A user-specific human-machine interaction strategy for a prosthetic shank adapter

Abstract

For people with lower limb amputation, a userspecific human-machine interaction with their prostheses is required to ensure safe and comfortable assistance. Especially during dynamic turning manoeuvres, users experience high loads at the stump, which decreases comfort and may lead to long-term tissue damage. Preliminary experiments with users wearing a configurable, passive torsional adaptor indicate increased comfort and safety achieved by adaptation of torsional stiffness and foot alignment. Moreover, the results show that the individual preference regarding both parameters depend on gait situation and individual preference. Hence, measured loads in the structure of the prosthesis and subjective feedback regarding comfort and safety during different turning motions are considered in a user-specific human-machine interaction strategy for a prosthetic shank adaptor. Therefore, the interrelations of gait parameters with optimal configuration are stored in an individual preference-setting matrix. Stiffness and foot alignment are actively adjusted to the optimal parameters by a parallel elastic actuator. Two subjects reported that they experienced appropriate variation of stiffness and foot alignment, a noticeable reduction of load at the stump and that they could turn with less effort.

A Prosthetic Shank With Adaptable Torsion Stiffness and Foot Alignment

“…To take different gait situations and velocities into account, a test cycle that models a typical day of an amputee is generated. This test cycle facilitates the comparison of actuator (Stuhlenmiller et al, 2017 Each combination of gait situation and velocity is conjugated with the corresponding user-specific optimal torsional stiffness and foot alignment.…”

New technologies applied to canine limb prostheses: A review

“…Similar to humans, one approach could be to indirectly measure the kinematic interactions between the socket and the underlying bone using marker-based motion capture technology based on assumptions about joint constraints imposed on the system [ 80 ]. Further analysis involves the development and validation of tissue mechanics models using the collected marker-based information [ 81 ]. Moreover, most prostheses do not reproduce concentric muscle action and mainly have a passive function.…”

Design and Analysis of a Clutched Parallel Elastic Actuator

“…The gearbox and the engine are connected via the joint connection part (8), and the test bench mount is also mounted here. The load connection (5) for the test bench is connected directly to the output of the gear unit (6). The gearbox is a Harmonic Drive HFUS-2SO with a reduction ratio of 50:1 (6) (Harmonic Drive AG, Limburg an der Lahn, Germany).…”

“…The application of PEAs in prosthetics has already proven successful with prototypes. The interaction between human and machine can be improved by optimizing the stiffness and foot alignment to the walking situation [6]. Grimmer et al showed in a simulation study that the energy consumption and the peak power are reduced by a PEA for the ankle joint over a range between 0.5 m/s and 2.6 m/s [7].…”