ARIA – the UK’s Advanced Research + Invention Agancy – is funding our development and construction of leg designs exploiting linkage principles recently described for walking and running humans and animals. These legs have two major benefits: they are efficient, enabling both load support during translation with low power demand, and economical power supply; and they are minimally controlled, with simple changes in geometry loading and unloading the sequences of linkages supporting weight. They also have the potential to perform these functions on uneven, unpredicted and unsensed terrains. This tackles a functional demand that current engineered solutions – wheels, caterpillar tracks, or highly controlled conventional robot legs – have not been able to address.