Carlos Viegas

OmniClimbers: Omni-directional magnetic wheeled climbing robots for inspection of ferromagnetic structures

This paper introduces Omniclimber, a new climbing robot with high maneuverability for inspection of ferromagnetic flat and convex human made structures. In addition to maneuverability, adaptability to various structures with different curvatures and materials are addressed. The conceptual and detailed design of OmniClimbers are presented and two prototypes of the robot are introduced. Several laboratory and field tests are reported, and the results are discussed.

Magnetic omnidirectional wheels for climbing robots

This paper describes design and development of omnidirectional magnetic climbing robots with high maneuverability for inspection of ferromagnetic 3D human made structures. The main focus of this article is design, analysis and implementation of magnetic omnidirectional wheels for climbing robots. We discuss the effect of the associated problems of such wheels, e.g. vibration, on climbing robots. This paper also describes the evolution of magnetic omnidirectional wheels throughout the design and development of several solutions, resulting in lighter and smaller wheels which have less vibration and adapt better to smaller radius structures. These wheels are installed on a chassis which adapts passively to flat and curved structures, enabling the robot to climb and navigate on such structures.

OmniClimber-II: An omnidirectional climbing robot with high maneuverability and flexibility to adapt to non-flat surfaces

This paper introduces, OmniClimber II, an evolution of OmniClimber I, a novel climbing robot with high maneuverability for inspection of ferromagnetic 3D human made structures. The robot takes advantage of novelties which allows an excellent maneuverability on the structure and can adapt to flat and non-flat structures. In this paper we present the conceptual and detailed design of the robot, the implementation and improvements over the first version and a set of tests: laboratory tests on a flat surface; and a set of field tests performed on a wind turbine foundation and another field test on a curved steel structure in Mechanical Engineering, to prove the applicability of the robot on both structures.

A single DOF arm for transition of climbing robots between perpendicular planes

This paper introduces a novel single DOF plane transition mechanism, designed to enable wheel based climbing robots to transit between perpendicular planes. The developed mechanism is composed of an arm with two revolute joints derived by a single motor. An innovative transmission mechanism is designed based on the required trajectory and relative position for each arm link, enabling individual or simultaneous rotation of the two joints during the transition movement. An electromagnetic unit which adapts to both flat and curved structures is also designed and integrated in the arm. This solution was installed on the omnidirectional climbing robot, OmniClimber. The mechanism was successfully tested on a curved structure with a diameter of 220mm.

SCALA: Scalable Modular Rail based Multi-agent Robotic System for Fine Manipulation over Large Workspaces

Current industrial fabrication and automation systems are faced with the challenge of obtaining great accuracy and fine manipulation over a large workspace. In this article, SCALA, a novel framework for robots that move on modular ad-hoc dedicated rails is presented. The goal is to have several agents moving simultaneously and rapidly on these scaffolds, with excellent positional accuracy. Such modular rails can be used to form 2D or 3D scaffolds that can be installed vertically and horizontally. The pros and cons of each of the designs are discussed, and some early stage prototypes are developed for validation purposes. The final prototype is demonstrated passing a junction in vertical, horizontal and hang-down scenarios.

InchwormClimber: A light-weight biped climbing robot with a switchable magnet adhesion unit

This article presents an inchworm climbing robot that is designed with switchable magnets and a single DOF arm. The InchwormClimber works on ferromagnetic structures and consumes little energy when climbing and can descend safely with almost zero energy consumption. Furthermore, considering the critical role of the adhesion unit in the overall functionality of the robot (weight, climbing speed and the payload), we optimized the switchable magnet unit for a higher adhesion force per mass unit.

SCALA—A Scalable Rail-based Multirobot System for Large Space Automation: Design and Development

In this paper, a prototype of the SCAlable ModuLar (SCALA) multiagent robotic system is developed and implemented. This system for automation in large spaces relies on mobile agents that move on a planar and modular mesh of rails with embedded accurate positioning sensors. Groups of three mobile agents are joined together to drive a parallel manipulator, thus allowing fine manipulation tasks to be performed on a large workspace. The mechanical, mechatronics, and control solutions adopted on the prototype are reported and discussed, as well as its performance on the several tests performed.

Switchable magnets for robotics applications

The goal of this work is to study the application of switchable magnets (SM) for climbing robots. A switchable magnet is a device which uses moving permanent magnets to change the magnetic flux path and switch on or off the magnetic attraction force. In our work we used Comsol Multiphysics, a physics simulation software in order to simulate the flow of the magnetic flux on switchable magnets on its different states and study the effect of different design and material parameters on the attraction force of the unit. Bearing in mind the lessons learned from this study, we developed a novel device in a smaller scale with the best holding force/mass ratio, for using in climbing robot applications. As a case study, three of these optimized SM units are then equipped with an actuator that can rotate the moving magnets, turning the device on and off. This new device is employed in a novel adaptive adhesion unit for the OmniClimber robot, replacing its previous system which was relying on electromagnets magnets. We demonstrate this novel device application on a climbing robot and the advantages relative to electromagnet or permanent magnet based devices.

State estimation and path following on curved and flat vertical surfaces with Omniclimber robots: Kinematics and control

Omnidirectional wheels used on Omniclimber inspection robot and in other robots enable a holonomic drive and a good maneuverability. On the other hand, they have a poor wheel traction and suffer from vertical and horizontal vibration, decreasing the trajectory following accuracy of the robot. In this study, we address this problem by integrating an orientation estimation and correction algorithm in the Omniclimber control by integration of an accelerometer. Moreover, since the Omniclimber chassis adapts to curved structures, the kinematics of the robot change when moving on a curved surface. We integrated an additional algorithm which corrects the robots kinematics based on the curvature diameter and the current robot orientation. By integrating these two algorithms we could make remarkable improvements on the path following accuracy of the Omniclimber on flat and curved structures.

Novel Nanocrystalline Hydroxyapatite for BoneRegeneration

Novel Nanocrystalline Hydroxyapatite for Bone Regeneration Maxillofacial bone defects resulting from disease or trauma are one main problem for modern dentistry. Regenerative treatments aim to provide the lost initial conditions improving the patient’s life quality. Bone graft substitutes have been regarded as suitable alternatives to obtain regenerative outcomes. Among these, synthetic hydroxyapatites are successfully evaluated bone substitutes, both in pre-clinical as well as clinical studies. The aim of this study is to evaluate the bone regenerative potential of a nanocrystalline hydroxyapatite (nHA), in a delayed healing cranial rabbit model.