Paoletti, P.Mahadevan, Lakshminarayanan2017-07-072014Paoletti, P., and L. Mahadevan. 2014. “Intermittent Locomotion as an Optimal Control Strategy.” Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 470 (2164) (January 22): 20130535–20130535. doi:10.1098/rspa.2013.0535.1364-5021http://nrs.harvard.edu/urn-3:HUL.InstRepos:33184895Birds, fish and other animals routinely use unsteady effects to save energy by alternating between phases of active propulsion and passive coasting. Here, we construct a minimal model for such behaviour that can be couched as an optimal control problem via an analogy to travelling with a rechargeable battery. An analytical solution of the optimal control problem proves that intermittent locomotion has lower energy requirements relative to steady-state strategies. Additional realistic hypotheses, such as the assumption that metabolic cost at a given power should be minimal (the fixed gear hypothesis), a nonlinear dependence of the energy storage rate on propulsion and/or a preferred average speed, allow us to generalize the model and demonstrate the flexibility of intermittent locomotion with implications for biological and artificial systems.en-USintermittent locomotionswimmingflightoptimal controlJournal Article10.1098/rspa.2013.0535