6-DOF positioner

6-DOF positioner

June 29, 2020

Alio Industries

https://www.alioindustries.com
Motion Control

The 60° tip/tilt travel of the Angulares Hybrid Hexapod is the most angular travel range available from any 6-Degree-Of-Freedom (6-DOF) positioner on the market and offers the same unmatched positioning performance found in any of ALIO’s full line of Hybrid Hexapod systems.

The Angulares features precision crossed roller bearing guides, optical incremental or absolute encoder feedback on all axes, linear motor and/or servo ball screw drives, unlimited programmable tool center point locations and coordinate offsets, and zero backlash on all axes. The design makes the Angulares capable of unlimited XY travel, Z travel for 62mm which can be increased to 208mm using other tripod models, tip/tilt travel of 60 degrees (+/- 30 degrees) with continuous 360 degree Theta-Z, XYZ bidirectional repeatability of less than +/- 0.6 arc-seconds, velocity up to 100mm/sec XY and Z, and less than 10 nanometers linear and 0.1 arc-seconds angular minimum incremental motion.

The Hybrid Hexapod was developed by ALIO Industries to address the inherent performance limitations of conventional hexapods. ALIO’s Patented 6-DOF design seamlessly blends and takes advantage of the strengths of serial and parallel kinematic structures while avoiding their weaknesses. The Hybrid Hexapod offers far greater functional versatility, nanometer-level accuracy, repeatability, and superior 6-DOF trajectories than is possible with any traditional hexapod or stacked stage configuration.

Standard hexapods satisfactorily service applications where micron motion tolerances are required, but as the demand for nanometer requirements expands, standard hexapods struggle. This is because there are performance limitations inherent in all conventional hexapod designs. They operate within 3-dimensional space and have errors in all 6 DOF. However, hexapod motion systems have typically only been characterized by performance data of a single DOF. This practice leaves error sources unaccounted for in several degrees of freedom, especially in the areas of flatness and straightness, which are critical precision needs at the nanometer-level. The hexapod’s best flatness and straightness of travel is still no more precise than more than 2 orders of magnitude (2 decimal point less) for basic XY motion.

Because hexapods have six independently controlled links joined together moving a common platform, the motion error of the platform will be a function of the errors of ALL links and joints. Hexapods are known to have optimum precision when performing Z-axis moves, because all links perform the same motion at the same relative link angle. However, when any other X, Y, pitch, yaw or roll motion is commanded, precision and geometric path performance of the hexapod degrades substantially because all links are performing different motions. In the case of conventional hexapods built with non-precision joints, bearings, and motion controllers that are not capable of forward and inverse kinematics equations, the source of error is even more pronounced.

The unique design of the Hybrid Hexapod is comprised of a parallel kinematic tripod to deliver Z plane and tip/tilt motion. This tripod is integrated with a monolithic serial kinematic stage for XY planar motion. A rotary stage integrated into the top of the tripod (or beneath depending on application needs) provides 360- degree continuous (Theta-Z) rotation.

In this hybrid design, individual axes can be customized to provide XY travel ranges from millimeters to virtually unlimited ranges while maintaining nanometer-levels of precision. Novel forward and inverse controller kinematics provide an unlimited number of programmable tool center point locations plus unmatched path precision and performance.

The 60 degree tip/tilt travel of the Angulares Hybrid Hexapod, by far the most angular travel range available from any 6-DOF positioner on the market, is perfectly suited for applications including aspheric and freeform optical metrology, silicon photonics packaging and probing, laser micro processing (non-planar substrates and taper control), wafer metrology, camera module alignment and assembly, sensor/image stabilization testing, and optical element and fiber alignment. 

To find out more about ALIO’s Angulares or its full range of Hybrid Hexapod systems, contact a member of the team today.