where τ c denotes the identified coulomb friction torque. The cutoff
frequency of F is determined as 200 [rad/s] in consideration
of the fact that the first and the second order vibration modes
exists around 25 [rad/s] and 300 [rad/s], respectively.
2) Adaptive GainK: From Fig. 3, the transfer function from
τ ref to τ reac are written as