Methodology for designing and manufacturing complex biologically inspired soft robotic fluidic actuators: prosthetic hand case study

Abstract

A novel methodology for the design and manufacture of complex biologically inspired soft robotic fluidic actuators is presented. The methodology is applied to the design and manufacture of a prosthetic for the hand. This methodology is significant as it removes the need to perform complex ad hoc and in depth analysis of biological or soft robotic motions, when designing soft robots. This methodology provides a significant step towards developing more robust and complex, biologically inspired soft robots, with considerably improved performance. Real human hands are scanned to produce a 3D model of a finger, and pneumatic networks are implemented within it, to produce a biomimetic bending motion. The finger is then partitioned into material sections, and a genetic algorithm based optimization, using finite element analysis, is employed to discover the optimal material for each section. This is based on two biomimetic performance criteria. Two sets of optimizations using two material sets are performed. Promising optimized material arrangements are fabricated using two techniques to validate the optimization routine, and the fabricated and simulated results are compared. The optimization is successful in producing biomimetic soft robotic fingers, and fabrication of the fingers is possible. Limitations and paths for development are discussed. This methodology can be applied to other fluidic soft robotic devices. A study from the University of Auckland School of Psychology into the perception of soft robots is also assisted. Two soft robotic prosthetic fingers and one rigid prosthetic finger are fabricated, as well as a testing rig, to aid in the carrying out of experiments. The results reveal that stiffer soft robotic materials similar to SmoothSil 940, are better suited for the fabrication of fluidic soft robots, which are intended for applications involving interactions with human beings via touch, such as prosthetics. This project is funded by the New Zealand Artificial Limb Service. Thus, the end user of the prosthetic device is considered throughout the work, as both the physical and social and emotional features of a prosthetic for the hand, are addressed.