Hello, this is our presentation on automatic improper loading
posture detection and correction utilizing electrical muscle
stimulation. Loading posture is the manner in which we lift
objects while maintaining the proper lifting form, and proper
loading posture occurs when we lift objects with poor lifting
form, which may cause strain injury to the lower back
muscles, chronic lower back pain effects from the 80% of the
population at some point in their lifetime, and in this work we
investigate the effectiveness of use of electrical muscle
stimulation to automatically correct lifting posture when the
proper lifting is detected, although multiple resources.
theory establishes that humans are capable of performing multiple
parallel tasks in spite of the increased and cognitive demand.
Workers are often found to be highly engaged in the task to
automatically identify their poor posture assess the correction
required and finally correct their posture. The current
intervention technologies are only capable of detecting and
alerting the user and require the user to assess and self correct
their posture. These systems also rely completely on the user's
desire or willingness and intent to correct posture while
performing highly engaging tasks. This presents a gap in
research for the design and development of a wearable intervention
technology for automatically detecting and subsequently
correcting the proper lifting posture and for maintaining
healthy posture.
ILP detection is primarily a domain of occupational therapy
research for assessment of lifting techniques, injury and
post surgery rehabilitation and improving ergonomics of worker
safety and health. ILP detection primarily employs motion sensor
based systems to monitor the torso, inclination and knee bend
angles followed by vision based systems and posture are
appropriate for validation of the detection systems. All of
the above mentioned poor posture detection systems for ILP
utilized traditional.
Audio, visual and vibrotactile feedback systems. These systems
only deliver alerts to the user and rely completely on the
user's willingness to self correct posture and require a
conscious effort by the user that places a cognitive load and
causes task disruption. Additionally, the preventative
healthcare wearables and exoskeletons do not
automatically detect and correct poor posture and are always
required to be worn by the user and have proven to be cumbersome
and place a physical string on the user. The limitations of
these systems can be addressed by utilizing
electrical muscle stimulation based feedback for automatic
posture correction.
EMS is a non invasive technique for delivering electrical
impulses for invoking involuntary muscular
contractions. EMS has been traditionally utilized in pain
management for muscle strains and spasms and to regain muscle
strength and mobility post surgery. Traditional EMS has
utilized and rehabilitation for our system disabled or paralyzed
people and restoring essential motor functions like hand grasping,
swallowing, standing, and in post surgery care for rejuvenating
injured muscles and promoting muscle activation. Therefore,
EMS is the way to induce involuntary muscle contractions
and can be a good way to automatically.
Correct posture if integrated into a real time feedback loop
based on posture detention. ILP increases the risk of lower
back injuries which damages the weakness lumbar muscles and
which have not treated may result in intervertebral disc
degeneration or herniation to determine the ideal torso
inclination and knee bend angles for ILP detection. We conducted
a validation study with ten young adults and five certified
trainers. All participants were required to look at four
different sized boxes with different weights in them. The
young adults performed the lifting task in their natural
way.
The trainers perform task with correct or good lifting posture.
The young adults demonstrated high torso inclination and low
knee bend indicative of improper lifting techniques, while the
trainers who perform the same task with correct lifting
technique demonstrated lower torso inclination and high knee
bend. The high torso inclination and the low knee bend during the
lift places an unnatural or excessive stress on the lower
back, while a low torso inclination and high knee bend
allows the user to leverage the stronger leg muscles to support
the lift.
With little stress on the lower back, the average maximum torso
inclination and knee bend angle from the trainers were recorded
as threshold angles for each of the boxes to make our ILP
detection more accurate and robust. The graph shows the
torso inclination and knee bend angular patterns for each of the
boxes across the two groups.
As ILP is mainly characterized by high torso
inclination and low knee bend, we developed the physiological
feedback loop utilizing wireless motion sensors and EMS
for detecting and subsequently correcting ILP. We placed
wireless motion sensors on the center of the collarbone, above
the chest and on the knees to monitor the torso inclination
and knee bend ankles respectively.
