Modular design and actuation system comparison for underactuated tendon-driven soft anthropomorphic robotic finger


The objective of this project is to propose an alternative design for hyper-redundant, tendon-driven, discrete-joint manipulators which allows for independent removal of intermediate modules, as well as to conduct a comparative study between two alternative forms of tendon-driven actuation
systems, twisted string actuation and spooling actuation. Hyper-redundant discrete-joint manipulators have individual modules connected in series and when paired with a tendon-driven actuation system, intermediate modules cannot be isolated. This lack of modularity limits the ability to quickly replace intermediate modules without the need to disassemble the entire system. Efficacy of modularity is measured by the fastest time required to remove and add intermediate modules to a series of modules.
Comparison between maximum force generated by twisted string actuation and spooling actuation is done. The effects of different materials and diameter on the maximum force generated for twisted string actuation are also tested. Subjects are able to add and remove intermediate modules from the proposed design faster than a benchmark design. Twisted string actuation tests suggest that it is able to generate a larger force as compared to spooling actuation. Different string material and diameter are
also shown to affect the maximum force generated. If needed,further research should be done to better quantify factors which contribute to failure of the string in twisted string actuation.

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