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Thesis
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Studii şi cercetări privind acţionarea pneumatică de precizie a roboţilor
Cartal, Laurenţiu Adrian
2012-06-17
Abstract: Studies and research regarding precision pneumatic actuation of the robots Doctorate thesis abstract Author: eng. LaurenŃiu Adrian CARTAL Scientific coordinator: Prof. dr. eng. Nicolae ALEXANDRESCU In connection with the development of new types of robots, the research and development activities in this area continuously aim at the improvement of technical and functional performances by using new manufacturing techniques and materials, but also at the optimization of the command and control algorithms in accordance with the accomplished tasks. In this context, the main objective of the doctorate thesis is the increase of precision in pneumatic driving systems, a problem that has not been solved so far. The accomplishment of this objective was achieved following two directions: the first direction consisting of the research, development, manufacturing and testing of a new control equipment for the air flow at entry in the pneumatic linear motor, which can respond in the least possible time to the command signal – proportional flow regulator; the second direction is represented by the development of a driving algorithm which in the positioning cycle should accomplish control of the movement regimes and control of the displacement velocities, while constantly maintaining them at the necessary values for obtaining precise positioning, regardless of the variations of the driving force. This proportional flow regulator consists of two sub assemblies: the first – flow control pneumatic sub assembly, and the second, an electro mechanic convertor to drive it. Considering all electro mechanical convertors used in the proportional pneumatic area, it can be concluded that the best performances are ensured by piezoelectric actuators with regard to the driving forces and work frequencies, with the small disadvantage of developing relatively small displacements. This led to the study of several mechanical amplifying structures, with a single identified solution of a double compliant mechanism that met technical and functional requirements, with the significant advantage of providing clearance free amplification with no friction forces in the joints. Finally, for the accomplishment of the main objective – increase of precision in pneumatic driving systems, the proportional flow regulator was integrated in a pneumatic positioning unit and a mathematical model was developed by analyzing the functioning of the linear positioning unit. Observing form the laws of velocities that the error is dependant of the positioning velocity and the response time of the proportional regulator, it has been decided that the unit will move with a high velocity for most of the run and in the area where the positioning is required, the velocity will be dramatically reduced, so that the positioning error will be significantly diminished. This velocity depends on the opening chair-valve; from the functioning of the regulator this opening is dependent on the command tension of the primary piezoelectric actuator. By using the driving algorithm for the control of the functional model for a positioning unit, the objective of the research paper was met and opened future research directions by optimization of the electro mechanic convertor and of the command algorithm.
Keyword(s): Robotică -- Teză de doctorat ; Acţionări pneumatice -- Teză de doctorat ; Roboţi industriali -- Acţionări pneumatice -- Teză de doctorat
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Record created 2017-03-09, last modified 2017-03-09
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