Diseño y construcción de un brazo robot para trazado de diagramas

Abstract

The thesis objective was to design and build a low–cost robot arm appropriate for drawing diagrams on a plane. The robot arm has two rotational joints attached directly to servomotors. The end-effector consists of a simple mechanism whose function is to move up and down the tool that could be a pencil, pen, etc. The dynamic model of the robot arm was developed by using the Lagrangian formulation, motors and sensors were also modeled. The developed models contain parameters which must have been found, the robot arm model parameters were found through simple methods of basic physics, whereas the motors model parameters were found by stimulus-response experiments, these experiments demonstrated that the model is close to reality. A model-based control system was developed, i.e., using the dynamic model of the system. Due to its high computational cost, the control system was developed on MATLAB, leaving aside the control circuit included in the servomotors. A PIC microcontroller was used as an interface between the PC and the robot arm. Integrated circuits such as PIC, H bridge and MAX232 enormously simplified the task of supplying power, acquire data, and communicate with a PC. The robot arm did not require a complex mechanical design since it is exposed to low stresses, besides that the motors have a structure of great adaptability. The cost of the prototype was S/. 150.00 (US $54). The total weight of the robot arm was 410 g. The author considers that the design and building of a lowcost robot arm to produce satisfactory results is feasible, provided that the associated theoretical foundations are correctly applied.