Implementación de la electrónica para el control dinámico de un manipulador Scorbot-ER: desarrollo de la comunicación

Abstract

This project consists of the development of an electronic circuit that allows the dynamic control of the handling robot Scorbot-ER V. The electronics designed has to handle the information provided by the encoders of the handling robot. To handle the data received from the counters, to move the motors and to carry out the control of the Scorbot, an Arduino Mega 2560 which works with the microcontroller ATmega 2560 is used. The counters LS7166 are in charge of the quadrature count of the signals of the encoders. Due to the limitations regarding the number of pins available on the board, it has been decided to use the PCA9535 integrated circuit, which work with I2C communication. This integrated circuit will be connected to a counter, one I2C chip for each counter, so it dumps its account value in the I2C to be transmitted to the Arduino later by using only two pins for the six counters (those of the I2C protocol, the data line SDA and the SCL watch line). The L298N modules are the drivers in charge of the movement of the motors, prepared to work with the PWM signal generated from the Arduino. The alarm management has been done via software, using the counters account for obstacle detection. During a movement, if it is detected that the handling robot can not advance, the controller stops all movements to prevent the engine from being damaged. Regarding the control of the Scorbot-ER V, a PID control has been developed using the Arduino libraries. To avoid saturations in the input, the integral action is not used until reaching the middle of the setpoint. We choose the software Phyton to carry out the communication between the Arduino and the equipment. Phyton has a library that allows the the communication with the Arduino. A program has been designed to carry out several commands using our own coding. The main objective is the implementation of an electronics circuit that allows the Scorbot-ER V to be controlled with a dynamic control so that it is not necessary to use the controller provided by the manufacturer. In addition, with this electronics the delays of the controller’s protocols will be eliminated and the hardware currently occupied by the current controller of the manipulator will be reduced. Some of the Specific objectives are the following: Move the motors of each axis of the Scorbot using a PWM signal generated with Arduino for the L298N module. Quadrature counting, through the integrated LS7166, of the signals that come out of the encoders associated with each motor. Reading of the account carried out by integrated LS7166 through I2C communication (integrated PCA9535) in Arduino. Establish communication of the Arduino and the scorbot (hardware-I2Cand software -python). Carry out the instruction ’home’ on all axes of the Scorbot-ER V Plus. Set alarm against over-intensities. Implementation of a descentraliced PID control loop.