Actuation compensation for flexible surgical snake-like robots with redundant remote actuation
This paper presents two actuation compensation methods for a snake-like robot implementing multi flexible backbones and actuation redundancy. This snake-like robot is designed for distal dexterity enhancement in MIS surgery of the throat. Actuation compensation is required to account for the flexibility of the actuation lines that connect this snake-like robot with its remote actuation units. The paper presents both a naive model-based compensation approach and a combined model-based recursive linear-estimation approach that uses data gathered from external measurements of the snake-like unit configuration such as vision. The kinematic and static model of this multi-backbone snake-like unit is reviewed and a simplified redundancy resolution is implemented in the error compensation model. The results show that the performance of the snake-like unit is significantly improved when compensation is implemented. The combined model-based recursive linear estimation method showed 1deg accuracy in path tracking. Finally, an updated Jacobian that accounts for the required compensation is presented. All the work done here strides the crucial step towards a successful clinical task such as suturing in the throat

title: System design of an Insertable Robotic Effector Platform for Single Port Access (SPA) Surgery
abstract: 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 Ø15mm 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.

title: Design and Integration of a Telerobotic System for Minimally Invasive Surgery of the Throat
abstract: In this paper we present the clinical motivation, design specifications, kinematics, statics, and actuation compensation for a newly constructed telerobotic system for Minimally Invasive Surgery (MIS) of the throat. A hybrid dual-arm telesurgical slave, with 20 joint-space Degrees-of-Freedom (DoFs), is used in this telerobotic system to provide the necessary dexterity in deep surgical fields such as the throat. The telerobotic slave uses novel continuum robots that use multiple super-elastic backbones for actuation and structural integrity. We present the kinematics of the telesurgical slave and methods for actuation compensation to cancel the effects of backlash, friction, and flexibility of the actuation lines. A method for actuation compensation is presented in order to overcome uncertainties of modeling, friction, and backlash. This method uses a tiered hierarchy of two novel approaches of actuation compensation for remotely actuated snake-like robots. The tiered approach for actuation compensation uses compensation in both joint space and configuration space of the continuum robots. These hybrid actuation compensation schemes use intrinsic model information and external data through a recursive linear estimation algorithm and involve compensation using configuration space and joint space variables. Experimental results validate the ability of our integrated telemanipulation system through experiments of suturing and knot tying in confined spaces.

title: A Pilot Study of Robot-Assisted Cochlear Implant Surgery Using Steerable Electrode Arrays
abstract: This paper presents results of a pilot study evaluating the efficacy of robotic assistance using novel steerable electrode arrays for cochlear implant surgery. The current surgical setup of cochlear implant surgery is briefly reviewed and its limitations are highlighted. In an effort to reduce trauma to the structure of the cochlea, the kinematics and path planning for novel cochlear steerable electrodes are developed to minimize the interaction forces between the electrode and the cochlea. An experimental robotic system is used to compare the electrode insertion forces of steerable implants with those of nonsteerable electrodes. The results of these experiments show about 70% reduction in the insertion forces when steerable electrodes are used with our proposed path planning and control. A distance metric explaining this reduction in the insertion force is defined and experimentally validated. Although this is only a preliminary study, we believe that these results provide a strong indication to the potential of robot-assisted cochlear implant surgery to provide a significant reduction in trauma rates during cochlear implant surgery.

title: Intrinsic Wrench Estimation and Its Performance Index for Multisegment Continuum Robots
abstract: This paper presents the intrinsic capability of full-wrench estimation of multisegment continuum robots with multiple flexible backbones. Intrinsic-full-wrench estimation refers to the ability of continuum robots to also serve as force and moment sensors by using measurements of axial loads on their backbones. This end-effector-as-sensor approach fulfills the rapidly increasing needs for miniature-robotic-surgical tools with haptic sensing ability subject to various limitations, such as size, magnetic resonance imaging (MRI) compatibility, sterilizability, etc. A performance index for the intrinsic wrench-sensing capability is introduced and evaluated to show how this index can serve as a design guide for continuum robots that provide force sensing.

