Open Control Architecture Research Articles

Polishing Robot Using Joystick Controlled Teaching

In this article, an impedance model following force control, which uses a position/orientation compensator based on joystick-taught data, is proposed for an industrial robot with an open architecture controller. The present method has two characteristics: it is easily applied to the task where an industrial robot polishes an object with desired contact force and orientation and does not need conventional complicated teaching. The effectiveness and promise of the proposed method are demonstrated through experiments in a polishing task using an industrial robot FS-30.

Comparison of Three Different Open Architecture Controllers

Since the late 80s there are a growing need of the machine tool builders and the end users to have open architecture controllers. Different levels of openness can be defined analyzing the available research results and products. The main initiatives leading the current research in these efforts are the European OSACA, the American OMAC and the OSEC from Japan. A complex comparison of these projects and their goals and achievements is presented in this paper. It is stated that in their present form it is not possible to merge easily the three results to get a unified and potentially worldwide accepted open architecture controller.

A feature-based inspection and machining system

This paper 1 1 Certain commercial products are identified in this paper to describe our study adequately. Such identification is not intended to imply recommendation or endorsement by NIST, neither is it intended to imply that the products identified are necessarily the best available for the purpose. describes an architecture for a system for machining and inspecting mechanical piece parts and an implementation of it called the Feature-Based Inspection and Control System (FBICS). In FBICS, the controller of a machining center or coordinate measuring machine uses a standard feature-based description of the shape of the object to be made as a principal input for machining and/or inspection. FBICS is a hierarchical control system and performs automated hierarchical process planning. FBICS serves: (1) to demonstrate feature-based inspection and control in an open-architecture control system; (2) as a testbed for solving problems in feature-based manufacturing; and (3) to test the usability of STEP methods and models.

High-speed contouring using a novel dynamic interpolation mechanism

The authors examine the development of algorithms to minimise position error during high-speed contouring operations. The approach taken is to dynamically modify the interpolation process at each loop closing based upon an examination of the current actual and desired state of all axes. The decision rules arising from the analysis are implemented within an existing open architecture control system which allows both the rapid communication of state and actioning of decisions. Experiments demonstrating the effectiveness of the approach are presented.

Open Controller Architecture – Past, Present and Future

Open Control Systems are the key enabler for the realization of modular and re-configurable manufacturing systems. The large number of special purpose machines and the high level of automation have led to an increasing importance of open control systems based on vendor neutral standards. This paper gives an overview on the past, present and future of Open Controller Architecture. After reflecting on the different criteria, categories and characteristics of open controllers in general, the CNC products in the market are evaluated and an overview on the world-wide research activities in Europe, North America and Japan is given. Subsequently the efforts to harmonize the different results are described in order to establish a common world-wide standard in the future. Due to the “mix-and-match” nature of open controllers concentrated attention must be paid to testing mechanisms in the form of conformance and interoperability tests.

1P1-G4 オープンアーキテクチャ型の産業用ロボットをベースとした研磨ロボット : オープンNCコントローラを用いたフレキシブル研磨工具の試作開発(47. PC/AT互換機を用いたオープンロボットコントローラ)

1P1-G4 オープンアーキテクチャ型の産業用ロボットをベースとした研磨ロボット : オープンNCコントローラを用いたフレキシブル研磨工具の試作開発(47. PC/AT互換機を用いたオープンロボットコントローラ)

Vertical machining center accuracy characterization using laser interferometer: Part 2. Angular errors

This paper presents the results of accuracy characterization of a vertical machining center (VMC) in the form of angular errors and temperature variation using a low powered He–Ne (Renishaw ®) laser calibration system along with environmental controller unit. The machine investigated is Cincinnati Milacron Sabre 750 3-axes VMC with Acramatic 2100 CNC open architecture controller. During angular error measurements, pitch and yaw errors of the X-, Y- and Z-axes were obtained. The accuracy of the VMC is characterized in the form of geometric and thermal errors as a function of machine tool nominal axis position, temperature distribution and environmental effect (air temperature, air pressure and relative humidity). The measured temperatures in conjunction with the geometric models are used to predict machine tool geometric and thermal errors. Results show that axis drive motors are the major heat sources. X-, Y- and Z-axes pitch errors are all sinusoidal in nature with an approximate wavelength of 4 in. X-axis pitch and Y-axis yaw errors are highest angular errors of the VMC.

