Why Hexapod Platform Parallel Kinematics (PKM)?

Subscribe to / Visit the Hexapod Forum
on Google Groups
Email:
Google Groups
Download the Hexapod Platform Catalog
Example: Parallel-Kinematics Micropositioning Systems
vs. Serial Kinematics (Stacked) Systems

The comparision clearly shows the advantages of the low-inertia hexapod
approach over a serial kinematics system.
Advantages of Parallel Kinematics (PKM)
Micro- and Nanopositioning Systems:
  • Lower Inertia
  • Better Dynamic Behavior
  • Smaller Package Size
  • Higher Stiffness
  • No Accumulation of Position Errors
  • Reduced Runout Errors
  • No Moving Cables: Better Repeatability
    and Reliability



Parallel Kinematics Hexapod Robot 6 Axis Micropositioning System.
  • Six struts support one common lightweight platform. 
  • No accumulation of runout errors. 
  • Virtual center of rotation, set by one software command. 
  • No moving cables, no cable tension: better repeatability & higher reliability. 

Serial-Kinematics "Stacked" 6-Axis Stage.

  • The bottom stage supports its own moving platform plus all stages above. 
  • Runout errors and tilt errors accumulate. 
  • Up to 5 moving cables cause friction and cable management problems. 
Watch M-840 Hexapod in Motion Video below.
Hexapod based on electrical linear actuators
Product Examples: PI Precision Electro-Mechanical Hexapod 6-Axis Stages

Download the Hexapod Catalog

PI piezo Hexapod (Stewart-Gough) platform positioners and electro-mechanical Hexapod positioners have many advantages over hydraulic hexapods. They are smaller, offer much higher precision and most are self locking. Available in many sizes, configurations for loads from 2 kg to more than 1000 kg.

M-850 Hexapod M-824 Vacuum-Compatible Hexapod M-840 HexaLight Hexapod
M-850 6-Axis Hexapod M-824 Compact Vacuum Compatible
6-Axis Hexapod
M-840 HexaLight 6-Axis Hexapod Platform

F-206 Micro-Hexapod Miniature M-810 Hexapod Custom High Precision Non-Magnetic Hexapod
F-206 Mini Flexure Hexapod, ideal for photonics alignment Ultra Compact Miniature Hexapod (PDF) Custom High Precision non-magnetic Piezo-Hexapod with NEXLINE® Piezo-Walk® Drives

Nonapod Secondary Hexapod for Telescope 2000lb Hexapod
Hexapod +3 Medical Robot with Highest Levels of Reliability. Read PDF on Spine Surgery application Active Secondary Hexapod with Tip/Tilt Mirror 1000kg-Class Hexapod Alignment System (1m diam.) Compared to 100kg-Class Hexapod (0.3m diam.)

Active Secondary Hexapod with Tip/tilt Mirror Custom Hexapod for Brain Surgery Custom Secondary Hexapod, Water-Resistant
Active Secondary Hexapod with Tip/tilt Mirror for Telescopes Hexapod as Surgical Robot (photo courtesy of IPA) Custom Secondary 6-Axis Hexapod for APEX Radio Telescopy in Chile

Hexapod for Wide Temperature Changes Hexapod for Inspection Systems Ultra-High Load Hexapod, 1 Ton in Any Orientation
Vacuum Hexapod Positioner System for Wide Temperature Ranges 6-Axis Precision Positioning & Alignment System for Inspection Systems Ultra-High Load Hexapod, Long Travel, Micron Precision, 1 Ton in Any Orientation



Downloads

Hexapod Brochure: Products & Applications
Click here to see M-840 Hexapod video (mpeg format)
Parallel-Kinematics Technotes
Hexapod Information (German Site)


PI's Hexapod Catalog (PDF)

