Soft knee exosuit
Completely supports sit to stand
References
[1] Chung, J., Heimgartner, R., O'Neill, C.T., Phipps, N.S. and Walsh, C.J., 2018, August. BioRob (pp. 509-516). [2] Nesler, C.R., Swift, T.A. and Rouse, E.J., 2018. Soft robotics, 5(2), pp.138-148.
[3] Veale, A.J., Staman, K., van der Kooij, H., 2018, October. WeRob (pp. 39-43).
This work is supported by NWO,
Domain Applied and Engineering Sciences, Project no. 14429.
Allan J. Veale,* Kyrian Staman, and Herman van der Kooij *a.j.veale@utwente.nl
Department of Biomechanical Engineering, Faculty of Engineering Technology
Introduction
Flexible tube P θ τ Air in/out Flexion angle TorquePleated PIA (PPIA) [3]
Pleat constraint Pleat Valley fold Mountain fold
Pleated PIA (PPIA)
SLAK (soft lifting assister for the knee) STS prototype construction
Attachment: Overview: Pleat constraint Air in/out Flexible tube Valley fold Mountain fold Cross section
Discussion
Cords for lateral stability
Actuator
torque torqueCord
Knee joint Cord
forces
Conclusion and future work
Results
Pressure fixed:
+ Quasistatic standing movement + Torque requirement met over + 93 % of STS motion + Torque of 320 Nm at 82 ° + decreases parabolically to + 3.8 Nm at 7.9 ° Pneumatic Interference Actuator (PIA) [2]:
+ Torque generated by volume change + of buckling tube
+ No torque produced when straight
+ Pleat added to tube (two valley folds + and a mountain fold)
+ Pleat constraint keeps pleat in tube
+ Torque produced when + straight
+ Increased torque
SLAK fully supports STS motion when worn, but not on the test leg:
+ Test leg rigidity and smoothness (compared to the body) made it + difficult to keep the SLAK in the same place
+ Shifting of the SLAK misaligned it, reducing its torque output + The body's compliance and friction coefficient are important
+ factors in determining how much torque can be transmitted to it
Parallel PPIAs effectively stabilize each other:
+ The previous PPIA STS pants [3] required cords to laterally stabilize + the PPIA. Tension in these cords produced counter torques.
+ Parallel PPIAs do not have these cords, yet do not buckle sideways
PPIA performance:
+ Met the STS torque requirement for 93 (100) %
+ of the STS range of motion when worn on the test + leg (body)
+ Produced ≥ 320 Nm @ 320 kPa
+ Had a torque generating range of motion of ≥ 74.1 °
Next:
+ Test the ability of the SLAK to assist healthy subjects + with STS
+ Characterize the power and speed of the SLAK
Soft actuators:
+ Safe (yield to excessive forces)
+ Ergonomic (move with/conform to the + body)
+ Don't fully support many everyday + movements like sit to stand (STS) [1]
High torque actuators:
+ Assist the completely paralyzed
+ Augment workers in demanding situations + Apply rehabilitation therapy to stiff joints
Velcro Zip Padding Pants Stitched nylon shell Flexible tube Buckle Leg end stop Previous actuator [3]: Angle fixed:
+ Torque increased with
+ pressure and flexion angle + Linearity increased with + flexion angle
+ Hysteresis low and changes + direction with pressure
+ Shown are results ± 2 SD + (n = 6)
