Spatial Compliance Measurement of a Clamping Table with Integrated Force Sensors

Force sensor integration into machine components is a promising approach to measure spatial process forces, especially, when regarding hexapod structures and kinematics. Rigid still-standing hexapod frameworks, such as clamping tables, are particular suitable for this approach, as no dynamic influences need to be taken into account within the measurement model and they allow a measurement in 6 degrees of freedom. On the other hand, the stiffness of rigid frameworks is reduced by force sensor integration significantly. In addition, many approaches apply joints or flexure hinges to reduced lateral forces and improve the measuring quality, which reduce the stiffness even more. In this contribution, the compliance of a clamping table with integrated force sensors and flexure hinges is determined by experimental measurements using a multiline laser interferometer, by analytic calculation, and by finite element simulation. In conclusion, the amount of stiffness reduction by force sensors and flexure hinges is quantified and different methods for compliance determination are compared.