Mechanics of walking and running up and downhill: A joint-level perspective to guide design of lower-limb exoskeletons.
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 mechan...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Public Library of Science (PLoS)
2020-01-01
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| Series: | PLoS ONE |
| Online Access: | https://doi.org/10.1371/journal.pone.0231996 |
| _version_ | 1819142057496674304 |
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| author | Richard W Nuckols Kota Z Takahashi Dominic J Farris Sarai Mizrachi Raziel Riemer Gregory S Sawicki |
| author_facet | Richard W Nuckols Kota Z Takahashi Dominic J Farris Sarai Mizrachi Raziel Riemer Gregory S Sawicki |
| author_sort | Richard W Nuckols |
| collection | DOAJ |
| description | 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 -8.53°, -5.71°, 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). |
| first_indexed | 2024-12-22T12:04:18Z |
| format | Article |
| id | doaj.art-82b30d9b1c214d2f8c98f35c7584a47c |
| institution | Directory Open Access Journal |
| issn | 1932-6203 |
| language | English |
| last_indexed | 2024-12-22T12:04:18Z |
| publishDate | 2020-01-01 |
| publisher | Public Library of Science (PLoS) |
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| series | PLoS ONE |
| spelling | doaj.art-82b30d9b1c214d2f8c98f35c7584a47c2022-12-21T18:26:28ZengPublic Library of Science (PLoS)PLoS ONE1932-62032020-01-01158e023199610.1371/journal.pone.0231996Mechanics of walking and running up and downhill: A joint-level perspective to guide design of lower-limb exoskeletons.Richard W NuckolsKota Z TakahashiDominic J FarrisSarai MizrachiRaziel RiemerGregory S SawickiLower-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 -8.53°, -5.71°, 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).https://doi.org/10.1371/journal.pone.0231996 |
| spellingShingle | Richard W Nuckols Kota Z Takahashi Dominic J Farris Sarai Mizrachi Raziel Riemer Gregory S Sawicki Mechanics of walking and running up and downhill: A joint-level perspective to guide design of lower-limb exoskeletons. PLoS ONE |
| title | Mechanics of walking and running up and downhill: A joint-level perspective to guide design of lower-limb exoskeletons. |
| title_full | Mechanics of walking and running up and downhill: A joint-level perspective to guide design of lower-limb exoskeletons. |
| title_fullStr | Mechanics of walking and running up and downhill: A joint-level perspective to guide design of lower-limb exoskeletons. |
| title_full_unstemmed | Mechanics of walking and running up and downhill: A joint-level perspective to guide design of lower-limb exoskeletons. |
| title_short | Mechanics of walking and running up and downhill: A joint-level perspective to guide design of lower-limb exoskeletons. |
| title_sort | mechanics of walking and running up and downhill a joint level perspective to guide design of lower limb exoskeletons |
| url | https://doi.org/10.1371/journal.pone.0231996 |
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