Developing a vision-based auto-recharging system for mobile robots

This article describes a vision-based auto-recharging system that guides a mobile robot moving toward a docking station. The system contains a docking station and a mobile robot. The docking station contains a docking structure, a control device, a charger, a safety detection device, and a wireless RF interface. The mobile robot contains a power detection module (voltage and current), an auto-switch, a wireless RF interface, a controller, and a camera. The controller of the power detection module is a Holtek chip. The docking structure is designed with one active degree of freedom and two passive degrees of freedom. For image processing, the mobile robot uses a webcam to capture a real-time image. The image signal is transmitted to the controller of the mobile robot via a USB interface. We use an Otsu algorithm to calculate the distance and orientation of the docking station from the mobile robot. In the experiment, the proposed algorithm guided the mobile robot to the docking station.     

基于RFID的磁盘加密系统

文章在跟踪和分析最新磁盘加密技术研究成果的基础上,设计了一种基于RFID的磁盘分区加密系统。该系统由磁盘分区加密软件Partition Crypt与RFID射频卡、USB射频读写端等硬件模块共同组成。软件部分对计算机硬件系统要求低、安装方便、使用简单、加密效果好;硬件部分由单片机与射频模块完成。其中,USB接口采用虚拟USB接口的方法,降低硬件复杂性与成本,具有很高的性价比。经过测试,整个系统功能稳定、性价比高、保密性好,可为广泛使用的基于Windows操作系统的涉密计算机提供加密技术保障,应用前景广阔。     

Implementation of a strain energy-based nonlinear finite element in the object-oriented environment

The objective of the paper is to describe a novel finite element computational method based on a strain energy density function and to implement it in the object-oriented environment. The original energy-based finite element was put into the known standard framework of classes and handled in a different manner. The nonlinear properties of material are defined with a modified strain energy density function. The local relaxation procedure proposed as a method used to resolve a nonlinear problem is implemented in C++ language. The hexahedral element with eight nodes as well as the adaptation of the nonlinear finite element is introduced. The chosen numerical model is made of nearly incompressible hyperelastic material. The application of the proposed element is shown on the example of a rectangular parallelepiped with a hollow port.     

A design scheme for incomplete state or output feedback with applications to boiler and power system control

The problem of designing a linear feedback when all state variables are not available is discussed. The design scheme is based on computation of a complete state feedback and a reduction to a specified structure. The reduction is made by approximation of the eigenspace corresponding to a set of dominant eigenvalues. The method consists of successive choices of weightings on this space. The method is applied to the control of a boiler and a three-machine power system. In the power system case the complete state feedback can be replaced by local output feedback without significant decrease in performance.The examples indicate that the proposed method is a realistic design method for multivariable systems.     

Modeling of fluid flow in a tube with a moving indentation

The time-dependent flow in a tube with a moving indentation is numerically simulated using a dynamic mesh model. The model was used to simulate the flow in a tube with an indentation moving at different frequencies. The model was validated for a two-dimensional channel with a moving indentation. The results exhibited good agreement with the available experimental results. The results show that a single vortex was formed at a wall frequency of 0.1 Hz and was swept out of the tube at the end of the period. At a higher frequency of 1 Hz, vortex doubling occurred with reverse flow dominating downstream of the indentation. The results also show that the wall shear stress was larger for the higher frequency case of the moving indentation.     

Knowledge based fuzzy control of systems

A method of fuzzy control of systems based on a concept of human thinking is investigated. The fuzzy controller consists of a knowledge base containing a number of time responses of a process. The elements of this base are cells in which an input and a corresponding output of a system are stored. The cells are organized according to different types of relations. The result is a knowledge structure which contains a model of the process to be controlled. The following phases are distinguished: the learning phase, during which the relation between the imput and the output of a system is learned and the knowledge structure is constructed; and a phase in which the knowledge structure is applied to control the process. The method also provides an indication of the reliability of the control action     

Hybrid fuzzy-neural systems in handwritten word recognition

Two hybrid fuzzy neural systems are developed and applied to handwritten word recognition. The word recognition system requires a module that assigns character class membership values to segments of images of handwritten words. The module must accurately represent ambiguities between character classes and assign low membership values to a wide variety of noncharacter segments resulting from erroneous segmentations. Each hybrid is a cascaded system. The first stage of both is a self-organizing feature map (SOFM). The second stages map distances into membership values. The third stage of one system is a multilayer perceptron (MLP). The third stage of the other is a bank of Choquet fuzzy integrals (FI). The two systems are compared individually and as a combination to the baseline system. The new systems each perform better than the baseline system. The MLP system slightly outperforms the FI system, but the combination of the two outperforms the individual systems with a small increase in computational cost over the MLP system. Recognition rates of over 92% are achieved with a lexicon set having average size of 100. Experiments were performed on a standard test set from the SUNY/USPS CD-ROM database     

