Mathias Haage

Extending an industrial robot controller: implementation and applications of a fast open sensor interface

This paper describes the design and implementation of a platform for fast external sensor integration in an industrial robot control system. As an application and motivating example, the implementation of force controlled grinding and deburring within the AUTOFETT-project (EU Growth Programme) is reported.

On the integration of skilled robot motions for productivity in manufacturing

Robots used in manufacturing today are tailored to their tasks by system integration based on expert knowledge concerning both production and machine control. For upcoming new generations of even more flexible robot solutions, in applications such as dexterous assembly, the robot setup and programming gets even more challenging. Reuse of solutions in terms of parameters, controls, process tuning, and of software modules in general then gets increasingly important. There has been valuable progress within reuse of automation solutions when machines comply with standards and behave according to nominal models. However, more flexible robots with sensor-based manipulation skills and cognitive functions for human interaction are far too complex to manage, and solutions are rarely reusable since knowledge is either implicit in imperative software or not captured in machine readable form. We propose techniques that build on existing knowledge by converting structured data into an RDF-based knowledge base. By enhancements of industrial control systems and available engineering tools, such knowledge can be gradually extended as part of the interaction during the definition of the robot task.

Implementation of Industrial Robot Force Control Case Study: High Power Stub Grinding and Deburring

In this paper, the results from a joint industry-academia project in industrial robotic force control are presented. The extension and implementation of an external sensor system for an industrial robot system, which can be used for high-bandwidth force control, are described. Results from two industrial applications using the system are presented, a stub grinding application using a new compliant grinding end-effector integrated with the robot control system, and a deburring application with a stiff tool requiring high-bandwidth force control in six degrees of freedom. Using the system an easily reconfigurable control structure was achieved, which was able to control contact forces with a sampling bandwidth of an order of magnitude higher than for conventional robot controllers

Declarative-knowledge-based reconfiguration of automation systems using a blackboard architecture

This article describes results of the work on knowledge representation techniques chosen for use in the European project SIARAS (Skill-Based Inspection and Assembly for Reconfigurable Automation Systems). Its goal was to create intelligent support system for reconfiguration and adaptation of robot-based manufacturing cells. Declarative knowledge is represented first of all in an ontology expressed in OWL, for a generic taxonomical reasoning, and in a number of special-purpose reasoning modules, specific for the application domain. The domain/dependent modules are organized in a blackboard-like architecture.

Robot Joint Modeling and Parameter Identification Using the Clamping Method

The usage of industrial robots for milling tasks is limited by their lack of absolute accuracy in presence of process forces. While there are techniques and products available for increasing the absolute accuracy of free-space motions, the mechanical weaknesses of the robot in combination with the milling forces limits the achievable performance. If the dynamic effects causing the deviations can be compensated for, there would be several benefits of using industrial robots for machining applications. To enable the compensation, the causes of the path deviations have to be adequately modeled, and there must be a method for determining the model parameters in a simple and inexpensive way. To that end, we propose a radically new method for identification of robot joint model parameters, based on clamping of the robot to a rigid environment. The rigidity of the environment then eliminates the need for expensive measurement equipment, and the internal sensors of the robot give sufficient feedback. An experimental validation shows the feasibility of the method.

Configuration Support and Kinematics for a Reconfigurable Gantry-Tau Manipulator

Affordable and competitive industrial automation is of key importance for small and medium enterprises, in Europe and elsewhere. A key factor is the introduction of new robot automation concepts that ease fast deployment and extend available task repertoire. The Gantry-Tau manipulator is a new robot concept. In contrast to other parallel kinematic manipulators (PKMs), it has a large working range. The high stiffness makes it ideal for a wide range of tasks such as grinding, deburring, and cutting. An additional aspect of such a PKM is the modularity, which in this work has been studied in terms of possibilities for assembly and mechanical reconfiguration at the end-user site, integration of such a kinematically different robot with a standard industrial controller, and new needs for methods/tools to support simple (re)configuration. What is needed for fully utilizing the modularity of the concept in typical SME manufacturing scenarios? A range of software tools and methods were found to be useful and necessary for efficient engineering and integration. For experimental evaluation, a full-scale prototype robot was designed and built, the kinematic software was developed and integrated into the ABB kinematics software, robot CAD software was adapted to the configuration needs, and both simulations and physical experiments were carried out. Our findings make us believe that enhanced software tools should be integrated on a higher symbolic (or meta-) level to better support transformation of data and code generation, but also that the Gantry-Tau type of robot (with adequate software support) will bring a new dimension of flexibility into SME manufacturing.

A prototype robot speech interface with multimodal feedback

Speech recognition is available on ordinary personal computers and is starting to appear in standard software applications. A known problem with speech interfaces is their integration into current graphical user interfaces. This paper reports on a prototype developed for studying integration of speech into graphical interfaces aimed towards programming of industrial robot arms. The aim of the prototype is to develop a speech system for designing robot trajectories that would fit well with current CAD paradigms.

On the scalability of visualization in manufacturing

Computer graphics plays an important role in modern engineering of manufacturing systems, both during design using virtual engineering environments and also as part of user interfaces to various machines. Existing and emerging systems today make use of software components, usually providing a graphical view to the user. In manufacturing, 3D graphics is desirable to visualize geometries of equipment and workpieces, sometimes also via small dedicated user interfaces. The established industrial technology does, however, neither scale down very well to such small platforms, nor scale up to safe operation of large systems. We put forward a notion of executable visualization and propose a solution based on the Java platform, using Java3D for 3D visualization in combination with VRML for external representation. Fully implemented prototypes including both real and virtual industrial robots, and industrial case studies, have verified the scalability which appears to be unique.

Variable Time Delays in Visual Servoing and Task Execution Control

We study an image-based visual servoing system implemented on a non-dedicatednetwork with non-deterministic computationalnodes. A problem is thattime delays aretypically non-deterministic and variable and may causesignificant degradation of control system performance, stability androbustness if not compensated for.Another problem is thepresence of noise due to information loss and measurement errors inthe image and vision processing part of the loop also resultingin decreased control performance.This paper focuses on an image plane linear predictionstrategy implemented using time-stamped data and a nonuniformly updating Kalman filter tocompensate for time delays and noise. Control performance isexperimentally verified by presenting prediction errormeasurements from an image-based visual servoing experiment ofgripping a moving object using a 6-DOF industrial robot anduncalibrated cameras. (Less)

On the Use of Force Feedback for Cost Efficient Robotic Drilling

Drilling is one of the most costly and labour-intensive operations in aircraft assembly. Rather than automating with expensive fixtures and precise machinery, our approach is to make use of standard low-cost robot equipment in combination with sensor feedback. The focus is to eliminate the sliding movement of the end-effector during the clamp-up, called the skating effect, and to keep the end-effector orthogonal to the surface, thus avoiding holes that are not perpendicular. To that end, force feedback is used for building up pressure to clamp up an end-effector to the work-piece surface prior to drilling. The system, including the planning of force parameters for each hole to be drilled, was programmed in DELMIA. The drilling was accomplished with the aid of an extension to the ABB Rapid language called ExtRapid, which is an XML-like code that is interpreted by the force feedback controller downstream in the process. Although experimental results are from drilling, the conceptual idea is believed to be useful in many other applications requiring external sensor feedback control of industrial robots.