Hydraulic Power Cylinder

The VariStroke Remote Servo can be connected to any hydraulic cylinder,

however; proper operation requires that the VariStroke Stability Equation be

satisfied (see Chapter 2. Stability Specifications). In order to control cylinder

position, the Cylinder must be equipped with a position feedback sensor. The

position sensor must meet the following specifications:

 Output Signal: 4–20 mA

 Input voltage (provided by the VariStroke Circuit Board): 15 Vdc

 Update Rate: ≤1 ms

 Linearity: ±0.04% Full Stroke

 Current Drain: < 100 mA

 Sensor Length must not exceed 2 times the Cylinder Stroke Length

Cylinder Position Control

The cylinder position controller adjusts the hydraulic power cylinder position to

match the feedback signal to the demand.

Both the servo position controller and cylinder position controller are monitored to

ensure accurate tracking.

The position controller regulates a pulse width modulated (PWM) drive signal to

the actuator. The drive current to the actuator is regulated, transiently allowing up

to 10 A to be provided to move the actuator at its maximum speed and torque. A

steady-state current limit becomes active after a period of a few seconds to

protect the actuator and electronics.