Tesi etd-03292022-145205
Link copiato negli appunti
Tipo di tesi
Dottorato
Autore
LIVOLSI, CHIARA
URN
etd-03292022-145205
Titolo
Design and clinical testing of new control strategies for an hip exoskeleton for individuals with moderate gait impairments.
Settore scientifico disciplinare
ING-IND/34
Corso di studi
Istituto di Biorobotica - BIOROBOTICS
Commissione
relatore Dott.ssa CREA, SIMONA
Parole chiave
- discrete wavelet transform
- gait event detection
- gait phase estimation
- hip exoskeleton
- neurorehabilitation
- transfemoral amputees
- walking energy expenditure
Data inizio appello
08/06/2022;
Disponibilità
parziale
Riassunto analitico
Gait impairments due to aging and pathological conditions, such as neurological disorders or
lower-limb amputation, are among the major causes of restricted life and loss of personal
independence. Early rehabilitation provided along a continuum of care from hospital to
community is essential to improve recovery outcomes and the quality of life of individuals with
movement disabilities. In this scenario, lower-limb exoskeletons are seen as a cutting-edge
technology that can support impaired people in activities of daily living and improve rehabilitation
programs in ecological conditions. The robotics research community is fostering the growth of
the wearable robotics industry, by promoting technology transfer actions and translating research
outcomes into market products. Several full lower-limb exoskeletons have already reached the
commercial market internationally. However, for individuals who retain walking capacity, such
as the majority of stroke survivors (up to 80%), and lower-limb amputees (up to 60%), individuals
at the early stage of multiple sclerosis or with incomplete spinal cord injury, these devices may
not be the best approach to promote a more functional walking pattern. Lightweight lower-limb
exoskeletons which selectively assist some of the lower-limb joints are emerging as promising
alternative robotic tools. Despite recent advances, yet, major challenges in designing effective
exoskeletal robots relate to realizing natural and synergistic cooperation between the human user
and the robot. To accomplish this objective, several aspects of the system must be considered. On
one hand, the physical human-robot interface has to guarantee safe and comfortable fitting of the
device; on the other hand, the control interface for the human-robot interaction should ensure
intuitive movement intention decoding, as well as adaptive and reliable assistance in different
locomotion tasks.
Within this framework, the aim of this thesis was the design and clinical testing of innovative
control strategies for a hip exoskeleton to assist individuals with mild-to-moderate gait
impairments. To pursue this goal, the research activity followed two lines of action. Firstly, a
novel method for real-time gait phase estimate was developed. Secondly, novel assistive strategies
were explored to investigate the effects of hip assistance in specific end-users, i.e., individuals
with mild-to-moderate neurological gait disorders and transfemoral amputees.
This thesis proposed a novel wavelet-based gait phase estimation method capable of: (i)
continuously tracking the user gait phase and (ii) identifying in real time relevant biomechanical
gait events (i.e., initial and final foot contact) of physiological and pathological gait patterns. The
algorithm uses only hip joint angle signals (measured by encoders onboard the hip exoskeleton),
thus avoiding the use of additional sensors that could challenge the overall system
usability/acceptability and dependability in out-the-lab applications. The proposed method
(patented method WO2022053934) proves that distal events, related to foot–ground interaction
can be reliably detected by using hip joint angles. Experimental tests with healthy subjects
indicated that the method can robustly adapt to different walking speeds. Experimental tests
carried out with transfemoral amputees and post-stroke subjects showed that the proposed method
is reliable and accurate also with pathological gait patterns.
