A different safety problem than a fenced-off arm
An industrial robot arm operating inside a fenced cell solves safety largely by exclusion: humans and the robot are never in the same physical space at the same time, and the fence enforces that. A warehouse fleet cannot rely on that approach, because the entire point of the system is that human workers, forklifts, and mobile robots share the same aisles, intersections, and open floor throughout a shift. Exclusion isn't available, so the safety strategy has to shift from keeping humans and robots apart to managing safe behavior while they're together.
This changes what 'safe' means at a system level. Instead of one hard boundary, warehouse safety is built from layered, dynamic zones around each robot and around known human work areas, plus rules about how a robot's behavior should change as those zones overlap. It's a probabilistic, continuously updated safety posture rather than a fixed physical barrier.