The state feedback controller can stabilise the nonlinear system at the equilibrium point x = (0, 0, 0, 0) if the initial angular position is less than 0.5. The state feedback controller can stabilise the linearised system at the equilibrium point x = (0, 0, 0, 0) for any initial value of the angular position.

The state feedback controller can stabilise the nonlinear system at the equilibrium point x = (0, 0, 0, 0) if the initial angular position is less than 0.5. The state feedback controller can stabilise the linearised system at the equilibrium point x = (0, 0, 0, 0) only if the initial value of the angular position is less than 0.1.

The state feedback controller can stabilise the nonlinear system at the equilibrium point x = (0, 0, 0, 0) if the initial angular position is less than 1. The state feedback controller can stabilise the linearised system at the equilibrium point x = (0, 0, 0, 0) only if the initial value of the angular position is less than 0.5.