HEXAPODS | FEATURE
HEXAPODS HELP MEASURE STRESS IN A MODEL: Precise Positioning with Six Degrees of Freedom in Measurement Setups
BIRGIT BAUER, Business Development Manager Health Care at PI (Physik Instrumente) GmbH & Co. KG, MARTIN GEIGER, Research Assistant at the University Hospital of Ulm, Hospital for Orthodontics, and ELLEN-CHRISTINE REIFF,M.A., Editorial Office Stutenseefilm
computer-aided simulation processes. This is one of the reasons why the finite element method has become a standard tool in solid-state simulation. It can be used to calculate solutions to problems from a wide range of physical disciplines. Not only automobile manufacture, tool making and mechanical engineering, but also medical technology and the manufacturers of musical instruments can benefit from the results thus obtained. However, despite their simulation of reality, they can only provide calculated and thus fictitious values. This is why in particular for biomechanical and biomedical problems also hardware models are readily used for simulation. Hexapods, which provide high-precision positioning with six degrees of freedom, offer interesting options for measurement setups used to test how well the models reproduce reality.
T
Hexapods have a parallel kinematic structure, i.e. six drives act together on a single moving platform (figure 1). Depending on their design, Hexapods can position loads from a few kg to several tons with high precision in any spatial orientation in three linear and three rotational axes. The best-known application of six-axis parallel-kinematic systems are probably flight simulators. Hexapods, suitable for applications in metrology, industry or research, are however much more accurate. Depending on the requirements of the application, they are driven by high-precision drive screws and precisely controllable DC motors or directly by linear motors, e. g. based on piezo actuators, instead of using hydraulic drives.
>> Continued on page 36
<< Figure 2:Te biomechanical structure of the simulation system is
based on a parallel-kinematic Hexapod of series H-850 (image: PI). >>
oday many new and further developments would not be possible in the absence of
<< Figure 1: Hexapods are parallel-kinematic systems
(a) Teir design is much more compact than that of serially stacked multi-axis systems
(b) and their moving mass is much lower (image: PI). >>
35 | commercial micro manufacturing international Vol 7 No.4
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