Shape-shifting modular robot fast-tracks 60 million years of evolution

Researchers at the University of Michigan have developed TROT (The Robot of Theseus), a modular, open-source quadruped robot that can rapidly alter its body proportions to study how anatomical changes affect movement. Built from commercially available motors and primarily 3D-printed parts costing under $4,000, TROT allows researchers to easily reconfigure limb lengths, weight distributions, and joint ranges of motion. This design enables fast experimentation—simulating 60 million years of evolutionary changes in just 20 minutes—addressing challenges in biomechanics where multiple variables change simultaneously in living animals, making it difficult to isolate individual factors influencing locomotion. TROT was inspired by difficulties in understanding how limb morphology impacts energy efficiency and movement, exemplified by a 1974 study comparing cheetahs and goats that could not isolate the effect of limb mass distribution on running energy costs. By varying only the weight distribution in TROT’s limbs, the researchers could directly measure the energetic consequences of that single variable. The robot