US Patent 8626406 Method and system for transferring material between vehicles

A user interface alerts an operator of the lead vehicle if the follower vehicle location is within a predefined radius of the lead vehicle location and a predetermined angular difference with respect to a heading of the lead vehicle. A user interface response mechanism is configured such that the operator can accept or reject jointly coordinated movement of the lead vehicle and follower vehicle for unloading the lead vehicle during an unloading period. The first wireless communications device is adapted to transmit an alignment data message to the follower vehicle to maintain a target offset between the lead vehicle and the follower vehicle, where the target offset is based on a first vehicle identifier of the follower vehicle, a second vehicle identifier of the lead vehicle, and preset target offset stored in at data storage device associated with the lead vehicle.