Rodrigues, Mário Manuel SilveiraVitorino, Miguel VargasFreixo, Pedro Nuno Brunheta Pinheiro Dias2023-05-032023-05-0320232022http://hdl.handle.net/10451/57338Tese de Mestrado Integrado, Engenharia Física, 2022, Universidade de Lisboa, Faculdade de CiênciasThis work deals with the implementation of a fine and coarse tip-sample distance control as well as with the tuning of several other features that will make one AFM prototype more user friendly. The main goal was to design and integrate a PI (Proportional-Integral) Analog Controller with digitally controllable gains. The development of the controller started by identifying and characterizing the system, with emphasis on the Z-axis Scanner’s response, which in turn allowed to build models for all the different components that make up the AFM. The PI Controller’s gains were arranged to be independently tuned via a digital potentiometer in conjunction with an analog multiplexer. The digital potentiometer provides a fine gain adjustment while the analog multiplexer increments the gains by an order of magnitude. These devices receive instructions from a microcontroller. In parallel, several other important enhancements were carried out, which include an implementation of an Auto-Approach functionality that automatically approaches the probe and sample without crashing onto each other. In order to achieve this, it was conducted an experimental study of the instrument’s motorized coarse motion structure. All the new features developed here were integrated in the existing prototype via the Arduino platform. To interface the signals outputted by the AFM circuitry and the microcontroller, as well as providing robust tolerance against faulty use, additional circuitry was included. This allows the reading of important signals within the instrument’s context, such as the deflection signal, amplitude signal and controller output. By taking advantage of the microcontroller’s features, it was designed a voltage source that serves as an adjustable setpoint via the PWM outputs from the Arduino. Finally, it was design and developed a GUI providing the user direct control of the tasks mentioned above and also displaying some quantitative and qualitative data, acquired by the microcontroller, about the state of the AFM.engMicroscopia de Força AtómicaControlador PI Analógico com ganhos digitaisInstrumentaçãoArduinoAlgoritmo Auto-ApproachTeses de mestrado - 2023master thesis203509994