Force and hydraulic displacement amplification of fiber reinforced soft actuators

Soft robots allow for complex continuum motions and shapes that conform to their environment. Using a fiber-reinforced elastomeric enclosure (FREE) driven by fluid provides a high power density, soft continuum actuator. While the force generation for a small subset of this structure known as McKibben actuators has been studied extensively, the force and moments generated by a wider set of fiber reinforcements have not been previously investigated. Using virtual work and kinematics derived from fiber inextensibility and fluid incompressibility, the force and moments for the entire design space of FREEs has been determined analytically. Graphical representations have been created, providing easy tools for synthesis and analysis of force and moments in all possible FREEs. The hydraulic displacement amplification, or volumetric transduction, of output motion to fluid displacement has also been determined using kinematics; this transduction gives an indication of stiffness of the structure. Graphical representations have also been created, providing a designer with an intuitive understanding of the behavior all FREE topologies.