Design of a PID-like compound fuzzy logic controller

The paper describes a novel method for the design of a fuzzy logic controller (FLC) with near-optimal performance for a variety of operating conditions. The approach is based on the analysis of the system behaviour in the error state-space. The final control structure, in a form of a compound FLC, is arrived at in two stages. The first stage encompasses design and tuning of a PID-like fuzzy controller. The second stage consists of placing an additional fuzzy controller, of a structure similar to that of the first one, in parallel with the PID-like fuzzy controller designed in the first stage. The resulting compound controller is characterised with high performance in the wide range of operating conditions, and with small number of parameters that can be adjusted using simple optimisation methods. The controller is developed and tested for a plant comprising a vector controlled induction motor drive.     

Minimization of joint reaction forces of kinematic chains by a multi-objective approach

The paper describes a procedure of simultaneous minimization of joint reaction forces of planar kinematic chains. The best design is sought using the methods of mathematical programming. The optimization model of the kinematic chain is based on a multi-objective approach where the objective functions may be related to the generalized joint forces. The design variables are the geometric parameters of the links. The implementation of the optimization model is illustrated with two examples. The first example considers the minimization of joint reaction forces of an open loop system of a two-arm manipulator. The second example considers optimization of a closed loop system representing a four-bar mechanism being an actual part of a hydraulic support employed in the mining industry.     

An Application of a Neural Self-Tuning Controller to an Overhead Crane

A neural network-based self-tuning controller is presented. The scheme of the controller is based on using a multilayer perceptron, or a set of them, as a self-tuner for a controller. The method proposed has the advantage that it is not necessary to use a combined structure of identification and decision, common in a standard self-tuning controller. The paper explains the algorithm for a general case, and then a specific application on a nonlinear plant is presented. The plant is an overhead crane which involves an interesting control problem related to the oscillations of the load mass. The method proposed is tested by simulation in different conditions. A comparison was made with a conventional controller to evaluate the efficiency of the algorithm.     

Design of servo systems for distributed parameter systems by finite dimensional dynamic compensator

The design problem of servo systems for distributed parameter systems is investigated. The output regulator of integral type is designed in order to guarantee internal stability and output regulation. The design procedure based on a dynamic stabilizing compensator is discussed. The output regulation of a wide class of distributed parameter systems is proved under the condition that a closed-loop system is stabilized by a dynamic compensator of general type. Then a closed-loop system can be stabilized by a finite dimensional dynamic compensator under some additional conditions. The reducabitity of the design procedure to a purely finite dimensional one is discussed.     

Distributed real-time control of a spatial robot juggler

The Yale spatial juggler and an emerging set of working principles for the design and implementation of embedded real-time distributed controllers are described. The robot uses a distributed network of transputers to process stereo camera data and control the torque of a three-degree-of-freedom arm to juggle a ball. The juggling algorithm is a direct extension of a novel class of nonlinear feedback controllers, called mirror laws. The algorithm takes the form of a mathematical expression that specifies robot position as a function of the ball's position and velocity. The programming approach, called geometric programming, substitutes event-driven dynamical processes and geometrical transformations for a more syntactically oriented if-then-else approach     

A new deterministic approach in a decision support system for ship’s trajectory planning

The paper introduces a Decision Support System for ships, developed to solve a problem of collision avoidance with static and dynamic obstacles. The system maps the decision making capability of a human (navigation) expert to solve the path planning problem for a ship in a complex navigation environment. It can be further developed to provide automatic control of a ship. It utilizes a new, fast and effective, deterministic method, called the Trajectory Base Algorithm, to calculate a safe, optimal path for a ship. The system structure, a detailed explanation of a new method, followed by results of simulation tests are all presented in the paper. The results proof a successful application of the method to solve a path planning problem for ships with the consideration of both static and dynamic obstacles in the environment, marine traffic regulations and dynamic properties of a ship, what makes this approach applicable in commercial systems. The approach can also be adapted for application in mobile robots path planning. The experimental results and ability of the system to achieve a new functionality of full autonomy show significance of this contribution to the development of Expert and Intelligent Systems domain. The author believes that autonomous systems constitute the future of Expert and Intelligent Systems.     

