Vision-Based Task-Level Control of a Flexible-Link Manipulator

This paper discusses a vision-based approach to implement task-level control in flexible-link manipulators. The proposed approach emphasizes the advantage of using vision in the control of flexible manipulators. It is pointed out that taking advantage of the inherent robustness, implementation of an image-based visual servo can be regarded as a synthetic solution to precise task-level control of flexible manipulators. This approach is implemented in a three-dimensional flexible-link manipulator. The implementation makes good use of filters in decoupling task-level control and vibration suppression control. Moreover, we point out that although the robustness of the approach can help to overcome the difficulty in control resulting from the complex measurement of the link's elastic deformation, it lacks in capability of tip trajectory specification. This problem is analyzed in this research and it leads to the proposal for the integration of the image interpolation technique. This technique makes the proposed approach adequate for tasks involved with complex tip trajectories. For flexible-link manipulators, the proposed approach with the remedy is the first vision-based synthetic solution that attempts to make a flexible manipulator usable for a practical task.     

A study on a brachiation controller for a multi-locomotion robot — realization of smooth,continuous brachiation

In this paper, we present a control method to realize smooth continuous brachiation. The target brachiation is basically divided into two actions: a swing action and a locomotion action. In order to realize the continuous brachiation effectively and smoothly, it is necessary to start the swing action as soon as the robot grasps the front target bar at the end of the locomotion action. The collision, which occurs at the moment the robot grips the target bar, affects the pendulum motion of the robot. The action of bending the elbow joint of the swinging arm is proposed in order to solve this gripping problem. The elbow-bending action enables the robot to decrease the impact forces and use the excess mechanical energy after the end of the locomotion phase. Thus, there is no loss of energy and waste of time during the subsequent swing phase. Experimental results show that the robot can successfully achieve smooth, continuous brachiation.     

High-Order Sliding Modes for a Robot Driven by Pneumatic Artificial Rubber Muscles

It is known that classical sliding mode control generates chatter which is undesirable. One way to reduce this chatter is the use of high-order sliding mode (HOSM) control. The HOSM control techniques are applied to the first 2 d.o.f. of a robot actuated by pneumatic artificial rubber muscles (PARMs). The PARMs are arranged in opposite pairs (antagonistic configuration). The objective is to show that without the use of the equivalent control, it is still possible to control the robot by the use of HOSM and at the same time reduce the chatter. Experimental results are presented and comparison between two second-order sliding controls established.     

A Flexible and Robust Peer-to-Peer Architecture with XML-Based Open Communication for Laboratory Automation

Traditional lab automation systems are highly centralized: dispatch and coordination of activities are mediated by a system controller, usually via a single, monolithic control procedure. This approach, while conceptually simple, makes changes to the system difficult; adding or removing instruments and functionality can be a daunting task. In addition, most automated systems are tied to particular development languages and protocols, making operation in heterogeneous environments (i.e., the real world) problematic, since instrument software comes in many different implementations.We present a peer-to-peer architecture for lab automation, using an XML-based communication protocol. The architecture consists of peer instrument servers, an XML communication layer, and an open control center. Each instrument peer can control, be controlled by, and communicate information to other instrument peers to fulfill the automation task. Our protocol is based on XML-RPC, a lightweight communication standard built atop HTTP.This provides an open and flexible means of peer-to-peer interfacing. The control center serves as a convenient, Web-based interface to manage the instruments. The automated procedure can be distributed across all available instrument peers (each instrument assigned a set of responsibilities); the controller implements a limited set of high-level instructions. The software components included in our prototype system are implemented in various programming languages, including Java, C/C++, Visual Basic, and LabVIEW. Our approach facilitates rapid development of laboratory automation systems.     

Minimum-time control of coupled tendon-driven manipulators

Hyper-redundant manipulators have very large degrees of redundancy, thus possessing unconventional features such as the ability to enter a narrow space while avoiding obstacles. In this study, a time-optimal control scheme is proposed for a hyper-redundant manipulator that was realized by coupled tendon-driven mechanisms. In the mechanisms, a pair of tendons for driving a joint is pulled from base actuators via pulleys mounted on the base-side joints and the degrees of actuation redundancy exist. The time-optimal trajectory planning problem is solved by using the phase-plane analysis and the linear programming technique. Computer simulations were also performed to show that the proposed scheme makes full use of the actuation redundancy of tendons and their coupled function to shorten motion time.     

A Model ATM Network and APIs for Service Management on an ATM Network

The architectural reference point for our workis a reference model which associates functionality withoperational planes along three orthogonalabstractedmodels. Within the context of this reference model a service management model is proposed. Themodel makes use of APIs for communicating managementinformation between a management application and serviceentities distributed in an ATM network. The APIs are based upon native ATM APIs that are similarto those that have recently been adopted by the ATMForum. The viability of the model is demonstrated bybuilding ATM multimedia services with service management capabilities. The model and the APIs have beenapplied to services executing in a national ATM network.Although the work is motivated by an ATM network, theservice management model is general, and may be applied to other networks as well. Some openissues in service management are brought out.     

21—THE WIRA SHOWER TESTER: A NEW INSTRUMENT FOR THE QUALITY CONTROL OF FABRICS

A new instrument for measuring the absorption and penetration-resistance of fabrics is described. It is based on a novel method of drop propagation, and it is shown that the dynamical properties of the drops lie within the wide range of values provided by natural rain. The test procedure, which is intended to form the basis of a draft British Standard method of test, is described. Results of tests on a variety of apparel fabrics are given, and these include comparative tests on unproofed and treated cloth and tests on fabrics of known wear performance.     

3C-154型硬条包装机控制系统的改造

3C 154型硬条包装机的原电气控制系统采用的是分立元件构成的逻辑控制器,成本高,可靠性差,维护和维修困难,影响了生产的正常运行。采用西门子公司生产的S7 200PLC代替逻辑控制器,对3C 154型硬条包装机的控制系统进行了改造。对改造过程中的电路设计、程序设计以及工作原理进行了论述。改造后电气故障大幅度减少,提高了设备有效作业率,且节约了大量维修费用。     

Fracture strength of tensile loaded graphite–epoxy laminates containing cracks and circular holes

Abstract

A modified point stress criterion has been used to evaluate the fracture strength of tensile loaded graphite–epoxy laminates containing cracks and circular holes. The linear relationship between the asymptotic value of the centre cracked tension plate stress intensity factor and the fracture strength of the infinite plate was used for the evaluation of the characteristic length to predict the fracture strength of laminates having cracks and circular holes. The analytical based results were in good agreement with existing test results.     

Experimental investigation and numerical simulation of cooling process in water assisted injection moulded parts

Abstract

This report investigated, both experimentally and numerically, the cooling process in water assisted injection moulded parts. Experiments were carried out on a laboratory developed water assisted injection moulding system, which included an injection moulding machine, a water pump, a water injection pin, a water tank equipped with a temperature regulator, and a control circuit. The resin used was semi-crystalline polypropylene. The in-mould temperature of the polymeric materials during the cooling process was measured. A transient heat transfer finite element model was adopted to simulate and predict the temperature variation within water assisted injection moulded products. Simulated results matched well with the experimental data. Experimental investigation and numerical simulations of a water assisted injection moulding cooling process can provide an improved understanding of the influence of water related parameters on the cooling process of water assisted injection moulded parts.