Keywords
IEM-N (KL0-electronica), Seguridad, montacargas, control, velocidad, láser, Simulink, Arduino., Security, hoist, control, speed, laser, Simulink, Arduino.
Optimización de un montacargas
Abstract
OPTIMIZACIÓN DE UN MONTACARGAS
Autor: Méntrida Zamarra, Sergio.
Director: Gourdeau, Richard.
Entidad Colaboradora: Université de Montréal, École Polytechnique.
RESUMEN DEL PROYECTO:
Introducción
En la Universidad Politécnica de Montreal se utilizan dos plantas piloto de forma didáctica para las prácticas en laboratorio de la asignatura “Commande des processus industriels”. Esta asignatura enseña sobre el control y la automatización de procesos industriales. Cada planta piloto está compuesta de un montacargas: un carro que se desplaza en horizontal a lo largo de un raíl y que transporta una carga que se desplaza verticalmente con una cuerda.
La Universidad quiere modernizar las plantas piloto, debido al elevado coste de mantenimiento de los equipos del sistema actual, y a problemas de seguridad con el alumnado a lo largo de las prácticas. Aprovechando el reemplazo de los equipos que se han quedado anticuados se quiere optimizar el funcionamiento del montacargas, añadiendo un sistema de seguridad más completo y cambiando el sistema de control del carro. Es un proyecto grupal, compuesto por dos profesores, un técnico y mi aportación. Nuestro trabajo se centra principalmente en dar respuesta al sistema de seguridad.
Con el sistema actual, los desplazamientos del carro a gran velocidad no están limitados hasta que éste llega al extremo del raíl por lo que la carga y el carro pueden impactar violentamente contra las paredes del laboratorio. Ante este problema, se pretende diseñar un sistema de seguridad que funcione de forma independiente y que limite la velocidad del carro para que no choquen ni el carro ni la carga que transporta contra los extremos del raíl.
Para ello, los objetivos que se han fijado para el proyecto son los siguientes:
• Diseñar un sistema de seguridad basado en el control del voltaje de un motor que desplaza un carro mediante la medición de la posición de éste último.
• Implementar la comunicación entre un motor y una herramienta de software, pudiendo controlar el voltaje y sentido de giro del motor. La comunicación se va a efectuar mediante un módulo UART y también mediante un potenciómetro que regule el voltaje del motor.
• Medir mediante tecnología láser la posición absoluta de un carro móvil y poder manipular los datos de distancia obtenidos.
• Adquirir un montaje final que simule el funcionamiento de la futura planta piloto provista de un sistema de seguridad completo.
Una vez se tenga un montaje con un sistema de seguridad funcional, se podrá probar el diseño en la planta piloto final que servirá a futuros alumnos para la realización de sus prácticas.
Metodología
La herramienta principal de software que se ha usado para la realización del proyecto es Matlab-Simulink, y para otras tareas subordinadas se ha utilizado el software Arduino. El diseño del sistema de seguridad se ha realizado en una pequeña maqueta, compuesta por un motor que desplaza un carro por un rail de 1m de longitud. No se ha podido implementar el sistema de seguridad diseñado en la planta piloto final por motivos de calendario, pero los resultados extraídos de la maqueta servirán para su implementación en la planta piloto.
Resultados
Los resultados finales del proyecto se han obtenido experimentando en la maqueta diseñada a efectos del proyecto. Los pasos para realizar los objetivos marcados han sido los siguientes.
En primer lugar, se ha logrado realizar la comunicación entre el software Matlab-Simulink y el motor que desplaza el carro. Con una placa de control de motor de corriente continua, un microcontrolador y un potenciómetro lineal se ha implementado un modelo en el cual el desplazamiento del carro es dirigido por el potenciómetro. Con el sistema que se ha montado, variando un voltaje de referencia (de 3V) con el potenciómetro se puede decidir cuál es el sentido y la potencia de giro del motor. De modo que un extremo del potenciómetro (0V) representa un punto de trabajo máximo del motor con un sentido de giro, y el otro extremo (3V) representa también un punto de trabajo máximo del motor pero con el otro sentido de giro. Siendo la potencia de giro del motor proporcional al voltaje generado por el potenciómetro. A parte de este modelo se ha introducido otra forma de generar el mando, sustituyendo el potenciómetro por un módulo UART (Universal Asynchronous Receiver Transmitter) para comandar ganancias al motor desde el propio Matlab-Simulink.
