Experimental Validation of a Novel Auto-Tuning Method for a Fractional Order PI Controller on an UR10 Robot

Classical fractional order controller tuning techniques usually consider the frequency domain specifications (phase margin, gain crossover frequency, iso-damping) and are based on knowledge of a process model, as well as solving a system of nonlinear equations to determine the controller parameters. In this paper, a novel auto-tuning method is used to tune a fractional order PI controller. The advantages of the proposed auto-tuning method are two-fold: There is no need for a process model, neither to solve the system of nonlinear equations. The tuning is based on defining a forbidden region in the Nyquist plane using the phase margin requirement and determining the parameters of the fractional order controller such that the loop frequency response remains out of the forbidden region. Additionally, the final controller parameters are those that minimize the difference between the slope of the loop frequency response and the slope of the forbidden region border, to ensure the iso-damping property. To validate the proposed method, a case study has been used consisting of a pick and place movement of an UR10 robot. The experimental results, considering two different robot configurations, demonstrate that the designed fractional order PI controller is indeed robust.

[1]  Francesco Pappalardo,et al.  Auto-Tuning and Fractional Order Controller Implementation on Hardware in the Loop System , 2013, J. Optim. Theory Appl..

[2]  K. Åström,et al.  Revisiting the Ziegler-Nichols step response method for PID control , 2004 .

[3]  Robain De Keyser,et al.  Benchmark Challenge: a robust fractional order control autotuner for the Refrigeration Systems based on Vapor Compression , 2018 .

[4]  Robin De Keyser,et al.  An efficient algorithm for low-order direct discrete-time implementation of fractional order transfer functions. , 2018, ISA transactions.

[5]  Tore Hägglund,et al.  Automatic tuning of simple regulators with specifications on phase and amplitude margins , 1984, Autom..

[6]  Xiangdong Zhou,et al.  Model-free tuning strategy of fractional-order PI controller for speed regulation of permanent magnet synchronous motor , 2019, Trans. Inst. Meas. Control.

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

[8]  Chitralekha Mahanta,et al.  Auto-tuning of Fractional Order PID Controller for a Class of Processes and Experimental Validation Using a Coupled Tank System , 2016 .

[9]  Robin De Keyser,et al.  Calibration of UR10 Robot Controller through Simple Auto-Tuning Approach , 2018, Robotics.

[10]  Robin De Keyser,et al.  Comparative evaluation of a novel principle for PID autotuning , 2017, 2017 11th Asian Control Conference (ASCC).

[11]  Ramli Adnan,et al.  Fractional-order PI controller with relay auto-tuning method , 2013, 2013 IEEE 4th Control and System Graduate Research Colloquium.

[12]  Kevin L. Moore,et al.  Relay feedback tuning of robust PID controllers with iso-damping property , 2003, 42nd IEEE International Conference on Decision and Control (IEEE Cat. No.03CH37475).

[13]  YangQuan Chen,et al.  Tuning and auto-tuning of fractional order controllers for industry applications , 2008 .

[14]  Ramon Vilanova,et al.  PID Control in the Third Millennium , 2012 .

[15]  J. F. Gómez-Aguilar,et al.  On the trajectory tracking control for an SCARA robot manipulator in a fractional model driven by induction motors with PSO tuning , 2018 .

[16]  Yangquan Chen,et al.  Auto-tuning of FOPI and FO[PI] controllers with iso-damping property , 2009, Proceedings of the 48h IEEE Conference on Decision and Control (CDC) held jointly with 2009 28th Chinese Control Conference.

[17]  YangQuan Chen,et al.  Fractional-order Systems and Controls , 2010 .

[18]  Robin De Keyser,et al.  A novel auto-tuning method for fractional order PI/PD controllers. , 2016, ISA transactions.

[19]  C. Yeroglu,et al.  A new tuning method for PIλDμ controller , 2009, 2009 International Conference on Electrical and Electronics Engineering - ELECO 2009.