  Granular jamming is a popular soft robotics technology that has seen recent
widespread applications including industrial gripping, surgical robotics and
haptics. However, to date the field has not fully exploited the fundamental
science of the jamming phase transition, which has been rigorously studied in
the field of statistical and condensed matter physics. This work introduces
vibration as a means to improve the properties of granular jamming grippers
through vibratory fluidisation and the exploitation of resonant modes within
the granular material. We show that vibration in soft jamming grippers can
improve holding strength, reduce the downwards force needed for the gripping
action, and lead to a simplified setup where the second air pump, generally
used for unjamming, could be removed. In a series of studies, we show that
frequency and amplitude of the waveforms are key determinants to performance,
and that jamming performance is also dependent on temporal properties of the
induced waveform. We hope to encourage further study in transitioning
fundamental jamming mechanisms into a soft robotics context to improve
performance and increase diversity of applications for granular jamming
grippers.