To correct ILP we employed 2 separate correction strategies
to automatically restore proper lifting posture by applying EMS
to the two different affected locations. Separately, in the
torso inclination correction strategy, EMS is applied to the
rhomboid muscles to stabilize the torso in the upright
position. In the knee bend correction strategy, EMS is
applied to the hamstring muscles to cause the knees to bend
towards ideal knee bend angles.
The ILP detection and correction system is described with an
example as follows. The graph illustrates the activation and
deactivation of EMS production feedback when ILP was detected
and corrected for one participant during the torso
correction strategy part of the study. When the participants
torso inclination exceeded the ideal threshold and then the
bend was sufficiently lower than the ideal knee bend threshold,
ILP was detected. The ILP detection automatically
activates the EMS correction feedback by applying a
calibrated electrical stimulus.
To invoke an involuntary rhomboid muscle contraction for
stabilizing the torso, which in turn causes the user to bend
knees in order to reach and lift the box with good lifting
posture, the EMS is automatically deactivated when
the ideal torso inclination and knee bend angles are achieved. A
correction response time of approximately 1.3 seconds was
recorded between activation and deactivation of the EMS
for torso stabilization. We conducted the two by three mixed
design study with 36 participants. The within subjects
factor was the feedback
type, either audio or private tactile and EMS. The between
subjects factor was the correction strategy and the task
was to lift each box from zone A to B and then back from zone B
to A.
During the preparation phase of the experiment, participants
were fitted with the wireless motion sensors on their torso
and knees and EMS. Electrodes were placed on the rhomboid
muscles for choice of correction and on the hamstring muscles
sporting event correction. After the preparation, the
participants were calibrated for optimal EMS intensity for
correcting ILP posture and restoring balance in both
correction strategies. The study has three parts where
participants had to complete the three feedback types and either
correction strategy.
And each part lasted 5 minutes with a 5 minute break in
between.
For the audio feedback modality, when ILP was detected, an
auditory bell sound notification is presented to the
user to correct their ILP posture until a second auditory
bell sound notification is presented to the user indicating
restored posture. For the vibrotactile feedback modality,
in the torso inclination correction strategy, a
continuous vibrotactile feedback notification is presented
through the IMU placed on the torso until the ideal torso and
knee angles are achieved in the knee bend correction strategy, a
continuous vibrotactile feedback notification is
presented through the IMUs, placed on the knees until the
ideal torso and knee angles are achieved.
For the EMS feedback modality in the torso inclination
correction strategy, EMS is applied to the rhomboid muscles
until the ideal torso and knee angles are achieved, and the
knee bend correction strategy applied to the hamstring muscles
until the ideal torso and knee angles are achieved.
We found that EMS delivered significantly faster corrections
with an average of 1.4 seconds.
We also found that EMS and vibrotactile feedback are
equally highly accurate and audio is the least accurate.
Additionally, we found that EMS feedback was equally comfortable
as the audio and vibrotactile feedback and across the two
correction strategies. Finally, we also found that EMS was no
more disruptive than the traditional feedback types it
was tested against and across the two correction strategies.
The main takeaways from this study are that EMS was able to
deliver corrections up to 25% faster and outperformed the
visual and audio feedbacks, which place an additional
cognitive load on the user while they were already engaged in the
task. Additionally, EMS and vibrotactile feedback were
perceived to be equally highly accurate. While the audio
feedbacks often resulted in over corrections. EMS was also
equally comfortable and no more disruptive than the traditional
feedback systems.
Participants also reported shared responsibility
demonstrating learning effects and involvement in the
correction process. And finally, 67% of the study population
preferred the torso correction strategy while 33% preferred the
knee correction strategy. In conclusion, we demonstrated our
automatic poor posture detection and correction systems for ILP
correction. We found the EMS delivered significantly faster
corrections in comparison to the traditional feedback mechanisms
was perceived to be highly accurate equally.
Comfortable and no more disruptive. In a different
context it was tested against. Therefore EMS based feedback
shows promising potential to be developed into smart wearable
intervention technology and could be a useful alternative or
inclusion to existing EHS guidelines for mitigating risk
of workplace injury and improving employee health and
preventive healthcare.
Thank you.