TY - JOUR
T1 - Soft, wearable, and pleated pneumatic interference actuator provides knee extension torque for sit-to-stand
AU - Veale, Allan Joshua
AU - Staman, Kyrian
AU - Van Der Kooij, Herman
PY - 2021
Y1 - 2021
N2 - Soft wearable actuators can help connect machines and humans, providing a personalized, ergonomic, and cooperative physical interface between people and their world. Until now, the torque of these interfaces has been limited, restricting their ability to assist the completely paralyzed. This article presents a method for realizing a soft structure that stably and comfortably applies a knee extension torque to the body that is sufficient for sit-to-stand (STS). The structure, the pleated pneumatic interference actuator (PPIA), is based on pleated inflatables; is lightweight, collapsible, and clothing integratable; and generates torque from buckling of a constrained fabric-reinforced rubber tube. Multiple PPIAs were integrated into a soft orthosis, the soft lift assister for the knee (SLAK). The SLAK was inflated to a pressure of 320 kPa, and it produced a maximum 324 Nm torque at a flexion angle of 82°. This exceeds the peak 180 Nm torque required for STS and torques required for other everyday tasks. The SLAK met the torque requirement for STS, which is more than 93% of the STS motion when worn by a test leg. Worn by a human, it shows potential for complete support, which is more than 100% of the motion. The PPIA's theoretical model overestimated torque at low to moderate flexion angles and underestimated PPIA torque at high flexion angles. Further development of the PPIA will focus on testing the SLAK with human subjects; increasing the PPIA's speed and flexibility; reducing the PPIA's bulk; and improving the PPIA's model accuracy.
AB - Soft wearable actuators can help connect machines and humans, providing a personalized, ergonomic, and cooperative physical interface between people and their world. Until now, the torque of these interfaces has been limited, restricting their ability to assist the completely paralyzed. This article presents a method for realizing a soft structure that stably and comfortably applies a knee extension torque to the body that is sufficient for sit-to-stand (STS). The structure, the pleated pneumatic interference actuator (PPIA), is based on pleated inflatables; is lightweight, collapsible, and clothing integratable; and generates torque from buckling of a constrained fabric-reinforced rubber tube. Multiple PPIAs were integrated into a soft orthosis, the soft lift assister for the knee (SLAK). The SLAK was inflated to a pressure of 320 kPa, and it produced a maximum 324 Nm torque at a flexion angle of 82°. This exceeds the peak 180 Nm torque required for STS and torques required for other everyday tasks. The SLAK met the torque requirement for STS, which is more than 93% of the STS motion when worn by a test leg. Worn by a human, it shows potential for complete support, which is more than 100% of the motion. The PPIA's theoretical model overestimated torque at low to moderate flexion angles and underestimated PPIA torque at high flexion angles. Further development of the PPIA will focus on testing the SLAK with human subjects; increasing the PPIA's speed and flexibility; reducing the PPIA's bulk; and improving the PPIA's model accuracy.
KW - active orthosis
KW - exosuit
KW - high torque
KW - pleated pneumatic interference actuator
KW - sit-to-stand
KW - soft fluidic actuator
KW - wearable inflatable actuator
UR - http://www.scopus.com/inward/record.url?scp=85101237072&partnerID=8YFLogxK
U2 - 10.1089/soro.2019.0076
DO - 10.1089/soro.2019.0076
M3 - Article
AN - SCOPUS:85101237072
SN - 2169-5172
VL - 8
SP - 28
EP - 43
JO - Soft Robotics
JF - Soft Robotics
IS - 1
ER -