  The continuum robot has attracted more attention for its flexibility.
Continuum robot kinematics models are the basis for further perception,
planning, and control. The design and research of continuum robots are usually
based on the assumption of piecewise constant curvature (PCC). However, due to
the influence of friction, etc., the actual motion of the continuum robot is
approximate piecewise constant curvature (APCC). To address this, we present a
kinematic equivalent model for continuum robots, i.e. APCC 2L-5R. Using
classical rigid linkages to replace the original model in kinematic, the APCC
2L-5R model effectively reduces complexity and improves numerical stability.
Furthermore, based on the model, the configuration self-estimation of the
continuum robot is realized by monocular cameras installed at the end of each
approximate constant curvature segment. The potential of APCC 2L-5R in
perception, planning, and control of continuum robots remains to be explored.
