modell zur Simulation zweier Testgeometrien verwendet. Dabei wurde eine gute qualitative Übereinstimmungen zwischen den Ergebnissen der numerisch Simulation und den experimentellen Beobachtungen des EMK erreicht. Die Ursachen quantitativer Differenzen zwischen den experimentell ermittelten und den numerisch berechneten Temperaturen werden untersucht und diskutiert. Abgeleitet aus den Ergebnissen der numerischen Untersuchungen werden abschließend Vorschläge zu einer Verringerung der dissipationsbedingten Erwärmung unterbreitet. Diese Vorschläge sind durch konstruktive, beispielsweise geometrische oder materielle, Eigenschaften von DE-Aktoren begründet, oder können aufgrund der aktiven Anregung getroffen werden.

Smartness of technical systems relies also on appropriate actuators and sensors. Different to the prevalent definition of smartness to be embedded machine intelligence, in this paper elegance and simplicity of solutions is postulated be a more uniform and useful characterization. This is discussed in view of the current trends towards cyber physical systems and the role of components and subsystems, as well as of models for their effective realization. Current research on actuators and sensing in the fluid power area has some emphasis on simplicity and elegance of solution concepts and sophisticated modeling. This is demonstrated by examples from sensorless positioning, valve actuation, and compact hydraulic power supply.

ROBEX is a unique research project combining Airbus Defence and Space’s robotics expertise with deep-sea exploration technology to discover more about the most extreme environments environments known to man. As a part of this project, a deep-sea glider called MOTH, is under development with the objective to determine whether gliders can be used as a platform for bathymetric and electromagnetic soundings of the seafloor as well as for new water column research. This master’s thesis aims to design and implement the MOTH glider’s control system. The glider will have an independent emergency system, a power unit, an on-board computer (OBC), actuators, navigation sensors and scientific measurement instruments which can be swopped between missions and are connected via remote terminal units. The selected OBC is a Linux embedded Axotec GX-6300 with RS232 and CAN bus interfaces, as selected in the electrical architecture, and the chosen operative system is Linux Debian. The glider communicates with GNS/Iridium antenna and also has an ethernet cable link for ground station operations and a future option of an acoustic transceiver. To control actuation, the glider is equipped with a rudder, a left and a right wing flap, a moveable mass and a buoyancy tank. It travels in sawtooth patterns and is therefore always descending, ascending or transitioning during operation and at times ascending all the way to the surface to transmit and receive data via satellite communication. A model based feedback controller for longitudinal control has been programmed based on the equations of motion described in this report. The modelled longitudinal trajectory is as desired until a transition point is reached, the model is, presumable because of the uncertainty of the model parameters, unstable as the actuators are unable to correct the pitch angle. An AHRS navigation sensor emulator and an OBC emulator have been programmed to simulate the communication between these two and the emulated system is well operating both as a continuous stream and for polling data. The emulator and the pitch controller, when updated parameter values are available, will be used for simulation and verification tests in the laboratory environment. The ROBEX alliance will, if the objectives with the MOTH glider are met, continue to design gliders with the aim to increase the maximum duration time and speed in order to reach greater depths of the oceans.