Robots struggle to match warehouse workers on ‘really hard’ jobs

In the outbound dock of an Amazon warehouse near Nashville, Tennessee, a robotic arm named Cardinal on a recent day stacked packages, Tetris-style, into 6 1/2-foot-high carts. Then Proteus, an autonomous platform, moved the carts to the loading bay, flashing electronic eyes designed to make the robot more appealing to human colleagues.

As robots become more capable, they are performing an increasing number of tasks in warehouses and delivery centers with varying degrees of aptitude and speed. Machines can load and unload trucks. They can place goods on pallets and take them off. Robots can shift items around in inventory, pick up packages and move goods on warehouse floors. And they can do all this without a human minder guiding their every move.

Yet, even though robots are starting to take over some repetitive and cumbersome jobs, there are still many tasks they are...