2011
Authors
MacHado, JAT; Luo, ACJ; Barbosa, RS; Silva, MF; Figueiredo, LB;
Publication
Nonlinear Science and Complexity
Abstract
2008
Authors
Silva, MF; Machado, JAT;
Publication
Advances in Mobile Robotics - Proceedings of the 11th International Conference on Climbing and Walking Robots and the Support Technologies for Mobile Machines, CLAWAR 2008
Abstract
The interest in the development of climbing robots is growing rapidly. Motivations are typically to increase the operation efficiency by obviating the costly assembly of scaffolding or to protect human health and safety in hazardous tasks. Climbing robots are starting to be developed for applications ranging from cleaning to inspection of difficult to reach constructions. These robots should be capable of travelling on different types of surfaces, with varying inclinations, such as floors, walls, ceilings, and to walk between such surfaces. Furthermore, these machines should be capable of adapting and reconfiguring for various environment conditions and to be self-contained. Regarding the adhesion to the surface, they should be able to produce a secure gripping force using a light-weight mechanism. This paper presents a survey of different applications and technologies proposed for the implementation of climbing robots. Copyright © 2008 by World Scientific Publishing Co. Pte. Ltd.
2006
Authors
Silva, MF; MacHado, JAT;
Publication
IFAC Proceedings Volumes (IFAC-PapersOnline)
Abstract
This paper studies the performance of a Fractional Order PD a controller in a hexapod robot with three dof legs and leg joint actuators having saturation. For that objective the robot prescribed motion is characterized in terms of several locomotion variables. Moreover, two indices measure the walking performance based on the mean absolute density of energy per travelled distance and on the hip trajectory errors. A set of simulation experiments reveals the influence of the different controller tuning upon the proposed indices. Copyright © 2006 IFAC.
2008
Authors
Jesus, IS; Machado, JAT; Silva, MF;
Publication
Proceedings of the IASTED International Conference on Modelling, Identification, and Control, MIC
Abstract
The performance of electrical devices, depending on the processes of the electrolytes, have been fully described and the physical origin of each parameter is well established. However, the influence of the irregularity of the electrodes was not a subject of study and only recently, this problem became relevant in the viewpoint of fractional calculus. This paper describes an electrolytic process in the perspective of fractional order capacitors. In this line of thought, are developed several experiments for measuring the electrical impedance of the devices. The results are analyzed through the frequency response, revealing capacitances of fractional order that can constitute an alternative to the classical integer order elements.
2006
Authors
Silva, MF; Machado, JAT; Barbosa, RS;
Publication
IFAC Proceedings Volumes (IFAC-PapersOnline)
Abstract
This paper studies the performance of different order Padé Fractional Order (FO) PD0.5 controllers applied to the leg joint control of a hexapod robot with two dof legs and joint actuators with saturation. For simulation purposes the robot prescribed motion is characterized through several locomotion variables and for the walking performance evaluation are used two indices, one based on the mean absolute density of energy per travelled distance and the other on the hip trajectory errors. A set of simulation experiments reveals the influence of the different order Padé PD0.5 controllers tuning upon the proposed indices. Copyright © 2006 IFAC.
2009
Authors
Silva, MF; Barbosa, RS; Machado, JAT;
Publication
Proceedings of the IASTED International Conference on Applied Simulation and Modelling, ASM 2009
Abstract
Legged robots allow the locomotion on terrains inaccessible to other type of vehicles because they do not need a continuous support surface. Different strategies have been adopted for the optimization of these systems, during their design and construction phases, and during their operation. Among the different optimization criteria followed by different authors, it is possible to find issues related to energy efficiency, stability, speed, comfort, mobility and environmental impact. Evolutionary strategies are a way to "imitate nature" replicating the process that nature designed for the generation and evolution of species. The objective of this paper is to present a genetic algorithm, running over a simulation application of legged robots, which allows the optimization of several parameters of the robot model and of its gaits, for different locomotion speeds.
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