Mechatronics of a ball screw drive using a N degrees of freedom dynamic model

High performance position control in machine tools can only be achieved modelling the dynamic behavior of the mechatronic system composed by the motor, transmission and control during the design stage. In this work, a complex analytical model of a ball screw drive is presented and integrated in a mechatronic model of the actuator to predict the dynamic behaviour and analyze the impact of each component of the transmission. First, a simple 2 degrees of freedom model is presented, and is analysis sets the basis for the development of a more complex model of several degrees of freedom, whose resulting fundamental transfer functions are represented using natural and modal coordinates. The modeling in modal coordinates carries a reduction of the transfer function that reduces computational work. The two models are compared and experimentally validated in time and frequency domain by means of experimental tests carried out on a specifically developed ball screw drive test benchMinisterio de Economía y Competitividad: Project DPI2015-64450-R (MINECO/FEDER, UE) University of the Basque Country (UPV/EHU) under the program UFI 11/29 Departamento de Educación, Política Lingüística y Cultura” of the regional government of the Basque Country (IT949-16

CONTINUOUS MOTION NOMINAL CHARACTERISTIC TRAJECTORY FOLLOWING CONTROL FOR POSITION CONTROL OF AN AC DRIVEN X-Y BALL SCREW MECHANISM

AC servo mechanisms are widely used in industrial application due to its advantages in higher efficiency, less maintenance, and smoother operation than DC servo mechanism. However, AC servomechanism frequently suffers from its inherently non-linear characteristics and more difficult to be controlled in positioning applications. A general step input easily drove the mechanism and stop smoothly in the open-loop environment, however, it is not the same for AC driven ball screw mechanism. Hence, the contributions in this paper are: (1) the realization of the practical control method - continuous motion nominal characteristic trajectory following (CM NCTF) control to an AC driven ball screw mechanism, (2) the design of a suitable input signal that produces sufficient rapid and smooth response during deceleration motion in the open-loop experiment. The open-loop responses used to construct nominal characteristic trajectory (NCT) are important because it significantly affects the reference following characteristic of the control system. The experimental evaluations were carried out for CM NCTF control system and PI-D control system. The results show that the designed input signal has successfully produced rapid and smooth open-loop responses during deceleration that benefit the reference position near NCT origin. Besides that, the CM NCTF control system that designed with the newly constructed NCT has demonstrated better positioning results than the PID controller with almost 10 times of motion error reduction for Y-axis for both amplitudes of 5 mm and 10 mm respectively

Análisis mecatrónico de accionamientos de máquinas herramienta teniendo en cuenta la flexibilidad de la estructura

253 p.Debido al crecimiento en los últimos años de los sectores de energías renovables, ferrocarril, aviación,plataformas marinas, la energía de fusión en grandes plantas científicas, etc se ha requerido el desarrollode máquinas-herramienta de escala convencional y grande. Para dar servicio a dichos sectores se requierede máquina-herramienta como pueden ser prensas, tornos o fresadoras. La principal aportación de estatesis es el desarrollo de un modelo mecatrónico de 3 grados de libertad que integra la dinámica del motor,la cadena de transmisión del accionamiento, los elementos estructurales de la máquina herramienta y elcontrol en cascada, aportando la formulación completa del modelo, funciones de transferencia relevantesy obtención del amortiguamiento. El modelo ha sido sido simulado en Matlab/Simulink, obteniéndosecomo resultado que en general el elemento terminal de la estructura, donde se colocaría la herramienta,sufre un desplazamiento distinto al que se experimenta al final del accionamiento. El modelo permitecomprobar si un diseño de accionamiento y estructura determinado es capaz de lograr unos requisitos demovimiento predefinidos, es decir, alcanzar una posición dada siguiendo un perfil de movimiento conuna velocidad de avance, aceleración y jerk determinados. El análisis se ha validado experimentalmentesimulando la flexibilidad de una máquina-herramienta en un banco de ensayos con una masa situadasobre dos placas finas en voladizo sujetas a la mesa de un accionamiento husillo a bolas y control Fagor8035 situado en el taller de Máquina Herramienta del Departamento de Ingeniería Mecánica de laUPV/EHU