More Hexapod / Tripod Links


Ultra-Precise 6D-Measuring System for Optical Surfaces
Tripod 3-Axis Piezo Z-Tip/Tilt Stage for Semiconductor Test & Metrology
Hexapod Progress Article in EMDT European Medical Device Technology Magazine
Tripod Low-Profile XY/Rotation Stage for LCD & Semiconductor Inspection
Hexapod for ALMA Millimeter Radio Telescope
PI Hexapod Chosen for: LISA Pathfinder Space Mission
PI High Precision Hexapod Stewart Platform Application in: Small-angle reciprocal space mapping of silkworm silk fibres
PI High Precision Hexapod Bio-Medical Application in: Prospective head-movement correction for high-resolution MRI using an in-bore optical tracking system
Hexapod for Mechanical and Medical Engineering: Six-Axis Positioner Has Nanoscale Resolution
Small Vacuum Compatible Hexapod
PI Hexapod Beamline Application: The High Energy Materials Science Beamline at PETRA III
PI Hexapod Stewart Platform Application in: Flight-Like Ground Demonstrations of Precision Maneuvers for Spacecraft Formations-Part I
M-800 Hexapod Stewart Platform Application in Medical Engineering: Adaptation of a hexapod-based robotic system for extended endoscope-assisted transsphenoidal skull base surgery
Hexapod Stewart Platform Application Astronomy: Fringe Tracking in the StarLight Formation Interferometer Testbed
Hexapod Stewart Platform Application in Medical Engineering: A technical review on the orthopedic compliant robotic arms
Design, fabrication, and testing of a three-dimensional, plastically-deformed, monolithic compliant HexFlex Nanomanipulator
Motion Feedback as a Navigation Aid in Robot Assisted Surgery
Hexapod Alignment System in The University of Hawaii 2.2 Meter Fast Tip/Tilt Secondary System
Hexapod Robot in Waveguide Alignment Application
University of Bremen Study uses PKM Hexapod for Photothermics / Non-Destructive Testing
Hexpod in Biomechanical Dental Application at Universität Bonn, Germany
In-Situ Surface Diffractometer Hexapod
Hexapod Robot in a Beamline
Hexapod Paralelni manipulatori
Hexapod for Satellite Antenna Alignment Control
Robot Tools
Hexapod as Surgical Robot
PI Custom Hexapod Robot for Spine Surgery
Hexapod for Active and Passive Fiber Alignment
Hexapod Alignment System for UKIRT Telescope
Hexapod Sub-Micron Precision Article from Motion System Designs Magazine Feb/2011
Hexapod in Dental Research Application (German)
Hexapod for Secondary Mirror Control in SOFIA telescope
Hexapod in Photonics Collimator Alignment Application
Hexapod as Mirror Manipulator in the SRRC Beamline
Hexapod Parallel-Kinematik in der Industriellen Prüftechnik, Univ. Bremen, Germany
PI Gewinnt ALMA Hexapod Auftrag
Hexapod Structures in Surgical Applications
Ultrapräzises 6D-Messsystem für optische Oberflächen
PI Hexapod Stewart Platform Application in Medical Engineering: Eine konfokale Messsonde zur hochpräzisen navigierten Felsenbeinchirurgie
PI Hexapod Stewart Platform Application in: Iterative learning-based laser beam tracker
Medical Application of PI Hexapod Stewart Platform: A Stewart platform for precision surgery
Medical Application of PI Hexapod Stewart Platform: Aufbau und Erprobung eines neuartigen Meßsystems für die dentale Biomechanik-Meßprinzip und Beispielmessungen des Hexapod-Meß-Systems/Design
Medical Application of PI Hexapod Stewart Platform: A robotic neuro-surgery system and its calibration by using a motion tracking system
Optical Applications of PI Hexapod for Test & Measurement: Ultrapräzises Messsystem für optische Oberflächen
Hexapod in Medial Engineering: Active Handrest For Haptic Guidance and Ergonomic Support
PI Hexapod Stewart Platform Application in: Subcellular Motion Compensation for Minimally Invasive Microscopy, In Vivo. Evidence for Oxygen Gradients in Resting Muscle


Parallel Kinematics Piezo-

Driven

Nanopositioning

Systems

Serial Kinematics vs. Parallel Kinematics in Nanopositioning Systems


Stacked Serial Kinematics Flexure Nanopositioning System
  • Simple Design, but: 
  • Slower response (lower stage carries inertial mass of upper stage);
  • Non-symmetric resonant frequencies (lower stage is slower than upper stage, requires different servo settings).
  • Orthogonality error is mounting-angle dependant.
  • Runout in Y cannot be monitored/compensated by the sensor in the X stage or vice versa. 
Nested Serial Kinematics Flexure Nanopositioning System
  • Thinner and better response than Stacked Serial Kinematics, but no other advantages
Parallel Kinematics Flexure Nanopositioning System (In-Plane Tripod)
  • Same ultra-low inertia for X and Y motion, providing higher responsiveness and axis-independent performance. 
  • Excellent, mounting independent orthogonality. 
  • Reduced runout: X sensor (PI uses non-contact two plate capacitance sensors) can monitor and correct for Y runout and vice versa (Active Trajectory Control). 
  • Additional rotation axis (Theta Z) feasible with 3 actuators / sensors and digital controller.

Active Trajectory Control
Active Trajectory Control requires parallel metrology feedback. It is available on single module parallel kinematics nanopositioning systems. It improves straightness and flatness to sub-nanometer precision. Digital controllers with
advanced coordinate transformation algorithms allow active trajectory control for up to 6 DoF.

More information on advanced control techniques for piezo nanopositioning systems



More Information on Low-Inertia Nanopositioning Systems?


Examples of Parallel Kinematics Piezostage Nanopositioning Systems


Custom 6 DOF Nanoposititioning PiezoStage P-587 Nanopositioning Stage P-733 XY Nanopositioning PiezoStage
Custom 6 DOF Single-Module
    Multi-Axis Design, Capacitive
    Feedback, Clear Aperture.
P-587 6-DOF Most Advanced
    Six-Axis Nanopositioning PiezoStage.
    Travel to 800 µm and 10 mrad.
P-733 XY Nanopositioning
   PiezoStage. Capacitive Feedback,
   Clear Aperture.

P-734 Nanopositioning PiezoStage 541 PiezoStage Scanning Stage P-714 Low-Profile XY Scanner
P-734 Ultra-High Flatness XY
    Nanopositioning PiezoStage. Capacitive
    Feedback, Clear Aperture.
P-541 Low-Profile, Z/Tip/Tilt
    Tripod Scanning PiezoStages for
    Microscopy. To 200µm
    Travel Range. Clear Aperture
P-714 Low-Profile XY PiezoStage Scanners for
    Imaging.Compact Size, Highly Cost-
    Efficient Design, Clear Aperture.



Examples of Parallel Kinematics Steering Mirrors

Parallel Kinematics Differential DriveTriple-Piezo-Drive Active Optics Platform
Parallel Kinematics
    Differential Drive
Tripod-Piezo-Drive Active Optics Platform Featuring
    3 Actuators (Tripod) and 4 Sensors

S-330 Piezo Tip/Tilt Platforms S-316 3-Axis Steering Mirror Active Tip/Tilt mirror for Subaru Telescope
S-330 Ultra-Fast Piezo
    Tip/Tilt Platforms
S-316 High-Speed, Tripod Tip/Tilt
    Steering Mirror
Active Tip/Tilt mirror for Subaru
    Telescope (Mauna Kea, Hawaii).