Hexapod Structures in Surgical Applications: Hexapod Structures in Surgical Applications Presented by Sanjay Shirke Muhammad Umer


The Hexapod - A Brief History of Design: The Hexapod - A Brief History of Design 1800’s –Mathematician Augustine Cauchy studies rigidity of polygons 1947 – Dr. Eric Gough applies the parallel kinematic platform to a tire testing machine developed working under Dunlop. 1962 – Klaus Cappel develops vibration equipment for Franklin Institute. 1965 – Stewart platform developed for aircraft simulation. 1995 – Frauhofer Institute in Stuttgart, Germany approaches Physik Instrumente to develop the surgical robot.


The Hexapod - A Brief History of Design: The Hexapod - A Brief History of Design Fig.1. 1949-2000 (a)The original Dunlop tire testing machine invented by Eric Gough, (b) The modern tire testing machine. (a) (b)


The Hexapod - A Brief History of Design: The Hexapod - A Brief History of Design Fig.2. 1965 -1970 (a)The original Stewart Platform for aircraft simulation, (b) later incorporating the design of an octahedral hexapod. (a) (b)


The Hexapod - A Brief History of Design: The Hexapod - A Brief History of Design Fig.3. 6 DOF motion achieved through 6 strut linear actuators. The resulting rapid, submicron multi-axis translation and rotation makes the hexapod ideal for precision surgical applications.


The Hexapod - A Brief History of Design: The Hexapod - A Brief History of Design Universal Joints - offer 2 rotational DoF Linear Hydraulic Actuators - offer 2 DoF: 1 translation and 1 rotation Source: Marks’ Standard Handbook for Mechanical Engineers


Hexapods – Engineering and Kinematic Principles: Hexapods – Engineering and Kinematic Principles Mobility – The Kutzbach Criterion: n = 12 (struts) + 1(base) + 1(platform) = 14 c = 3 x 6 x 4 = 72 M = 6(14 – 1) – 72 = 6 DoF


Hexapods – Engineering and Kinematic Principles: Hexapods – Engineering and Kinematic Principles Range of Motion and Resolution Fig 4. The Physik Instrumente M-800.11


Hexapods – Engineering and Kinematic Principles: Hexapods – Engineering and Kinematic Principles Design Criteria Minimize mass and inertia for maximum speed and acceleration. Strut Operation – linear hydraulic actuators Joint Design – Universal or Ball and Socket Integrity tested with CAD, FEA, and laser vibrometery tools.


Is the Hexapod really worth it?: Is the Hexapod really worth it? advantages Complete range of motion. High precision and accuracy Computer visualization tools High stiffness High load/weight ratio limitations Friction Length of struts Dynamic thermal growth Calibration


Development of Surgical Applications: Development of Surgical Applications Hexapod vs. Nonapod Extra legs contain redundant sensors Insures against failure of standard measuring system Reliability increase is of the essence


The future of Parallel Kinematics: The future of Parallel Kinematics Minimize Friction, hysteresis, and backlash Improve material composition to limit thermal growth Actuators – A future in the voice coil? Currently, applications are limited to endoscopy. Incorporate use of scissors, forceps, balloon catheters and coagulation probes. Endorse the use of a cockpit to create a “virtual surgery” environment Expand to the fields of orthopedics, ear/nose/throat surgery, and ophthalmology.


Bibliography and References: Bibliography and References Avallone, E.A., Baumeister III, T., Marks’ Standard Handbook for Mechanical Engineers 10th Edition, McGraw-Hill, New York, 1996 Hale, Layon C., “Principles and Techniques for Designing Precsion Machines”, UCRL-LR-133066, Lawrence Livermore National Laboratory, 1999. Smith, S.T., Chetwynd, D.G., Foundations of Ultraprecision Mechanism Design, Gordon and Breach Science Publishers, Switzerland, 1992. “Low-Inertia Parallel-Kinematics Systems for Submicron Alignment and Handling” (http://www.parallemic.org/Reviews/Review012.html) “Why Hexapods and Parallel Kinematics?” (http://www.hexapods.net/hexapod.htm)


Bibliography and References: Bibliography and References “Six DOF Hexapod: Challenge of Design and Innovation” (http://biotsavart.tripod.com/hexapod.htm) “Surgeon Navigates … from Operating Cockpit” (http://www.hoise.com/vmw/articles/LV-VM-05-98-17.html) “History of the Universal Joint” (http://www.driveshafts.com/u-joint.html) “M-850 Hexapod 6-Axis Parallel Kinematics Robot” (http://www.physikinstrumente.com/micropositioningsystems/8_4.html)