Trailers, tonnes, four legs

Different stations create different physical problems. Matching them to one “default robot” usually produces an expensive compromise.

Match the body to the station

At a trailer mouth, the task is repeated unloading on a stable floor. A heavy mobile base with a vacuum gripper or arm can reach into the trailer and handle cases. Some systems weigh more than a tonne because stability matters when they repeatedly lift loads such as a 23-kilogram case.

For pallets, cages, and other loads moving over mostly flat floors, a wheeled platform with a lift is usually a better fit than legs. It is designed to carry mass efficiently and predictably.

Legs solve a different access problem

Four-legged machines can be useful for inspection on stairs, metal grating, uneven ground, or dirty industrial sites where wheels struggle. Their value is access and sensing in difficult terrain, not a general replacement for every worker or vehicle.

For North Stack, choose the machine by asking what makes each station hard: load weight, reach, terrain, hazards, or access. That produces a clearer plan than choosing the most human-looking machine first.