Deadband Compensation
The controller jumping the current straight to the threshold at which the valve starts delivering flow as soon as the lever leaves center, and increasing it proportionally from there. This way the first ten to thirty percent of lever travel is not wasted and motion begins with the very first lever movement.
Compensation means adding a step to the curve between command and current. With the lever at zero, current is zero; as soon as the lever passes the neutral region the current jumps abruptly to the minimum threshold value, then climbs linearly to maximum over the remaining lever travel.
- The current at which the valve starts delivering flow is found experimentally and recorded as the minimum current.
- The current corresponding to full opening is recorded as the maximum.
- The controller rescales the full lever travel between these two values.
Too much of this setting is as much a problem as too little: if the threshold is raised above the real value, the machine lurches on the lever's first movement, which makes precise load placement impossible. With correct tuning every millimeter of lever travel does useful work. The joystick characteristic in AXI's HCT402 kit being millimeter-fine in the middle region and fast at the ends serves a similar aim: dedicating the usable lever travel to the region the operator actually needs.
Where this term is used: The Importance of Hydraulic Control: Why Should It Be Commanded by an Electronic Signal?