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4: Rotation of a vector about an axis leaves the component along the axis unchanged. Hence, only the component perpendicular to the axis can be retrieved from the initial and nal positions.
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The focus of this dissertation is on the design, virtual prototyping and physical realization of one-of-a-kind assistive devices that are physically coupled or attached to the human user. This class of articulated assistive devices called teletheses are designed to be passive. The intimate physical coupling enables their use as “extensions” powered...
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Citations
... several digitalhuman modeling tools such as Jack allowed kinematic modeling of human device-environment interactions. The ability to monitor internal human variables, such as joint angles and torques, from the virtual avatar formed the basis of a user-customized development of human-worn products [8,9]. In recent times, a number of computational musculoskeletal-analysis tools such as SIMM [1,10] or AnyBody [11], or the even more recent OpenSim [3,4] framework has become available. ...
... Design variables can encompass geometry, dynamics as well as regimen parameters. Geometric parameters could include individual user geometries such as limb length, joint angle etc [9,21], dynamics parameters may include joint velocities, frequency of motion etc [6,8] while the regimen parameters such as dynamically adjustable springiness, damping and amplitude of a desired motion can also serve as design variables. These design variables can be used to systematically explore the space of feasible alternatives. ...
... However, system-level interactions between patients and rehabilitation equipment make it difficult for therapists to select the " best " set of options/parameters to realize desired therapeutic outcomes. In this paper, we examine the application of Virtual Prototyping (VP) [4], [5] methodology to study, evaluate, and refine interactions Manuscript received February 19, 2009; revised March 23, 2009. First published May 8, 2009; current version published June 5, 2009. ...
... In such a setting, design decisions can be made by systematic generation of candidate designs, evaluation by quantitative criteria, and, finally, elimination of undesirable candidate designs. VP tools in engineering have capitalized on setting up and solving such problems by coupling parametric models with functional simulation tools and optimization methods [4]. In particular, the availability of low-cost PC-based parametric simulation and analysis tools, and integrating multiple functionalities into a unified environment, has favored the adoption and rapid proliferation of the " computational/virtual exploration " approach. ...
... Varying levels of such simulations are possible, e.g., several digital human modeling tools such as Jack allow kinematic modeling of human–device–environment interactions . The ability to monitor internal human variables, such as joint angles and torques, from the virtual avatar formed the basis of a usercustomized development of human-worn products [4], [5]. The recent availability of professional-grade computational musculoskeletal analysis tools [10]–[14] now facilitates virtual simulation-based analysis of detailed and biomechanically accurate models. ...
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.
... several digitalhuman modeling tools such as Jack allowed kinematic modeling of human device-environment interactions. The ability to monitor internal human variables, such as joint angles and torques, from the virtual avatar formed the basis of a user-customized development of human-worn products [8, 9]. In recent times, a number of computational musculoskeletal-analysis tools such as SIMM [1, 10] or AnyBody [11], or the even more recent OpenSim [3, 4] framework has become available. ...
... Design variables can encompass geometry, dynamics as well as regimen parameters. Geometric parameters could include individual user geometries such as limb length, joint angle etc [9, 21], dynamics parameters may include joint velocities, frequency of motion etc [6, 8] while the regimen parameters such as dynamically adjustable springiness, damping and amplitude of a desired motion can also serve as design variables. These design variables can be used to systematically explore the space of feasible alternatives. ...
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.
... To quantify the driving performance of the subject, we adopted the Error Value Parameter (EVP) measure. The Error Value Parameter (EVP), shown in Figure 16 was developed in [23] to closely resemble and complement the Structural Error Metric used in mechanism synthesis [24]. The EVP is a normalized quantity that measures the discrepancy between the desired path and the subject generated path at equal arc-length correspondence points. ...
