MODEL-BASED COMPENSATION FOR BURST MESSAGE LOSS IN WIRELESS NETWORKED CONTROL SYSTEMS: EXPERIMENTAL RESULTS

A recent trend in networked control systems (NCSs) is the use of wireless networks enabling interoperability between existing wired and wireless systems. One of the major challenges in these wireless NCSs (WNCSs) is to overcome the impact of the message loss that degrades the performance and stability of these systems. Moreover, this impact is greater when dealing with burst or successive message losses. This paper discusses and presents the experimental results of a compensation strategy to deal with this burst message loss problem in which a NCS mathematical model runs in parallel with the physical process, providing sensor virtual data in case of packet losses. Running in real-time inside the controller, the mathematical model is updated online with real control signals sent to the actuator, which provides better reliability for the estimated sensor feedback (virtual data) transmitted to the controller each time a message loss occurs. In order to verify the advantages of applying this model-based compensation strategy for burst message losses in WNCSs, the control performance of a motor control system using CAN and ZigBee networks is analyzed. Experimental results led to the conclusion that the developed compensation strategy provided robustness and could maintain the control performance of the WNCS against different message loss scenarios.

Tm-afm nonlinear motion control with robustness analysis to parametric errors in the control signal determination

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Control of Limit Cycle Oscillation in a Three Degrees of Freedom Airfoil Section Using Fuzzy Takagi-Sugeno Modeling

This work presents a strategy to control nonlinear responses of aeroelastic systems with control surface freeplay. The proposed methodology is developed for the three degrees of freedom typical section airfoil considering aerodynamic forces from Theodorsen's theory. The mathematical model is written in the state space representation using rational function approximation to write the aerodynamic forces in time domain. The control system is designed using the fuzzy Takagi-Sugeno modeling to compute a feedback control gain. It useds Lyapunov's stability function and linear matrix inequalities (LMIs) to solve a convex optimization problem. Time simulations with different initial conditions are performed using a modified Runge-Kutta algorithm to compare the system with and without control forces. It is shown that this approach can compute linear control gain able to stabilize aeroelastic systems with discontinuous nonlinearities.

Demonstration of non-collocated vibration control of a flexible manipulator using electrical dynamic absorbers

This paper describes an experimental study into the vibration control of a servo system comprising a servo motor and a flexible manipulator. Two modes of the system are controlled by using the servo motor and an accelerometer attached to the tip of the flexible manipulator. The control system is thus non-collocated. It consists of two electrical dynamic absorbers, each of which consists of a modal filter and, in case of an out-of-phase mode, a phase inverter. The experimental results show that each absorber acts as a mechanical dynamic vibration absorber attached to each mode and significantly reduces the settling time for the system response to a step input.

Projeto e desenvolvimento de robô cartesiano de baixo custo para manipulação de produtos em linhas de média cadência

Pós-graduação em Engenharia Elétrica - FEB

Nonlinear control in an electromechanical transducer with chaotic behaviour

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Interface com o AEDROMO (Ambiente experimental e didático com robôs móveis) utilizando sistema Android

The AEDROMO (Experimental and Didactic Environment with Mobile Robots) is a versatile, user friendly and scalable environment that supports a wide range of experiments. In it there is an area that is similar to a desk where objects can interact with each other, including robots and other objects, and thus can perform numerous activities. In it's current state, AEDROMO has client computers that interact with the system through an interface, and thus realize the communication between the user and AEDROMO. This project offer support to create a new form of interface for AEDROMO and can therefore be used for devices running Android, the app developed in this project will serve as a basis for future work on this new interface

Desenvolvimento de objeto de aprendizagem para dispositivos móveis explorando os sensores internos do sistema operacional Android

The traditional model of teaching little is modernized in recent decades. When in contact with this system, it is normal that the new-generation students feel unmo tivated in carrying out the proposed activities in the classroom. Considers Prensky (2001) these students, called Digital Natives, born with a modern way of thinking and learn and feel encouraged and motivated with activities that invite to interact. For this reason, it has been proposed the development of an object of learning in the form of application for Android tablets, exploring the internal sensors available in them, with the purpose of offering an interactive activity to students on the physical concepts involved in the process of photosynthesis in plants. For the construction, informational texts written in didactic language and easy to understand, illustrative images and animations were employed. In addition, we used the light sensor in the interactive activity on the process of photosynthesis so that the student could observe and understand how the environment is able to interfere with this process

