US student's rope-driven robot dog walks naturally with clever math

A mechanical engineering student from Purdue University, Aaed Musa, has developed an innovative quadrupedal robot dog named CARA, distinguished by its rope-driven capstan drive system rather than traditional gears or pulleys. CARA, which stands for "Capstans Are Really Awesome," uses tensioned high-strength Dyneema DM20 ropes wrapped around smooth drums to transfer motion and torque, offering benefits such as zero backlash, high torque transparency, low inertia, low cost, and quiet operation. The robot incorporates 12 brushless pancake motors (three per leg), custom 3D-printed parts made from durable materials like PET and carbon fiber, carbon fiber tubes for lightweight strength, and ODrive S1 motor controllers for precise control. Its brain is a Teensy 4.1 microcontroller, supported by sensors including a BNO086 IMU for 3D orientation, all powered by a portable 24-volt battery. CARA’s movement is governed by inverse kinematics (IK)