Browsing by Author "Heckathorne, Craig W."

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Open Access
EVALUATION OF A PROTOTYPE ELECTRIC-POWERED PARTIAL-HAND PROSTHESIS
(2005) Heckathorne, Craig W.; Weir, Richard F.
A prototype partial hand mechanism has been developed for fittings at the trans-metacarpal level. Subjects selected for evaluation of the prototype device have absence of all fingers of the affected hand, all or some portion of the metacarpals present, at least one active intrinsic hand muscle, and relatively unimpaired wrist movement. The presence of one or two intrinsic hand muscles allows for proportional myoelectric control without resorting to forearm muscles that would be recruited during wrist positioning. The mechanism is suspended from the hand structure with a custom silicone socket. The socket extends no more proximal than the styloids so that the physiological wrist motion is unencumbered, allowing for orientation of the hand in a near physiological manner.
Open Access
Experience With The Rimjet Locking Humeral Rotator
(1999) Uellendahl, Jack E.; Heckathorne, Craig W.
Open Access
Neurofuzzy Logic as a Control Algorithm for an Externally Powered Multifunctional Hand Prosthesis
(2002) Ajiboye, Abidemi Bolu; Weir, Richard F.; Heckathorne, Craig W.; Childress, Dudley S.
We propose an algorithm based upon neurofuzzy technology. We believe that because of the inherent “fuzziness” of human activity, a control algorithm based on fuzzy logic may have advantages for multifunctional prosthesis control. We seek an acceptable compromise between the number of electrode sites used and processing complexity, and thereby desire not more than three to four control sites to control three to four DOF. This approach delivers more information to the system and, by using fuzzy logic, reduces the complexity of the processing.
Open Access
REAL-TIME COMPUTER MODELING OF A PROSTHESIS CONTROLLER BASED ON EXTENDED PHYSIOLOGICAL PROPRIOCEPTION (EPP)
(2002) Farrell, Todd; Weir, Richard F.; Heckathorne, Craig W.; Childress, Dudley S.
Proprioception utilizes the physiological components of the nervous and musculoskeletal systems to allow an individual to sense the position of their limbs subconsciously. By providing a rigid connection to an object this proprioceptive ability can be extended to the object and allow the user to sense the spatial location and orientation of these objects with respect to his or her body. This concept explains how a person can use a tennis racquet to hit a tennis ball without having to observe the position of the racquet during their swing or the way a blind person uses a long cane to ‘feel’ the location of objects in their surroundings. Body-powered prostheses take advantage of this proprioceptive ability by relating the motion and position of the prosthesis to the motion and position of an intact joint of the amputee via the control cable. However, most externally powered prostheses do not have any mechanism with which to provide feedback regarding the state of the prosthesis to the proprioceptive system of the amputee. In these cases the amputee must rely on vision and other incidental sources of feedback such as motor whine and socket pressure to control their prostheses and this may place a significant cognitive load on the user.
Open Access
THE EFFECT OF CONTROLLER DELAY ON BOX AND BLOCK TEST PERFORMANCE
(2005) Farrell, Todd R.; Weir, Richard F.; Heckathorne, Craig W.
Multifunctional prosthesis controllers have shown higher classification accuracies when EMG feature extraction and pattern recognition are performed on time windows of longer duration [1] (see figure 1). However, there is a limit to the time over which EMG data can be collected and analyzed before the delay causes the control of the prosthesis to become cumbersome. While no one has objectively examined the impact of controller delays on performance, the controller delay that can be present before prosthesis control degrades has been debated. Childress and Weir [2] believe that controller delays should be kept below 50 ms to ensure that these delays are imperceptible to the user. However, another group has stated that delays as large as 300 ms are not perceivable by the user [3-4] and, while they have not commented on the effect of these delays on performance, they have stated that a 300 ms delay is acceptable for control of a prosthesis. The desired controller delay may affect the choice of signal processing and pattern recognition algorithms that can be utilized. Thus it would be beneficial to establish this value for future investigations. Experiments were designed to find the longest period of delay that does not significantly degrade prosthesis performance and can thus be dedicated to EMG collection and processing.
Open Access
The Prosthetics Needs Of Farmers And Ranchers With Upper-Limb Amputations
(2011) Heckathorne, Craig W.; Waldera, Kathy
Farming and ranching are among the most hazardous occupations in the United States with many non-fatal accidents resulting in amputation. In addition, those who continue to farm using prostheses are at risk of secondary injuries related to the prosthesis, such as falls, entanglement, and overuse injuries to the intact limb. Furthermore, the hazards of the farm environment are not limited to affecting the adult farmer, but also lead to a higher incidence of amputation among children of farmers than is experienced in children of the general population. Many advances have been made in prosthetics technology since the 1970s, especially with regard to lower-limb prostheses and electric-powered upper-limb prostheses. However, in 2008, the National Institute on Disability and Rehabilitation Research (NIDRR) identified farmers as an underserved population with respect to assistive technology including prosthetics. In response, the Northwestern University Prosthetics-Orthotics Center (NUPOC), as the NIDRR-funded Rehabilitation Engineering Research Center in Prosthetics and Orthotics, partnered with the National AgrAbility Project, a program of the U.S. Dept. of Agriculture that provides support services to farmers and ranchers with disabilities, to improve prosthetics options available to farmers and ranchers. The goals of this collaborative project include identification of activities supported by or hindered by use of a prosthesis, provide prosthetics-related educational materials to farmers and ranchers and to the prosthetists who serve them, and to improve prosthetics technology through analysis of failed components and engineering development projects. The project has completed the first phase of a two-part survey of farmers, ranchers, and prosthetists.