This article introduces the analysis and control of a meso-scale two degree-of-freedom robotic endoscopic tool body for minimally invasive surgeries. The design of the robotic tool uses two types of a tendon-driven joint known as a bending flexure joint that allows us to control each degree-of-freedom by minimizing interjoint coupling by design. Pure kinematic modeling and control for these robots may not provide precise control performance due to kinematic uncertainties arising from tendon elongation, tendon slacking, gear backlash, etc. We propose a static model for each of the joints of the robotic tool that avoids several of these problems. Depending on the direction of tendon tension application, the proximal joint displays considerable hysteresis due to the superelastic material characteristics and this is included in our static model. The statics of a highly compliant distal joint is also modeled and validated using finite element analysis and experimental data. Using these models, we develop a control system that comprises of a disturbance observer and the proposed static model to provide precise force control and compensate for joint hysteresis.

Hydrocephalus in the pediatric population is often treated with endoscopic procedures, in which a rigid endoscope provides a working channel and needed visualization for brain manipulation. The lack of flexible and steerable endoscopic tools limits the ability of the surgeon to conduct complex operations. In this paper, we propose the design of a novel tool for such procedures that uses the compliance of a bending flexural joint to build a compact steerable multi-joint tool. These joints are machined into a tube made of a super-elastic material to create two joints near the tip of the tool. The directional stiffness properties of the flexural joint are exploited to minimize inter-joint coupling. We perform a static analysis of each joint and a kinematic analysis of the entire robot. We follow this with the design of a hand-held controller for this robot, and analyze its ability to control multiple degrees-of-freedom of the robot while minimizing the coupling between joints.