Inertia artefacts and their effect on the parameterisation of keyboard reaction forces

Area of Science:

• Ergonomics
• Biomechanics
• Occupational Health

Background:

• Reaction force measurements during typing are affected by keyboard tray movement artefacts.
• These inertia artefacts can impact the accuracy of typing force data.
• Understanding and mitigating these artefacts is crucial for workplace musculoskeletal disorder research.

Purpose of the Study:

• To evaluate the impact of inertia artefacts on typing force measurements.
• To assess signal processing methods for artefact reduction.
• To improve the accuracy of typing force measurements in different work surface conditions.

Main Methods:

• Measured vertical forces and accelerations during typing on rigid and compliant surfaces.
• Applied low-pass filtering (20 Hz cut-off) and inertial force cancellation.
• Compared artefact reduction effectiveness between methods.

Main Results:

• Low-pass filtering removed high-frequency artefacts.
• Inertial force cancellation attenuated low-frequency artefacts specific to compliant surfaces.
• Artefact reduction altered force signal statistics by up to 7%.

Conclusions:

• Inertia artefacts significantly affect typing force measurements, especially on compliant surfaces.
• Inertial force cancellation is effective in reducing low-frequency artefacts.
• Accurate typing force measurement requires considering and mitigating artefacts for reliable workplace risk assessment.