Open Control Architecture Research Articles

Intelligent automation of electron beam physical vapour deposition

The present paper presents an intelligent automation of the electron beam physical vapour deposition (EBPVD) process to achieve high quality and cost efficient coatings for low volume part production, using realtime feedback control. A computational model of EBPVD for predicting coating thickness is used with an optimisation heuristic for reducing coating thickness variance and feedback control approaches for substrate temperature control and melt pool control. The computational model can be readily generated using a standard computer aided design (CAD) model of the workpiece, which makes the method applicable to workpieces with complex three-dimensional geometry. Based on this model, an optimisation heuristic for the EBPVD process is developed to control workpiece motion systematically with the objective of reducing coating thickness variance, i.e. providing a uniform coating. These computational developments are illustrated using a simulation of a turbine blade coating in which the coating thickness variance is reduced significantly. Process level intelligence is incorporated using realtime feedback control for substrate temperature and melt pool control using an open architecture control system. Results using thermocouple based temperature control and realtime vision for melt pool control are presented. Video images of the melt pool are analysed on a block by block basis, using a technique to identify critical regions of the melt pool. Simulation results demonstrate the feasibility of automating the electron gun beam steering sequence. The proposed methods offer the prospect of eliminating dedicated tooling/fixtures and improving the cost effectiveness of the process, especially for low volume production.

A Process Monitoring System for Process-Based Product Validation

A process monitoring and visualization system was developed for three-axis milling. The hardware consisted of several sensors that monitored spindle power, cutting force, machine vibration, and acoustic emission output. The visualization routine then color-coded the sensor data and overlaid them onto a 3-D CAD model of the machined part. Hyperpoints were used to relate the sensor data to part geometry. The hyperpoints were Cartesian points in space that augmented the 3-D CAD model with additional information such as force or vibration sensor readings. The key strategy was to detect, diagnose, and correct machining errors at the earliest possible opportunity. In the experimental work, the sensors were integrated into an open architecture machine tool platform. Therefore, the paper also describes the advances in machine tool functionality and process capability that were made possible by using the open architecture controller. Results for two standard test parts are presented.

A scheme for an internet-based checking method of machine-tools with variant CNC architecture

This paper proposes an Internet-based checking technique for machine-tools with variant Computerized Numerical Controller (CNC). According to its architecture, CNC is classified into one of two types: Closed Architecture Controller (CAC), which is the conventional CNC, or Open Architecture Controller (OAC), which is a recently introduced PC-based controller. Since CAC has a closed architecture, it is dependent on CNC vender specification. Because of this, it has been very difficult for users to implement application programs in the CNC domain. Recently, the conventional CNC of machine-tools has been replaced by a PC-based open architecture CNC. However, now many conventional CAC machines are being operated together with OAC machines in inadequately equipped shop floors. For Internet-based checking for variant CNC machines with CAC and OAC, a suitable systematic environment is necessary. Through this research, for the global management of variant CNC machines both a CAC and an OAC in the manufacturing system, a suitable environment for Internet-based checking of variant CNC machines was designed, and the checking methods for CAC and OAC machines were compared. The results of this research may serve as a base model for global monitoring and remote control in an integrated manufacturing system with variant CNC machines. Checking points defined in this research are classified into two categories: structured point and operational point. The former includes the vibration of bearing, temperature of spindle unit, and other points of periodical management, while the latter includes oil checking, clamp locking/ unlocking, and machining on/off status.

An evaluation space for open architecture controllers

Existing open architecture controllers have different architectures and methods for realization, but none of them have been generally accepted or been widely applied in industry. Moreover, there is little literature that analyzes and compares these different open architecture controllers synthetically. So this paper establishes an evaluation space for open architecture controllers, a new method to analyze and compare the different open architecture controllers. The evaluation space enables the full evaluation of the open architectures and can easily find the controller’s advantages and disadvantages. The evaluation space for open architecture controllers is a multidimensional space, whose dimensions can be categorized as the requirement dimensions and the architecture dimensions. The requirement dimensions define different requirements of the open architecture controllers, and the architecture dimensions define the different realization methods of open architecture controllers. Establishing the relationships between the requirement dimensions and the architecture dimensions, the evaluation space can calculate the degree to which the different architectures meet the requirements of open architecture controllers, and then the integrated evaluation of different open architecture controllers can be obtained. Several typical open architecture controllers, such as NGC, OSACA, OMAC and OSEC, are compared based on the evaluation space; some valuable conclusions have been drawn.

