Measurement uncertainty evaluation of a hexapod-structured calibration device for multi-component force and moment sensors

Abstract

As a reference measurement machine for multi-component force and moment sensors of up to six components, a hexapod-structured calibration device was developed at the Physikalisch-Technische Bundesanstalt in 2001. The machine can generate and measure forces of up to 10 kN and moments of up to 1 kN • m. In this paper, the measurement uncertainty budget of the machine is analyzed, beginning with an improved physical model and calculation of sensitivity coefficients using the implicit function theorem and the Monte Carlo method. The main influencing factors for the measurement uncertainty are discussed and suggestions for further reduction of the uncertainty are given.

A self-calibrating multicomponent force/torque measuring system

“…Several calibration setups for multi component force and torque sensors have been presented in the literature. For instance, the Physikalisch-Technische Bundesanstalt (PTB) in Germany have two calibration setups [7,12] used for calibrating multi-component force sensors. The first system can be used to calibrate six component force and torque sensors and has a measuring range of up to 10 kN for the forces and 1 kN•m for the torques.…”

Spatial Compliance Measurement of a Clamping Table with Integrated Force Sensors

“…In the following years, the topic has been studied further _____________ [7][8][9], including first finite element simulations [10,11] and first evaluations on flexure hinges [12,13]. The most promising actual works show application-oriented results, such as a multicomponent calibration system [14,15], a sensor for heavy duty applications [16][17][18][19], an endoscope with integrated force measurement for minimal invasive surgery [20,21], or a measuring system for industrial applications [22]. Further, the approach has been evolved to moving hexapod structures and hexapod kinematics [23,27].…”

Model Calibration for a Rigid Hexapod-Based End-Effector with Integrated Force Sensors

“…Integrated torque sensors in joints [7] still require large mechanical and modelling efforts (friction, stick-slip) and are not advantageous for the desired application in parallel structures and kinematics, where mainly longitudinal forces appear. Concerning the use of rigid Stewart or hexapod structures as force sensors, the most promising works with practical results are a multicomponent calibration system [8,9], a sensor for heavy duty applications [10][11][12], miniaturised sensors, for example, for surgery [13,14], and a measuring system for industrial applications [15]. Still, all of these sensors have been designed as pure (machine independent) measuring devices with static calibration.…”