WM Keck Science
A center manifold reduction and numerical calculations are used to demonstrate the presence of limit cycles, two-tori, and multistability in the damped harmonic oscillator with delayed negative feedback. This model is the prototype of a mechanical system operating with delayed feedback. Complex dynamics are thus seen to arise in very plausible and commonly occurring mechanical and neuromechanical feedback systems.
Campbell, Sue Ann, Jacques Belair, Toru Ohira, and John Milton. "Complex Dynamics and Multistability in a Damped Harmonic Oscillator with Delayed Negative Feedback." Chaos 5.4 (1995): 640-645. DOI: 10.1063/1.166134