The Steer-By-Wire (SBW) paradigm for vehicle control offers many advantages over traditional use of mechanical steering systems but comes at the cost of loss of proprioception (“road feel”). To this end, haptic interfaces for SBW systems have been proposed to restore the intimacy of interactive control back to the driver. However, the degree of realism for the interaction is dependent on the fidelity of the underlying computational vehicle dynamics model. Hence we focus on quantitative comparative testing of the role of vehicle dynamics modeling fidelity for haptic SBW tasks. Additionally the SBW paradigm can simplify implementation of shared/collaborative control (steering) of the underlying mechanical system (vehicle). Possibilities range from sharing of control between multiple individual users or between user and automation technology. Performance evaluation of 3 modes of shared control vs. individual control of driving was carried out and preliminary analysis of results is presented in the paper.
... Design variables can encompass geometry as well as regimen parameters for the user-device interaction. Geometric parameters could include individual user geometries such as limb length, etc [14] [15], device properties for customizable devices [5] [6], as well as properties determined by the ergonomics of placement of the user with respect to the device. Regimen parameters such as dynamically adjustable springiness, damping, as well as frequency, amplitude of a desired motion can also serve as design variables. ...
... Design variables can encompass geometry as well as regimen parameters for the user-device interaction. Geometric parameters could include individual user geometries such as limb length, etc [14, 15], device properties for customizable devices [5, 6], as well as properties determined by the ergonomics of placement of the user with respect to the device. Regimen parameters such as dynamically adjustable springiness, damping, as well as frequency, amplitude of a desired motion can also serve as design variables. ...
Rehabilitation is a complex multifaceted process with complexity and variability that depends not only on human patients and/or specialized equipment but also on the nature of their functional interaction. Rapid and effective customization of the functional interactions between the patient and the rehabilitation device thus becomes critical for any rehabilitation program. Two principal dimensions govern the effectiveness of such functional interactions: geometric placement of user-device (ergonomics) and exercise selection and performance (regimen). In this paper, we discuss aspects of creation of a virtual design environment, leveraging tools from musculoskeletal analysis, optimization, and simulation-based design, which will permit a therapist to rapidly evaluate and systematically customize various candidate rehabilitation programs. Specifically, this framework: (i) permits study of parametric performance variability due to ergonomic or regimen variability; and (ii) facilitates use of all design tools such as optimization to determine the best program. We illustrate various aspects of this customization using an illustrative case-study of a motor-rehabilitation haptic virtual driving environment
... Such a configuration is obtained by physically coupling the distal joint rotations of a revolute-jointed, multi-link, serial chain mechanism to the rotation of the proximal joint resulting in an Single Degree-of-freedom Coupled Serial Chain (SDCSC) mechanism. The rotation of the base link now drives all the other coupled links and increasing the number of links enables us to trace curves of increasing complexity and variety while retaining the single degreeof-freedom operation [15], [16]. @BULLET The alternate design is one that uses the well-known fourbar configuration as shown inFigure 3(c). ...
... The requirement to match specifications exactly at precision points creates constraints between the various parameters of the mechanism, which aids the final selection of the parameters of the designed device. The design constraint equations themselves are created from the loop-closure equations for end-effector position specifications or by application of the Principle of Virtual Work for endeffector force specifications [15],[16]. These constraints can be combined within the previously described optimization-based framework to create a constrained design optimization problem. ...
... In this case, the goal of the articulation is to guide the attached wheel axle through several positions while supporting a set of specified external loads. Building on the work presented in [15],[16], we examine the kinetostatic design process for selection of the optimal configuration (and determine the minimum torques required) to support these external loads by structural equilibration. We also consider the addition of torsional springs at each joint to minimize/optimize the peak actuator torques by a judicious combination of structural equilibration design and spring assists. ...
In this paper, we examine and evaluate candidate articulated leg-wheel subsystem designs for use in vehicle systems with enhanced uneven-terrain locomotion capabilities. The leg-wheel subsystem designs under consideration consist of disk wheels attached to the chassis through an articulated linkage containing multiple lower-pair joints. Our emphasis is on creating a design that permits the greatest motion flexibility between the chassis and wheel while maintaining the smallest degree-of-freedom (d.o.f.) within the articulated chain. In particular, we focus our attention on achieving two goals: (i) obtaining adequate ground clearance by designing the desired/feasible motions of the wheel axle, relative to the chassis, using methods from kinematic synthesis; and (ii) reducing overall actuation requirements by a judicious mix of structural equilibration design and spring assist. We examine this process in the context of two candidate designs – a coupled-serial-chain configuration and four-bar-configuration – for the articulated-leg-wheel subsystem. The performance of planar variants of these designs, operating in the sagittal plane, is evaluated and representative results are presented to highlight the process.
