First steps towards an intelligent laser welding architecture using deep neural networks and reinforcement learning

Abstract To address control difficulties in laser welding, we propose the idea of a self-learning and self-improving laser welding system that combines three modern machine learning techniques. We first show the ability of a deep neural network to extract meaningful, low-dimensional features from high-dimensional laser-welding camera data. These features are then used by a temporal-difference learning algorithm to predict and anticipate important aspects of the system's sensor data. The third part of our proposed architecture suggests using these features and predictions to learn to deliver situation-appropriate welding power; preliminary control results are demonstrated using a laser-welding simulator. The intelligent laser-welding architecture introduced in this work has the capacity to improve its performance without further human assistance and therefore addresses key requirements of modern industry. To our knowledge, it is the first demonstrated combination of deep learning and Nexting with general value functions and also the first usage of deep learning for laser welding specifically and production engineering in general. This work also provides a unique example of how predictions can be explicitly learned using reinforcement learning to support laser welding. We believe that it would be straightforward to adapt our approach to other production engineering applications.

[1]  Farbod Fahimi,et al.  Online human training of a myoelectric prosthesis controller via actor-critic reinforcement learning , 2011, 2011 IEEE International Conference on Rehabilitation Robotics.

[2]  Philip S. Thomas,et al.  Application of the Actor-Critic Architecture to Functional Electrical Stimulation Control of a Human Arm , 2009, IAAI.

[3]  P. M. Lugarà,et al.  Optical Sensor for real-time Monitoring of CO(2) Laser Welding Process. , 2001, Applied optics.

[4]  M. Vicanek,et al.  Dynamic behaviour of the keyhole in laser welding , 1993 .

[5]  Gilmore Jh,et al.  The four faces of mass customization. , 1997 .

[6]  Martin A. Riedmiller,et al.  Autonomous reinforcement learning on raw visual input data in a real world application , 2012, The 2012 International Joint Conference on Neural Networks (IJCNN).

[7]  Joerg Beersiek,et al.  A CMOS camera as a tool for process analysis not only for laser beam welding , 2001 .

[8]  Patrick M. Pilarski,et al.  Model-Free reinforcement learning with continuous action in practice , 2012, 2012 American Control Conference (ACC).

[9]  Patrick M. Pilarski,et al.  Acquiring a broad range of empirical knowledge in real time by temporal-difference learning , 2012, 2012 IEEE International Conference on Systems, Man, and Cybernetics (SMC).

[10]  Cesare Alippi,et al.  A methodological approach to multisensor classification for innovative laser material processing units , 2001, IMTC 2001. Proceedings of the 18th IEEE Instrumentation and Measurement Technology Conference. Rediscovering Measurement in the Age of Informatics (Cat. No.01CH 37188).

[11]  Shigenobu Kobayashi,et al.  Reinforcement learning of walking behavior for a four-legged robot , 2001, Proceedings of the 40th IEEE Conference on Decision and Control (Cat. No.01CH37228).

[12]  Richard S. Sutton,et al.  Reinforcement Learning: An Introduction , 1998, IEEE Trans. Neural Networks.

[13]  Patrick M. Pilarski,et al.  Horde: a scalable real-time architecture for learning knowledge from unsupervised sensorimotor interaction , 2011, AAMAS.

[14]  Stefan Schaal,et al.  2008 Special Issue: Reinforcement learning of motor skills with policy gradients , 2008 .

[15]  Xing Yanqiu,et al.  The research of welding parameters on weld shape in the laser deep penetration welding , 2010, 2010 International Conference on Mechanic Automation and Control Engineering.

[16]  Patrick M. Pilarski,et al.  Real-time prediction learning for the simultaneous actuation of multiple prosthetic joints , 2013, 2013 IEEE 13th International Conference on Rehabilitation Robotics (ICORR).

[17]  Paul H. Zipkin,et al.  The Limits of Mass Customization , 2001 .

[18]  Alex Graves,et al.  Playing Atari with Deep Reinforcement Learning , 2013, ArXiv.

[19]  Yoshua Bengio,et al.  Practical Recommendations for Gradient-Based Training of Deep Architectures , 2012, Neural Networks: Tricks of the Trade.

[20]  Klaus Diepold,et al.  A cognitive system for autonomous robotic welding , 2009, 2009 IEEE/RSJ International Conference on Intelligent Robots and Systems.

[21]  Fred A. Hamprecht,et al.  Sputter Tracking for the Automatic Monitoring of Industrial Laser-Welding Processes , 2008, IEEE Transactions on Industrial Electronics.

[22]  A. Clark Whatever next? Predictive brains, situated agents, and the future of cognitive science. , 2013, The Behavioral and brain sciences.

[23]  Simon Haykin,et al.  Cognitive Control , 2012, Proceedings of the IEEE.

[24]  Geoffrey E. Hinton,et al.  Reducing the Dimensionality of Data with Neural Networks , 2006, Science.

[25]  Yong Yan,et al.  Review of techniques for on-line monitoring and inspection of laser welding , 2005 .

[26]  Geok See Ng,et al.  Neural network model for time series prediction by reinforcement learning , 2005, Proceedings. 2005 IEEE International Joint Conference on Neural Networks, 2005..

[27]  Richard S. Sutton,et al.  Multi-timescale nexting in a reinforcement learning robot , 2011, Adapt. Behav..

[28]  Pascal Vincent,et al.  Stacked Denoising Autoencoders: Learning Useful Representations in a Deep Network with a Local Denoising Criterion , 2010, J. Mach. Learn. Res..