Fig. 8 shows an exemplary section of a measurement using
the regular skyhook control law. As before, F∗ denotes the
reference damper force obtained from the suspension controller,
Fd,meas represents the actual damper force determined
from the load cell measurement mentioned in Section II and
Fd, fb indicates the feedback signal for the controller. In the
upper plot the signal-based feedback is illustrated, which
employs the measured chassis acceleration to determine the
actual damper force by using (2). The lower plot depicts the
results of the model-based feedback using the output signal
of the damper model from the parallel simulation. As can be
seen, the damper model matches the dynamic characteristics
of the damper better than the damper force based on the
acceleration signal. Due to high-frequency vibrations, measurement
noise in the signal and inaccuracy in the chassis
mass estimation, some errors between the measured and the
estimated damper force occur. Since the performance of the
two feedback controllers depends highly on the quality of
the feedback signal, this imprecision reduces the benefit of
the signal-based feedback controller alternative (FB-PIs).