Furthermore, in this thesis, clinical investigations were designed to explore the effectiveness
of hip assistance for two different objectives: (i) to improve the walking economy in transfemoral
amputees and (ii) to increase the walking speed and induce the recovery of a physiological gait
pattern in individuals with neurological disorders. For the first application, although achieved
results showed that tailored energy injection at the residual and intact limbs of transfemoral
amputees could be promising, further research is needed for a better understanding of the real
benefits in daily-life scenarios. For the second application, the use of the hip exoskeleton was
investigated both as a gait trainer and as a mobility extender. In addition, a method for tailoring
the hip assistance based on subject-specific gait impairments was developed (patented method
WO2022137031). Experimental tests carried out with eighteen post-stroke survivors suggested
that the proposed approach is promising to improve their walking performance, paving the way
for future clinical investigations.
lower-limb amputation, are among the major causes of restricted life and loss of personal
independence. Early rehabilitation provided along a continuum of care from hospital to
community is essential to improve recovery outcomes and the quality of life of individuals with
movement disabilities. In this scenario, lower-limb exoskeletons are seen as a cutting-edge
technology that can support impaired people in activities of daily living and improve rehabilitation
programs in ecological conditions. The robotics research community is fostering the growth of
the wearable robotics industry, by promoting technology transfer actions and translating research
outcomes into market products. Several full lower-limb exoskeletons have already reached the
commercial market internationally. However, for individuals who retain walking capacity, such
as the majority of stroke survivors (up to 80%), and lower-limb amputees (up to 60%), individuals
at the early stage of multiple sclerosis or with incomplete spinal cord injury, these devices may
not be the best approach to promote a more functional walking pattern. Lightweight lower-limb
exoskeletons which selectively assist some of the lower-limb joints are emerging as promising
alternative robotic tools. Despite recent advances, yet, major challenges in designing effective
exoskeletal robots relate to realizing natural and synergistic cooperation between the human user
and the robot. To accomplish this objective, several aspects of the system must be considered. On
one hand, the physical human-robot interface has to guarantee safe and comfortable fitting of the
device; on the other hand, the control interface for the human-robot interaction should ensure
intuitive movement intention decoding, as well as adaptive and reliable assistance in different
locomotion tasks.
Within this framework, the aim of this thesis was the design and clinical testing of innovative
control strategies for a hip exoskeleton to assist individuals with mild-to-moderate gait
impairments. To pursue this goal, the research activity followed two lines of action. Firstly, a
novel method for real-time gait phase estimate was developed. Secondly, novel assistive strategies
were explored to investigate the effects of hip assistance in specific end-users, i.e., individuals
with mild-to-moderate neurological gait disorders and transfemoral amputees.
This thesis proposed a novel wavelet-based gait phase estimation method capable of: (i)
continuously tracking the user gait phase and (ii) identifying in real time relevant biomechanical
gait events (i.e., initial and final foot contact) of physiological and pathological gait patterns. The
algorithm uses only hip joint angle signals (measured by encoders onboard the hip exoskeleton),
thus avoiding the use of additional sensors that could challenge the overall system
usability/acceptability and dependability in out-the-lab applications. The proposed method
(patented method WO2022053934) proves that distal events, related to foot–ground interaction
can be reliably detected by using hip joint angles. Experimental tests with healthy subjects
indicated that the method can robustly adapt to different walking speeds. Experimental tests
carried out with transfemoral amputees and post-stroke subjects showed that the proposed method
is reliable and accurate also with pathological gait patterns.
Furthermore, in this thesis, clinical investigations were designed to explore the effectiveness
of hip assistance for two different objectives: (i) to improve the walking economy in transfemoral
amputees and (ii) to increase the walking speed and induce the recovery of a physiological gait
pattern in individuals with neurological disorders. For the first application, although achieved
results showed that tailored energy injection at the residual and intact limbs of transfemoral
amputees could be promising, further research is needed for a better understanding of the real
benefits in daily-life scenarios. For the second application, the use of the hip exoskeleton was
investigated both as a gait trainer and as a mobility extender. In addition, a method for tailoring
the hip assistance based on subject-specific gait impairments was developed (patented method
WO2022137031). Experimental tests carried out with eighteen post-stroke survivors suggested
that the proposed approach is promising to improve their walking performance, paving the way
for future clinical investigations.
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