[Explainer] What Is Null-Space Control? How Robots Move an Elbow Without Moving the Hand

Seven-axis robot changing its elbow path while holding the hand target

Null-space control lets a redundant robot preserve a primary task, such as holding its hand pose, while using remaining joint freedom for obstacle, joint-limit or singularity avoidance. We explain the Jacobian projector, practical priorities and why modeling error, latency and saturation can still disturb the primary task.