Bio-inspired Control of Joint Torque and Knee Stiffness in a Robotic Lower Limb Exoskeleton Using a Central Pattern Generator
Loading...
Author / Producer
Date
2017-07-02
Publication Type
Conference Paper
ETH Bibliography
yes
Citations
Altmetric
Data
Rights / License
Abstract
Robotic lower limb exoskeletons are becoming
increasingly popular in therapy and recreational use. However,
most exoskeletons are still rather limited in their locomotion
speed and the activities of daily live they can perform. Furthermore,
they typically do not allow for a dynamic adaptation to
the environment, as they are often controlled with predefined
reference trajectories. Inspired by human leg stiffness modulation
during walking, variable stiffness actuators increase flexibility
without the need for more complex controllers. Actuation
with adaptable stiffness is inspired by the human leg stiffness
modulation during walking. However, this actuation principle
also introduces the stiffness setpoint as an additional degree of
freedom that needs to be coordinated with the joint trajectories.
As a potential solution to this issue a bio-inspired controller
based on a central pattern generator (CPG) is presented in this
work. It generates coordinated joint torques and knee stiffness
modulations to produce flexible and dynamic gait patterns
for an exoskeleton with variable knee stiffness actuation. The
CPG controller is evaluated and optimized in simulation using
a model of the exoskeleton. The CPG controller produced
stable and smooth gait for walking speeds from 0.4 m/s up
to 1.57 m/s with a torso stabilizing force that simulated the use
of crutches, which are commonly needed by exoskeleton users.
Through the CPG, the knee stiffness intrinsically adapted to the
frequency and phase of the gait, when the speed was changed.
Additionally, it adjusted to changes in the environment in the
form of uneven terrain by reacting to ground contact forces.
This could allow future exoskeletons to be more adaptive to
various environments, thus making ambulation more robust.
Permanent link
Publication status
published
External links
Editor
Book title
2017 International Conference on Rehabilitation Robotics (ICORR)
Journal / series
Volume
Pages / Article No.
1387 - 1394
Publisher
IEEE
Event
15th IEEE International Conference on Rehabilitation Robotics (ICORR 2017)
Edition / version
Methods
Software
Geographic location
Date collected
Date created
Subject
Organisational unit
03827 - Gassert, Roger / Gassert, Roger
Notes
Video 1:22