Technology and Disability - Volume 17, issue 3

Authors: Sebelius, F. | Axelsson, M. | Danielsen, N. | Schouenborg, J. | Laurell, T.

Article Type: Research Article

Abstract: A myoelectric control system for prostheses was developed and evaluated on six healthy subjects. These were able to control a computer-animated hand in real-time with a 20 Hz update rate. A data glove, equipped with joint angle sensors, was used to train the system and to evaluate the continuous predictions of joint angles. A linear envelop filter was used for EMG signal pre-processing and the recognition of muscle patterns was carried out with local approximation using the “lazy learning” algorithm. Furthermore, an on-line learning was used to provide feedback to the subjects. The results show that the subjects …increased their performance during the experiment and all subjects performed eight or more movements with 100% accuracy in their last recording session. The final median delay for the predicted hand joint positions, compared with the recorded, was in the range of 50 to 100 ms. Off-line evaluation has earlier been done on amputees while using a data glove on the contralateral hand. The real-time control system outlined in this paper offers an effective myoelectric prosthesis control that is suitable for a miniaturized low cost implementation. This paper is a part of a ongoing development and refinement of hand prosthesis carried out within the Artificial Hand Project. Show more

Keywords: EMG, myoelectric, hand prosthesis, recognition, real-time control, local approximation

DOI: 10.3233/TAD-2005-17301

Citation: Technology and Disability, vol. 17, no. 3, pp. 131-141, 2005

Authors: Sigafoos, Jeff | O'Reilly, Mark | Ganz, Jennifer B. | Lancioni, Giulio E. | Schlosser, Ralf W.

Article Type: Research Article

Abstract: Self-determination applied to augmentative and alternative communication (AAC) interventions suggests the need to assess students' preferences for various communication devices. We describe a potentially promising methodology for enabling students to indicate preference for communication devices. Implementation of this methodology is illustrated in two controlled demonstrations. In the first demonstration, two adolescents with developmental disabilities were taught to use each of three voice-output communication aids (VOCAs) to request snacks. Following acquisition, all three VOCAs were simultaneously available across repeated opportunities and the student could select which one of the three devices to use. Both students demonstrated a consistent preference for one …of the VOCAs. In the second demonstration, these same two students were provided with a choice between their preferred VOCA and a communication board containing line drawings. Both students demonstrated a preference for the VOCA over the communication board. These cases illustrate a potentially useful methodology that might enable non-speaking students with developmental disabilities to participate in communication device selection. Show more

Keywords: developmental disability, preference assessment, self-determination, voice-output communication aids, communication boards

DOI: 10.3233/TAD-2005-17302

Citation: Technology and Disability, vol. 17, no. 3, pp. 143-153, 2005

Authors: Cook, Albert M. | Dobbs, Bonnie M. | Warren, Sharon | McKeever, Rebecca

Article Type: Research Article

Abstract: The purpose of this study was to determine the impact on performance of repeated trials of the Tracker system in a series of target acquisition tasks for persons with cerebral palsy (CP). Twelve persons with CP participated in the single case experimental study. Data were collected on their time to target, time to select, and distance moved to targets of increasingly smaller size across four, once weekly sessions of one hour length. Time and distance were measured using the software programs Speaking Dynamically Pro and Mouse Offroad. Nine of the 12 participants were able to achieve a smaller target at …the end of the session compared to the initial target size of 2.5 inches square. Results across sessions for targets of the same size indicated that six participants reduced their times to target and seven reduced the distance moved to acquire the target. However, only two participants showed a decrease in their time to select scores. The findings are discussed in terms of the application of the Tracker One system for individuals with CP. Show more

Keywords: computer access, cerebral palsy, target acquisition

DOI: 10.3233/TAD-2005-17303

Citation: Technology and Disability, vol. 17, no. 3, pp. 155-163, 2005

Authors: Snider-Riczker, Paula | Ryan, Stephen | Campbell, Kent | Bortolussi, Joseph

Article Type: Research Article

Abstract: Objective: Bathtub drowning is a leading cause of unintentional injury death for infants in the United States. Most drownings occurred during a lapse in adult supervision. We studied whether parents of children with postural control needs and parents of infants who can sit unsupported report the same levels of child supervision during bath time activities. Method: Sixteen parents of preschoolers with physical disabilities participated in one of two focus groups. Results: Although parents reported that they would never leave their children alone in the bathtub, a few acknowledged that they would leave their children unsupervised for …brief moments if they believed that their children were safe, secure and well supported. Further, many participants felt that supervision of their young children could be assigned to older, responsible siblings. Conclusion: The self-reported behaviours of parents in our study are similar to those reported by other parents. This finding suggests that the injury risk in bathtubs is potentially higher for children who use devices for postural support. Further research is needed to study whether this heightened risk is reasonable considering the benefits of specialty bath seats for young children with physical disabilities. Show more

Keywords: children, physical disabilities, adaptive seating, injury risk

DOI: 10.3233/TAD-2005-17304

Citation: Technology and Disability, vol. 17, no. 3, pp. 165-171, 2005

Authors: Capilouto, Gilson J. | Higginbotham, D. Jeffery | McClenaghan, Bruce | Williams, Harriet G. | Dickerson, John

Article Type: Research Article

Abstract: This study investigated the relative performance of two computer input devices appropriate for persons sharing similar motor challenges: a head operated device and expanded membrane cursor keys. Performance was evaluated in the context of a Fitts' law target acquisition task. For this initial phase of investigation, subjects without disabilities were selected to focus on performance differences inherent in the devices and their operation. Results indicated that the total time to acquire a target was significantly faster for the head device than for the expanded cursor keys. For typical young adults, the head-operated device required less time to reach asymptote performance …by simplifying the cognitive demands for device operation. These results suggest that for persons unable to isolate their fingers, head-operated controls may offer advantages over input devices operated by the upper extremities. Show more

Keywords: assistive technology, computer access, mouse emulation, severe disabilities

DOI: 10.3233/TAD-2005-17305

Citation: Technology and Disability, vol. 17, no. 3, pp. 173-183, 2005