André Schneider de Oliveira

Adhesion Force Control and Active Gravitational Compensation for Autonomous Inspection in LPG Storage Spheres

This paper presents a climbing robot based in wheel locomotion and magnetic adherence, a common mechanical topology applicable to a wide range of industrial tasks. The robot is applied to perform internal/external inspection in liquefied petroleum gas (LPG) storage spheres, hence, some severe operation features like adherence and force balance impose necessary conditions to the robot. In order to satisfy these conditions, a dynamic control system is developed in two steps, active gravitational compensation and adhesion force control.

Navigation's Stabilization System of a Magnetic Adherence-Based Climbing Robot

This paper presents a climbing robot based on wheel locomotion and magnetic adherence. The proposed mechanical design stands on four unaligned magnetic wheels disposed in two parallel axes, which provides a great advantage when passing over obstacles. The goal of the robot is to perform internal/external inspection in liquefied petroleum gas (LPG) storage tanks and other industrial storage structures. Thus, there are a few of severe operation features (like adherence and force balance) that impose hard conditions to robot’s navigation. To satisfy these conditions, a dynamic control system was developed in two modules: active gravitational compensation system and adherence stabilization system. Simulated and experimental tests were carried out in order to verify the satisfaction of mechanical constraints and to validate the control system performance.

Environment Identification and Path Planning for Autonomous NDT Inspection of Spherical Storage Tanks

This paper presents a novel approach to inspection planning in spherical storage tanks by an autonomous climbing robot. The objective is the automatic extraction of some environment characteristics, by robot, to predict the tank dimensions and robot localization. Three distinct perception sources (long range laser rangefinder, light detection and ranging, and depth camera) are used to predict a 3D occupancy grid wrapping calculated tank. From this grid, a path for tank inspection is computed that ensuring a complete icon at the entire tank surface. This scanning must consider kinematic constraints of magnetic wheels and NDT standard. The approach is evaluated in four LPGs spherical tanks virtually designed with same characteristics that real tank projects.

ROS Navigation: Concepts and Tutorial

This tutorial chapter aims to teach the main theoretical concepts and explain the use of ROS Navigation Stack. This is a powerful toolbox to path planning and Simultaneous Localization And Mapping (SLAM) but its application is not trivial due to lack of comprehension of the related concepts. This chapter will present the theory inside this stack and explain in an easy way how to perform SLAM in any robot. Step by step guides, example codes explained (line by line) and also real robot testing will be available. We will present the requisites and the how-to’s that will make the readers able to set the odometry, establish reference frames and its transformations, configure perception sensors, tune the navigation controllers and plan the path on their own virtual or real robots.

Localization and Navigation of a Climbing Robot Inside a LPG Spherical Tank Based on Dual-LIDAR Scanning of Weld Beads

Mobile robot localization is a classical problem in robotics and many solutions are discussed. This problem becomes more challenging in environments with few and/or none landmarks and poor illumination conditions. This article presents a novel solution to improve robot localization inside a LPG spherical tank by robot motion of detected weld beads. No external light source and no easily detectable landmarks are required. The weld beads are detected by filtering and processing techniques applied to raw signals from the LIDAR (Light Detection And Ranging) sensors. A specific classification technique—-SVM (Support Vector Machine)—is used to sort data between noises and weld beads. Odometry is determined according to robot motion in relation with the weld beads. The data fusion of this odometry with another measurements is performed through Extended Kalman Filter (EKF) to improve the robot localization. Lastly, this improved position is used as input to the autonomous navigation system, allowing the robot to travel through the entire surface to be inspected.

Scheduled Fuzzy Controllers for Omnidirectional Motion of an Autonomous Inspection Robot with Four Fully Steerable Magnetic Wheels

This work presents a scheduled fuzzy controllers for an autonomous inspection robot designed to work inside and outside spherical storage tanks. The robot is designed with four fully steerable magnetic wheels and a mechanical topology which promotes the correct adjustment of adhesion system. The proposed motion control works according with robots specific characteristics to ensure the quasi-omnidirectional motion over strong adhesion with tank surface and minimizes wheels kinematics constraints.

