Advanced Servo Algorithm Adapts to Different Loads on Positioning Stage in Real Time:

 ServoBoost™ is a real-time automatic adaption to load changes for ACS motion controllers: The video shows how an ACS motion controller with ServoBoost™ automatically maintains the performance and stability of a high-precision motion stage despite a significant load changes.

More Information on Precision Automation and Motion Control

Piezo Motors and Interferometers: Nanometer Precision

The video shows how a piezo linear motor can be controlled using feedback from a laser interferometer. Resolution to 0.15 nanometers is feasible.

Learn More on Piezo Linear Motor Control with Interferometer Feedback

Positioning Technology Gets Smart - Active Alignment

Intelligent precision motion and positioning systems can perform active alignment tasks important in optics, and photonics applications such as fiber-to-chip alignment, SiP wafer level alignment, lens optimization etc. Autonomous and simultaneous optimization, will affect a range of global industrial sectors.
Even the smallest camera lenses today consist of multiple elements that need to be aligned for optimized resolution and performance

Silicon photonics wafer prober integrates a fast active photonics alignment system based on hexapods and parallel-kinematic piezo scanners for high-throughput optical probing of on-wafer silicon photonic devices. Courtesy of Cascade Microtech, division of FormFactor Inc.

Advances in Compact Precision Motorized Linear Stages

Advances in drive and encoder technology have made it possible to design compact positioning equipment, such as used in scientific and industrial applications that can combine high precision, with load capacity and affordability.

The L-505 linear translation stage family is available with integrated linear encoders down to 5 nanometers resolution. Applications include photonics, optics assembly and high resolution microscopy.

Technical specifications on the miniature precision linear stage

A Forceful Answer to the Latest Challenge in Precision Industrial Motion Control

A host of applications can benefit from high-throughput, high-precision position control combined with accurate force control and metrology.  These include:
  • Delicate, fast automated assembly procedures where position vs. force is important;
  • Materials testing of compliance, damping or other physical characteristics;
  • Production testing of touch- and force-sensitive and haptic components;
  • Precision pick-and-place of sensitive componentry at high speeds.
Until now, no integrated solution has been available that addresses the needs of OEM and industrial applications of this sort-- especially their throughput and uptime requirements, but also including sensitivities to the milli-Newton level, submicron positional resolution, and smooth, automatic transitions between position- and force-control regimes.

Besides offering ultraprecision position control with up to 250mm/sec speeds, PI's innovative new V-273 PIMag™ Voice Coil Linear Actuator and compact C-413 PIMag™ Controller provide a revolutionary combination of capabilities for high-throughput generation of precision forces and positions.

High-speed interfaces including real-time DIO, and high-speed TCP/IP Ethernet and USB 2 interfaces are available.  A 100nm position encoder is integrated into the mechanism; a force sensor with 5 milli-Newton resolution is optional.  The C-413 controller allows swift position or force control and offers combined force-and-position control.  An integrated data recorder provides sub-sub-millisecond acquisition for later retrieval, or the standard DIO interface is programmable and can provide triggering of motions or external equipment based on position or increment.

C-413 is supported by PI's extensive software offering, including PI MikroMove (a comprehensive Windows GUI) and comprehensive dynamic libraries for Windows, Linux and OS X.  Alternatively, since this unit utilizes the same General Command Set that all PI controllers do, you can communicate with it via simple ASCII strings-- ideal for legacy automation controllers often found on factory floors.  Broad and deep support for LabVIEW is provided, and also offered is support for National Instruments' CompactRIO Programmable Automation Controllers.  The system is readily controlled via its standard TTL DIO interface or available 24V EMI-resistant DIO interface, suitable for the noisiest factory floors.  If desired, an integrated ground path to the tip can be configured.

We introduced this new system with a compelling demonstration at BIOS/Photonics West in San Francisco, where it ran all week generating nearly a quarter million mN-precision force/position transitions with speeds to 250mm/sec, with in informative graphical application that explained what was going on.  A brief close-up video of the force-actuator tip is presented below; it includes a 120 fps segment that vividly shows the fast, smooth, force-controlled motions of this remarkable new actuator as it gently impacts a glass substrate, each step concluding with the precisely calibrated force set-point.

V-273 is just part of a rapidly-growing family of catalog and custom solutions offering different travels and force capabilities.  Contact one of our global offices for expert consultation, responsive support, and cost-effective recommendations for your application.

Many Tacks to Attack the Stack

When faced with a multi-axis motion application, many users stack motion stages, and in fact that is
a fine approach for assemblies of just a few axes.  But as applications become more complex, so do the equivalent stacks-of-stages, and very real and practical considerations begin to come into play:

  • Stiffness.  Some stage manufacturers publish stiffness specifications in terms of axial deviation per unit force, but this is of little utility in estimating the dynamic performance of a stage ...or a stack.  A more pertinent metric is the resonant frequency, as it integrates both the effective coefficient of stiffness of a mechanism and the summed mass of its construction.  (Accordingly, knowing Fres means you can easily estimate the possible step/settle time for a well-tuned closed-loop stage: approximately [3 Fres]-1).  In our experience, most high-quality conventional linear stages will exhibit resonant frequencies on the order of 75-120Hz, unloaded.  Stack them, and the resulting structure can have significantly limited responsiveness and long settling times.
  • Inconsistent dynamics.  The bottom stage in a stack carries the mass of the entire stack, and so on up to the top stage, which carries only the application load.  So tuning is a laborious, axis-by-axis process, with different settings for each axis... and consequently different responsiveness.