Vertical machining center accuracy characterization using laser interferometer: Part 1. Linear positional errors

This paper presents the results of accuracy characterization of a Vertical Machining Center (VMC) in the form of linear errors and temperature variation using a low powered He–Ne laser (Renishaw ®) calibration system along with environmental controller unit. The machine investigated is Cincinnati Milacron Sabre 750 three axes CNC VMC with Acramatic 2100 CNC open architecture controller. Temperature distribution of the machine was measured using three temperature sensors strategically attached to predetermined locations on each axis guides. The accuracy of the VMC is characterized in the form of geometric and thermal errors as a function of machine tool nominal axis position, temperature distribution and environmental effect (air temperature, air pressure and relative humidity). Results show that axis drive motors are the major heat sources. Linear positional accuracy is best when the machine is in cold condition and deteriorates with increasing machine operation time for all three axes. X-axis had worst linear displacement accuracy and maximum reversal errors among the three axes being tested.

On-line Reconfiguration of Real-Time Robot Motion and Force Control

Combining position and force control is highly desirable in many robot applications. Many years of extensive research has resulted in a number of promising control approaches, but often too much engineering effort is required in order to evaluate a low level (high performance) control scheme on a real manipulator. The new control system we have obtained has two main advantages: first it provides a total open control architecture, and second it is the simplicity and the interactivity of the platform developed. Using this new control architecture, any force and motion control strategy can be programmed and implemented in a graphical and easy way.

Derivation of machine tool error models and error compensation procedure for three axes vertical machining center using rigid body kinematics

Volumetric positional accuracy constitutes a large portion of the total machine tool error during machining. In order to improve machine tool accuracy cost-effectively, machine tool geometric errors as well as thermally induced errors have to be characterized and predicted for error compensation. This paper presents the development of kinematic error models accounting for geometric and thermal errors in the Vertical Machining Center (VMC). The machine tool investigated is a Cincinnati Milacron Sabre 750 3 axes CNC Vertical Machining Center with open architecture controller. Using Rigid Body Kinematics and small angle approximation of the errors, each slide of the three axes vertical machining center is modeled using homogeneous coordinate transformation. By synthesizing the machine's parametric errors such as linear positioning errors, roll, pitch and yaw etc., an expression for the volumetric errors in the multi-axis machine tool is developed. The developed mathematical model is used to calculate and predict the resultant error vector at the tool–workpiece interface for error compensation.

An experimental study of adaptive force/position control algorithms for an industrial robot

Presents the results of an experimental study of force/position control algorithms for an industrial robot with open control architecture, equipped with a wrist force sensor. The robot's end effector is in contact with a compliant surface of unknown stiffness. Two types of control schemes are considered which respectively achieve regulation and tracking of position on the contact surface and force along the direction normal to the surface. The desired position is scaled along the constrained direction so as to fulfill the force control objective; adaptive mechanisms are designed for the two schemes to compute the scaling factor, which depends on the unknown stiffness coefficient of the environment. A number of case studies are developed throughout the paper to illustrate the effectiveness of the force/position control algorithms under nonideal conditions.

An Open Control Architecture for a Distributed Robot Controller

This paper presents an open control architecture for a highly distributed robot controller and its application to the humanoid robot, Centaur, under developed at KIST (Korea Institute of Science and Technology). While existing commercial robot controllers are based on a centralized controller, this paper proposes a highly distributed compact controller connected through the real-time networks, with which modularity and vendor-neutral openness are easily achieved in hardware level. In the software point of view, the control jobs for a humanoid robot are classified into four major levels, and they are coded using reusable software blocks that are executed by multiple distributed processing nodes as well as by a single centralized controller. To demonstrate the feasibility of the proposed control architecture, a testbed system is implemented using VMEbus-based and CAN network-based controllers.

Integration of an open architecture controller with a diamond turning machine

Older machine tools are often mechanically sound but their proprietary controls are outdated and can be economically upgraded to modern open architecture control. The objective of this paper is to present a procedure for integrating these new flexible control architectures into machine tools. As an example, this paper presents the integration of an open architecture controller and a diamond turning machine. The open architecture control permits research into various types of control such as position, velocity, force, and adaptive control that will improve the quality of manufactured optics and other high precision components. The goal of incorporating an open architecture controller into an existing diamond turning machine required the identification, integration and installation of many components. After installing these components, the machine was calibrated to improve its performance. The most important aspect in improving the overall performance of the machine was correcting its vibration characteristics. Spindle imbalance, the spindle shaft coupler and the table and slide amplifiers were found to play a significant role in producing vibration. The sidewise amplitude of acceleration was reduced from approximately 2.5 to 0.6 g due to reduction in vibration after correcting these sources. The remaining level of vibration is normal for this type of diamond turning machine allowing it to produce finishes with 90.24 nm (3.56 μin) RMS surface roughness using a radius tool and 24.13 nm (0.95 μin) RMS with the straight-edge tool.

