Publications by authors named "J J Harlaar"
The Design of the Dummy Arm: A Verification Tool for Arm Exoskeleton Development.
Biomimetics (Basel)
September 2024
Article Synopsis
- Motorised arm supports are needed for individuals with severe arm muscle weakness, requiring accurate compensation for arm weight and joint stiffness from muscle atrophy.
- A newly designed dummy arm replicates human arm features to help estimate parameters like arm mass and joint impedance more effectively than subjective human assessments.
- This dummy arm aids in the development of the Duchenne ARm ORthosis (DAROR), providing a cost-effective tool for optimizing arm-assistive device designs and ensuring better functionality.
Minimization of metabolic cost of transport predicts changes in gait mechanics over a range of ankle-foot orthosis stiffnesses in individuals with bilateral plantar flexor weakness.
Front Bioeng Biotechnol
May 2024
Neuromuscular disorders often lead to ankle plantar flexor muscle weakness, which impairs ankle push-off power and forward propulsion during gait. To improve walking speed and reduce metabolic cost of transport (mCoT), patients with plantar flexor weakness are provided dorsal-leaf spring ankle-foot orthoses (AFOs). It is widely believed that mCoT during gait depends on the AFO stiffness and an optimal AFO stiffness that minimizes mCoT exists.
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- - This study compares two types of coordinate systems used to analyze foot movement: marker-based coordinate systems (MCSs) and bone morphology-based coordinate systems (BCSs), focusing on how they relate to the foot's underlying anatomy.
- - The research involved placing markers on the feet of fifteen healthy adults and using CT scans to examine the orientation differences between MCSs and BCSs, measured in angles like helical and 3D Euler.
- - Findings revealed that MCSs were often misaligned with BCSs, particularly showing different orientations in the hindfoot and forefoot, and only certain models (RFM and AFM) effectively captured variability in foot bone poses across individuals.
Article Synopsis
- Orthotic wrist supports assist individuals with muscular weakness by maintaining a neutral hand position and preventing wrist contractures.
- Two weight compensation strategies were tested against a theoretical ideal profile to evaluate their effectiveness in reducing electromyography activity in healthy subjects.
- Results showed all strategies significantly reduced muscle activity for extensors but increased activity in flexors, indicating that simpler compensation approaches can be as effective as complex models, though no approach provided perfect support.
Background: People with Duchenne muscular dystrophy (DMD) cope with progressive muscular weakness and consequential upper extremity function loss. They benefit from arm supports, or arm exoskeletons, to assist arm function. Especially for severe muscle weakness (DMD ≥ Brooke Scale 4), the design of such arm support is challenging.
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