Construção de atuador de rigidez variável e simulação de braço robótico

Abstract

Series elastic actuators have been studied for various applications since 1995. Despite not yet being widely used commercially, a lot of different models were created in the academia using different types of springs, or simulating compliance by the means of softwares. This work presents the design and construction of an unprecedented, controllable stiffness, elastic series actuator, using two flat spiral torsion springs. This actuator has some advantages compared to elastic series actuators with fixed-spring rigidity, which, depending on the application in which they are used, either have little rigidity and end up deforming undesirably or have a lot of rigidity and end up damaging themselves and the environment which they are in. The proposed solution aims to maintain the functionality of protecting the robot and its surroundings, absorbing any unexpected impact that may happen during this interaction. Compliance, combined with intelligent control systems capable of dealing with dynamic environments, has the potential of allowing the development of more versatile and inexpensive robots, as compliant actuators can be under-actuated and embedded computer systems tend to increase in capacity and reduce in cost. This work also describes the design and simulation of a robotic arm and claw that will be used for research on manipulation using compliance with the new variable stiffness series elastic actuator. The research goes from computer-aided mechanical design, mathematical modeling of a spring, design of components that fit certain force and size constraints, to testing a new actuator under different working conditions. After designing the new actuator, it was possible to assemble and test the robotic arm in a simulated testing virtual environment. The path used for the design of the parts during tests that identified structural problems in the assembly of the arm was detailed in this work. At the end of the research, the first prototype of the actuator with manual stiffness control and a 7 degrees-of-freedom robotic arm with a claw, tested in a virtual environment with parts designed mostly from folded, laser cutted, aluminum plates for easy fabrication were obtained.