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Monthly Report for Space Robotic FMS PreCommercialization Development Sept 30, 2019

Summary

Completed testing over narrower frequency range, investigating influence of phase shift on torsion mode peakiness. Wrote quartely report of findings.

Specification

No change.

Design

No change.

Analysis

Examination of influence of non-symmetry of piezo ceramic excitation on quality of torsion response.

Software Simulation

Completed times series model of torsion mode excitation for segment 1& 3 excitation, comparing with test results.

Breadboard Manufacturing

no change

Breadboard Testing

Confirmed symmetry between half saddle mode segment (0 & 2) and other half saddle mode (1 &3).

Plans for October.

Develop means of applying 'gentle' torsion loads for next test stage.

What's so tough?

Temperature Lack of atmosphere drives temperatures to be either hot in sun or cold in shade. Robots are for moving things around, so they go into and out of shade repeatedly.

Force not directly measureable. It can be inferred from strain or deflection. Such measures are affected by thermal distorsion.

Large dynamic range linear vs rotation forces. Long robot arms and the need to capture 'free flyers' generates large rotational forces.

High Stiffness A high stiffness requirement, makes measurement of strain or deflection more difficult to isolate from thermal distorsion.

Drift Space operations tend to be slow - often taken over a period of hours.

6 dof It is important to distinguish all 6 degrees of force measurement, but the shear and moment loading cases can produce difficult to distinguish effects