Madusudanan Sathia Narayanan

Case Studies of Musculoskeletal-Simulation-Based Rehabilitation Program Evaluation

Variability in motor rehabilitation program outcomes can be attributed not only to individual components (human patient/rehabilitation equipment) but also to their system-level interactions. Thus, effective deployment of a rehabilitation program depends upon: 1) suitable therapist selection of user-device ergonomics; 2) adjustable device settings; and 3) exercise regimen parameters; to achieve desired system-level motor performance. In this paper, we discuss aspects of creation of a virtual design environment, leveraging tools from musculoskeletal analysis, optimization, and simulation-based design, to permit therapists to rapidly evaluate and systematically customize rehabilitation programs. Specifically, this framework is intended to facilitate 1) parametric study of ergonomic/device/regimen settings on musculoskeletal performance; 2) use of design tools such as optimization for decision support in arriving at the best program; and 3) scaffolded examination of linkage between form and function by iterative what-if type of analyses. We use two case studies (bicep-curling and motor rehabilitative driving) to highlight benefits of such simulation-based rehabilitation program evaluation.

Simulation-Based Design of Exoskeletons Using Musculoskeletal Analysis

Exoskeletons are a new class of articulated mechanical systems whose performance is realized while in intimate contact with the human user. The overall performance depends on many factors including selection of architecture, device, parameters and the nature of the coupling to the human, offering numerous challenges to design-evaluation and refinement. In this paper, we discuss merger of techniques from the musculoskeletal analysis and simulation-based design to study and analyze the performance of such exoskeletons. A representative example of a simplified exoskeleton interacting with and assisting the human arm is used to illustrate principal ideas. Overall, four different case-scenarios are developed and examined with quantitative performance measures to evaluate the effectiveness of the design and allow for design refinement. The results show that augmentation by way of the exoskeleton can lead to a significant reduction in muscle loading.© 2010 ASME

Evaluation of robotic minimally invasive surgical skills using motion studies

Robotic Minimally Invasive Surgery, and the engendered computer-integration, offers unique opportunities for quantitative computer-based surgical-performance evaluation. In this work, we examine extension of traditional manipulative skill assessment, having deep roots in performance evaluation in manufacturing industries, for applicability to robotic surgical skill evaluation. This method relies on: defining task-level segmentation of modular sub-tasks/micro-motions called ‘Therbligs’ that can be combined to perform a given task; and analyzing intra- and inter-user performance variance by studying surgeons’ performance over each ‘Therbligs’. Any of the performance metrics of macro-motions—from motion-economy, tool motion measurements to handed-symmetry—can now be extended over the micro-motion temporal segments. Evaluation studies were based on video recordings of surgical tasks in two settings: first, we examined performance of two representative manipulation exercises (peg board and pick-and-place) on a da Vinci surgical SKILLS simulator. This affords a relatively-controlled and standardized test-scenarios for surgeons with varied experience-levels. Second, task-sequences from real surgical videos were analyzed with a list of predefined ‘Therbligs’ in order to investigate its overall usefulness.

Kinematics analysis of in-parallel 5 DOF haptic device

Parallel-architecture haptic devices offer significant advantages over serial-architecture counterparts in applications requiring high stiffness and high accuracy. To this end, many haptic devices have been created and deployed by modularly piecing together several serial-chain arms to form an in-parallel system. However, the overall system performance depends both on the nature of the individual arms as well as their interactions. We build on the rich theoretical background of constrained articulated mechanical systems to provide a systematic framework for formulation of system-level kinematic performance from individual-arm characteristics. Specifically, we develop the system-level kinematic model in a symbolic (yet algorithmic) fashion that facilitates: (i) computational development of pertinent symbolic equations; (ii) generalization to arbitrary architectures; and (iii) combined symbolic/numeric analyses of performance (workspace, singularities, design sensitivities). These various aspects are illustrated using the example of the Quanser High Definition Haptic Device (HD)2 — an in-parallel haptic device formed by coupling two 3-link Phantom 1.5 type serial chain manipulators with appropriate passive joints. We also briefly discuss aspects of ongoing work for design-prototyping and validation, taking advantage of tools from Virtual Prototyping and Hardware-in-the-Loop testing.

Surgical tool attributes from monocular video

HD Video from the (monocular or binocular) endoscopic camera provides a rich real-time sensing channel from surgical site to the surgeon console in various Minimally Invasive Surgery (MIS) procedures. However, a real-time framework for video understanding would be critical for tapping into the rich information-content provided by the non-invasive and well-established digital endoscopic video-streaming modality. While contemporary research focuses on enhancing aspects such as tool-tracking within the challenging visual scenes, we consider the associated problem of using that rich (but often compromised) streaming visual data to discover the underlying semantic attributes of the tools. Directly analyzing the surgical videos to extract more realistic attributes online can aid in the decision-making and feedback aspects. We propose a novel probabilistic attribute labelling framework with Bayesian filtering to identify associated semantics (open/closed, stained with blood etc.) to ultimately give semantic feedback to the surgeon. Our robust video-understanding framework overcomes many of the challenges (tissue deformations, image specularities, clutter, tool-occlusion due to blood and/or organs) under realistic in-vivo surgical conditions. Specifically, this manuscript performs rigorous experimental analysis of the resulting method with varying parameters and different visual features on a data-corpus consisting of real surgical procedures performed on patients with da Vinci Surgical System [9].

