Towards In Situ Backlash Estimation of Continuum Robots Using an Endoscopic Camera

Accurate control of continuum robots requires handling non-linear behaviors between actuators and distal effectors. In this letter, we develop a method for estimating the non-linearities of tendon-driven degrees of freedom of flexible endoscopic systems by using a distal endoscopic camera and encoders at the proximal side. The proposed approach separates the non-linearities in two parts, namely a pure non uniform backlash and a non-linear function. The backlash is estimated without relying on any model, while the non-linear function is obtained by a pose estimation process. Experiments realized on a robotic flexible endoscopy platform (STRAS) show the validity of the approach for estimating in situ the quasi-static behavior of the robot and for compensating the non-linearities of the motion transmission.