Browsing by Subject "myoelectric control"

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    APPLICATION INDEPENDENT ASSESSMENT OF CAPACITY FOR MYOELECTRIC CONTROL
    (2008) Higuchi, Tetsuya; Kajitani, Isamu
    There is a growing need for objective and quantitative tools to measure the outcome of assistive technologies (AT), such as powered prostheses and communication aides for people with disabilities [1,2]. The most typical types of assessment are task completion tests or performance tests, where the user performs specific tasks relating to practical daily activities and the time required for task completion is used as the assessment. The main purposes for such outcome measurements are the assessment of patient improvements, the selection of appropriate AT devices for patients and the evaluation of newly developed AT devices. The appropriate choice of an assessment method requires careful consideration, because assessment results can be influenced by many factors. For instance, applications to AT device selection, where a therapist would investigate the outcome differences for different AT devices; assessment results may be influenced primarily by task proficiency, which thus makes the appropriate selection of an AT device difficult. This paper introduces a basic form of assessment that is both task- and applicationindependent, which focuses on the operation capacity of an input device to an AT. In most AT devices, single or multiple switches are widely accepted as the de facto standard input devices, so the proposed method evaluates the operation capabilities of single switches. At the same time, there are also a number of research projects that are seeking to develop augmentative and alternative input methods for AT devices. However, because of the wide variety of impairments, certain restrictions still remain on increasing the number of candidate input methods. Accordingly, we are working on general purpose myoelectric interfaces that are compatible with various commercial AT devices. Preliminary evaluations of the myoelectric interface are also presented in this report.
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    ItemOpen Access
    ASSESSMENT OF CAPACITY FOR MYOELECTRIC CONTROL: CONSTRUCT VALIDITY AND RATING SCALE STRUCTURE
    (2008) Lindner, Helen Y. N.; Linacre, John M.; Norling Hermansson, Liselotte M.
    The Assessment of Capacity for Myoelectric Control (ACMC) is a 30-item standardized clinical assessment designed for the upper limb prosthesis group [1, 2]. It measures the quality of prosthetic hand movement performed by the prosthesis user during a self-chosen two-handed functional task. ACMC is suitable for prosthesis users of all ages and of all prosthetic sides/levels [2, 3] . Previously, repeated ACMC assessments of upper limb prosthesis users were used to evaluate the validity of the construct [1]. Since the strengths and weaknesses among these users were likely to be repeated several times in the data obtained, the abilities of the prosthesis users in that sample might not give the best picture of the functioning of the items. It was hypothesised that a wider range of ability across the sample might provide a better picture of the functioning of items. Therefore, a further validation of ACMC based on single measures was considered. The performance of the 30 ACMC items is rated on a 4-point scale, ranging from 0-not capable – to 3-spontaneously capable. One concern is if the four ACMC categories are sufficient to differentiate the prosthesis users on the basis of their abilities. Another concern is whether the raters have used the four categories in the expected manner. The overall aim of this study was therefore (a) to evaluate the construct validity of ACMC and (b) to examine the 4-point rating scale structure and its use. With a larger sample of single measures, specific questions were asked: Does a larger number of subjects provide a wider range of prosthetic ability than was found in the first validity study? Does the hierarchical order of ACMC items match the clinical knowledge about the difficulty of the items? Do all the items work together to measure a single “prosthetic control” dimension? Do all the items function as expected? Is the 4-point rating scale appropriately constructed to differentiate between prosthesis users with different abilities? Have the four rating-scale categories been used in the expected manner?
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    ItemOpen Access
    REAL-TIME MYOELECTRIC CONTROL IN A VIRTUAL ENVIRONMENT TO RELATE USABILITY VS. ACCURACY
    (2005) Lock, B.A.; Englehart, K.; Hudgins, B.
    Many clinically available, upper-extremity prosthetic limbs provide myoelectric control of a single device, such as a hand, elbow, or wrist. Most commonly, these systems yield control information from myoelectric signal (MES) amplitude [1] or rate of change of MES [2]. Such systems have been beneficial; however, prosthetic users would no doubt find enhanced functionality and usability if they could reliably control more than a single function (or device). Seeking to address this issue, extensive work has gone into developing schemes that provide multifunction myoelectric classification with very high accuracy [3]. However, for all continuous multifunction MES classifiers, no matter how accurate and repeatable, there exists no defined threshold (classification accuracy) of acceptability. This is due, in large part, to the limited availability of prosthetic devices housing multiple electromechanical functions. Described in this paper is a recently developed MES control software tool that incorporates state-of-the-art multifunction control and a multifunction, real-time virtual limb. Twelve subjects have performed a virtual clothes pin functional test [4] yielding results that relate classification accuracy and multifunction device usability. Preliminary results indicate no strong relationship between accuracy and usability scores as determined by this tool.