Skip to main content

A High-Performance Flexible Manufacturing System Robot with Dynamic Compensation

Objective

The objective of this project was to develop the necessary know-how to control a high-performance robot for use in Flexible Automated Assembly System (FAAS) environments. The major design aims were to compensate for the reduced rigidity of the mechanical structure, while improving speed of operation and overall static and dynamic control. Solutions to the critical problems associated with active control of articulated non-rigid structures were implemented within a comprehensive software package which, following the modelling of the structural dynamics, permitted computer-aided design of control rules. The programme was as follows:
-development of innovative sensors, aimed at improving the global positioning accuracy of FMS robots while ensuring tracking and vibration control
-development of software tools for test and identification, modelling and design of control laws for flexible poly-articulated mechanisms
-development of sensor systems adapted to the online control of robot vibrations and to the testing of robot performance
-demonstration of the improvement is performance obtained with the new control methods on an industrial robot.
In flexible manufacturing system (FMS) robot applications there is a need to compensate for the reduced rigidity of the mechanical structure and to enhance operational speed and overall static and dynamic control. The project partners are developing innovative sensors for improved global positioning accuracy and for assured tracking and vibration control, software tools for the computer aided design (CAD) of control rules for flexible polyarticulated mechanisms, and sensor systems for on line control of robot vibrations and robot performance testing. An industrial robot is used to prove the enhanced performance capability attainable with the new control methods.

Mechanical manipulators exhibit, when submitted to high speed and acceleration rates, vibrations which limit their performances and generate additional stresses on their structure. Up to now, robot designers have solved this problem by building stiff structures, yielding bulky, energy consuming, and expensive robots. An alternative to this solution is proposed, relying on an intensive use of computer aided engineering (CAE) methods such as modal analysis and dynamic modeling. An advanced robot control is used to avoid structural vibrations. The project succeeded in demonstrating on a spot welding robot an antivibration robot control running on industrial hardware. The final results of the ESPRIT project SACODY are presented. Besides the feasibility of active vibration control, the SACODY control approach has shown significant improvements in terms of robot system behaviour and performance. The main advantages of the new control are: an important gain in robot cycle time; a robot positioning without overshooting and vibrations; a reduction of dynamic stresses on the robot structure. This control, which runs on state of the art industrial controller boards, offers a software alternative to the structure stiffening traditionally used to avoid robot vibrations. The fields of application of the antivibration control are very wide, and cover all systems that suffer from lack of structural rigidity. As well as a completely new methodology of servomechanisms control, the results of the project are: a software package for computer aided dynamic analysis; an upgraded software package for the dynamic simulation of flexible multibody systems; a high performance servo level hardware; prototypes of sensor systems for robot testing.

The objective of this project was to develop the necessary know how to control a high performance robot for use in flexible automated assembly system (FAAS) environments. The major design aims were to compensate for the reduced rigidity of the mechanical structure, while improving speed of operation and overall static and dynamic control. Solutions to the critical problems associated with active control of articulated nonrigid structures were implemented within a comprehensive software package which, following the modelling of the structural dynamics, permitted computer aided design (CAD) of control rules.
Improved control and indentification methodologies are available and have been demonstrated on laboratory prototypes. The modelling and simulation software is completed and commercialized. Some of the identification techniques developed have been integrated in commercial versions of computer aided testing (CAT) systems. Development of identification control methods continues and development of sensor systems has been initiated.
Improved control and identification methodologies are available and have been demonstrated on laboratory prototypes. The modelling and simulation software is completed and commercialised. Some of the identification techniques developed have been integrated in commercial versions of Computer-aided Testing (CAT) systems.
Development of identification control methods continues and development of sensor systems has been initiated.
Exploitation
At the end of 1989 the modelling and simulation software was adapted to control design purposes and interfaced with a CAT system. By the end of 1990 a fully operational demonstrator with a new generation industrial robot controller has been completed.

Coordinator

Bertin & Cie
Address
59 Rue Pierre Curie Zone Industrielle Des Gatines
78373 Plaisir
France

Participants (5)

AEG Olympia AG
Germany
Address
Goldsteinstraße 235
60528 Frankfurt Am Main
KATHOLIEKE UNIVERSITEIT LEUVEN
Belgium
Address
Celestijnenlaan
3030 Heverlee
KUKA Schweißanlagen und Roboter GmbH
Germany
Address
Blücherstraße 144
86165 Augsburg
LEUVEN MEASUREMENT & SYSTEMS INTERNATIONAL
Belgium
Address
Interleuvenlaan
3001 Heverlee
UNIV COLLEGE DUBLIN
Ireland
Address
Belfield
X Dublin 4