Tras obtener un procedimiento por el cual controlamos la velocidad del carro y su sentido de desplazamiento, se ha constituido la medición de la posición del carro mediante tecnología láser. Se ha buscado un método económico y preciso en el contexto de nuestra aplicación. Desde el software Arduino se han captado los datos provenientes del láser y se ha extraído la posición del carro medida en todo momento.
Una vez reunidas todas las partes, se ha logrado implementar un sistema de seguridad funcional, comunicando los software de Matlab-Simulink y Arduino con el motor que desplaza el carro. Se ha obtenido un modelo en el cual el mando es controlado por un potenciómetro y el programa de Arduino es el que toma el control del motor cuando el carro se sitúa en una situación de riesgo. Se ha dividido el raíl en distintas zonas, de modo que hemos definido dos situaciones de riesgo:
• Primeramente cuando el carro se desplaza a gran velocidad y cerca del extremo, en una zona que hemos denominado zona de frenado. En esta zona se compara el mando generado por el potenciómetro con un patrón de referencia y si la ganancia del mando es mayor que la del patrón entonces el patrón de referencia toma el control del motor. Este patrón es una señal PWM generada por el propio Arduino que varía en función de la posición del carro. De forma que la señal PWM disminuye su ciclo de trabajo de forma lineal según se aproxima el carro al extremo del raíl. Con este sistema, en la zona de frenado no podremos superar ciertas velocidades debido a la limitación del patrón de referencia, que se ha comprobado que es suficientemente seguro.
• La segunda situación de riesgo se da cuando el carro ya se encuentra muy próximo al extremo. En estos casos, la influencia del programa de Arduino obliga al motor a detenerse por completo. Esta zona que hemos definido como zona de detención se sitúa más al extremo que la zona de frenado, y asegura que el carro se detenga por completo para evitar su impacto con el fin del raíl.
Se ha puesto a prueba el sistema de seguridad y los resultados han sido satisfactorios. El carro jamás impacta contra ninguno de los extremos, y el sistema diseñado puede adaptarse a otro tipo de plantas. Los únicos parámetros que se deben variar para implementar este sistema de seguridad en otras plantas son la delimitación de las zonas de frenado y detención fijadas en el programa de Arduino. Si se desea reemplazar el mando que se genera con el potenciómetro se debe modificar el modelo Matlab-Simulink a efectos de estos cambios.
Conclusiones
Los resultados obtenidos del proyecto han sido verificados exclusivamente en una maqueta montada a efectos de este mismo. Sin embargo, el sistema diseñado es adaptable a otros montacargas bajo la modificación de pocos parámetros. El futuro de este proyecto es que se implemente el sistema de seguridad diseñado en la planta piloto de la Universidad de Montreal.
Sin embargo, podemos afirmar que es un sistema aplicable en plantas piloto similares, y por tanto viable para ser utilizado en la industria. Las principales ventajas de nuestro sistema son que es muy sencillo, flexible y fácilmente modificable. Este proyecto puede dar solución de una forma sencilla a la implantación de sistemas de seguridad en plantas industriales que empleen montacargas, ayudando a que el lugar de trabajo y los equipos que se manejen sean más seguros.
