Leonimer Flávio de Melo

Condition-based diagnosis of mechatronic systems using a fractional calculus approach

While fractional calculus (FC) is as old as integer calculus, its application has been mainly restricted to mathematics. However, many real systems are better described using FC equations than with integer models. FC is a suitable tool for describing systems characterised by their fractal nature, long-term memory and chaotic behaviour. It is a promising methodology for failure analysis and modelling, since the behaviour of a failing system depends on factors that increase the model’s complexity. This paper explores the proficiency of FC in modelling complex behaviour by tuning only a few parameters. This work proposes a novel two-step strategy for diagnosis, first modelling common failure conditions and, second, by comparing these models with real machine signals and using the difference to feed a computational classifier. Our proposal is validated using an electrical motor coupled with a mechanical gear reducer.

Virtual simulator with mobile robot rapid prototyping for navigation systems

This paper presents the virtual environment implementation for project simulation and conception of supervision and control systems for mobile robots, that are capable of operate and adapting in different environments and conditions. The purpose of this virtual system is to facilitate the development of embedded architecture systems, emphasizing the implementation of tools that allow the simulation of the kinematic conditions, dynamic and control, with real time monitoring of all important system points. For this, an open control architecture is proposal, integrating the two main techniques of robotic control implementation in the hardware level: systems microprocessors and reconfigurable hardware devices. The implemented simulator system is composed of a trajectory generating module, a kinematic and dynamic simulator module, and an analysis module of results and errors. All the kinematic and dynamic results obtained during the simulation can be evaluated and visualized in graphs and table formats in the results analysis module, allowing the improvement of the system, minimizing the errors with the necessary adjustments and optimization. For controller implementation in the embedded system, it uses the rapid prototyping which is the technology that allows in set, with the virtual simulation environment, the development of a controller project for mobile robots. The validation and tests had been accomplished with nonholonomic mobile robot models with differential transmission.

Mobile robots and wheelchairs control navigation design using virtual simulator tools

This work presents the virtual environment implementation for project simulation and conception of supervision and control systems for mobile robots, which are capable of operating and adapting in different environments and conditions. The purpose of this virtual system is to facilitate the development of embedded architecture systems, emphasizing the implementation of tools that allow the simulation of the kinematic conditions, dynamic and control, with real time monitoring of all important system points. To accomplish this, an open control architecture is proposed, integrating the two main techniques of robotic control implementation in the hardware level: systems microprocessors and reconfigurable hardware devices. The utilization of a hierarchic and open architecture, distributing the diverse actions of control in increasing levels of complexity, the use of resources of reconfigurable computation are made in a virtual simulator for mobile robots. The validation of this environment is made in a nonholonomic mobile robot and in a wheelchair; both used an embedded control rapid prototyping technical for best navigation strategy implementation. After being tested and validated in the simulator, the control system is programmed in the control board memory of the mobile robot or wheelchair. In this way, an economy of time and material are obtained, sooner validating the entire model virtually for later operating the physical implementation of the navigation system.

Virtual Simulator for Design of Mobile Robot Control and Navigation Systems

The development of control systems for independent mobile robots has appear as a great challenge for the researchers until the current days. Different platform for the project of control system for independent mobile robots come being used in diverse research areas. Per many years the researchers have constructed control systems that present an intelligent behavior in controlled environments, with ideal situations, but that normally does not keep the same performance in the real world. Innumerable systems of control exist to be used in the real world, but generally these systems are limited and they do not present an independent or intelligent behavior. Diverse possible applications for the mobile robots already exist. In the transport, monitoring, inspection, cleanness of houses, space exploration, aid the physical deficient, among others. However, the independent mobile robots had not yet caused much impact in domestic or industrial applications, mainly had the lack of a system with robust, trustworthy and flexible control that it would allow these robots operated in dynamic environments, less structuralized, and inhabited by human beings. The development of a mobile robotic model system with open architecture and flexible control, with robust control system, that incorporates what exists of modern in terms of embedded hardware technology and that makes possible the operation of a mobile robotic systems in a real world environment is one of the motivations of this work. The locomotion planning, under some types of restrictions, is a very vast field of research in the area of the mobile robotics (Graf, 2001). The basic planning of trajectory for the mobile robots imply the determination of a way in the space-C (configuration space) between an initial configuration of the robot and a final configuration, in such a way that the robot does not collide with no obstacle in the environment, and that the planned movement is consistent with the kinematic restrictions of the vehicle. In this context, one of the boarded points in this work was development of a trajectory calculator for mobile robots. One of the main motivations of this work is to propitiate a virtual environment that facilitates the development of archetypes of embedded systems, emphasizing the implementation 26

Analysis and Modeling of Brazilian Indoor PLC Channels Controlled Environment - Testing and Validation

This work is a revision, application and comparison of the main models found in the literature for the transfer and noise functions in the channel for communications in power transmission lines (PLC - power line communication). Considering the characteristics of brazilian residential electrical installations, comparisons of measurements with models for the transfer function, the ABCD transmission matrix model as the most efficient and flexible in the increase of the channel sections and branches. The series resonant circuit model may be very precise and allows the implementation of an analog channel emulator using discrete components. However the classical model with eco demonstrated a better theoretical basis for transmission lines. The six different types of noise present on the power grid were measured and modeled. A very realistic model is simulated using Markov chains for modeling the non-periodic impulsive and burst noise.

Wheelchairs Embedded Control System Design for Secure Navigation with RF Signal Triangulation

In the mobile robotic systems a precise estimate of the robot pose Cartesian [x y] position plus orientation angle ? with the intention of the path planning optimization is essential for the correct performance, on the part of the robots, for tasks that are destined to it, especially when intention is for mobile robot autonomous navigation. This work uses a ToF Time-of-Flight of the RF digital signal interacting with beacons for computational triangulation in the way to provide a pose estimative at bi-dimensional indoor environment, where GPS system is out of range. Its a new technology utilization making good use of old ultrasonic ToF methodology that takes advantage of high performance multicore DSP processors to calculate ToF of the order about ns. A mobile robot platform with differential drive and nonholonomic constraints is used as base for state space, plants and measurements models that are used in the simulations and for validation the experiments. After being tested and validated in the simulator, the control system is programmed in the control board memory of the mobile robot or wheelchair. Thus, the use of material is optimized, firstly validating the entire model virtually and afterwards operating the physical implementation of the navigation system.

MOBILE ROBOT NAVIGATION CONTROL DESIGN USING VIRTUAL SIMULATOR WITH RAPID PROTOTYPING

This paper presents the virtual environment implementation for simulation and design conception of supervision and control systems for mobile robots, that are capable to operate and adapt in different environments and conditions. The purpose of this virtual system is to facilitate the development of embedded architecture systems, emphasizing the implementation of tools that allow the simulation of the kinematic conditions, dynamic and control, with monitoring in real time of all important system points. For this, an open control architecture is proposed, integrating the two main techniques of robotic control implementation in the hardware level: systems microprocessors and reconfigurable hardware devices. The implemented simulator system is composed of a trajectory generating module, a kinematic and dynamic simulator module, and an analysis module of results and errors. All the kinematic and dynamic results obtained during the simulation can be evaluated and visualized in graphs and table formats in the results analysis module, allowing the improvement of the system, minimizing the errors with the necessary adjustments and optimization. For controller implementation in the embedded system, it uses the rapid prototyping which is the technology that allows in set, with the virtual simulation environment, the development of a controller project for mobile robots. The validation and tests had been accomplished with nonholonomic mobile robot models with differential transmission.