... 3. Computer aided design: The mechanical design is accomplished using Pro/Engineer (Parametric Technologies Corporation), which was chosen for its parametric part and assembly modeling capabilities and because of the interfaces offered to a variety of other graphics, finite element analysis and manufacturing packages. The Pro/Develop module of Pro/Engineer offers a powerful scripting interface which enables the designer to make parametric changes in the Jack environment interactively, which are then used to update the original CAD model automatically [10]. ...
This paper presents examples of a class of human-worn manipulation aids for people with disabilities, and a para- digm for the cost-effective design and manufacture of such devices. Also dis- cussed is a software design environ- ment that integrates a variety of sup- port tools to facilitate human-centered product design.
... Hardware-based motion and force constraints can also be created by mechanically coupling the joint rotations of a multi-joint articulated linkage. Coupled Serial Chain mechanisms [2] are a novel class of manipulators formed by physically coupling the distal joint rotations of a multilink serial chain to their proximal joint rotations, using either pulley or gear drives as shown inFigure 2(a). Each hardware-coupling between distal and proximal joints reduces a degree of freedom and repeated coupling reduces the overall degrees of freedom to 1. ...
Articulated mechanical systems with multiple joints possess
multiple degrees-of-freedom which are often not required for performing
typical low-dimensional manipulation tasks. These excessive degrees of
freedom then need to be reduced by application of constraints, either
actively by suitable control or passively in hardware, prior to
performance of the task. Our interest is in creating articulated
manipulation assistive aids, which combine the motion flexibility due to
the multiple articulations with the simplicity of reduced
degree-of-freedom control due to the presence of hardware constraints.
Specifically we investigate the process of design and prototyping of
such reduced-degree-of-freedom manipulators whose end-effector is
required to closely approximate a desired planar path. We also examine
design enhancements that permit easy reconfiguration of our prototype
manipulator for multiple sets of tasks, by a controlled variation of the
principal structural parameters
... Interactive modifications to the parameters of the design made in the central interface are propagated back to the original CAD model via a scripting interface. The mechanism design module, implemented in MATLAB, supports the dimensional synthesis, optimization and analysis of mechanisms and is used to create feasible design alternatives (Krovi et al., 1997;Krovi, 1998) for selection by the designer. We have developed and automated the tools that permit a designer to take a preliminary design, convert it into a detailed design, and quickly produce prototypes for evaluation and eventually for production. ...
This paper presents the methodology for virtual prototyping of a class of one-of-a-kind assistive devices customizable to the human user. This class consists of passive, articulated mechanical manipulation aids which are physically coupled to the user. We address the synthesis, design, optimization and analysis of such mechanisms in a virtual environment containing models of both the product and the human user. We also develop the theory and methodology for design of planar serial chain mechanisms with revolute joints coupled by cable-pulley transmissions. Finally, we present the design and prototyping of a customized head controlled feeding aid for quadriplegics, as an illustrative example. 1 INTRODUCTION We address the customized design and virtual prototyping of one-of-a-kind products that require physical interaction with the human user. The considerable variability in performance across individuals creates a critical need for designing aids that are specific to an individual (Kum...
Single Degree-of-freedom Coupled Serial Chain (SDCSC) mechanisms are a novel class of mechanisms that can be realized by coupling successive joint rotations of a serial chain linkage, by way of gears or cable-pulley drives. Such mechanisms combine the benefits of single degree-of-freedom design and control with the anthropomorphic workspace of serial chains. The forward kinematics equations take the form of a finite trigonometric series in terms of the input crank rotations. The proposed Fourier-based synthesis method exploits the special structure of these equations to achieve the combined number and dimensional synthesis of SDCSC mechanisms for planar path following tasks.