Open Signaling for ATM, INTERNET and Mobile Networks (OPENSIG'98)

The ability to rapidly create and deploy new transport, control and management architectures in response to new service demands is a key factor driving the programmable networking community. Competition between service providers may hinge on the speed at which one provider can respond to new market demands over another. The notion of open programmable networks is having broad impact on service providers and vendors across a range of telecommunication sectors calling for major advances in open network control architecture, network programmability and distributed systems technology. In this paper we discuss the origins of the Open Signalling Working Group (OPENSIG) and present a summary of the fifth Workshop on Open Signaling for ATM, Internet and Mobile Networks (OPENSIG'98), which was held at the University of Toronto, Ontario, October, 1998. We also discuss a number of new initiatives in the area of open programmable networks that have recently emerged.

Open signaling for ATM, internet and mobile networks (OPENSIG'98)

The ability to rapidly create and deploy new transport, control and management architectures in response to new service demands is a key factor driving the programmable networking community. Competition between service providers may hinge on the speed at which one provider can respond to new market demands over another. The notion of open programmable networks is having broad impact on service providers and vendors across a range of telecommunication sectors calling for major advances in open network control architecture, network programmability and distributed systems technology. In this paper we discuss the origins of the Open Signalling Working Group (OPENSIG) and present a summary of the fifth Workshop on Open Signaling for ATM, Internet and Mobile Networks (OPENSIG'98), which was held at the University of Toronto, Ontario, October, 1998. We also discuss a number of new initiatives in the area of open programmable networks that have recently emerged.

A survey of robot interaction control schemes with experimental comparison

A great many control schemes for a robot manipulator interacting with the environment have been developed in the literature. This paper is aimed at presenting a survey of robot interaction control schemes for a manipulator, the end effector of which comes in contact with a compliant surface. A salient feature of the work is the implementation of the schemes on an industrial robot with open control architecture equipped with a wrist force sensor. Two classes of control strategies are considered, namely, those based on static model-based compensation and those based on dynamic model-based compensation. The former provide a good steady-state behavior, while the latter enhance the behavior during the transient. The performance of the various schemes is compared in the light of disturbance rejection, and a thorough analysis is developed by means of a number of case studies.

Passivity-Based Interaction Controller and Observer for Robot Manipulators

This work presents the design of a passivity-based controller and observer for a robot manipulator interacting with a compliant environment. Regulation of the contact force along the constrained direction and tracking of the end-effector position along the unconstrained directions is achieved; semiglobal exponential stability is proved. The control scheme is implemented in the joint space, and experimental results are illustrated for an open control architecture industrial robot which is endowed with joint position sensors and wrist force sensor, but no joint velocity sensors.

Resolved-acceleration control of robot manipulators: A critical review with experiments

The goal of this paper is to provide a critical review of the well-known resolved-acceleration technique for the tracking control problem of robot manipulators in the task space. Various control schemes are surveyed and classified according to the type of end-effector orientation error; namely, those based on Euler angles feedback, quaternion feedback, and angle/axis feedback. In addition to the assessed schemes in the literature, an alternative Euler angles feedback scheme is proposed which shows an advantage in terms of avoidance of representation singularities. An insight into the features of each scheme is given, with special concern to the stability properties of those schemes leading to nonlinear closed-loop dynamic equations. A comparison is carried out in terms of computational burden. Experiments on an industrial robot with open control architecture have been carried out, and the tracking performance of the resolved-acceleration control schemes in a case study involving the occurrence of a representation singularity is evaluated. The pros and cons of each scheme are evidenced in a final discussion focused on practical implementation issues.

In-process monitoring and control of thickness error in machining hollow shafts

This paper presents the capability of a new ultrasonic system for in-process monitoring and control of part wall thickness during machining. The sensor is non-contact, requires access to the workpiece surface from one side only and provides continuous high speed monitoring. The cutting fluid is used as the medium to transmit the sound waves to and from the machined surface. The system is based on a multi-probe setup in order to compensate for sensor mis-alignment errors. The design of the ultrasonic transducers is optimized to provide high accuracy and a practical working range. The performance of the proposed system is evaluated by adapting it to a CNC lathe retrofitted with an Open Architecture Controller (OAC). The system is applied to monitor and control the external turning of slender hollow shafts. The thickness data obtained during cutting is used in a closed feedback control loop to govern the tool position and compensate for thickness errors in real time. The experimental results demonstrate the accuracy and robustness of the inspection system. The control results show a significant reduction in thickness variation along the cut, especially that due to workpiece flexure.

Open Architecture Controllers for Machine Tools, Part 1: Design Principles

In Part 1 of this two-part paper, we review the development of open architecture controllers for machine tools. General design principles are described, followed by specific hardware and, software recommendations. These specific recommendations are then used for the construction of an open architecture device, MOSAIC-PM, (Machine tool Open System Advanced Intelligent Controller for Precision Machining). The machine has now been used in a wide variety of experiments to demonstrate open architecture control. These experiments include sensor based machining, rapid prototyping and manufacturing over the Internet. In Part 1, a specific application on feature based precision machining with on-machine acceptance is described. A more specific implementation of a quintic spline interpolation method is described in Part 2.