OPTIMIZATION OF A HOIST Introduction At the University Polytechnic of Montreal there are currently in use two hoist simulations for laboratory tests of the subject “Commande des processus industriels”. This course teaches students about the control and automation of industrial processes. Each hoist simulation is composed of a car that moves horizontally along a rail and transports a load that moves vertically thanks to a rope. The University wants to modernize the laboratory, due to the high cost of maintenance of the equipment in the current system, and due to safety problems with the students throughout the practices. Taking advantage of the replacement of the outdated equipment, we want to optimize the hoist simulation, adding a broader safety system and changing the control system of the car. It is a group project, composed by two teachers, a technician and my contribution. This work focuses mainly on responding to the security system. With the current system, the displacements of the car at high speed are not limited until it reaches the end of the rail so the load and the car can impact violently against the walls of the laboratory. To solve this problem, the intention was to design a safety system that works independently and limits the speed of the car so that neither the car nor the load will collide against the ends of the rail. The objectives set for the project are the following: • To design a safety system based on the voltage control of an engine that moves a car by measuring its position. • To implement the communication between an engine and a software tool, being able to control the voltage and direction of rotation of the motor. The communication will be made through a UART module and also a potentiometer that regulates the voltage of the motor. • Measuring by laser technology the absolute position of a mobile car and being able to manipulate the obtained distance data. • Acquiring a final assembly putting together all the components; simulating the functioning of the future laboratory equipped with a complete safety system. Once the montage with the functional safety system is made, experiments will be done in order to test the design. This system shall be tested in the final laboratory that will serve future students to carry out their practices. Methodology The main software tool that has been used for the realization of the project is Matlab-Simulink. For other subordinate tasks, the Arduino software has been used. The design of the security system has been made in a small model, composed of a motor that moves a car by a rail of 1m in length. It has not been possible to implement the safety system designed in the final laboratory due to schedule reasons, but the results extracted from the model will be used for its implementation. Results The final results of the project have been obtained by experimenting with the model designed for the project. The steps to accomplish the objectives have been the following. First of all, communication between the Matlab-Simulink software and the motor that moves the car has been achieved. With a DC motor control board, a microcontroller and a potentiometer; a model has been implemented in which the displacement of the car is controlled by the potentiometer. With the system that has been created, by varying a reference voltage (3V) with the potenciometer, the direction and the power of rotation of the motor can be elected. One extreme point of the potentiometer (0V) represents a maximum working point of the motor with one direction of rotation, and the other extreme point (3V) also represents a maximum working point of the motor, but on the other direction of rotation. Therefore, the power of rotation of the motor is proportional to the voltage generated by the potentiometer. Apart from this model, a similar one has been introduced to generate the command to the motor, replacing the potentiometer for a UART module (Universal Asynchronous Receiver Transmitter) to command gains to the motor from the Matlab-Simulink itself. After obtaining a procedure by which we control the speed of the car and its direction, we will move onto the measurement of the position that has been constituted by a laser. An inexpensive and precise method has been sought in the context of our application. It has been possible to capture the absolute position of the car by communicating the software Arduino with the laser. Once all the parts have been assembled, a functional safety system has been implemented, communicating Matlab-Simulink and Adruino software with the motor that moves the car. A model has been obtained in which the command is controlled by a potentiometer and the Arduino program is the one that takes control of the engine when the car is placed in a risky situation. The rail has been divided into different zones, so we have defined two risky situations: • Firstly, when the car moves at high speed and near the end of the rail, in an area that we have called the braking zone. In this zone, the command generated by the potentiometer is compared with a reference pattern and if the gain of the command is greater than the pattern one, then the reference pattern takes control of the motor. This pattern is a PWM signal generated by the Arduino itself that varies depending on the position of the car. Due to this, the PWM signal decreases its duty cycle linearly as the car approaches the end of the rail. With this system, in the braking zone we cannot exceed certain speeds due to the limitation of the reference pattern, which has been checked to be safe. • The second risky situation occurs when the car is already very close to the end of the rail. In these cases, the influence of the Arduino program forces the motor to stop completely. This area, which we have defined as the stopping area, is located more in the extreme than the braking zone, and ensures that the car stops completely to avoid its impact with the end of the rail. The security system has been tested and the results have been satisfactory. The car never hits any of the extremes, and the designed system can be adapted to other types of hoist. The only parameters that must be changed to implement this security system into other hoists are the delimitation of braking and stopping zones, set in the Arduino program. If a replacement of the command system (the potentiometer in this case) is needed, the Matlab-Simulink model must be modified in consequence. Conclusions The results obtained from the project have been verified exclusively in a model assembled for the purposes of the project. Nevertheless, the designed system is adaptable to other hoist under the modification of a few parameters. The future of this project is to implement the security system in the future laboratory of the University of Montreal. However, we can affirm that this system is applicable in similar models, and therefore viable to be used in the industry. The main advantages of our system are that it is very economical, simple and easily modified. This project can provide a simple solution to the implementation of security systems in industrial plants that use mobile hoist, helping to make the workplace and the equipment handling safer.
