  Instrument-tissue interaction forces in Minimally Invasive Surgery (MIS)
provide valuable information that can be used to provide haptic perception,
monitor tissue trauma, develop training guidelines, and evaluate the skill
level of novice and expert surgeons.Force and tactile sensing is lost in many
Robot-Assisted Surgery (RAS) systems. Therefore, many researchers have focused
on recovering this information through sensing systems and estimation
algorithms.
  This article provides a comprehensive systematic review of the current force
sensing research aimed at RAS and, more generally, keyhole endoscopy, in which
instruments enter the body through small incisions. Articles published between
January 2011 and May 2020 are considered, following the Preferred Reporting
Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. The
literature search resulted in 110 papers on different force estimation
algorithms and sensing technologies, sensor design specifications, and
fabrication techniques.
