Roger E. Goldman

Design, simulation and evaluation of kinematic alternatives for Insertable Robotic Effectors Platforms in Single Port Access Surgery

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.

Design and Coordination Kinematics of an Insertable Robotic Effectors Platform for Single-Port Access Surgery

Single port access surgery (SPAS) presents surgeons with added challenges that require new surgical tools and surgical assistance systems with unique capabilities. To address these challenges, we designed and constructed a new insertable robotic end-effectors platform (IREP) for SPAS. The IREP can be inserted through a Ø15 mm trocar into the abdomen and it uses 21 actuated joints for controlling two dexterous arms and a stereo-vision module. Each dexterous arm has a hybrid mechanical architecture comprised of a two-segment continuum robot, a parallelogram mechanism for improved dual-arm triangulation, and a distal wrist for improved dexterity during suturing. The IREP is unique because of the combination of continuum arms with active and passive segments with rigid parallel kinematics mechanisms. This paper presents the clinical motivation, design considerations, kinematics, statics, and mechanical design of the IREP. The kinematics of coordination between the parallelogram mechanisms and the continuum arms is presented using the pseudo-rigid-body model of the beam representing the passive segment of each snake arm. Kinematic and static simulations and preliminary experiment results are presented in support of our design choices.

Integration and preliminary evaluation of an Insertable Robotic Effectors Platform for Single Port Access Surgery

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 surgeons knot with minimal training, suture passing was difficult due to the limited axial rotation of the distal wrists.

Design and Theoretical Evaluation of Micro-Surgical Manipulators for Orbital Manipulation and 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

Design and Performance Evaluation of a Minimally Invasive Telerobotic Platform for Transurethral Surveillance and Intervention

Bladder cancer, a significant cause of morbidity and mortality worldwide, presents a unique opportunity for aggressive treatment due to the ease of transurethral accessibility. While the location affords advantages, transurethral resection of bladder tumors can pose a difficult challenge for surgeons encumbered by current instrumentation or difficult anatomic tumor locations. This paper presents the design and evaluation of a telerobotic system for transurethral surveillance and surgical intervention. The implementation seeks to improve current procedures and enable development of new surgical techniques by providing a platform for intravesicular dexterity and integration of novel imaging and interventional instrumentation. The system includes a dexterous continuum robot with access channels for the parallel deployment of multiple visualization and surgical instruments. This paper first presents the clinical conditions imposed by transurethral access and the limitations of the current state-of-the-art instrumentation. Motivated by the clinical requirements, the design considerations for this system are discussed and the prototype system is presented. Telemanipulation evaluation demonstrates submillimetric RMS positioning accuracy and intravesicular dexterity suitable for improving transurethral surveillance and intervention.

Performance Evaluation for Multi-arm Manipulation of Hollow Suspended Organs

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.

Compliant motion control for continuum robots with intrinsic actuation sensing

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.

Algorithms for autonomous exploration and estimation in compliant environments

This paper investigates algorithms for enabling surgical slave robots to autonomously explore shape and stiffness of surgical fields. The paper addresses methods for estimating shape and impedance parameters of tissue and methods for autonomously exploring perceived impedance during tool interaction inside a tissue cleft. A hybrid force-motion controller and a cycloidal motion path are proposed to address shape exploration. An adaptive exploration algorithm for segmentation of surface features and a predictor-corrector algorithm for exploration of deep features are introduced based on discrete impedance estimates. These estimates are derived from localized excitation of tissue coupled with simultaneous force measurements. Shape estimation is validated in ex-vivo bovine tissue and attains surface estimation errors of less than 2.5 mm with force sensing resolutions achievable with current technologies in minimally invasive surgical robots. The effect of scan patterns on the accuracy of the shape estimate is demonstrated by comparing the shape estimate of a Cartesian raster scan with overlapping cycloid scan pattern. It is shown that the latter pattern filters the shape estimation bias due to frictional drag forces. Surface impedance exploration is validated to successfully segment compliant environments on flexible inorganic models. Simulations and experiments show that the adaptive search algorithm reduces overall time requirements relative to the complexity of the underlying structures. Finally, autonomous exploration of deep features is demonstrated in an inorganic model and ex-vivo bovine tissue. It is shown that estimates of least constraint based on singular value decomposition of locally estimated tissue stiffness can generate motion to accurately follow a tissue cleft with a predictor-corrector algorithm employing alternating steps of position and admittance control. We believe that these results demonstrate the potential of these algorithms for enabling “smart” surgical devices capable of autonomous execution of intraoperative surgical plans.

Compliant Motion Control for Multisegment Continuum Robots With Actuation Force Sensing

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.

Configuration and joint feedback for enhanced performance of multi-segment continuum robots

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 Lyapunovs 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 robots sub-segments and decreases phase lag. These results suggest that this tiered controller will enhance telemanipulation performance of multi-segment continuum robots.