Relationship between the respective (actual) velocity V and the following velocity error Δs (= control deviation) during positioning. Kv is a measure therefore of velocity amplification in the stationary state:
The Kv factor (speed/stroke gain) is a specific variable for the closed loop position control system associated with machine tools, for example, and incorporates the loop gain. As such, it indicates the velocity with which a given position error is reduced to zero: the larger Kv is, the faster the system. Kv must not become too large, however, or the system will start to oscillate (Figure K 42). Kv is also
a measure of the stiffness and accuracy of a drive. Kv is limited by the stability of the control circuit, which can be simplified and calculated as follows (Figure K 43):
At a given level of damping D, the maximum Kv factor (speed/stroke gain) is limited by the natural angular frequency ω e.
Figure K 42: Influence of Kv on system stability
Figure K 43: Damping based on Kv