Design and development of ankle-foot prosthesis with delayed release of plantarflexion

Abstract

Abstract-A computer-controlled mechanism that fits a standard ankle-foot prosthesis was designed to capture the absorbed energy in the ankle and delay its release until specific times in the gait cycle. This mechanism used a direct current motor to take up and hold the compression of a carbon-fiber ankle joint. Based on the timing of the contact forces between the foot and the ground, a microprocessor released the spring at preset times later in the gait cycle. This mechanism was added to a Talux prosthetic foot and was employed by a user of a conventional energy-storage ankle-foot prosthesis. His gait was recorded using a motion analysis system. Five settings: 0, 55, 65, 75, and 85 ms delay were tested on separate days, and the standard kinematic and kinetic gait data were recorded. The user reported some settings were more comfortable than others. When these preferences were tested with a randomized doubleblind trial, the preferences were not consistent. A second user showed a preference for the 55 ms delay. The modifications to the device resulted in changes to the gait of the subjects, including increased cadence and kinematics of the unaffected joints and a longer, slower push from the ankle, which was noticed by both of the subjects.

Dorsiflexion and Plantarflexion Test and Analysis for a new Carbon Fiber Ankle-Foot Prosthesis

“…The testing devise head recorded a displacement about 14.6 mm when the test was ended. The loaddeflection curve was recorded figure (6), which shows a non-linear behavior of the prosthesis under the dorsiflexion test conditions.…”

“…The ankle joint will take a positive angle (dorsiflexion) through the mid stance phase and continue progress in positive angle during the heel off to the toe off. During the pre-swing phase, the ankle will develop a large negative angle, then returns back to the neutral position through the period of swing phase preparing for the next gait cycle [6]. These sequences of dorsi-plantarflexion of the ankle joint can be summarized in the following as seen in the figure (1):…”

Advances in Propulsive Bionic Feet and Their Actuation Principles

“…Although these devices are highly elaborated mechatronical systems, they fall out of the state of the art in propulsive bionic, feet since they do not make use of external mechanical power generation to provide their wearer with active stabilization or push-off properties. Comprised in the category of articulated ESR feet are Brackx et al's AMP-Foot 1.0 and 1.1 [16], Collins and Kuo's CESR foot [17], and Mitchell et al ankle-foot prosthesis with delayed plantarflexion [18], to name a few. A complete state-of-the-art study of CF and ESR feet can be found in [19].…”

The AMP-Foot 2.1 : actuator design, control and experiments with an amputee

“…5 To replace the missing limb, numerous prosthetic feet have been developed. These can be subdivided into the so-called 'Conventional Feet' (CF), 'Energy-Storing-and-Returning Feet' (ESR) [6][7][8] and 'Bionic Feet'. [9][10][11][12][13][14] While the first prosthetic feet were made to restore basic functional mobility, the latest advances in ESR and Bionic feet aim at raising the 3C-level (control, comfort and cosmetics) 15 of a patient by mimicking, as precisely as possible, the characteristics of an intact limb.…”

“…[9][10][11][12][13][14] While the first prosthetic feet were made to restore basic functional mobility, the latest advances in ESR and Bionic feet aim at raising the 3C-level (control, comfort and cosmetics) 15 of a patient by mimicking, as precisely as possible, the characteristics of an intact limb. 16,17 This evolution is mostly due to the technological advancements in engineering in the past decades in mechanical parts production and control, 12,[18][19][20] computer aided design and simulation software, cheap and miniaturised electronics, micro-controller technology, and various new types of actuators like Pneumatic Artificial Muscles (PAM), 21 Parallel Elastic Actuators (PEA), 22,23 Series Elastic Actuators (SEA), 24,25 Variable Stiffness Actuators (VSA) 26 and Series-Parallel Elastic Actuators (SPEA), 27 to name a few.…”