Active compliance and force estimation of a continuum surgical manipulator based on the tip-pose feedback

Continuum manipulators have been applied in different surgical scenarios due to their dexterity and multi-DoF (degree of freedom) design compactness. To improve surgery safety, it is preferable to enable active compliance and force sensing abilities for a continuum manipulator. Existing works on active compliance and force sensing often rely on force sensors at the proximal or the distal ends, which inevitably increases the system complexity. In this paper, a shape reconstruction algorithm, a compliant motion controller, and a force estimation method are proposed successively based on the manipulator's tip pose via visual feedback. Four support vector regression (SVR) trainers are constructed and trained to compensate for the actuation residues, which are the differences between the actual actuation lengths outputs at the actuators and the ideal actuation lengths calculated from the estimated shape using the kinematics model, under no-load condition. Then, a compliant motion controller and a force estimation method are realized based on the current actuation residues, compared with the actuation residues under the no-load condition. In this way, no additional sensors are needed as an endoscopic camera is often available in a laparoscopic or endoscopic surgical system. The experiments were conducted on a & phi;3 mm-continuum manipulator to demonstrate the effectiveness of the proposed algorithms.