Non-Linear Observer-Based Control of Flexible-Joint Manipulators Used in Machine Processing

This paper proposes to use a non-linear observer to build the state and the external force of flexible manipulator robots during their machining (composite materials) processes or Friction Stir Welding (FSW) processes. These two different processes have a problem in common: the flexibility of the robot can not be neglected, that is to say, the errors due to the deformation of the links should be taken into account. However, in most industrial robots, the real positions and velocities of each link are not measured, so in this study, an observer is proposed to reconstruct the real angular positions and velocities of links by using the measured angular positions and the velocities of actuators. A simulation by Matlab/Simulink has been carried out with a 2 axis Robot during its machining processes: the proposed observer showed great performances in estimating the state of the robot (position and velocity). Then, in order to improve the tracking accuracy in the tool frame, the state of the external force along the forward direction (x) and its normal direction (y) are required, while they are also not measured by our robot. A disturbance observer has been added to reconstruct the processing force. A good precision during the proposed processes have been obtained using the latter. This study contributes to solve the problem from the point of view of accuracies during the machining processes.Copyright © 2012 by ASME

[1]  Costas Kravaris,et al.  Nonlinear observer design for state and disturbance estimation , 2007, Proceedings of the 2004 American Control Conference.

[2]  Sang-Hun Lee,et al.  Disturbance observer based robust control for industrial robots with flexible joints , 2007, 2007 International Conference on Control, Automation and Systems.

[3]  Bodo Heimann,et al.  Model-based Feedforward Control in Industrial Robotics , 2002, Int. J. Robotics Res..

[4]  Alessandro De Luca,et al.  An Acceleration-based State Observer for Robot Manipulators with Elastic Joints , 2007, Proceedings 2007 IEEE International Conference on Robotics and Automation.

[5]  Yi Xiong,et al.  Unknown disturbance inputs estimation based on a state functional observer design , 2003, Autom..

[6]  Zhijie Xia,et al.  Modeling and control of flexible manipulators , 1992 .

[7]  M. Spong,et al.  Robot Modeling and Control , 2005 .

[8]  Y. L. Yao,et al.  Model-Based Motion Planning for Robotic Assembly of Non-Cylindrical Parts , 1999 .

[9]  Jinna Qin,et al.  Commande robuste d'un robot d'usinage flexible : analyse de la précision , 2011 .

[10]  Claire Dumas.  Développement de méthodes robotisées pour le parachèvement de pièces métalliques et composites , 2011 .

[11]  K. Krishnamurthy,et al.  Design and Implementation of a Nonlinear Axial Force Controller for Friction Stir Welding Processes , 2007, 2007 American Control Conference.

[12]  Sarah K. Spurgeon,et al.  Sliding mode observers: a survey , 2008, Int. J. Syst. Sci..

[13]  Mrdjan Jankovic,et al.  Observer based control for elastic joint robots , 1995, IEEE Trans. Robotics Autom..

[14]  Claude Perron,et al.  Simulation of friction stir welding using industrial robots , 2010, Ind. Robot.

[15]  Wisama Khalil,et al.  Modeling, Identification and Control of Robots , 2003 .

[16]  Niranjan A. Subrahmanya,et al.  Adaptive divided difference filtering for simultaneous state and parameter estimation , 2009, Autom..

[17]  G. Oriolo,et al.  Robotics: Modelling, Planning and Control , 2008 .

[18]  Sandra Zimmer,et al.  Contribution a l'industrialisation du soudage par friction malaxage , 2009 .

[19]  Bin Yao,et al.  Observer-Based Adaptive Robust Control of Friction Stir Welding Axial Force , 2010, IEEE/ASME Transactions on Mechatronics.