  Fecal incontinence, arising from a myriad of pathogenic mechanisms, has
attracted considerable global attention. Despite its significance, the
replication of the defecatory system for studying fecal incontinence mechanisms
remains limited largely due to social stigma and taboos. Inspired by the
rectum's functionalities, we have developed a soft robotic system, encompassing
a power supply, pressure sensing, data acquisition systems, a flushing
mechanism, a stage, and a rectal module. The innovative soft rectal module
includes actuators inspired by sphincter muscles, both soft and rigid covers,
and soft rectum mold. The rectal mold, fabricated from materials that closely
mimic human rectal tissue, is produced using the mold replication fabrication
method. Both the soft and rigid components of the mold are realized through the
application of 3D-printing technology. The sphincter muscles-inspired actuators
featuring double-layer pouch structures are modeled and optimized based on
multilayer perceptron methods aiming to obtain high contractions ratios (100%),
high generated pressure (9.8 kPa), and small recovery time (3 s). Upon
assembly, this defecation robot is capable of smoothly expelling liquid faeces,
performing controlled solid fecal cutting, and defecating extremely solid long
faeces, thus closely replicating the human rectum and anal canal's functions.
This defecation robot has the potential to assist humans in understanding the
complex defecation system and contribute to the development of well-being
devices related to defecation.
