Glossary
open and closed loop postitioning
Open Loop Positioning Closed Loop Positioning
In this mode, the positioner is simply driven forward or backward,
without an encoder to read back the actual position or a feedback loop
to control the desired target position. Many applications don‘t require
either of the latter or provide inherent external means of controlling
the position. Still, at least a rough estimate of the actual position
can be deduced by counting the number of steps (if the step size can
be determined from an external measurement). The step size itself
is relatively uniform under fixed conditions (temperature, humidity,
pressure, load, etc) and typically within 5% over the full range but
depends strongly on the applied force along the axis. The forward/
backward asymmetry is also typically 5% (no external force assumed). Positioners with an integrated /NUM(+) or external /FPS encoder can be
used for closed loop position control.
All of the Industrial Line positioners are optionally available with
built-in encoders for closed loop control. The encoder allows to read
back the actual position, while a feedback loop integrated into the
corresponding electronics is used to minimize the difference between
target position and actual position. Setpoints can either be defined in a
software interface (ANC350, ECC100) or on the front panel of the closed
loop electronics (ANC350). Settling time depends on the resonance
frequency of the setup, speed of the feedback loop and measurement
bandwidth.
Recommended Controller
ECC100 (open & closed loop)
• three axes
• USB and (optionally) Ethernet
• controllable via: LabVIEW | DLL | Windows software