Development of lower limb stroke rehabilitation machine
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Date
2018-06
Authors
Dalbir Singh Banwait Amrik Singh
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Abstract
The function of the lower limb can be affected by stroke, accident or even aging.
Paralysis on one side of the body is a common effect of stroke which diminishes the
strength and control of the lower limb. The lower limb can be rehabilitated by means of
exercise. The passive exercise is when the muscle is moved by the means of external
force and the active exercise is when the muscle exerted the force necessary to create
the motion. Passive range of motion exercises are for stroke survivors who are left with
mild to severe paralysation, or paresis. These exercises can help prevent muscle
stiffness and spasticity which is the limited coordination and muscle movement.
Resistive exercises involve conscious control of the muscle and physical effort exerted
into muscular activity to improve neural path formation.
The aim of this project is to develop a combination of rehabilitation system based on
Continuous Passive Motion (CPM) and Active Resistive Motion (ARM) which cover
the flexion-extension of the hip and knee. The system is providing goal-oriented visual
feedback in real-time. The mean value of engagement metric of healthy subjects using
this machine with visual feedback was 24.53% higher than without visual feedback.
This proved that the use of visual feedback can help the patients to be fully engaged
during the rehab session strengthening the neuromotor pathways. The assistive mode of
motion is set at three cycles per 120 seconds which allows a high intensity and repetitive
form of knee extension and flexion. A desktop computer is used as the data entry and
also for data display for monitoring and recording purposes. A simulated paretic limb
for a 55 kg subject has carried out the passive mode of motion and an average force of
35 N is obtained. The range of motion of the lower limbs achieved 49.8% of average
hip flexion of 120° and 84.8% of average knee flexion of 143.7°. Then healthy leg force
measurement is carried out at which the person has exerted the maximum pushing force
when the cylinder is at rest in retraction mode and obtained a simulated maximum force
of 65 N.
Resistive rehabilitation exercise is for patient who has slowly regain some strength. It
aims to regain lost movement after stroke by strengthening the neural pathways in the
brain that enable the performance of the movement. The patient is required to exert
force on the leg and the force being exerted by the patient during the hip-knee joint
extension will be measured by the load cell at the foot rest. The reading from the load
cell is taken as an input to a control system within myRIO to determine whether enough
force has been applied to allow the motion. A pre-set force value of 10 N is set in ARM.
The system will only complete the hip-knee flexion-extension motion if the paretic limb
has achieved the threshold force value and it will end the process when it is unable to
achieve the threshold value. This provides a mean for quantitatively monitoring the
motor recovery during rehabilitation. This active mode of motion provides positive
feedback on the recovery of the muscle strength that motivates the patient to work
harder to overcome the threshold force value. The developed system highlight the
advantages of goal-oriented feedback on the level of engagement during rehabilitation, the
system in driving the actuators, providing suitable resistance level for active exercise based
on closed loop control system and to record the achievement of the patient.