Meet TROT: The $4,000 Robot Decoding How Animals Move

Scientists at the University of Michigan have built a new robotic platform called The Robot of Theseus, or TROT. Designed to study animal movement, the system lets researchers test how different limb designs affect energy use and locomotion. Its modular, reconfigurable parts mimic real animal limbs in a controlled lab setting.

TROT's design focuses on simplicity and speed. Most components can be printed on standard FDM 3D printers, keeping costs below $4,000. This affordability makes the platform accessible even to teams without advanced robotics skills.

The system's actuation relies on backdrivable motors that mimic spring-like behaviour. These motors allow precise measurement of the energetic effects tied to changes in limb mass or positioning. In one experiment, TROT resolved a long-standing paradox from a 1974 study by isolating the limb mass distribution variable. The results demonstrated how small shifts in limb mass directly affect energy expenditure.

Researchers can quickly reconfigure TROT's limbs to test theoretical designs. This flexibility lets them explore biomechanical trade-offs and evolutionary constraints in minutes rather than over millions of years. The platform's open-science approach means all schematics, instructions, and component lists are freely available for download.

Beyond academic research, TROT's methods could shape commercial quadruped robotics. By quantifying how limb variations affect performance, engineers may develop robots with specialised limbs for different tasks.

TROT provides a low-cost, adaptable tool for studying locomotion and energy efficiency. Its modular design and open-access resources enable rapid experimentation with limb configurations. The findings could advance both evolutionary biology and the development of more capable robotic systems.