A class of nonlinear time-delay systems and related optimal problems

The method of synthesis for a class of time-delay nonlinear systems affine in control is considered. The proposed approach is based on the solution of a special optimal control problem. The integrand of the optimized functional is chosen in such a way that the Bellman equation has a desired solution. The nonlinear system design is reduced to the examination of the integrand of the optimized functional. To extend the domain of asymptotic stability of the nonlinear system, a sequence of the Lyapunov-Krasovskii functionals is used. The whole system becomes the system with variable structure. The proposed approach gives a systematic framework for an “almost sliding mode control”.     

Mobile Fair Diary: hybrid interface for taking,browsing and sharing context-aware notes

This paper describes the Mobile Fair Diary (MFD), which is designed to allow a housing fair customer to make a personalized digital recording of his/her visit to a hectic fairground for later use. The MFD is a hybrid interface service comprising of an application for a camera equipped smart phone and a website accessed by a PC. The smart phone application is used for taking context-aware notes such as visual codes, photos, dictations and text. The notes are uploaded onto a website, where they can be viewed with a PC in a contextually ordered view for browsing, organizing and sharing. The MFD was empirically evaluated in a real-life environment of use with genuine end users by a large-scale field trial at a national housing fair. The results testify to the very successful design of the MFD with high usefulness.     

Drivers and Road Signs

The function of the road sign system as an information channel for car drivers was investigated. The data were gathered from more than 5,000 car drivers stopped after passing a road sign on a Swedish highway. The main results are as follows.

1. The overall probability of a road sign being noticed on passing is not higher than about 0·5.

2. The different signs studied form a scale of recording probability of perception extending from a low group with a probability of being perceived of about 0·25 up to a group with probabilities between 0·60-0·75. The rank order of the signs is consistent between occasions.

3. The results verified the outcome of a previous investigation by Johansson and Rumar, 1966.

The main conclusion must be that the road sign system to a high degree does not achieve its purpose.     

A heuristic approach to reinforcement learning control systems

This paper describes a learning control system using a reinforcement technique. The controller is capable of controlling a plant that may be nonlinear and nonstationary. The only a priori information required by the controller is the order of the plant. The approach is to design a controller which partitions the control measurement space into sets called control situations and then learns the best control choice for each control situation. The control measurements are those indicating the state of the plant and environment. The learning is accomplished by reinforcement of the probability of choosing a particular control choice for a given control situation. The system was stimulated on an IBM 1710-GEDA hybrid computer facility. Experimental results obtained from the simulation are presented.     

基于触摸屏和单片机共同控制的定位系统

本文介绍了一种由SST89C58单片机控制伺服电机的系统方案,包括硬件设计和软件设计.详细介绍了电子控制中常用的Modbus协议,采用Modbus协议中的ASCII模式通过串口通信实现单片机与触摸屏的通信.用单片机代替工业控制中常用的PLC做作为从机,节省了成本,单片机接收触摸屏传来的参数控制电机的运行,有效且经济地实现单片机对交流电机的控制.     

The generalized Radon transform: Sampling, accuracy and memory considerations

The generalized Radon (or Hough) transform is a well-known tool for detecting parameterized shapes in an image. The Radon transform is a mapping between the image space and a parameter space. The coordinates of a point in the latter correspond to the parameters of a shape in the image. The amplitude at that point corresponds to the amount of evidence for that shape. In this paper we discuss three important aspects of the Radon transform. The first aspect is discretization. Using concepts from sampling theory we derive a set of sampling criteria for the generalized Radon transform. The second aspect is accuracy. For the specific case of the Radon transform for spheres, we examine how well the location of the maxima matches the true parameters. We derive a correction term to reduce the bias in the estimated radii. The third aspect concerns a projection-based algorithm to reduce memory requirements.     

Application of stochastic optimal control to a hydrofoil boat problem

In this paper the solution of a stochastic optimal control problem described by linear equations of motion and a nonquadratic performance index is presented. The theory is then applied to the dynamics of a single-foil and a hydrofoil boat flying on rough water. The random disturbances caused by sea waves are represented as the response of an auxiliary system to a white noise input. The control objective is formulated as an integral performance index containing a quadratic acceleration term and a nonquadratic term of the submergence deviation of the foil from calm water submergence. The stochastic version of the maximum principle is used in the formulation of a feedback control law. The Riccati equations and the feedback gains associated with a nonquadratic performance index are non-linear functions of the state and auxiliary state variables. These equations are integrated forward with the state equations for the steady-state solution of the problem. The controller for a nonquadratic performance index contains computing elements which perform the integration of the Riccati equations to generate the instantaneous values of the feedback gains. The effect of a nonquadratic penalty on the submergence deviation and the effect of a nonquadratic control penalty on the response of the system are investigated. A comparison between an optimal nonlinear control law and a suboptimal linear control law is presented.