title: An Investigation of the Intrinsic Force Sensing Capabilities of Continuum Robots
abstract: This paper presents the theoretical analysis and the experimental validation of the force sensing capabilities of continuum robots. These robots employ superelastic NiTi backbones and actuation redundancy. The paper uses screw theory to analyze the limitations and provide geometric interpretation to the sensible wrenches. The analysis is based on the singular value decomposition of the Jacobian mapping between the configuration space and the twist space of the end effector. The results show that the sensible wrenches belong to a 2-D screw system and the insensible wrenches belong to a 4-D screw system. The theory presented in this paper is validated through simulations and experiments. It is shown that the force sensing errors have an average of 0.34 g with a standard deviation of 0.83 g. Another experiment of generating the stiffness map of a silicone strip suggests possible medical application of palpation for tumor detection. The presented study allows force sensing in challenging environments where placing force sensors at the distal end of a robot is not possible due to limitations such as size and MRI compatibility.

title: GraphScape: integrated multivariate network visualization
abstract: In this paper, we introduce a new method, GraphScape, to visualize multivariate networks, i.e., graphs with multivariate data associated with their nodes. GraphScape adopts a landscape metaphor with network structure displayed on a 2D plane and the surface height in the third dimension represents node attribute. More than one attribute can be visualized simultaneously by using multiple surfaces. In addition, GraphScape can be easily combined with existing methods to further increase the total number of attributes visualized. One of the major goals of GraphScape is to reveal multivariate graph clustering, which is based on both network structure and node attributes. This is achieved by a new layout algorithm and an innovative way of constructing attribute surface, which also allows visual clustering at different scales through interaction. A simplified attribute surface model is also proposed to reduce computation requirement when visualizing large networks. GraphScape is applied to networks of three different size (20, 100, and 1500) to demonstrate its effectiveness.

title: Multiresolution Query Optimization in an Online Environment
abstract: Multiresolution (or multi-scale) techniques make it possible for Web-based GIS applications to access large dataset. The performance of such systems relies on data transmission over network and multiresolution query processing. In the literature the latter has received little research attention so far, and the existing methods are not capable of processing large dataset. In this paper, we aim to improve multiresolution query processing in an online environment. A cost model for such query is proposed first, followed by three strategies for its optimization. Significant theoretical improvement can be observed when comparing against available methods. Application of these strategies is also discussed, and similar performance enhancement can be expected if implemented in online GIS applications.

title: A multi-resolution surface distance model for k-NN query processing
abstract: A spatial k-NN query returns k nearest points in a point dataset to a given query point. To measure the distance between two points, most of the literature focuses on the Euclidean distance or the network distance. For many applications, such as wildlife movement, it is necessary to consider the surface distance, which is computed from the shortest path along a terrain surface. In this paper, we investigate the problem of efficient surface k-NN (sk-NN) query processing. This is an important yet highly challenging problem because the underlying environment data can be very large and the computational cost of finding the shortest path on a surface can be very high. To minimize the amount of surface data to be used and the cost of surface distance computation, a multi-resolution surface distance model is proposed in this paper to take advantage of monotonic distance changes when the distances are computed at different resolution levels. Based on this innovative model, sk-NN queries can be processed efficiently by accessing and processing surface data at a just-enough resolution level within a just-enough search region. Our extensive performance evaluations using real world datasets confirm the efficiency of our proposed model.

title: A Multiresolution Terrain Model for Efficient Visualization Query Processing
abstract: Multiresolution triangular mesh (MTM) models are widely used to improve the performance of large terrain visualization by replacing the original model with a simplified one. MTM models, which consist of both original and simplified data, are commonly stored in spatial database systems due to their size. The relatively slow access speed of disks makes data retrieval the bottleneck of such terrain visualization systems. Existing spatial access methods proposed to address this problem rely on main-memory MTM models, which leads to significant overhead during query processing. In this paper, we approach the problem from a new perspective and propose a novel MTM called direct mesh that is designed specifically for secondary storage. It supports available indexing methods natively and requires no modification to MTM structure. Experiment results, which are based on two real-world data sets, show an average performance improvement of 5-10 times over the existing methods

title: Testing Scenario Implementation with Behavior Contracts
abstract: This paper presents behavior contracts as a new assertion mechanism and a tool that uses such contracts to support the testing of object-oriented (OO) systems. A behavior contract models how the scenarios for performing a designated task are expected to be implemented. Based on this contract, our tool can automatically monitor the program execution for checking important properties related to these scenarios. This capability can help testers to determine whether the scenarios have been implemented correctly. Our tool can also collect test coverage information w.r.t. the scenarios modeled by a behavior contract. Such information can be used to direct the testing efforts towards the less-covered scenarios, and to determine whether the implementation of these scenarios has been adequately tested. Therefore, using this tool should improve both the efficiency and effectiveness of testing OO systems