As the control force [f.sub.u](t) is determined by the sliding surface S(t), let S(t) replace [f.sub.u](t) in (10), to analyse the influence of the sliding surface parameters on the mechanical impedance
of pantograph head in the stage of the controller design.
where [Y.sub.U](s) is dynamic mobility, [V.sub.U](s) is admittance, s is variable determined as the Laplace operator, described by the formula s = i[omega], [Z.sub.U](s) is mechanical impedance
, and [U.sub.U](s) is dynamic stiffness.
for dynamic mechanical impedance
[26-27] and Lee et al.
Equation (17) indicates that EMI (or EMA) is directly related to the mechanical impedance
of a host structure.
It could be stated that the host structure mechanical impedance
behaves in a similar way with that described for PZT mechanical impedance
through (2) yielding a strong relation with host structure structural stiffness and mechanical properties too.
Physical aspects of soil fertility -- The response of roots to mechanical impedance
In their study, the 1D model in (1) shows the coupled relationship between the electrical admittance (inverse of impedance) of the PZT element Y([omega]) to the mechanical impedance
of the structure [Z.sub.s]([omega]), proving that any changes in [Z.sub.s]([omega]) will affect the electrical impedance of the attached PZT element.
This has prevented the existence of efficient mechanical impedance
transformers or matching elements suitable for enhancing vibration isolation.
Specifically, the mechanical impedance
interacting with the user is comprised of the internal impedance of the leg (i.e., the impedance imposed by the controller), in series with the impedance of the environment.
The mechanical impedance
of a joint is a function of both passive (e.g., mechanical stiffness of ligaments, tendons, and connective tissue) and active (e.g., muscle activation, contraction mediated by stretch reflex) mechanisms.
Electrical admittance Y([omega]) of the piezoelectric transducer (PZT) is a combined function of the mechanical impedance
of the PZT actuator [Z.sub.a]([omega]) and that of the host structure Z([onega])