Effects of Target Signal Shape and System Dynamics on Feedforward in Manual Control

• Published in: IEEE transactions on cybernetics Vol. 49; no. 3; pp. 768 - 780
• Main Authors: Drop, Frank M., Pool, Daan M., van Paassen, Marinus M., Mulder, Max, Bulthoff, Heinrich H.
• Format: Journal Article
• Language: English
• Published: United States IEEE 01-03-2019; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Computer simulation; Control systems; Control theory; Data models; Feedback control; Feedforward; Feedforward control; Feedforward systems; human control models; Manual control; predictable target signal; Segments; Shape; Shape effects; Silicon; System dynamics; System identification; Time lag; Vehicle dynamics
• ISSN: 2168-2267; 2168-2275
• DOI: 10.1109/TCYB.2017.2783952

The human controller (HC) in manual control of a dynamical system often follows a visible and predictable reference path (target). The HC can adopt a control strategy combining closed-loop feedback and an open-loop feedforward response. The effects of the target signal waveform shape and the system dynamics on the human feedforward dynamics are still largely unknown, even for common, stable, vehicle-like dynamics. This paper studies the feedforward dynamics through computer model simulations and compares these to system identification results from human-in-the-loop experimental data. Two target waveform shapes are considered, constant velocity ramp segments and constant acceleration parabola segments. Furthermore, three representative vehicle-like system dynamics are considered: 1) a single integrator (SI); 2) a second-order system; and 3) a double integrator. The analyses show that the HC utilizes a combined feedforward/feedback control strategy for all dynamics with the parabola target, and for the SI and second-order system with the ramp target. The feedforward model parameters are, however, very different between the two target waveform shapes, illustrating the adaptability of the HC to task variables. Moreover, strong evidence of anticipatory control behavior in the HC is found for the parabola target signal. The HC anticipates the future course of the parabola target signal given extensive practice, reflected by negative feedforward time delay estimates.