Fuzzy logic applied to control a one degree of freedom (DOF) pneumatic robot

Abstract

For many years, the vast majority of robots have been built with electrical actuators, and pneumatic actuators are not considered to control the position of a manipulator robot. Instead, electrical actuators are used. The main concern with pneumatic actuators is the highly non linear behavior, due to the high compressibility of the air. This work is focused on a one degree of freedom (DOF) robot, with pneumatic actuator to control the angle of the arm. A dynamic mathematical model of the manipulator is used, including the thermo-mechanical model. The air flow through the pneumatic cylinder is controlled by a 5/3 electro-valve. A pulse width modulation (PWM) signal is used to activate each coil of the electro-valve, where the duty cycle is set by a fuzzy logic algorithm. The fuzzy system is implemented into field-programmable gate array (FPGA), including the digital interface with a computer, an optical encoder and four seven-segment displays. This work is focused on the hardware implementation of fuzzy logic algorithm into FPGA system using the Sugeno algorithm, into a FPGA device, applied to the pneumatic electro-valve, with 25 ms of sample time.   Key words: Field-programmable gate array (FPGA) hardware, fuzzy logic, pneumatic robot, dynamic.