Control Bandwidth
The highest oscillation frequency at which the system can follow a command without serious attenuation. It is given in hertz; on mobile proportional valves it is typically on the order of a few hertz to ten hertz, and commands above that are almost never reflected at the actuator.
Bandwidth is the frequency-domain equivalent of how agile a system is. In measurement, the command is oscillated at a progressively increasing frequency; the frequency at which output amplitude falls to a certain ratio is recorded as the bandwidth.
- Spool inertia and solenoid inductance in the valve set the upper limit.
- Fluid compressibility and hose expansion create an additional soft-spring effect on the cylinder side.
- As load mass increases the system's natural frequency drops; the same valve appears far slower on a heavy boom.
The practical consequence is this: tuning the controller faster than the hydraulics can carry brings no benefit, only oscillation. On a wireless remote controlled lever the operator's hand cannot produce meaningful commands above a few hertz anyway; therefore latency on the order of milliseconds is sufficient. Instead of trying to make the system faster, reducing deadband and hysteresis usually makes more of a difference.
Where this term is used: What Is a Hydraulic Lever Retrofit Kit? Definition, Components, Operating Principle