Most of the inspection methods used for detection and localization of welding disturbances are based on the evaluation of some direct measurements of welding parameters. This direct measurement requires an insertion of sensors during the welding process which could somehow alter the behavior of the metallic transference. An inspection method that evaluates the GMA welding process evolution using a non-intrusive process sensing would allow not only the identification of disturbances during welding runs and thus reduce inspection time, but would also reduce the interference on the process caused by the direct sensing. In this paper a nonintrusive method for weld disturbance detection and localization for weld quality evaluation is demonstrated. The system is based on the acoustic sensing of the welding electrical arc. During repetitive tests in welds without disturbances, the stability acoustic parameters were calculated and used as comparison references for the detection and location of disturbances during the weld runs.

The present study shows the relationship between welding quality and optical-acoustic emissions from electric arcs, during welding runs, in the GMAW-S process. Bead on plate welding tests was carried out with pre-set parameters chosen from manufacturing standards. During the welding runs interferences were induced on the welding path using paint, grease or gas faults. In each welding run arc voltage, welding current, infrared and acoustic emission values were acquired and parameters such as arc power, acoustic peaks rate and infrared radiation rate computed. Data fusion algorithms were developed by assessing known welding quality parameters from arc emissions. These algorithms have showed better responses when they are based on more than just one sensor. Finally, it was concluded that there is a close relation between arc emissions and quality in welding and it can be measured from arc emissions sensing and data fusion algorithms.

The design, implementation, and testing of an Attitude Control System (ACS) for nanosatellites require a simulated environment that replicates the conditions of Low Earth Orbit. Key factors such as the absence of friction and gravitational effects must be achieved in an attitude control testbed. Additionally, a platform with low weight and inertia ensures that the small actuators of a CubeSat can rotate the system without requiring excessive effort. The testbed developed at Universidad Católica San Pablo was built using lightweight materials, including 3D-printed PLA parts, carbon fiber tubes, and acrylic boards. Unlike other self-balancing testbeds, this work introduces a shifting-mass approach, where a DC motor serves as both actuator and shifting-mass, significantly reducing weight. The position of the shifting masses along their axis is controlled by a Linear Quadratic Regulator (LQR). The platform’s attitude estimation is performed using an Extended Kalman Filter (EKF), which combines data from low-cost accelerometer, gyroscope, and magnetometer sensors. A nonlinear control system is implemented for the automatic balancing procedure, mitigating gravitational disturbance torque by using the estimated gravity vector to drive the shifting masses and minimize platform tilt. Finally, a Least Squares Method (LSM) compensates for residual vertical misalignment after the balancing procedure, enabling precise center of mass (CM) control in all axes. Obtained results demonstrate the DC motor shifting-mass approach reduces total platform weight by 72% compared to other works while achieving precise balancing with less than $210~\mu $ m residual misalignment between the center of mass (CM) and center of rotation (CR) and 92% reduction in kinetic energy variance during operation.

This project aims to develop a yaw controller system for a CubeSat prototype, which tracks a remote set point signal. This prototype is oriented to education and entertainment in aerospace technologies. Aiming to reducing the costs, commercial off-the-shelf devices (COTS) were used. Thus, a Atmel 8-bit AVR microcontroller was utilized for computational work, a couple of 2.4GHz transceiver for communication between CubeSat and base station (where is the set point command), accelerometer and gyroscope sensors, H bridge circuit for driving a DC motor. The firmware was divided in two parts: The setup and the principal loop. After tests was noticed that the controller performance is restricted to nonlinearities that appear due to reaction wheel nature (saturation). This device can be very helpful in education and entertainment to understand the yaw dynamic of spacecrafts (such as satellites), the principles of feedback control, as well as embedded systems applications.

Garantizar la calidad en soldadura no es una tarea trivial. Para ello diversas inspecciones de control de calidad son realizadas, en detrimento, los costos y tiempos de producción se elevan. Existen diversos sistemas automatizados de soldadura, éstos son auxiliados por sistemas de control basados en el monitoreo de parámetros de soldadura. Sin embargo son reducidos los sistemas automatizados de monitoreo de calidad que en su mayoría son diseñados para el proceso TIG. Durante la soldadura, el arco eléctrico produce emisiones acústicas y electromagnéticas que se manifiestan como sonido y luminosidad. El objetivo del presente trabajo es mostrar que estas emisiones del arco pueden ser utilizados para el monitoreo de la calidad de la soldadura para el proceso MAG-S. Se realizaron múltiples experimentos de soldadura en posición plana donde se indujeron perturbaciones consistentes presencia de grasa y ausencia de gas de protección. En cada experimento se adquirió simultáneamente señales de tensión y corriente así como señales de emisiones del arco eléctrico. A partir de las emisiones acústicas y electromagnéticas en la banda de ultravioleta, se midió la frecuencia de cortocircuitos. A partir de la emisión electromagnética en la banda infrarroja se midió la estabilidad del proceso de soldadura. Los resultados muestran que las emisiones del arco pueden ser utilizadas para el monitoreo y detección de perturbaciones en soldadura y con el entendimiento de las variaciones de cada emisión podría identificarse determinados tipos de perturbaciones. Ensuring quality in welding is not a trivial task. For this purpose several quality control checks are performed, at the expense, costs and production times are increased. There are several automated welding systems and they are assisted by control systems based on monitoring of welding parameters. However, automated quality monitoring systems are limited and they are mostly designed for the TIG welding processes. During welding, the arc produces acoustic and electromagnetic emissions that occur as sound and light. The aim of this paper is to show that the emissions of the welding arc can be used to monitoring the quality of welding in MAG-S process. Multiple welding experiments were performed in flat position; in each experiment were induced perturbations by grease on plate and shielding gas absence. Current and voltage signals and arc emission signals were acquired simultaneously. The short circuit frequency was measured from acoustic and electromagnetic emission in the ultraviolet band. The welding stability was measured from infrared emission. The results show that the emissions of welding arc can be used for monitoring and detecting of disturbances in welding and with the understanding of the variations of each disturbance could be possible to identify certain types of disturbances

El sonido del proceso de soldadura es una consecuencia de la modulación en amplitud de la corriente por la tensión del arco. Experimentaciones pasadas demostraron que un soldador experimentado tiene una dependencia absoluta de la acústica en el control del proceso de soldadura. En este trabajo se presenta una nueva técnica de detección de defectos de soldadura basada en la estabilidad de la acústica aerotransportada del proceso MIG/MAG para el modo de transferencia por corto-circuito. Se determinaron parámetros estadísticos de la presión acústica generada por el arco eléctrico del proceso de soldadura MIG/MAG en el modo de transferencia por corto-circuito a partir de múltiples soldaduras en posición plana sobre cuerpos de ensayo libres de defectos. Con estos resultados se desarrollo un algoritmo de detección de defectos basado en una ventana móvil que se desplaza a través de las señales estadísticas calculadas a partir de la acústica del proceso. Finalmente sobre un conjunto de cuerpos de prueba con y sin defectos fueron hechas soldaduras en posición plana para la evaluación del desempeño de la técnica de detección de defectos propuesta. El algoritmo de detección de defectos basado en la acústica aerotransportada del proceso, mostró resultados satisfactorios.