  Tendon-driven continuum manipulators (TDCM) are commonly used in minimally
invasive surgical systems due to their long, thin, flexible structure that is
compliant in narrow or tortuous environments. There exist many researches for
precise tip control of the articulating section. However, these models do not
account for the proximal shaft shape of TDCM, affecting the tip controls in
practical settings. In this paper, we propose a gradient-based shift detection
method based on motor current that can easily find the offset of task space
models (i.e., hysteresis). We analyze our proposed methods with multiple
Intra-cardiac Echocardiography catheters, which are typical commercial example
of TDCM. Our results show that the errors from varied proximal shape are
considerably reduced, and the accuracy of the tip manipulation is improved when
changing external environmental structures.
