International Journal of Advanced Robotic Systems
Volume 1 Number 2 June 2004 |
Dynamic Simulation of Task Constrained of a Rigid Flexible Manipulator, Page 61-66 Abstract: A rigid-flexible manipulator may be assigned tasks in a moving environment where the winds or vibrations affect the position and/or orientation of surface of operation. Consequently, losses of the contact and perhaps degradation of the performance may occur as references are changed. When the environment is moving, knowledge of the angle a between the contact surface and the horizontal is required at every instant. In this paper, different profiles for the time varying angle a are proposed to investigate the effect of this change into the contact force and the joint torques of a rigid-flexible manipulator. The coefficients of the equation of the proposed rotating surface are changing with time to determine the new X and Y coordinates of the moving surface as the surface rotates.
Assembly and Disassembly Planning by Using Fuzzy Logic & Genetic Algorithms, Page 67-74 Abstract: The authors propose the implementation of hybrid Fuzzy Logic-Genetic Algorithm (FL-GA) methodology to plan the automatic assembly and disassembly sequence of products. The GA-Fuzzy Logic approach is implemented onto two levels. The first level of hybridization consists of the development of a Fuzzy controller for the parameters of an assembly or disassembly planner based on GAs. This controller acts on mutation probability and crossover rate in order to adapt their values dynamically while the algorithm runs. The second level consists of the identification of the optimal assembly or disassembly sequence by a Fuzzy function, in order to obtain a closer control of the technological knowledge of the assembly/disassembly process. Two case studies were analyzed in order to test the efficiency of the Fuzzy-GA methodologies.
Modelling, Specification and Robustness Issues for Robotic Manipulation Tasks, Page 75-86 Abstract: In this paper, a system for modeling of service robot tasks is presented. Our work is motivated by the idea that a robotic task may be represented as a set of tractable modules each responsible for a certain part of the task. For general fetch-and-carry robotic applications, there will be varying demands for precision and degrees of freedom involved depending on complexity of the individual module. The particular research problem considered here is the development of a system that supports simple design of complex tasks from a set of basic primitives. The three system levels considered are: i) task graph generation which allows the user to easily design or model a task, ii) task graph execution which executes the task graph, and iii) at the lowest level, the specification and development of primitives required for general fetch-and-carry robotic applications. In terms of robustness, we believe that one way of increasing the robustness of the whole system is by increasing the robustness of individual modules. In particular, we consider a number of different parameters that effect the performance of a model-based tracking system. Parameters such as color channels, feature detection, validation gates, outliers rejection and feature selection are considered here and their affect to the overall system performance is discussed. Experimental evaluation shows how some of these parameters can successfully be evaluated (learned) on-line and consequently improve the performance of the system.
Robotic Applications in Cardiac Surgery, Page 87-92 Abstract: Traditionally, cardiac surgery has been performed through a median sternotomy, which allows the surgeon generous access to the heart and surrounding great vessels. As a paradigm shift in the size and location of incisions occurs in cardiac surgery, new methods have been developed to allow the surgeon the same amount of dexterity and accessibility to the heart in confined spaces and in a less invasive manner. Initially, long instruments without pivot points were used, however, more recent robotic telemanipulation systems have been applied that allow for improved dexterity, enabling the surgeon to perform cardiac surgery from a distance not previously possible. In this rapidly evolving field, we review the recent history and clinical results of using robotics in cardiac surgery.
One-Chip Solution to Intelligent Robot Control: Implementing Hexapod Subsumption Architecture Using a Contemporary Microprocessor, Page 93-98 Abstract: This paper introduces a six-legged autonomous robot managed by a single controller and a software core modeled on subsumption architecture. We begin by discussing the features and capabilities of IsoPod, a new processor for robotics which has enabled a streamlined implementation of our project. We argue that this processor offers a unique set of hardware and software features, making it a practical development platform for robotics in general and for subsumption-based control architectures in particular. Next, we summarize original ideas on subsumption architecture implementation for a six-legged robot, as presented by its inventor Rodney Brooks in 1980’s. A comparison is then made to a more recent example of a hexapod control architecture based on subsumption. The merits of both systems are analyzed and a new subsumption architecture layout is formulated as a response. We conclude with some remarks regarding the development of this project as a hint at new potentials for intelligent robot design, opened up by a recent development in embedded controller market.
How to Achieve Various Gait Patterns from Single Nominal, Page 99-108 Abstract: In this paper is presented an approach to achieving on-line modification of nominal biped gait without recomputing entire dynamics when steady motion is performed. Straight, dynamically balanced walk was used as a nominal gait, and applied modifications were speed-up and slow-down walk and turning left and right. It is shown that the disturbances caused by these modifications jeopardize dynamic stability, but they can be simply compensated to enable walk continuation.
Real-Time Simulation of Robot Controlled Belt Grinding Processes of Sculptured Surfaces, Page 109-114 Abstract: Industrial robots are introduced to belt grinding processes of free-formed surface with elastic wheel nowadays in order to obtain high quality product and high efficiency. However, it is a laborious task to plan grinding paths and write programs for the robot. To release people from it partially, it is necessary to simulate the belt grinding processes which are useful for path generating and dynamic robot control. In this paper, we present a framework of the robot controlled belt grinding simulation system and some key issues in it. We enhance the global removal model to local process model, which can simulate the grinding process more exactly. We also point out the bottleneck of the real-time simulation and put forward a neural network based regression method to meet this difficulty. At the end of the paper, some simple simulation examples are given.
An Adaptive Fuzzy Logic Controller for Robot Manipulator, Page 115-117 Abstract: In this paper, an adaptive fuzzy controller is designed for the robot-manipulator. The synthesized controller ensures that 1) the close-loop system is globally stable and 2) the tracking error converges to zero asymptotically and a cost function is minimized. The fuzzy controller is synthesized from a collection of IF-THEN rules. The parameters of the membership functions characterizing the linguistic terms change according to some adaptive law for the purpose of controlling a plant to track a reference trajectory. The proposed control scheme is demonstrated in a typical nonlinear plant two link manipulator. The computer simulation of control is done by the language MATLAB. The results of simulation show that the adaptive controller well operates and provides good qualities of the control system. The presented results are analyzed.
|
ARS Web 2004 |