Kinematic-, Static- and Workspace Analysis of a 6-P-U-S Parallel Manipulator

This paper examines the symbolic kinematic modeling of a general 6-P -U-S (prismatic-universal-spherical) parallel kinematic manipulator (PKM). The base location of actuators has been previously shown to lead to: (i) reduction of the (motor) weight carried by the legs; (ii) elimination of the actuation transmission requirement (through intermediary joints as in the case of the Stewart-Gough platform); and (iii) most-importantly absorption of reaction-forces by the ground. We focus on using the symbolic equations to derive the conditions for type I and II singularities of this class of parallel manipulators. Based on these conditions, this system of equations is specialized to a specific configuration of the platform that has superior structural design and comparatively minimal singularities within its workspace. A series of studies were conducted to investigate the quality of workspace as well as estimate the actuation requirements for a unit payload carried over their workspace using the symbolic Jacobian model for this specialized configuration.Copyright

CAD-enhanced workspace optimization for parallel manipulators: A case study

The challenges of workspace determination of parallel manipulators (PMs) arise principally from the lack of analytical solutions of the forward kinematics. The inverse-position kinematics based approach for determining workspace tends to be inefficient, time consuming and unsophisticated. In this paper, we present a geometry-based method for accurate and computationally effective calculation of the workspace of a constrained parallel manipulator. We illustrate how boolean geometric operations can simplify the process of finding the workspace and optimizing the designs. Comparative performance studies, in terms of accuracy and computational performance, are performed to benchmark the approach against more conventional methods. Finally, we examine ways to further automate the process using a CAD package.

Virtual musculoskeletal scenario-testing case-studies

Doctors, dentists, nurses, athletic trainers, occupational therapists and allied health-care professionals are expected to learn the linkage between anatomy, physiology and ultimately functional-performance of muscles i.e. how muscles affect movement or which sets of muscles carry various loads. However the extent of understanding of functional-performance that can be imparted in a didactic-lecture or cadaver-lab setting of a ldquoGross Anatomyrdquo class is limited. Hence we seek to create the architecture and algorithms for scaffolded interaction with human musculoskeletal simulation models (virtual prototypes) that can make varied ldquowhat-ifrdquo type analyses and hypothesis-testing possible. This is very pertinent in the context of the target audience of healthcare professionals who may lack prior exposure to such virtual computational scenario testing tools. Providing such access is vital to training of the next generation of health care professionals to leverage ubiquitous computing and the quantitative-paradigm.

Data Driven Development of Haptic Models for Needle Biopsy Phantoms

Needle biopsy is an important and common procedure for lesion detection or tissue extraction within the human body. Physicians conducting such procedures rely primarily on the sense of “touch” (kinesthetic feedback from needle) to estimate the current needle position and organs within its vicinity. This skill takes time to acquire and mature, often by biopsies on live patients. Medical residents and fellow trainees thus have limited opportunities both in terms of real life scenarios as well as testing platforms to develop and validate their skills. This paper focuses on building a biopsy simulator for training on virtual phantoms (using both visual and force feedback) and cross validation using a real physical phantom. In order to develop a virtual-haptic model of biopsy phantom, material testing experiments were conducted to obtain motion-force profiles from an instrumented 6-DOF robot platform serving as a needle driver. The measured force-displacement data was then used to develop three types of haptic models for the phantom to calculate the force feedback for the haptic device. Neural network based models provided a more accurate force-reflection model compared to the other two methods from the literature and will form the basis of the virtual phantoms within our framework.Copyright

An Engineering Approach to Utilizing Bio-Inspiration in Robotics Applications

As an interdisciplinary field lying at the intersection of biology and robotics, bio-inspired robotics has seen considerable interest from a research, education, and ultimately application perspective. The scope of this interest has ranged from creating and operating walking, crawling, and flying robots based on biological counterparts; to evaluating biological algorithms for potential engineering applications; to deconstructing the functioning of living organisms from the macro- to the microlevels; and ultimately to constructing the next generation of bio-inspired robots from the bottom up. Significant synergies are forthcoming from such an approach, but numerous limitations still exist. We begin with the discussion of general principles behind taking inspiration from a biological source and converting it into implementable engineering concepts using case studies of bird-inspired robots, snake-inspired robots, and mastication robots. These case studies describe how useful features of the biological creatures were selected and simplified so that they can be implemented using the existing technologies.