OPTIMIZATION OF A HOIST Introduction At the University Polytechnic of Montreal there are currently in use two hoist simulations for laboratory tests of the subject “Commande des processus industriels”. This course teaches students about the control and automation of industrial processes. Each hoist simulation is composed of a car that moves horizontally along a rail and transports a load that moves vertically thanks to a rope. The University wants to modernize the laboratory, due to the high cost of maintenance of the equipment in the current system, and due to safety problems with the students throughout the practices. Taking advantage of the replacement of the outdated equipment, we want to optimize the hoist simulation, adding a broader safety system and changing the control system of the car. It is a group project, composed by two teachers, a technician and my contribution. This work focuses mainly on responding to the security system. With the current system, the displacements of the car at high speed are not limited until it reaches the end of the rail so the load and the car can impact violently against the walls of the laboratory. To solve this problem, the intention was to design a safety system that works independently and limits the speed of the car so that neither the car nor the load will collide against the ends of the rail. The objectives set for the project are the following: • To design a safety system based on the voltage control of an engine that moves a car by measuring its position. • To implement the communication between an engine and a software tool, being able to control the voltage and direction of rotation of the motor. The communication will be made through a UART module and also a potentiometer that regulates the voltage of the motor. • Measuring by laser technology the absolute position of a mobile car and being able to manipulate the obtained distance data. • Acquiring a final assembly putting together all the components; simulating the functioning of the future laboratory equipped with a complete safety system. Once the montage with the functional safety system is made, experiments will be done in order to test the design. This system shall be tested in the final laboratory that will serve future students to carry out their practices. Methodology The main software tool that has been used for the realization of the project is Matlab-Simulink. For other subordinate tasks, the Arduino software has been used. The design of the security system has been made in a small model, composed of a motor that moves a car by a rail of 1m in length. It has not been possible to implement the safety system designed in the final laboratory due to schedule reasons, but the results extracted from the model will be used for its implementation. Results The final results of the project have been obtained by experimenting with the model designed for the project. The steps to accomplish the objectives have been the following. First of all, communication between the Matlab-Simulink software and the motor that moves the car has been achieved. With a DC motor control board, a microcontroller and a potentiometer; a model has been implemented in which the displacement of the car is controlled by the potentiometer. With the system that has been created, by varying a reference voltage (3V) with the potenciometer, the direction and the power of rotation of the motor can be elected. One extreme point of the potentiometer (0V) represents a maximum working point of the motor with one direction of rotation, and the other extreme point (3V) also represents a maximum working point of the motor, but on the other direction of rotation. Therefore, the power of rotation of the motor is proportional to the voltage generated by the potentiometer. Apart from this model, a similar one has been introduced to generate the command to the motor, replacing the potentiometer for a UART module (Universal Asynchronous Receiver Transmitter) to command gains to the motor from the Matlab-Simulink itself. After obtaining a procedure by which we control the speed of the car and its direction, we will move onto the measurement of the position that has been constituted by a laser. An inexpensive and precise method has been sought in the context of our application. It has been possible to capture the absolute position of the car by communicating the software Arduino with the laser. Once all the parts have been assembled, a functional safety system has been implemented, communicating Matlab-Simulink and Adruino software with the motor that moves the car. A model has been obtained in which the command is controlled by a potentiometer and the Arduino program is the one that takes control of the engine when the car is placed in a risky situation. The rail has been divided into different zones, so we have defined two risky situations: • Firstly, when the car moves at high speed and near the end of the rail, in an area that we have called the braking zone. In this zone, the command generated by the potentiometer is compared with a reference pattern and if the gain of the command is greater than the pattern one, then the reference pattern takes control of the motor. This pattern is a PWM signal generated by the Arduino itself that varies depending on the position of the car. Due to this, the PWM signal decreases its duty cycle linearly as the car approaches the end of the rail. With this system, in the braking zone we cannot exceed certain speeds due to the limitation of the reference pattern, which has been checked to be safe. • The second risky situation occurs when the car is already very close to the end of the rail. In these cases, the influence of the Arduino program forces the motor to stop completely. This area, which we have defined as the stopping area, is located more in the extreme than the braking zone, and ensures that the car stops completely to avoid its impact with the end of the rail. The security system has been tested and the results have been satisfactory. The car never hits any of the extremes, and the designed system can be adapted to other types of hoist. The only parameters that must be changed to implement this security system into other hoists are the delimitation of braking and stopping zones, set in the Arduino program. If a replacement of the command system (the potentiometer in this case) is needed, the Matlab-Simulink model must be modified in consequence. Conclusions The results obtained from the project have been verified exclusively in a model assembled for the purposes of the project. Nevertheless, the designed system is adaptable to other hoist under the modification of a few parameters. The future of this project is to implement the security system in the future laboratory of the University of Montreal. However, we can affirm that this system is applicable in similar models, and therefore viable to be used in the industry. The main advantages of our system are that it is very economical, simple and easily modified. This project can provide a simple solution to the implementation of security systems in industrial plants that use mobile hoist, helping to make the workplace and the equipment handling safer.
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