Eventos Anais de eventos
COBEM 2021
26th International Congress of Mechanical Engineering
A FOUR LEG ROBOT STABILITY ANALYSIS THROUGH A VIRTUAL ENVIRONMENT SIMULATION BASED IN DIRECT AND INVERSE KINEMATICS
Submission Author:
Lucas da Silva Rigobello , SP
Co-Authors:
Frederico Gomes Pires Azzolini, Lucas da Silva Rigobello, Thiago Boaventura, Glauco Caurin, Marcelo Becker
Presenter: Frederico Gomes Pires Azzolini
doi://10.26678/ABCM.COBEM2021.COB2021-1375
Abstract
The replication of nature’s characteristics through human technology and systems is denominated as Biomimetics and, when it comes to robotics, is one of the most complex challenges. This is easily illustrated when we look at quadrupedal movement, inspired by four-legged animals. Despite the high complexity involved in developing a system that functions on a four-legged posture, this kind of robots present some outstanding mobility characteristics, like: changing directions by shifting foot support, a higher degree of freedom for the robots body, advantage in advancing through irregular terrain and overcoming obstacles. Based on this idea and aiming to provide an initial contribution for future studies, this work presents a stability analysis of the robot platform displacement, through the development and the simulation of a quadruped robot in a virtual environment. For this purpose, some simplified techniques of locomotion and control were applied. Initially, for environment development, a four-legged model was created in the software Gazebo, along with a communication structure based on ROS. Additionally, the detailed calculations of the forward and inverse kinematics were presented and implemented in C ++. To achieve the robot’s movement, a simplified movement pattern, also known as gait, was defined and implemented in the code by means of an oscillatory function, e.g. sine function, which calculates the height and length of step for each paw. Finally, considering this previous development, the stability analysis for the four-legged robot locomotion is performed by varying the following parameters: height and step length, step frequency, and also the control PD gains. Next, the results discussion is based on the displacement, path deviation, height alternation, orientations, setted and real joint positions. Based on that, it was enlightened about the importance of the controller and body dynamics for successful robot walking. Furthermore, under the assumption of the defined robot model and analyzed parameter range, it was possible to observe that the height and length of the step are limited by the body and legs dimension, and that they influence the body dynamics as well. In addition, the results also showed that the frequency range between 1 Hz and 2 Hz resulted in the most stable walking movements.
Keywords
quadruped robot, Simulation, Gazebo, ROS