Research on Hierarchical Design Method of Open Modular Architecture CNC System

One reason for the delay of open-architecture control system in industry action is that no clear and hierarchical design method has evolved. Different application environment and object should have different open levels, applying platforms, system architectures and integration method. Abstract open control concepts or characters must be converted into specific and practical applying objects and contents of one designing of open-architecture CNC system. Then through analysis of the hierarchy or level of system open character, practical system functional objects to be realized, technical and non-technical issues to be considered, implementation contents and process and the method of component and system validation, a hierarchical design method of open modular architecture CNC system is established.

A PC-based Open Architecture Controller for Robot

A PC-based Open Architecture Controller for Robot

Breakage detection of small-diameter tap using vision system in high-speed tapping machine with open architecture controller

In this research, a vision system for detecting breakages of small-diameter taps, which are rarely detected by the indirect in-process monitoring methods such as acoustic emission, cutting torque and motor current, was developed. Two HMI (Human Machine Interface) programs to embed the developed vision system into a Siemens open architecture controller, 840D, were developed. They are placed in sub-windows of the main window of the 840D and can be activated or deactivated either by a softkey on the operating panel or the M code in the NC part program. In the event that any type of tool breakage is detected, the HMI program issues a command for an automatic tool change or sends an alarm signal to the NC kernel. An evaluation test in a high-speed tapping machine showed that the developed vision system was successful in detecting breakages of small-diameter taps up to M1.

Development and implementation of a real-time open-architecture control system for industrial robot systems

This paper presents a real-time open-architecture control system (ROACS) which has been developed for flexible manipulation of industrial robots. Flexible manipulation refers to robot manipulation that handles tasks with uncertainties; hence, decision-making based on feedback data is essential in realtime operation. A real-time open-architecture control system with the capacity of parallel processing of realtime events, extraction of information from realtime data, and intelligent decision-making, is developed. The entire system consists of a real-time subsystem which manages robot hardware and executes path planning and data processing, and an intelligent subsystem which performs intelligent decision-making and feedback task control. In the context of intelligent task control, information extraction, fuzzy-logic-based interpretation and decision-making, and a novel design of associated real-time robot task language (RTTL) are developed. The conflicts between high bandwidth requirements for real-time services and the undeterministic time length for intelligent decision-making are managed in a cooperative real-time intelligent system model. Client–server architecture is found quite suitable for implementation of the system. The entire system has been successfully developed, implemented, and demonstrated for a robotic salmon slicing task which requires online determination of the backbone position.

An innovative software architecture to improve information flow from CAM to CNC

Abstract Over the years, machine tool evolution has allowed faster equipment, using new configurations, to manufacture parts that were almost impossible to machine in the past. Despite this tremendous evolution in machine and control technologies, the metalworking industry is still using the old ISO 6983 G-Codes programming interface to control the motion of these machines. This programming interface is not the most flexible or most appropriate for use by new open-architecture machine controllers and object-oriented high-level machining interfaces such as ISO 14649 (STEP-NC). This work proposes an innovative language, the ‘Base Numerical Control Language (BNCL),’ which is based on a low-level simple instruction set-like approach. The architecture is designed around two concepts: the BNCL virtual machine, which acts as a virtual microprocessor, and the BNCL virtual hardware, which is an abstraction of the machine tool. The language is characterised by its simplicity and flexibility, two qualities that are critical in a market in which the capabilities and performance of machines are constantly improving. The proposed architectural concepts are validated through various computer simulation and physical tests, including performance throughput, trajectory driving, and CNC controller extension capabilities.

