Experimental determination of frequency response function estimates for flexible joint industrial manipulators with serial kinematics

Two different approaches for the determination of frequency response functions (FRFs) are used for the non-parametric closed loop identification of a flexible joint industrial manipulator with serial kinematics. The two applied experiment designs are based on low power multisine and high power chirp excitations. The main challenge is to eliminate disturbances of the FRF estimates caused by the numerous nonlinearities of the robot. For the experiment design based on chirp excitations, a simple iterative procedure is proposed which allows exploiting the good crest factor of chirp signals in a closed loop setup. An interesting synergy of the two approaches, beyond validation purposes, is pointed out. •Determination of frequency response functions of industrial manipulators via two distinct experimental methods.•Practical considerations for the experimental designs which allow avoiding the disturbing impact of the common nonlinearities.•Dedicated signal design and signal processing.•Experimental results obtained in a hardware testbed with an industrial manipulator.•Comparison and discussion of the two approaches based on the experimental results.