Design of a bending mechanism for automated cystoscope

Abstract

Bladder cancer has a high recurrence rate, which requires years of regular postoperative surveillance to monitor cancer recurrence. Both of patients and urologists will be benefited from automated monitor processes. This paper presents the preliminary design of a segmented bending mechanism to steer an embedded imaging probe for automated visual inspection of the inside surface of the bladder. The suggested bending mechanism consists of three bending segments connected in series and forms the shape of a continuum robot with redundant degree of freedom. Every segment is controlled by two pairs of distributed thin wires. Its bending angle and bending direction can be controlled independently. To obtain perpendicular view on the bladder surface and maintain the required safety distance, the positions and orientations of the tip of the imaging probe are controlled by synchronized bending motions of all segments. Forward kinematics model of the proposed hyper-redundant mechanism is developed. Inverse kinematics based on exhaustive searching algorithm in the configuration space is used to find suitable bending configurations for specific view centers. Kinematics simulation results verify the effectiveness of the proposed bending mechanism and control method for scanning the entire bladder inner surface.