A graphical tuning method for fractional order controllers based on iso-slope phase curves Articles uri icon

publication date

  • October 2020

start page

  • 296

end page

  • 307


  • 105

International Standard Serial Number (ISSN)

  • 0019-0578

Electronic International Standard Serial Number (EISSN)

  • 1879-2022


  • Fractional order controllers are widely used in the robust control field. As a generalization of the ubiquitous PID controllers, fractional order controllers are able to reach design specifications their integer counterparts cannot, and as a result they outperform them at particular situations. Their main drawback is that generalization of the design tools is not always evident, and therefore tuning this kind of controller is always a new and different challenge. Existing methods often use numerical computation to find the controller parameters that fit the specifications. This paper describes a graphical solution for fractional order controllers, which avoids the solution by nonlinear equations and helps designer to solve the control problem in a very intuitive way. This approach is tested in the servomotors of a real bio-inspired soft neck and results are compared with those obtained from other control strategies. The experiments show that the controller tuned by this method works as expected from a robust controller and that this approach is very competitive compared to other state of the art methods, while offering a more simplified and direct tuning process.


  • Robotics and Industrial Informatics


  • fractional order controller; tuning methods; robust control; soft robotics