An Open-architecture Robot Controller applied to Interaction Tasks

Many current robotic applications are limited by the industry state of art of the manipulators control algorithms. The inclusion of force and vision feedbacks, the possibility of cooperation between two or more manipulators, the control of robots with irregular topology will certainly enlarge the industrial robotics applications. The development of control algorithms to this end brings the necessity of using open-architecture controllers. Generally the robotic controllers are developed for position control, without accomplishing integrally the requirements of tasks in which interactions with the environment occur. Therefore, this is currently one of the main research areas in robotics, e.g., in (Abele et al., 2007) is presented the identification of characteristics to an industrial robot to execute machining applications. To consider this interaction the robot controller has to give priority to the force control time response, because in the instant of end-effectors contact with the surface, several forces act on the system. Depending on the speeds and the accelerations involved in the process, damages or errors can occur. To avoid these effects, compliances are inserted in tool or in surface of operation. A new reference model for a control system functional architecture applied to openarchitecture robot controllers is presented. Where, this model is applied for integrally development of a five-layer based open-architecture robotic controller for interaction tasks, which uses parallel and distributed processing techniques, avoiding the necessity of compliance in system, allowing a real-time processing of the application and the total control of information. This architecture provides flexibility, the knowledge of all the control structures and allows the user to modify all controller layers. The used controller conception aims to fulfill with the following requirements: high capacity of processing, low cost, connectivity with other systems, availability for the remote access, easiness of maintenance, flexibility in the implementation, integration with a personal computer and programming in high level. 5

A new approach to singularity-free inverse kinematics using dual-quaternionic error chains in the Davies method

The manipulation in singular regions promotes an instantaneous reduction in mechanism mobility, which can result in some disturbances in the trajectory tracking. The application of the quaternionic elements for motion representation not only guarantees an orthonormal transformation but also results in the smallest variance and minimizes the acceleration peaks. The use of a unit quaternion avoids these phenomena, but there are dimensional limitations that make it impossible to translate the representation. This work presents a methodology for using dual quaternions in the analysis of robot kinematics using the Davies method, which avoids kinematic singularities and ensures the optimal torque profiles.

On using fuzzy logic to control a simulated hexacopter carrying an attached pendulum

Fuzzy logic is used in many applications from industrial process control to automotive applications, including consumers trend forecast, aircraft maneuvering control and others. Considering the increased interest in using of multi-rotor aircrafts (usually called drones) for many kinds of applications, it is important to study new methods to improve multi-rotor maneuverability while controlling its stability in a proper way. Controlling the flight of multi-rotors, specially those equipped six rotors, is not a trivial task. When considering the design of such a control systems, traditional approaches such as PD/PID are very difficult to design, in spite of being easily implementable. This work proposes an approach based on multiple interconnected fuzzy controllers, aiming to control the various aspects related to maneuverability of a hexacopter carrying a free payload forming a pendulum. The behavior produced by such a control system has been simulated on a well-known robotics simulation environment and analyzed in terms of flight stability, as well as roll, pitch and yaw movements. The results show the feasibility of the proposed approach in keeping the hexacopter flying in a stable way.

Quasi-Omnidirectional Fuzzy Control of a Climbing Robot for Inspection Tasks

This work presents a novel method to quasi-omnidirectional control of an intelligent inspection robot designed to work inside and outside spherical storage tanks. The main objective is to promote a stable and smooth navigation during inspection tasks, ensuring the safety motion under adhesion and kinematic constraints. The robot is designed with four independent steerable magnetic wheels and a mechanical topology that allows the correct adjustment of adhesion system. A scheduled Fuzzy control is developed to achieve an optimal behavior and maximize the robot’s maneuverability, considering the magnetic restrictions of adhesion system and kinematic constraints of the inspection robot. The high adaptability of its mechanical topology (i.e., wheel misalignment, magnetic adhesion system, wheel camber and flexibilities in mechanical structure) and gravitational disturbance introduce many nonlinear characteristics in dynamic behavior that cannot be neglected, making the determination of its dynamic model a complex task. The Fuzzy approach allows to project a control system without a depth knowledge of its dynamic properties, to minimize the dynamic disturbances found in robot structure. Thus, the proposed motion control works according to the robot specific characteristics to ensure the quasi-omnidirectional motion over a reliable adhesion to tank surface and to minimize the effects of wheels kinematic constraints.