Materials

The Octopus Project

Stiff Flop dealt with several candidate technologies for the development of an actuating arm to be used in minimally invasive surgery. The technologies under investigation ranged from smart materials such as shape memory alloys, as well as pneumatic and hydraulic driven hyper-elastic silicone. Prototypes were fabricated and tested with primary interest of the use of pneumatically actuated soft silicone.

The performance of the actuating modules was characterised versus the material and geometrical properties, the performance is then simulated using finite element analysis and validated against the experimental results.

 

The FEA model is utilised to try to optimise the design and material specifications to achieve better actuation, in terms of increased bending angle, increased free space for the locking mechanism and various tools and sensors, as well as improved geometrical response. The FEA simulation would also serve a versatile tool for the control aspect of the project for serving as a map of the actuation response versus the input parameters. The affect incorporated technologies such as the braided structure, the locking mechanism, and sensors can be added onto the FEA model for quick and cost effective method todetermine the efficiency of such technologies in reference to the actuating performance. Finally the FEA model would serve as a preliminary test of the performance of the design for the intended surgical application as typical forces acting on the arm during the application can be modelled

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Nylon and PET braided tubes are used to develop bellow shaped sleeves that are used to force the actuation of the module as well as serve as a protective sheath for the core module and even incorporate sensor technologies are developed in the University of Surrey. A technique that would be able to control the physical and mechanical properties of these sleeves is developed for the fabrication of tailored sleeves for optimum performance as well as to limit any adverse effects to the biological tissue.
Further technologies currently under investigation at the University of Surrey include the development of a capacitance enabled bellow that would serve as a power source within the robotic arm for any other on-board technologies such as the cameras, surgical tools, as well serve as a bending and pressure sensor. Further research also includes the investigation of Stiffening techniques that can be incorporated within the currently suggested granular jamming method.

 

 
 
 
 
 

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