  There is a growing interest in social robots to be considered in the therapy
of children with autism due to their effectiveness in improving the outcomes.
However, children on the spectrum exhibit challenging behaviors that need to be
considered when designing robots for them. A child could involuntarily throw a
small social robot during meltdown and that could hit another person's head and
cause harm (e.g. concussion). In this paper, the application of soft materials
is investigated for its potential in attenuating head's linear acceleration
upon impact. The thickness and storage modulus of three different soft
materials were considered as the control factors while the noise factor was the
impact velocity. The design of experiments was based on Taguchi method. A total
of 27 experiments were conducted on a developed dummy head setup that reports
the linear acceleration of the head. ANOVA tests were performed to analyze the
data. The findings showed that the control factors are not statistically
significant in attenuating the response. The optimal values of the control
factors were identified using the signal-to-noise (S/N) ratio optimization
technique. Confirmation runs at the optimal parameters (i.e. thickness of 3 mm
and 5 mm) showed a better response as compared to other conditions. Designers
of social robots should consider the application of soft materials to their
designs as it help in reducing the potential harm to the head.
