Acrobots

This joint is powered (active). By moving this single joint, the robot must generate enough momentum to swing its entire body upward.

Whether it's a digital model in a physics simulator or a physical machine in a robotics lab, the Acrobot continues to be a vital tool for teaching machines how to move with the grace and intelligence of a human performer. Dynamics Showing Perfection in Acrobats- Robots by Boston Acrobots

Underactuated systems are often more energy-efficient because they utilize natural physics (like gravity and inertia) rather than fighting against them with heavy motors. This joint is powered (active)

In the field of robotics, the Acrobot is a benchmark for testing and nonlinear control algorithms. Developers use it to answer a critical question: How can a machine learn to perform a task when it doesn't have direct control over its primary pivot point? Dynamics Showing Perfection in Acrobats- Robots by Boston

Once at the peak, the Acrobot must perform a "handstand" on its passive joint. This requires constant, minute adjustments at the elbow to maintain a precarious equilibrium. Why Do We Build Them?