Contagem automatizada de veículos utilizando segmentação estatística

In this work was developed a program capable of performing automatic counting of vehicles on roads. The problem of counting vehicles is using expensive techniques for its realization, techniques which often involve manual counting or degradation of the pavement. The main motivation for this work was the importance that the vehicle counting represents to the Traffic Engineer, being essential to analyze the performance of the roads, allowing to measure the need for installation of traffic lights, roundabouts, access ways, among other means capable of ensuring a continuous flow and safe for vehicles. The main objective of this work was to apply a statistical segmentation technique recently developed, based on a nonparametric linear regression model, to solve the segmentation problem of the program counter. The development program was based on the creation of three major modules, one for the segmentation, another for the tracking and another for the recognition. For the development of the segmentation module, it was applied a statistical technique combined with the segmentation by background difference, in order to optimize the process. The tracking module was developed based on the use of Kalman filters and application of simple concepts of analytical geometry. To develop the recognition module, it was used Fourier descriptors and a neural network multilayer perceptron, trained by backpropagation. Besides the development of the modules, it was also developed a control logic capable of performing the interconnection among the modules, mainly based on a data structure called state. The analysis of the results was applied to the program counter and its component modules, and the individual analysis served as a means to establish the par ameter values of techniques used. The find result was positive, since the statistical segmentation technique proved to be very useful and the developed program was able to count the vehicles belonging to the three goal..

Multi-task control strategy for grid-tied inverters based on conservative power theory

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

SDRE control strategy applied to a nonlinear robotic including drive motor

A robotic control design considering all the inherent nonlinearities of the robot-engine configuration is developed. The interactions between the robot and joint motor drive mechanism are considered. The proposed control combines two strategies, one feedforward control in order to maintain the system in the desired coordinate, and feedback control system to take the system into a desired coordinate. The feedback control is obtained using State-Dependent Riccati Equation (SDRE). For link positioning two cases are considered. Case I: For control positioning, it is only used motor voltage; Case II: For control positioning, it is used both motor voltage and torque between the links. Simulation results, including parametric uncertainties in control shows the feasibility of the proposed control for the considered system.

Nonlinear angle control of a sectioned airfoil by using shape memory alloys

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Leveraging wireless devices for networked control systems in industrial applications

Networked control systems (NCSs) are distributed control system in which sensors, actuators and controllers are physically separated and connected through communication networks. NCS represent the evolution of networked control architectures providing greater modularity and control decentralization, ease maintenance and diagnosis and lower cost of implementation. A recent trend in this research topic is the development of NCS using wireless networks(WNCS)which enable interoperability between existing wiredand wireless systems. This paper presents the feasibility analysis of using serial to wireless converter as a wireless sensor link in NCS. In order to support this investigation, relevant performance metrics for wireless control applications such as jitter, time delay and messages lost are highlighted and calculated to evaluate the wireless converter capabilities. In addition the control performance of an implemented motor control system using the converter is analyzed. Experimental results led to the conclusion that serial ZigBee device isrecommended against the Bluetooth as it provided better metrics for control applications. However, bothdevices can be used to implement WNCS providing transmission rates and closed control loop times which are acceptable for NCS applications.Moreoverthe use of thewireless device delay in the PID controller discretization can improve the control performance of the system.

Nonlinear state estimation and control applied to a manipulator robotic including drive motor

A robotic control design considering all the inherent nonlinearities of the robot engine configuration is developed. The interactions between the robot and joint motor drive mechanism are considered. The proposed control combines two strategies, one feedforward control in order to maintain the system in the desired coordinate, and feedback control system to take the system into a desired coordinate. The feedback control is obtained using State Dependent Riccati Equation (SDRE). For link positioning two cases are considered. Case 1: For control positioning, it is only used motor voltage; Case 2: For control positioning, it is used both motor voltage and torque between the links. Simulation results, including parametric uncertainties in control shows the feasibility of the proposed control for the considered system.

On Modular Design of Field Robotic Systems

Robots are needed to perform important field tasks such as hazardous material clean-up, nuclear site inspection, and space exploration. Unfortunately their use is not widespread due to their long development times and high costs. To make them practical, a modular design approach is proposed. Prefabricated modules are rapidly assembled to give a low-cost system for a specific task. This paper described the modular design problem for field robots and the application of a hierarchical selection process to solve this problem. Theoretical analysis and an example case study are presented. The theoretical analysis of the modular design problem revealed the large size of the search space. It showed the advantages of approaching the design on various levels. The hierarchical selection process applies physical rules to reduce the search space to a computationally feasible size and a genetic algorithm performs the final search in a greatly reduced space. This process is based on the observation that simple physically based rules can eliminate large sections of the design space to greatly simplify the search. The design process is applied to a duct inspection task. Five candidate robots were developed. Two of these robots are evaluated using detailed physical simulation. It is shown that the more obvious solution is not able to complete the task, while the non-obvious asymmetric design develop by the process is successful.