The development of an open architecture control system for CBN high speed grinding

The aim of this project is the development of an open architecture controlling (OAC) system to be applied in the high speed grinding process using CBN tools. Besides other features, the system will allow a new monitoring and controlling strategy, by the adoption of open architecture CNC combined with multi-sensors, a PC and third-party software. The OAC system will be implemented in a high speed CBN grinding machine, which is being developed in a partnership between the University of Sao Paulo (USP - Manufacturing Processes Optimizing Group (OPF) - NUMA - EESC; and a traditional Brazilian grinding machine manufacturer. This new CNC generation allows the implementation of new monitoring and controlling strategies due to the two-way CNC and PC communication using a High Speed Serial Bus (HSSB). As a result, third-party software routines, such as LabVIEW VIs (Virtual Instruments), can be used to act in the CNC, interacting with HMI software, via Active X. As a result, the performance of high speed grinding can be increased by the adoption of the open architecture controlling solution combined with high performance monitoring systems.

리얼타임 리눅스기반 개방향제어기 개발

In the manufacturing industries, agility and flexibility are the key issues to meet the various market demands. From this point of view, open architecture control has many advantages. This paper suggests a real-time Linux-based open architecture controller. Linux-based and windows-based controllers are compared in several aspects, and Linux is shown to be advantageous over the windows. With the user friendly GUI, the suggested controller is applied to the X-Y stage which is made of two linear motors. Path following and repeatability performances are successfully observed, which shows the validity of the suggested controller.

Accurate Machining of Freeform Surfaces by Restraining Cutter Contouring Errors

Machined parts having sculptured surfaces pose challenges in the field of CAD/CAM. Sculptured surfaces are essential in the manufacture of components with curved geometry, which are demanded mostly in the aerospace and die and mould industries. This paper presents an adaptive cutter path restraining method for freeform surface machining and its implementation in milling. The ultimate goal is to achieve high contouring accuracy for sculptured parts machining which is a principal index for the performance evaluation of CNC machines. The proposed method is robust in achieving the desired surface cutting with the capability of satisfying pre-specified tolerance requirements using certain adaptive laws. The given tolerance is measured as the angular deviation by which the generated cutter path differs from the desired path. Since the feedrate is considered to be the most significant cutting parameter, only feedrate variations from 5 mm s-1 to 30 mm s -1 are applied in this system. The tool paths generated with and without the adaptive mechanism are compared. The proposed methodology has been tested on a CNC milling system with an open-architecture controller. The experimental results demonstrate that the proposed tolerance feedback mechanism is very effective for producing parts with sculptured surfaces.

Solving the inverse dynamic control for low cost real-time industrial robot control applications

This work deals with the real-time robot control implementation. In this paper, an algorithm for solving Inverse Dynamic Problem based on the Gibbs-Appell equations is proposed and verified. It is developed using mainly vectorial variables, and the equations are expressed in a recursive form, it has a computational complexity of O(n). This algorithm will be compared with one based on Newton-Euler equations of motion, formulated in a similar way, and using mainly vectors in their recursive formulation. This algorithm was implemented in an industrial PUMA robot. For the robot control a new and open architecture based on PC had been implemented. The architecture used has two main advantages. First it provides a total open control architecture, and second it is not expensive. Because the controller is based on PC, any control technique can be programmed and implemented, and in this way the PUMA can work on high level tasks, such as automatic trajectory generation, task planning, control by artificial vision, etc.

Platform for an open architecture controller based on a general operation system with a hard real-time extension

A new open architecture controller, Platform for Open Architecture Controller (POAC), is discussed. Using a general operating system with a hard real-time extension, POAC divides the application software of the controller into the developing and application systems. The developing system includes the function subsystem and communication subsystem, which respectively realize the function module capable of running on the different operating systems and the communication interface uniform to all kinds of operating systems. The application system defines the model of the task module, realizing the interoperability and interchangeability between the task modules. POAC establishes a modular developing method and implements the real-time and non-real-time functions separately. The comparison with Next Generation Controller (NGC), the Open System Architecture for Controls within Automation Systems (OSACA), the Open, Modular Architecture Controls (OMAC) and the Open System Environment for Controller (OSEC) shows that POAC is a good, open architecture controller with the advantages of real-time performance, simplicity and practicability. In summary, POAC develops a simple and practical architecture and a standard of open architecture controller that largely decreases the developing time from the standard to the product.

