Twist: Mechanical Design

design of a 13-DoF, actuated-spine quadruped

Researchers in Kod*Lab needed a research platform for investigating the impact of spines in legged locomotion applications. I designed a 13-actuated-degree-of-freedom quadrupedal robot to answer this call, featuring 3-DoF limbs and a 1-DoF axially-twisting spine. This project encompassed mechanical design in CAD, electrical routing, and integration with a commercial off-the-shelf brushless motor driver ecosystem. The final product is intended to be used in executing highly-dynamic, transitional (parkour-like) behaviors. As such, it was built to be simultaneously robust and lightweight, with mass concentrated at the torso. The parts were made with repeatability in mind, using simple, in-house fabrication methods (water jet, 2.5-D milling, turning) where possible to facilitate manufacturing replacements or duplicates. The actuator interfaces were designed to be adapted to several generations of actuator hardware which we had in stock in the lab, reducing sourcing costs significantly.

This project is under the supervision of J. Diego Caporale.

Chassis

Twist master CAD assembly.

Spine

Exploded view of the spine assembly.

Leg Assembly

On the left, a hip actuator bracket mounted to an abduction motor. Middle, a knee actuator bracket mounted to a hip motor. Right, the full leg actuator assembly.

Final Assembly

Fully assembled Twist sitting on a workbench.