Magnetic resonance imaging (MRI) offers many benefits, including unsurpassed soft-tissue characterization and the ability to combine detection and biopsy into a single procedure. However, limited patient access in the narrow scanner bore requires tedious iterative positioning or use of robotic assistants that isolate the physician from the patient. As an alternative, we present a teleoperation technology for percutaneous procedures to meet the needs of interventional radiologists and overcome challenges imposed by the MR environment. The technology is demonstrated for a 1-DOF needle insertion procedure. The technology uses rolling diaphragms, a clutch, and a cable-capstan drive to propel the needle while relaying forces and motions to the operator. The system demonstrates excellent position tracking (< 0.7° error in the unloaded case) and reliably transmits changes in force. During needle teleoperation, users were able to detect light membrane punctures and differentiate spring stiffnesses nearly as accurately as by hand manipulation.

During exploration through tortuous unstructured passages by continuum robots, methods are required to minimize the force interaction between the environment and the robot along its length. This paper presents and evaluates an algorithm for compliant motion control of continuum robots subjected to multiple unknown contacts with the environment. A mapping of external wrenches to a generalized force in the configuration space of a multisegment continuum robot is presented and related to measured joint-level actuation forces. These measurements are applied as inputs to a low-level compliant motion controller. Friction and modeling uncertainties, presenting an unknown nonlinear deviation from the nominal system model, are corrected via a feed-forward estimate provided by a support vector machine. The controller is evaluated on Ø9 and Ø5 mm multisegment continuum robots. We quantify the minimal interaction forces needed to generate compliant motion and demonstrate the ability of the controller to minimize interaction forces during insertion through tortuous passages.

In this paper, we present the integration and preliminary evaluation of a novel Insertable Robotic Effectors Platform (IREP) for Single Port Access Surgery (SPAS). The unique design of the IREP includes planar parallel mechanisms, continuum snake-like arms, wire-actuated wrists, and passive flexible components. While this design has advantages, it presents challenges in terms of modeling, control, and telemanipulation. The complete master-slave resolved-rates telemanipulation framework of the IREP along with its actuation compensation is presented. Experimental evaluation of the capabilities of this new surgical system include bi-manual exchange of rings, pick-and-place tasks, suture passing and knot tying. Results show that the IREP meets the minimal workspace and dexterity requirements specified for laparoscopic surgery, it allows for dual-arm operations such as tool exchange and knot tying in confined spaces. Although it was possible to tie a surgeon's knot with minimal training, suture passing was difficult due to the limited axial rotation of the distal wrists.

Multi-segment continuum robots offer enhanced safety during surgery due to their inherent passive compliance. However, they suffer poor position tracking performance due to flexibility of their actuation lines, structural compliance, and actuation coupling effects between segments. The need for control methods addressing accurate tracking for multi segment continuum robots is magnified by increased precision requirements of surgical procedures employing these structures. To address this need, this paper proposes a tiered controller that uses both extrinsic and intrinsic sensory information for improved performance of multi-segment continuum robots. The higher tier of this controller uses configuration space feedback while the lower tier uses joint space feedback and a feed-forward term obtained with actuation compensation techniques. We prove the stability of this controller using Lyapunov's direct method and experimentally evaluate its performance on a three-segment multi-backbone continuum robot. Results demonstrate its efficacy in enhancing regulation and tracking performance. It is shown that the controller mitigates the effects of actuation coupling between robot's sub-segments and decreases phase lag. These results suggest that this tiered controller will enhance telemanipulation performance of multi-segment continuum robots.

Novel minimally invasive surgical paradigms accessing deep surgical sites present a new challenge of safe instrument insertion and navigation. This paper addresses this challenge by presenting a new framework for compliant motion control of multi-backbone continuum robots subject to whole-arm contacts. This control framework does not rely on knowledge of contact locations along the length of a continuum robot. Instead, the forces at joint level are applied as controller inputs to generate compliant motion. The paper first presents a new mapping of the external wrenches to a generalized force in the configuration space of a single-stage multi-backbone continuum robot. A closed-form analytic expression for the passive stiffness of a multi-backbone continuum robot segment is also presented. A controller, robust to uncertainties of the system model, is proposed to provide compliant motion of the continuum robot segment by using the generalized force and stiffness definitions. Stability, convergence, and controller properties are shown through experimental validation. The presented framework defines a method for providing compliant motion to continuum robots without explicit knowledge of the environment. We believe this work enables new control algorithms for rapidly deployable surgical robots and supports novel surgical paradigms by increasing safety during unstructured interaction with flexible anatomy.