  • Inflexible rotation-centerpoint placement.  Stacked stages place the center of their tip/tilt and rotation motions at the geometric centers of each rotation-stage and goniometer bearing.  These can sometimes be arranged to coincide at a desired point in space (for example, at the focal point of a lens) via custom adaptor plates and fixtures, but this takes time and effort and is inflexible should application needs change.  And significant changes can alter the dynamics of the stack, necessitating a re-tuning of each axis... again.
  • Cabling.  Cables are a fact of life in motion control, and managing them deserves more attention than it often gets.  To begin, cables can be a conduit for vibration that can impact an entire application setup in un-obvious ways.  Even one's choice of draping the cables off an isolation platform can influence an application's overall stability and performance in profound ways.  As a stage moves, any cable being dragged along can contribute to parasitic motions and other errors.  Stiff cables can do so even if arranged in a non-dragging manner.  Cables can break and snag and come loose, contributing to premature failures that can be hard to diagnose.  And generally, these problems scale with the number of axes in a user-stacked system.  (Manufactured stacks sometimes benefit from integrated cable management.)  
  • Central aperture.  Many applications--especially in optics--benefit from transmissive construction of the motion stack.  This is difficult or impossible to achieve with a stacked structure of many axes.
  • Size, weight and fragility.  Simply stated, stacks can be substantial in height and mass.  And since the bottom stages bear the burden of the entire tall stack, their bearings are vulnerable to brinelling and other damage from inadvertent forces.  Besides inviting damage from elbow-knocks when set up, this often necessitates disassembly for shipping, adding cost and hassle and introducing variability when reassembled. 
  • Orthogonality and parasitic errors.  Stacked axes interact in complicated ways; for example, runout in the X axis is seen as unwanted motion in the Y and Z axes; angular deviation of an axis similarly imparts motion in the travel-directions of the other axes, with magnitude proportional to the distance to the moving axis.  And in stacks, that multiplicative lever-arm can be large.

Solution: Attack the stack

It may seem like hyperbole, but all these issues can be avoided by utilizing principles of parallel
kinematics.  Instead of a tall stack of all the necessary axes with the workpiece perched on top, such systems support a single workpiece in parallel by a tripod or hexapod structure, forming a much stiffer yet lighter-weight structure than is possible by stacking.  The best examples of the breed utilize non- or minimally-moving internal cables with conveniently integrated cabling to the controller.  User tuning requirements can be eliminated while providing precision and accuracy that can surpass the performance of some of the best available single-axis stages.

Today's easy-to-use controls

In prior years, the main obstacle to choosing this class of mechanism was the challenge of controlling the workpiece in a user-friendly way, using familiar Cartesian coordinates (X, Y, Z, θX, θY, θZ).  This changed with the introduction of PI's first hexapod two decades ago.  That instrument utilized a fully-integrated industrial PC-based digital controller running clever firmware that transparently managed the coordinate transformation process, providing unprecedentedly flexible control in all six degrees of freedom with a programmable rotational center-point, settable by a single software command.

One Stop, Many Solutions 

These innovations set the tone for PI miCos' broad array of parallel kinematic mechanisms: innovative solutions that can actually cost less than stacks of six stages of commensurate performance.  Today's offering benefits from years of continuous advancement in mechanical design and controls engineering.  Our newest controller integrates an ultra-modern, industrial-class real-time operating system and provides such features and options as TTL motion triggers, analog position-waveform definition, standard internal data recorder with optional analog input, and a high-speed network interface for integration into factory automation systems and remote access.  Its sophisticated software support includes comprehensive LabVIEW libraries, MATLAB support, a convenient GUI for setup and test, and well-documented dynamic libraries for Windows, Linux and OS X.

Two families of parallel kinematics

Today, PI miCos offers two basic architectures for six-DOF mechanisms: six-legged hexapods, and three-legged SpaceFabs:


The hexapods utilize a variety of motion technologies for the actuator legs, ranging from brushed or brushless DC servo-motors to high-force PiezoWalk™non-magnetic actuators.  Both fixed- and extendable-strut designs are utilized depending on application needs.

SpaceFabs (Planar Pods)

These innovative tripod mechanisms utilize three fixed-length legs and three XY actuation modules which provide extended transverse travels for the assembly.  Motion technologies can include piezomotors, rotary and linear DC servomotors, and stepper motors.

Many roles for stacks

Let's be clear: we like stage stacks.  We sell lots of stage stacks.  Stage stacks are entirely appropriate for applications of all kinds.  But that's the benefit of having a deep toolbox and a global team with broad and deep experience across a multitude of disciplines: we draw on that experience in consultation with our customers, choosing (or custom-developing) optimal solutions and cross-pollinating from related applications in other fields.

Bring us your "impossible" requests!

Maybe they are impossible... or maybe they just require a fresh approach, or a trick from another application field.  Mission-critical PI miCos technology is at the heart of much of today's highest tech, from semiconductor manufacturing, to photonics packaging and test, to genomics, to single-molecule biophysics, to ultra-resolution microscopy.  Put our experience to work on your problems!