which is inserted in the feedback loop. (For simplicity, a loadtorque feedforward involving positive feedback is assumed not to be used.) The next step is to find out how large L can get before performance deteriorates. For this purpose, we study the modified open-loop system, which is given by cf. Section III-D. It is reasonable to assume that L is small enough so that |GL(jωc)| ≈ 1 at the crossover frequency ωc, the latter which thus still is given by (21). The incurred phase lag argGL(jωc) is taken into account, though. Inspecting (21), it is seen that ωc decreases monotonically with ζ. Hence, the highest ωc, and consequently also the largest phase lag, is obtained for the smallest recommended relative damping, i.e., ζ = _ 3/8. For this value, we get ωc = 2αs/ √ 3 and