TY - JOUR
T1 - Stiffness evaluation of a novel ankle rehabilitation exoskeleton with a type-variable constraint
AU - Wang, Tun
AU - Lin, Yen Hua
AU - Spyrakos-Papastavridis, Emmanouil
AU - Xie, Sheng Quan
AU - Dai, Jian S.
N1 - Funding Information:
The authors gratefully acknowledge the support from the Engineering and Physical Sciences Research Council (EPSRC) of the United Kingdom under Grant No. EP/S019790/1 , the Science, Technology and Innovation Commission of Shenzhen Municipality unnder Grant ZDSYS20200811143601004 , and China Scholarship Council (CSC).
Publisher Copyright:
© 2022 The Author(s)
PY - 2023/1
Y1 - 2023/1
N2 - This paper presents a novel ankle rehabilitation exoskeleton with two rotational degrees of freedom, which is suitable for dynamical rehabilitation for patients with neurological impairments. Its stiffness performance is assessed in consideration that the interaction between the footplate and the ground may deflect the mechanism away from the desired/predefined motion patterns. The novel design employs a universal-prismatic-universal (U-P-U) joint link, whose constraint type changes between a couple and a line vector during manipulation of the exoskeleton. To conduct a stiffness analysis of such a mechanism with a type-variable constraint – for the first time – a modified screw-based method (SBM) is proposed. Comparisons with the results obtained from finite element analysis verified that, the modified SBM provides reliable estimates of the exoskeleton's stiffness within the complete workspace (covering the constraint-type transition configurations). The stiffness of the exoskeleton is further evaluated by acquiring the minimum/maximum stiffness values, after computing the distribution of the most crucial linear and angular stiffness parameters within the workspace. Moreover, the influence of the architectural parameters on the stiffness properties is considered for further design optimization.
AB - This paper presents a novel ankle rehabilitation exoskeleton with two rotational degrees of freedom, which is suitable for dynamical rehabilitation for patients with neurological impairments. Its stiffness performance is assessed in consideration that the interaction between the footplate and the ground may deflect the mechanism away from the desired/predefined motion patterns. The novel design employs a universal-prismatic-universal (U-P-U) joint link, whose constraint type changes between a couple and a line vector during manipulation of the exoskeleton. To conduct a stiffness analysis of such a mechanism with a type-variable constraint – for the first time – a modified screw-based method (SBM) is proposed. Comparisons with the results obtained from finite element analysis verified that, the modified SBM provides reliable estimates of the exoskeleton's stiffness within the complete workspace (covering the constraint-type transition configurations). The stiffness of the exoskeleton is further evaluated by acquiring the minimum/maximum stiffness values, after computing the distribution of the most crucial linear and angular stiffness parameters within the workspace. Moreover, the influence of the architectural parameters on the stiffness properties is considered for further design optimization.
KW - Ankle rehabilitation exoskeleton
KW - Stiffness analysis
KW - Transition configurations
KW - Type-variable constraint
UR - http://www.scopus.com/inward/record.url?scp=85139265439&partnerID=8YFLogxK
U2 - 10.1016/j.mechmachtheory.2022.105071
DO - 10.1016/j.mechmachtheory.2022.105071
M3 - Article
AN - SCOPUS:85139265439
SN - 0094-114X
VL - 179
JO - Mechanism and machine theory
JF - Mechanism and machine theory
M1 - 105071
ER -