|
Microscope x‐y stages need fast, smooth, and accurate motion for highest performance. In addition, we want to use
the most cost effective hardware that can get the job done. What control techniques are available to achieve these
goals?
| Feature/Function |
Units |
 |
| Number of Axis: |
2 independent servo motors |
| Motion mode: |
Multi‐axis point‐to point |
| Control architecture: |
Chip or card‐based |
The diagram on page two shows an all‐in‐one motion card design utilizing a Magellan® motion control IC. This card
connects to two motors and four encoders: one rotary encoder on each motor, and one linear encoder on each axis.
| Components |
Specification |
Description |
| Motors |
Brushless DC motor w/ encoder
feedback |
Rotary encoder resolution needs to be high enough to allow for
accurate velocity control. This depends on the ratio between rotary and linear position. 1,024 counts/rotation or less is typical.
|
| Controller: |
Custom designed card using
Magellan® MC58420 IC and two ICbased
Brushless DC motor amplifiers |
- Supports dual‐loop control
- Supports S‐curve velocity profile for smooth motion.
- Easy to tune using Pro‐Motion® Axis Wizard setup software
|
| X‐Y Stage |
Lead screw‐based linear stage with
linear encoders on each axis. |
Linear encoders translate directly to the final positioning accuracy
and should be at least twice the desired resolution required for the application.
|
To maximize positioning accuracy, a
dual encoder configuration (dualloop
control) is used. This owerful
technique allows one encoder (on
the motor) to be used to stabilize the
motion, while the second (on the
stage) is used for positioning
accuracy, with all of the control
details handled by the Magellan chip.
Dual‐loop corrects automatically for
mechanical errors from backlash, lead screw or table assembly non‐linearities. 
Adding S‐curve motion profiles can substantially reduce vibration over trapezoidal profiles. Often, only a small
amount of "S" (transition between acceleration and no acceleration) can substantially reduce induced vibration. The
form of the s‐curve will depend on the desired performance required. For X‐Y stages that involve liquid transfers or
fragile material that should not be jostled, it would be appropriate to choose an s‐curve profile that spreads the
acceleration transitions out as far as possible, thereby maximizing smoothness of motion. Other loads can use a
shorter "S" period. Magellan can also provide trapezoidal, velocity contouring, and electronic gearing motion profiles
as alternatives to s‐curve profiles.
The figure above illustrates the motion control card and connections needed to implement a precision X‐Y stage
controller. This system could also have been constructed using other PMD products such as a Prodigy® motion card.
Contact your PMD representative for more information.
 The Magellan® Family of Motion Control ICs provides high performance chipbased
motion control for multiple motor types. Magellan motion control ICs are
available in 1, 2, 3, and 4‐axis versions. They are designed for demanding and
precise applications such as this microscope X‐Y stage application and other
scientific instrumentation challenges.
X‐Y stage motion control card diagram
Contact our customer support team at +1 781 674 9860 for more information including details on
Developer’s Kits and application support. We would like to assist you in improving your motion system. |
