Transtibial (TT) amputations, or below-knee amputations, are among the most frequently performed major limb removals. To replace the missing limb, numerous prosthetic devices were developed. A study of the state-of-the-art in TT prostheses shows that none of the commercially available devices are capable of mimicking an able-bodied ankle-foot complex. Still on a research level, some powered prosthetic devices have the potential to improve amputee walking experience, but still need heavy and bulky actuators to provide the necessary power of propulsion. With the AMP-Foot 2.0, the authors propose a new concept for an energy efficient, powered transtibial prosthesis. Its design enables the use of a low power actuator which stores energy in springs during the complete stance phase that can be released at push-off. Thanks to this, the size and weight of the actuator can be decreased considerably while the ankle still provides the full power necessary for forward propulsion. A prototype of the AMP-Foot 2.0 has been built and experiments with a transfemural amputee were conducted. The captured data is presented and analyzed throughout this paper.

This paper discusses two ways to estimate the interaction force at the end-effector of a robot. The first approach that is presented combines filtered dynamic equations with a recursive least squares estimation algorithm to provide a smoothened force signal, which is useful in the (common) case of noisy torque measurements.The second approach, which uses a generalized momentum based disturbance observer, is mainly discussed to compare it to the first approach. Although very different in appearance, it is shown that a close connection exists between both approaches.Simulation results for both algorithms are shown, and experimental results derived from a sensorless admittance controller that was implemented using the algorithms are presented.

No abstract

No abstract

The Ankle Mimicking Prosthetic (AMP-) Foot 2 is a new energy efficient, powered transtibial prosthesis mimicking intact ankle behavior. The author's research is focused on the use of a low power actuator which stores energy in springs during the complete stance phase. At push-off, this energy can be released hereby providing propulsion forces and torques to the amputee. With the use of the so-called catapult actuator, the size and weight of the drive can be decreased compared to state-of-the-art powered prostheses, while still providing the full power necessary for walking.In this article, the authors present a detailed description of the catapult actuator followed by a comparison with existing actuator technology in powered prosthetic feet with regard to torque and power requirements. The implication on the actuator's design will then be outlined. Further, a description of the control strategy behind the AMP-Foot 2 and 2.1 will be given. In the last section of the article, the actuation principle and control are illustrated by experimental validation with a transfemoral amputee. Conclusions and future work complete the paper.