  Tendon-sheath-driven manipulators (TSM) are widely used in minimally invasive
surgical systems due to their long, thin shape, flexibility, and compliance
making them easily steerable in narrow or tortuous environments. Many
commercial TSM-based medical devices have non-linear phenomena resulting from
their composition such as backlash hysteresis and dead zone, which lead to a
considerable challenge for achieving precise control of the end effector pose.
However, many recent works in the literature do not consider the combined
effects and compensation of these phenomena, and less focus on practical ways
to identify model parameters in realistic conditions. This paper proposes a
simplified piecewise linear model to construct both backlash hysteresis and
dead zone compensators together. Further, a practical method is introduced to
identify model parameters using motor current from a robotic controller for the
TSM. Our proposed methods are validated with multiple Intra-cardiac
Echocardiography (ICE) catheters, which are typical commercial example of TSM,
by periodic and non-periodic motions. Our results show that the errors from
backlash hysteresis and dead zone are considerably reduced and therefore the
accuracy of robotic control is improved when applying the presented methods.
