Clad height control in laser solid freeform fabrication using a feedforward PID controller

  • Alireza Fathi
  • Amir Khajepour
  • Ehsan ToyserkaniEmail author
  • Mohammad Durali


In this paper, a feedforward proportional-integral-derivative (PID) controller is developed to effectively control the clad height in laser solid freeform fabrication (LSFF). The scanning velocity is selected as the input control variable and the clad height is chosen as the output. A novel knowledge-based Hammerstein model, including a linear dynamic and a nonlinear memoryless block, is developed, and its parameters are identified offline using experimental data. The architecture of the controller consists of a PID and a feedforward module, which is the inverse of the identified model. The advantage of adding a feedforward path to the PID controller is evaluated experimentally, in which the results show a lower overshoot and faster response times. Also, the performance of the controller is verified in the presence of geometrical disturbances, as well as in the fabrication of a nonplanar part.


Laser solid freeform fabrication Feedforward control Feedback control Clad height control Rapid prototyping 


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Copyright information

© Springer-Verlag London Limited 2006

Authors and Affiliations

  • Alireza Fathi
    • 1
  • Amir Khajepour
    • 1
  • Ehsan Toyserkani
    • 1
    Email author
  • Mohammad Durali
    • 2
  1. 1.Department of Mechanical and Mechatronics EngineeringUniversity of WaterlooWaterlooCanada
  2. 2.Department of Mechanical EngineeringSharif University of TechnologyTehranIran

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