Hexapod Mathematician

Augustin Louis Cauchy
21 August 1789 - 23 May 1857

Hexapod Tire Tester

Gough Tyre Tester

Stewart Platform

D. Stewart Paper

Flight Simulator

Klaus Cappel - Flight Simulator

 The Hexapod

  A Hexapod or Stewart Platform is a parallel link manipulator using an assembly of six struts to provide motion and accuracy for positioning. It has six degrees of freedom usually listed as x, y, z, pitch, roll, & yaw. If you remember your physics lessons you know that there are only 6 degrees of freedom available. Therefore if you build a Hexapod it is not only capable of moving in any possible direction or orientation but is also in control of all of those motions.

Though Hexapods have gained in popularity since the invention of the computer (trying to do all of that math in your head proved to be a challenge) they are not a new invention. In the 1800's a French mathematician named Augustine Louis Cauchy was a pioneer in Mathematical analysis. He proved calculus theorems, studied optics, mechanics, elasticity and stress. Cauchy's work has been applied not just in mathematics but in many practical engineering applications and is still used today in modern control theory textbooks. Cauchy also looked at the stiffness of an "articulated octahedron." An early design of the modern day Parallel Link Mechanism.

It was not, however named the "Cauchy Platform." In 1949, V. E. Gough built and used a parallel mechanism called the "Universal Tyre-Testing Machine" at the Dunlop Rubber Company in England. This machine, or "Universal Rig" as it was called, was able to mechanically test tires under combined loads. The original machine built by Gough was in use until the 1980 and is currently owned by the Science Museum of London. But, no. It is not known as the "Gough Platform" either.

In 1965, an engineer named D. Stewart published a paper describing a 6-DOF motion platform for use as a flight simulator. Since that time, almost every type of parallel mechanisms have been commonly referred to as  "Stewart platforms," even though Gough, Cauchy and many others had laid the foundation work in theory and in actual applications. That we know of, D. Stewart never actually built a flight simulator. But Klaus Cappel did.

Also in the 1960's, Klaus Cappel, an American engineer, designed and built a motion simulator that is in essence the basis for all flight simulators today. He filed for a patent in 1964 and was awarded that patent in 1971.

 The Advantages

The objective of most production or R&D "upgrades" is to improve quality and reliability, reduce cost, reduce time and increase flexibility and capability. The Hexapod is a perfect fit in all of these areas.

Six degrees of freedom - The ability to move all six legs in a coordinated fashion allows a Hexapod both a wide range of available motion and complete control of every degree of freedom..
High precision and accuracy - With a single light platform moving instead of moving the a progressively heavier load of motors and actuators the result is lower inertial forces, no accumulation or "stack" of errors and overall better dynamic behavior.
High stiffness - Due to the very compact frame vs. a conventional serial robot the result is very high stiffness no matter what orientation the platform is in.
Variety in size - Hexapods can be as small or as large as is necessary for the application.
Software control - With a single software control algorithm, both the programming and the actual control methodology becomes simpler

 The Future

Mikrolar is involved in many areas of Hexapod development including Bio-Mechanical Research, Flight and Driving Simulators, Industrial Applications, etc. Whether you need a "tyre tester" or something more exotic we specialize in Hexapods, Stewart Platforms, Parallel Link Mechanisms, Parallel Robots, Parallel Kinematic Manipulators, Motion Bases or whatever else they might be called.