US Patent 11305935 Robotic warehouse

A storage facility having lift robots and ground robots cooperating in transferring of totes within the facility, is disclosed. The transferring of totes between ground robots and lift robots in the facility through buffer locations, allows the totes to be carried on top of the lift robots, which are thereby secured against unintentional dropping of the tote. The efficiency of the storage facility may be further improved in that the buffer locations, and in various embodiments also short height storage locations, which are accessible directly to ground robots, are utilized for storing totes that are ranked as associated with high prevalence to be transferred by ground robots, without the involvement of lift robots.