TY - JOUR
T1 - Mechanics of walking and running up and downhill
T2 - A joint-level perspective to guide design of lower-limb exoskeletons
AU - Nuckols, Richard W.
AU - Takahashi, Kota Z.
AU - Farris, Dominic J.
AU - Mizrachi, Sarai
AU - Riemer, Raziel
AU - Sawicki, Gregory S.
N1 - Funding Information:
Supported by Grant 2011152 from the United States-Israel Binational Science Foundation (https://www.bsf.org.il/) to G.S.S. and R.R and U.S. Army Natick Soldier Research, Development and Engineering Center (http://nsrdec.natick.army.mil/) (W911QY18C0140) to G.S.S. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
PY - 2020/8
Y1 - 2020/8
N2 - Lower-limb wearable robotic devices can improve clinical gait and reduce energetic demand in healthy populations. To help enable real-world use, we sought to examine how assistance should be applied in variable gait conditions and suggest an approach derived from knowledge of human locomotion mechanics to establish a 'roadmap' for wearable robot design. We characterized the changes in joint mechanics during walking and running across a range of incline/decline grades and then provide an analysis that informs the development of lower-limb exoskeletons capable of operating across a range of mechanical demands. We hypothesized that the distribution of limb-joint positive mechanical power would shift to the hip for incline walking and running and that the distribution of limb-joint negative mechanical power would shift to the knee for decline walking and running. Eight subjects (6M,2F) completed five walking (1.25 m s-1) trials at -8.53̊, -5.71̊, 0∘, 5.71∘, and 8.53∘ grade and five running (2.25 m s-1) trials at -5.71∘, -2.86∘, 0∘, 2.86∘, and 5.71∘ grade on a treadmill. We calculated time-varying joint moment and power output for the ankle, knee, and hip. For each gait, we examined how individual limb-joints contributed to total limb positive, negative and net power across grades. For both walking and running, changes in grade caused a redistribution of joint mechanical power generation and absorption. From level to incline walking, the ankle's contribution to limb positive power decreased from 44% on the level to 28% at 8.53∘ uphill grade (p < 0.0001) while the hip's contribution increased from 27% to 52% (p < 0.0001). In running, regardless of the surface gradient, the ankle was consistently the dominant source of lower-limb positive mechanical power (47-55%). In the context of our results, we outline three distinct use-modes that could be emphasized in future lower-limb exoskeleton designs 1) Energy injection: adding positive work into the gait cycle, 2) Energy extraction: removing negative work from the gait cycle, and 3) Energy transfer: extracting energy in one gait phase and then injecting it in another phase (i.e., regenerative braking).
AB - Lower-limb wearable robotic devices can improve clinical gait and reduce energetic demand in healthy populations. To help enable real-world use, we sought to examine how assistance should be applied in variable gait conditions and suggest an approach derived from knowledge of human locomotion mechanics to establish a 'roadmap' for wearable robot design. We characterized the changes in joint mechanics during walking and running across a range of incline/decline grades and then provide an analysis that informs the development of lower-limb exoskeletons capable of operating across a range of mechanical demands. We hypothesized that the distribution of limb-joint positive mechanical power would shift to the hip for incline walking and running and that the distribution of limb-joint negative mechanical power would shift to the knee for decline walking and running. Eight subjects (6M,2F) completed five walking (1.25 m s-1) trials at -8.53̊, -5.71̊, 0∘, 5.71∘, and 8.53∘ grade and five running (2.25 m s-1) trials at -5.71∘, -2.86∘, 0∘, 2.86∘, and 5.71∘ grade on a treadmill. We calculated time-varying joint moment and power output for the ankle, knee, and hip. For each gait, we examined how individual limb-joints contributed to total limb positive, negative and net power across grades. For both walking and running, changes in grade caused a redistribution of joint mechanical power generation and absorption. From level to incline walking, the ankle's contribution to limb positive power decreased from 44% on the level to 28% at 8.53∘ uphill grade (p < 0.0001) while the hip's contribution increased from 27% to 52% (p < 0.0001). In running, regardless of the surface gradient, the ankle was consistently the dominant source of lower-limb positive mechanical power (47-55%). In the context of our results, we outline three distinct use-modes that could be emphasized in future lower-limb exoskeleton designs 1) Energy injection: adding positive work into the gait cycle, 2) Energy extraction: removing negative work from the gait cycle, and 3) Energy transfer: extracting energy in one gait phase and then injecting it in another phase (i.e., regenerative braking).
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U2 - 10.1371/journal.pone.0231996
DO - 10.1371/journal.pone.0231996
M3 - Article
C2 - 32857774
AN - SCOPUS:85090171998
VL - 15
JO - PLoS One
JF - PLoS One
SN - 1932-6203
IS - 8 August
M1 - e0231996
ER -