Continuum robots offer significant advantages for surgical intervention due to their down-scalability, dexterity, and structural flexibility. While structural compliance offers a passive way to guard against trauma, it necessitates robust methods for online estimation of the robot configuration in order to enable precise position and manipulation control. In this paper, we address the pose estimation problem by applying a novel mapping of the robot configuration to a feature descriptor space using stereo vision. We generate a mapping of known features through a supervised learning algorithm that relates the feature descriptor to known ground truth. Features are represented in a reduced sub-space, which we call eigen-features. The descriptor provides some robustness to occlusions, which are inherent to surgical environments, and the methodology that we describe can be applied to multi-segment continuum robots for closed-loop control. Experimental validation on a single-segment continuum robot demonstrates the robustness and efficacy of the algorithm for configuration estimation. Results show that the errors are in the range of 1°.

This paper presents the task specifications for designing a novel Insertable Robotic Effectors Platform (IREP) with integrated stereo vision and surgical intervention tools for Single Port Access Surgery (SPAS). This design provides a compact deployable mechanical architecture that may be inserted through a single Ø15 mm access port. Dexterous surgical intervention and stereo vision are achieved via the use of two snake-like continuum robots and two controllable CCD cameras. Simulations and dexterity evaluation of our proposed design are compared to several design alternatives with different kinematic arrangements. Results of these simulations show that dexterity is improved by using an independent revolute joint at the tip of a continuum robot instead of achieving distal rotation by transmission of rotation about the backbone of the continuum robot. Further, it is shown that designs with two robotic continuum robots as surgical arms have diminished dexterity if the bases of these arms are close to each other. This result justifies our design and points to ways of improving the performance of existing designs that use continuum robots as surgical arms.

This paper presents a novel design and preliminary kinematic analysis of an insertable robotic effector platform (IREP) for single port access (SPA) surgery. The IREP robot can be deployed into body cavity through a Ø15 mm skin incision to perform SPA procedures. It consists of two snake-like continuum robots as slave surgical assistants for tissue manipulation, two parallelogram mechanisms for the continuum robots' placement, and one controllable stereo vision module with integrated light source for depth perception and tool tracking. Design considerations and alternatives, calculations and preliminary simulations of this 17-DoF surgical robotic system are presented in this paper. The overall control system hierarchy for tele-manipulation using the IREP robot is also presented.

This paper presents a unified mathematical framework for modeling and evaluating the performance of multiple robotic arms that operate on hollow suspended organs. This framework is applied to a novel two-armed hybrid robotic system being developed for ophthalmic vitreous surgeries. Four cases are designated to capture the general movements required for any surgical procedure associated with hollow suspended organs. Dexterity measures, based on multiple characteristic lengths, are presented for procedures corresponding to these manipulation cases. Simulation results of the dual-arm robotic system for ophthalmic surgery are presented for all four manipulation cases. A comparison of this robotic system with current surgical tools shows a significant improvement in intraocular dexterity.

This paper addresses the design considerations and dexterity evaluation of a novel hybrid two-armed micro-surgical slave robot equipped with intraocular dexterity devices. A unified framework for the kinematic modeling of this robot is presented while using the kinematic constraints stemming from the constrained motion of the eye. An augmented Jacobian describing the kinematics of the eye and the relative motion of each one of the two intraocular dexterity robots (IODR) is presented. Using this framework, the capabilities of this two-armed robot in performing dexterous intraocular operations are evaluated and compared to a similar robot without intraocular dexterity. The kinematic conditioning index (KCI) for the proposed robot is shown to be significant. The results presented show an increase of approximately 33% and 47% in translational and rotational KCI respectively