Total Force Enlistment Programs Simulation. Volume 1

The discussion of the magnetic observations which have been made in different parts of the globe may now be considered to have established the three following important conclusions in regard to the magnetic disturbances: viz., 1. That these phenomena, whether of the declination, inclination, or total force, are subject in their mean effects to periodical laws, which determine their relative frequency and amount at different hours of the day and night. 2. That the disturbances which occasion westerly and those which occasion easterly deflections of the compass-needle, those which increase and those which decrease the inclination, and those which increase and those which decrease the magnetic force have all distinct and generally different periodical laws.

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Characterisation and Control of a Woven Biomimetic Actuator for Wearable Neurorehabilitative Devices

Actuators ◽

10.3390/act10020037 ◽

2021 ◽

Vol 10 (2) ◽

pp. 37

Author(s):

Vaughan Murphy ◽

Brandon P. R. Edmonds ◽

Ana Luisa Trejos

Keyword(s):

Performance Metrics ◽

Woven Fabric ◽

Total Force ◽

Control Methods ◽

Soft Actuator ◽

Sewing Thread ◽

And Control ◽

Fabric Mesh ◽

Biomimetic Actuator ◽

Multiple Units

Twisted coiled actuators (TCAs) are a type of soft actuator made from polymer fibres such as nylon sewing thread. As they provide motion in a compact, lightweight, and flexible package, they provide a solution to the actuation of wearable mechatronic devices for motion assistance. Their limitation is that they provide low total force, requiring them to actuate in parallel with multiple units. Previous literature has shown that the force and stroke production can be improved by incorporating them into fabric meshes. A fabric mesh could also improve the contraction efficiency, strain rate, and user comfort. Therefore, this study focused on measuring these performance metrics for a set of TCAs embedded into a woven fabric mesh. The experimental results show that the stroke of the actuators scaled linearly with the number of activated TCAs, achieving a maximum applied force of 11.28 N, a maximum stroke of 12.23%, and an efficiency of 1.8%. Additionally, two control methods were developed and evaluated, resulting in low overshoot and steady-state error. These results indicate that the designed actuators are viable for use in wearable mechatronic devices, since they can scale to meet different requirements, while being able to be accurately controlled with minimal additional components.

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