Experimental investigation of characteristics of pneumatic artificial muscles

The characteristics of pneumatic artificial muscles (PAMs) make them very interesting for the development of robotic and prosthesis applications. The McKibben muscle is the most popular and is made commercially available by different companies. The aim of this research is to acquire as much information about the pneumatic artificial muscles as we can with our test-bed that was developed by us and to be able to adopt these muscles as a part of prosthesis. This paper presents the set-up constructed, and then describes some mechanical testing results for the pneumatic artificial muscles

An Active Visual Estimator for Dexterous Manipulation

We present a working implementation of a dynamics based architecture for visual sensing. This architecture provides field rate estimates of the positions and velocities of two independent falling balls in the face of repeated visual occlusions and departures from the field of view. The practical success of this system can be attributed to the interconnection of two strongly nonlinear dynamical systems: a novel triangulating state estimator; and an image plane window controller. We detail the architecture of this active sensor, provide data documenting its performance, and offer an analysis of its soundness in the form of a convergence proof for the estimator and a boundedness proof for the manager

Heuristic Solutions for Loading in Flexible Manufacturing Systems

Production planning in flexible manufacturing system deals with the efficient organization of the production resources in order to meet a given production schedule. It is a complex problem and typically leads to several hierarchical subproblems that need to be solved sequentially or simultaneously. Loading is one of the planning subproblems that has to addressed. It involves assigning the necessary operations and tools among the various machines in some optimal fashion to achieve the production of all selected part types. In this paper, we first formulate the loading problem as a 0-1 mixed integer program and then propose heuristic procedures based on Lagrangian relaxation and tabu search to solve the problem. Computational results are presented for all the algorithms and finally, conclusions drawn based on the results are discussed

Mesterséges pneumatikus izomelemek modellezése és paramétereinek szimulációja MATLAB környezetben

Pneumatic artificial muscles (PAMs) are becoming more commonly used as actuators in modern robotics. The most made and common type of these artificial muscles in use is the McKibben artificial muscle that was developed in 1950's. The braided muscle is composed of gas-tight elastic bladder, surrounded by braided sleeves. Typical materials used for the membrane constructions are latex and silicone rubber, while nylon is normally used in the fibres. This paper presents the geometric model of PAM and different MATLAB models for pneumatic artificial muscles. The aim of our models is to relate the pressure and length of the pneumatic artificial muscles to the force it exerts along its entire exists

Vision Guided Force Control in Robotics

One way to increase the flexibility of industrial robots in manipulation tasks is to integrate additional sensors in the control systems. Cameras are an example of such sensors, and in recent years there has been an increased interest in vision based control. However, it is clear that most manipulation tasks can not be solved using position control alone, because of the risk of excessive contact forces. Therefore, it would be interesting to combine vision based position control with force feedback. In this thesis, we present a method for combining direct force control and visual servoing in the presence of unknown planar surfaces. The control algorithm involves a force feedback control loop and a vision based reference trajectory as a feed-forward signal. The vision system is based on a constrained image-based visual servoing algorithm, using an explicit 3D-reconstruction of the planar constraint surface. We show how calibration data calculated by a simple but efficient camera calibration method can be used in combination with force and position data to improve the reconstruction and reference trajectories. The task chosen involves force controlled drawing on an unknown surface. The robot will grasp a pen using visual servoing, and use the pen to draw lines between a number of points on a whiteboard. The force control will keep the contact force constant during the drawing. The method is validated through experiments carried out on a 6-degree-of-freedom ABB Industrial Robot 2000

Control visual de un robot móvil mediante una cámara cenital

This research project addresses the problem of controlling the motion of a small mobile robot by means of visual feedback provided by an overhead camera. This visual servoing problem has been previously addressed by many researchers due to its multiple applications to real world problems. In this document, we propose a software platform that rely on low cost hardware components to solve it. Based on the imagery supplied by the overhead camera, the proposed system is capable of precisely locating and tracking the robot within a planar ground workspace, using the CAMShift algorithm, as well as finding out its orientation at every moment. Then, an error measurement is defined between current and desired positions of the robot in the Cartesian plane (Position-Based Visual Servoing). In order to generate the suitable motion commands that lead the robot towards its destination, we make use of mathematical equations that model the control of the robot. The platform has been especially designed regarding its application to real time problems. One of the central goals of this work is analyzing the viability of the proposed system and the level of accuracy that it is capable of achieving taking into account the low cost components on which it is based. The validation of the system has come as a result of the real time experiments that have been conducted. Firstly, an exhaustive battery testing that comprehends 1400 experiments has been conducted in order to find a suitable set of parameter values that polished the control equations. Secondly, we have implemented three different applications to test these new control values: tracing a trajectory defined by a fixed set of points, pursuing a mobile target and integrating our system with a blockprogramming platform from which it receives a set of destination points to be followed. Having successfully completed all these tasks, we conclude that the proposed robotic system has well proven its feasibility and effectiveness facing the addressed visual servoing problem.Este proyecto de investigación aborda el problema de controlar el movimiento de un pequeño robot móvil por medio del feedback visual proporcionado por una cámara cenital. Este problema de control visual de servos ya ha sido abordado previamente por multitud de investigadores debido a sus múltiples aplicaciones a problemas del mundo real. En este documento, se propone una plataforma software que depende de componentes hardware de bajo coste para resolverlo. Basado en imágenes suministradas por la cámara cenital, el sistema propuesto es capaz de localizar y seguir de forma precisa al robot dentro de un entorno de trabajo en el plano del suelo, usando para ello el algoritmo de tracking CAMShift, así como averiguar su orientación en cada momento. Después, una medida de error se define entre la posición actual del robot y la deseada en el plano Cartesiano (control visual de servos basado en posición (PBVS)). Para generar los comandos de movimiento aporpiados que lleven al robot a su destino, hacemos uso de ecuaciones matemáticas que modelizan el control del robot. La plataforma ha sido especialmente diseñada teniendo en cuenta su aplicación a problemas en tiempo real. Uno de los objetivos centrales de este trabajo es analizar la viabilidad del sistema propuesto y el nivel de precisión que es capaz de obtener teniendo en cuenta los componentes de bajo coste en los que se basa. La validación del sistema viene dada como resultado de los experimentos en tiempo real que se han llevado a cabo. Primeramente, una exhaustiva batería de pruebas que comprende 1400 experimentos ha sido ejecutada con el fin de obtener un set de valores para los parámetros que puliesen las ecuaciones de control. A continuación, hemos implementado tres aplicaciones diferentes para probar estos nuevos valores de control: trazar una trayectoria definida por un conjunto de puntos fijos, perseguir un objetivo móvil e integrar nuestro sistema con la plataforma de programación por bloques desde la que recibe el conjunto de puntos a seguir. Habiendo completado todas estas tareas satisfactoriamente, concluimos que el sistema robótico propuesto ha demostrado con holgura su viabilidad y efectividad frente al problema de control visual de servos abordado