HAHA Adds a Robotic Arm That Is Ambidextrous, Hyperextending and Capable of Continuous Rotation
Stelarc – Performance nouvelle création « HAHA » – à la Chapelle Saint-Louis de la Salpêtrière | ISIR – Institut des Systèmes Intelligents et de Robotique
HAHA (Hypertrophic Ambidextrous Hand and Arm) is a performance work that adds an extra robotic arm to the human body with hyperextension, ambidextrous motion and continuous rotation. Developed by Stelarc with Sorbonne University's ISIR, it turns the simple idea of “one more arm” into a full body-machine choreography.
The performer is physically connected to the system through a magnetic lock and controls the installation using an exoskeleton plus ECG and EMG sensors. The robot's motion also drives live video switching and sound generation.

The bonus arm isn't merely extra; it gets movement abilities the original human arms never had. The upgrade has overtaken the base model.