A multi-joint fixture including a proximal base unit, one or more arms serially connected by electromagnetically lockable ball joints, and a distal hub. The ball joints unlock when not powered. A centering mechanism biases the ball joints toward a neutral position. A control system activates the electromagnetic brake with a high-then-low voltage profile. A headpiece attaches to the hub and holds a drape that covers the fixture. A connector connects a surgical device to the headpiece. A switch on the hub can be actuated via actuators on the headpiece or connector.
