Modeling of Bioinspired Apical Extension in a Soft Robot

Artificial apical extension in a soft robot, inspired by biological systems from plant cells to neurons, offers an interesting alternative to movement forms found traditionally in robots. Apically extending systems can move effectively in some environments that impede traditional locomotion. Artificial apical extension has been realized using a continuous stream of surface material, thin-walled, flexible plastic, which is everted at the tip by internal pressure. Understanding artificial apical extension as a form of movement requires a model to describe and predict the capabilities of the system. Unlike many other forms of movement, the model includes components that are dependent on the previous path in addition to path-independent terms associated with actuation. The model draws inspiration from biological models of apical extension and mechanical models of compliant Bowden cable actuation, and is verified though a series of tests on physical systems that isolate each term of the model.