| Notes on Specifications for PiezoWalk® Drives |
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| Motion and Positioning |
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Travel Range
The maximum allowed travel is limited by the length of the output shaft in a PiezoWalk® drive. If present, the distance between two limit switches defines the travel range.
Step size (in step mode)
In step mode, the step size can be defined within the given range. Bigger steps allow higher velocity while smaller steps are for fine adjustment tasks.
Analog mode travel range
The analog mode travel range describes approximately half of the maximum stepsize. The analog travel mode allows for sub-nanometer motion resolution.
Open-loop resolution
Resolution of PiezoWalk® drives is basically infinitesimal because it is not limited by stiction and friction. Instead of reso lution, the noise equivalent motion in analog mode is specified. Values are typical results (RMS, 1 sigma).
Closed-loop resolution
Requires position feedback. Resolution of PiezoWalk® drives is basically infinitesimal because it is not limited by stiction and friction. Instead of reso lution, the noise equivalent motion in closed-loop analog mode is specified. Values are typical results (RMS, 1 sigma). For linear encoders, the closedloop resolution describes the resolution of the of the position feedback sensor system.
Step frequency
Maximum operating frequency of the drive in step mode. The step frequency depends on the controller. It is recommended to operate PiezoWalk® drives with PI controllers only.
Max. velocity
The maximum velocity depends on the used controller. The main parameters which influence the velocity are the step frequency and the step size.
Mechanical properties
Stiffness in motion direction
The stiffness in motion direction has a typical tolerance of ±20%
Push/pull force (active)
Active force limit in operating direction. The maximum force depends on the velocity.
Holding force (passive)
A main feature of piezomotor linear drives is the self-locking capability at rest without current consumption and heat generation.
Drive properties
Operating voltage
Max. voltage range for the analog mode travel range. The voltage is supplied by the PI drive electronics.
Miscellaneous
Operating temperature range
Safe operation, no damage to the drive. All technical data specified in the data sheet refer to room temperature (22 °C ±3 °C)
Mass
Typical tolerance: ±5%
Cable length
Typical tolerance: ±10 mm
Recommended controller / driver
To reach the specifications and to avoid damage, it is strongly recommended to use PI drive and control electronics only. The drive electronics supplies the operating voltage and supports the motion modes of a PiezoWalk® drive.
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