Diamond turning using position and AE dual feedback control system

A control scheme to improve machining accuracy by means of an acoustic emission root mean square (AErms) signal measured on-line during diamond turning is proposed. Preliminary experiments have verified a correlation between a machining error and measured AErms. Based on the correlation, a control algorithm to apply a compensation signal to a position feedback control loop, named the position and AE dual feedback control scheme is proposed. Machining tests using a diamond turning machine controlled with a PC-based open architecture controller showed that the proposed control scheme accomplishes 20% reduction of machining error compared to conventional position feedback control. Machining tests using new and worn diamond tools showed that an on-line tool-wear recognition is possible using the AE feedback control system.

Three-dimensional dynamic interpolation using stateline based control architectures

The authors discuss a novel machine tool control architecture and mechanism that allows real-time manipulation of the nominal reference trajectory in three orthogonal directions (tangential, radial and axial). The previously developed UBC open architecture control system and high speed contouring algorithm are used to provide dynamic interpolation functionality in the tangential direction, while an extension to both the architecture and control scheme introduces dynamic interpolation in the orthogonal (radial and axial) directions. This permits the compensation of contouring errors due to both process and system dynamics, while avoiding both process constraint violations and undesirable effects due to system nonlinearities.

MD-SIR: a methodology for developing sensor—guided industry robots

In this paper, we present a generic methodology for the synthesis of industrial robot applications with sensory feedback at the end-effector level. The presented methodology assumes an open controller architecture and leads to the creation of a library of modular and reusable entities, which can be used to build new systems based on the proposed architectural framework. The library facilitates the integration of new algorithms and it evolves as new modular applications are built. The library components belong to the control objects layer of the open controller architecture and implement functionality for sensor interfacing, sensor modeling, pattern recognition, state estimation and state regulation. The validity of the approach is verified by composing real industrial applications. The experimental results indicate the high quality of the developed systems.

Analysis of open CNC architecture for machine tools

The evolution of digital circuit technology, leadind to higher speeds and more reliability allowed the development of machine controllers adapted to new production systems (e.g., Flexible Manufacturing Systems - FMS). Most of the controllers are developed in agreement with the CNC technology of the correspondent machine tool manufacturer. Any alterations or adaptation of their components are not easy to be implemented. The machine designers face up hardware and software restrictions such as lack of interaction among system's elements and impossibility of adding new function. This is due to hardware incompatibility and to software not allowing alterations in the source program. The introduction of open architecture philosophy propitiated the evolution of a new generation of numeric controllers. This brought the conventional CNC technology to the standard IBM - PC microcomputer. As a consequence, the characteristics of the CNC (positioning) and the microcomputer (easy of programming, system configuration, network communication etc) are combined. Some researchers have addressed a flexible structure of software and hardware allowing changes in the hardware basic configuration and all control software levels. In this work, the development of open architecture controllers in the OSACA, OMAC, HOAM-CNC and OSEC architectures is described.

Support Vector Machines Model for Classification of Thermal Error in Machine Tools

This paper addresses a change in the concept of machine tool thermal error prediction which has been hitherto carried out by directly mapping them with the temperature of critical elements on the machine. The model developed herein using support vector machines, a powerful data-training algorithm, seeks to account for the impact of specific operating conditions, in addition to temperature variation, on the effective prediction of thermal errors. Several experiments were conducted to study the error pattern, which was found to change significantly with variation in operating conditions. This model attempts to classify the error based on operating conditions. Once classified, the error is then predicted based on the temperature states. This paper also briefly describes the concept of the implementation of such a comprehensive model along with an on-line error assessment and calibration system in a PC-based open-architecture controller environment, so that it could be employed in regular production for the purpose of periodic calibration of machine tools.

A Study on an Open Architecture CNC System with a NURBS Interpolator for WEDM

This paper deals with the design and implementation of an open architecture CNC system for wire electrical discharge machining (WEDM) with a consideration of the differences between WEDM and NC cutting machines. Work using open architecture controllers (OACs) has focused mainly on metal cutting machines. WEDM has many aspects similar to milling machines. However, there are differences in the machining processes and control strategies. To close the gap between previous general work on OAC and the WEDM specific needs, an open architecture NC model for WEDM comprised of a synchronisation kernel and an NC functional module is proposed. The proposed CNC system is applied to an existing commercial WEDM system by a retrofitting method. A precise NURBS interpolation function is implemented and sample runs are conducted with a NURBS interpolator that is added to the proposed system.