PMD101 - Microstep Driver0 pages

PiezoMotor Microstep Driver 101
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Nanometer resolution
Closed loop regulation
Open loop mode
General I/O
The PMD101 is a 1-axis driver for use with Piezo LEGS
motors from PiezoMotor. It is one of the more advanced
drivers in the product range giving the Piezo LEGS motors
resolution down in the nanometer/microradian range. Driving
the motors in closed loop is possible when reading back
position from an positional sensor. The PMD101 supports
quadrature encoders, and serial SSi sensors. Issuing a single
command will guide the motor to the exact encoder count,
taking in to account the parameter settings for ramping
behavior.
The generated signal waveform is made up of a large number
of voltage target points in time. Each small voltage change will
move the motor only by a fraction of a wfm-step, defined as a
microstep. The PMD101 driver gives a maximum resolution of
2048 microsteps per full wfm-step. One microstep with highest
resolution settings equals ~2 nanometer of linear motion, or
~0.5 microradian of angular motion.
Working with the driver
The PMD101 communicates with the host (PC) via USB.
Communication with the driver is through a protocol language
(ASCII commands). The user can run in closed loop target
mode, or in open loop mode, with full access to set resolution,
step frequency (speed) etc. Positional sensors are used to keep
track of the precise position of the Piezo LEGS motors. The
driver can read limit switches and reset at index. Ramping
parameters are set to prevent overshooting when closing in on
target in closed loop operation. The PMD101 is a full featured
driver for demanding applications.
Functional principle
The driver controls the Piezo LEGS motor by feeding
waveform signals which elongates and bends each of the piezo
drive legs. The waveforms are specially designed to make the
drive legs perform a precise walking motion. The motion of
the drive legs is transferred via friction contact to a linear rod
or to a rotary disc.
For each waveform cycle the Piezo LEGS motor will take one
full step, by definition called a waveform-step (wfm-step). The
wfm‑step length is load dependant but in the range of a few
micrometers for a linear LEGS motor. Rotary Piezo LEGS
motors have their drive legs working on the perimeter of a
drive disc. The wfm-step angle depends on the diameter of the
rotary motor but is usually less than one milliradian.
Ordering information
Driver
PMD101
1-axis microstep driver for
Piezo LEGS motors
Accessories
LEGS-LT CONNECT Twin connect board
102431-05
Motor cable 0.5 m
105431-15
Motor cable 1.5 m