Amplitude control of limit cycles in Langford system

In this paper, we investigate the control of amplitude of limit cycle emerging from the Hopf bifurcation in Langford system under a nonlinear feedback controller. Explicit nonlinear control formulae and amplitude approximations in terms of control gains are derived from the center manifold theory and normal form reduction. The formulae and expressions for the Langford system present a convenient approach to obtain an effective analytical control and predict the amplitude of limit cycles in this system.