The aim of this work was to design a control system for the shape memory alloy (SMA) actuator operated airfoil (a cross section of wind turbine blade). Design of SMA control is focused on the reliable operation of the SMA actuators. The actuator should follow the targeted shape accurately and without too much delay. Another objective is to avoid overheating which is the most critical damage to the structure. SMA actuator shape control is in principle possible to do with any position control method, but the specific properties of the SMA actuators, like the hysteresis, the first cycle effect and the long term changes, need to be taken into account. In this work, a wing profile prototype was measured using optical fiber sensors and traditional strain gauges. Also, external laser sensors were used to measure displacements of upper/lower surface and trailing edge. Shape change was obtained by embedding SMA wire actuators into fiber reinforced polymer (FRP) composite structure. SMA actuators were laminated in such way that bending of trailing edge is always downwards. Actuators are activated with Joule heating and the temperature is measured with integrated thermocouples and optical fiber temperature sensors. As a result, this work gave information about the usability of optical fibers sensors in active FRP composite structures. Measurements also give information about the efficiency of SMA actuators in shape control of relatively stiff FRP structures.
Magnetic resonance imaging (MRI) is currently a widely used technology for obtaining a three-dimensional image of a patient’s internal structures. This study examines the measurement properties of an optical tracking system utilised in the MRI room. The results were used to assess the suitability of the device to be used as a part of the control system of a surgical robot. The position and orientation of the instrument, MRI scanner and the patient are measured using an optical tracking system in the MRI room. The measurement data can be used to display the instrument used as a part of the image of the patient. The optical tracking system used in the MRI room can also be considered as a part of the control system of a robot located in the room. When considering such use, the operations of the measuring device in different measurement conditions must be known. In terms of robot control, it is important to know the deviation attributed to measurement when defining the translation vector and orientation between two trackers. Five measurement series were carried out using the measurement device to examine the deviation in the translation vector and orientation data between two trackers. The distance and position between the trackers were changed between the measurement series. During the measurement series, the measurement device was moved to different distances from the trackers and the translation vector and orientation between the trackers were defined on the basis of the measurement results obtained. The measurements showed that the deviation of the translation vector did not significantly change as the measurement distance increased, but the deviation of orientation data between different trackers increased significantly. Deviation in the translation vector increased as the distance between trackers increased, but deviation in orientation did not change significantly.
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