Aerotech’s ALAR series direct-drive rotary stages provide
superior angular positioning and velocity control with exceptionally
large apertures. With the combination of a large aperture and
direct-drive motor, the ALAR series makes worm-drive large aperture
stages a thing of the past.
Advantage ALAR
Now customers can get large aperture rotary stages with zero backlash,
and no gear wear or gear vibration as is commonly seen in worm-drive
stages. The other added benefit is that direct drive is significantly
faster than worm drive, so testing can be completed in less time.
In production settings, this equates to faster testing, lower
cost manufacturing, and higher profits. From the standpoint of
system accuracy and repeatability, the stage will maintain its
performance over time with no need for maintenance because there
are no gears to wear out. With higher accuracy and no backlash,
customers can produce more accurate products because their test
system is now more accurate.
Applications
Applications for the ALAR include single and multiaxis electro-optic
sensor testing, missile seeker testing, antenna testing, inertial
navigation device testing, photonic component alignment, high-accuracy
laser machining, and precision wafer inspection. These include
testing in vacuum to 10-6 torr. These rotary stages
can also be configured as multiaxis gimbals.
High Speed
Conventional worm-drive rotaries with similar apertures and payload
capacity only operate to 15 rpm or less. These direct-drive stages
have been tested to 85 rpm continuous rotation – over 5
times faster than worm drives.
Superior Mechanical Design
Angular contact bearings are used to maximize performance with
respect to wobble, moment stiffness, and rotating friction. A
precision-machined shaft further minimizes wobble. The design
incorporates integral connections that minimize cable issues.
The ALAR works especially well in applications that require 360°
continuous motion, but have limited space. The stage is 65-160
mm tall and provides smooth motion without travel restrictions.
Brushless Direct-Drive
To maximize positioning performance, the ALAR series utilizes
Aerotech’s brushless, slotless motors. This motor has all
of the advantages of a brushless direct-drive motor – no
brushes to wear, no gear trains to maintain, and high acceleration
and high speeds. Since it is a slotless, ironless design, there
is zero cogging, meaning there is absolutely no torque ripple.
This makes the ALAR ideal for applications requiring outstanding
contoured motion, smooth scan velocity, or precise incremental
steps.
High Payload Capacity and Large Moment Load Stiffness
The ALAR comes in two different configurations. The standard profile
(SP) unit has high payload capacity and high moment load stiffness
so it can handle applications where its rotation axis is parallel
or perpendicular to gravity and the payload center of gravity
is cantilevered away from the stage. The low profile (LP) unit
has high payload capacity and is good for applications where the
axis of rotation is parallel to gravity. Both the SP and LP units
have the same aperture options and motor options. Either SP or
LP stages can handle between 300-1000 lb of axial load.
Accurate Positioning
Performance is assured with encoder line counts from 31000 to
74000 per rev, resulting in resolutions from 0.02 arc sec/count
to 0.009 arc sec/count. The motor and high-performance rotary
encoder are directly coupled to a common shaft. The absence of
gear trains and mechanical couplings means no position errors
caused by hysteresis, windup, or backlash. As a result, accuracy
of ±3.9 arc sec and bi-directional repeatability of ±0.5
arc sec is attainable.
Flexible Configurations
Aerotech manufactures a wide range of servo amplifiers and advanced
controllers to provide a complete, integrated package.
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