A simple method to counter the effects of gravity in articulated mechanisms is proposed. The scheme uses kinematics and linear springs to produce a nonlinear restoring force to oppose the gravitational moment. The method equilibrates a rotational mechanism for all postures. A solution for one link is obtained then general equations for n links are derived. The method is simpler than previous schemes and has applications in robotics, orthotics and a host of everyday mechanisms.
BackgroundSpastic cerebral palsy (CP) is the most common type of CP. Hip adductor spasticity leads to discomfort, stiffness, and difficulties in doing physical activities such as sitting, transfer, and walking. Management of hip adductor spasticity is still a challenge in the field of rehabilitation. Horse riding simulator (HRS) has been reported to have beneficial effects on spasticity, postural control, and motor function in children with spastic CP.ObjectiveThe aim of the study was to determine the immediate effect of HRS on adductor spasticity in children with CP.MethodsTwenty‐four children with CP were selected and were divided into two groups: experimental and control (12 children in each group). Experimental group was exposed to HRS and control group to the corner seat placement. Adductor tone and passive hip abduction range of motion were measured before and after the intervention.ResultsPost intervention scores in the group of HRS show significant reduction in adductor spasticity and improvement in hip abduction range of motion, whereas no difference have been reported in the control group. HRS has positive effects on reducing spasticity and improving range of motion in hip joint in spastic CP.ConclusionIt was concluded that immediate effect of HRS is successful in reducing the adductor spasticity and improving abduction range of motion in hip, which could be incorporated with regular physiotherapy intervention.
The paper describes the development of a passive/active orthosis for people with limited anti-gravity strength in their arms. This is symptomatic of conditions such as muscular dystrophy and spinal muscular atrophy. A passive orthosis was designed and developed using linear elastic elements. The system is being tested with children with disabilities and preliminary results are encouraging. An RT200 robot was also used as a test-bed for an active orthosis. The robot was instrumented with a six-axis force/torque sensor at the end-effector. The force acted as the input to the robot. The robot kinematics and dynamics were modelled. A number of control schemes were implemented on the test-bed including force proportional to velocity and acceleration; these schemes were evaluated with two subjects.
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