I shop in the logistics channel for ring form, inside the ring, a total of more than 40 stop logistics tractor 20 units (consider personnel were rested and tractor maintenance, etc., sometimes set less than 20 cars to online status), 1, dispatching center, according to the requirements of the SAP order sent via wireless network to each vehicle to m from n stop stop handling command, 2, the logistics channel does not meet the tractor overtaking conditions, must be in the order of 1 to 20 sets of tractor to follow, don't disturb the car sequence, 3, all tractor in clockwise direction one-way operation, 4, dispatching center through conditionally for each tractor factory GPS real-time location, 5, each tractor for current handling tasks when the operator press the finish button to inform the dispatch center, in order to get the new handling tasks, 6, and number of stops can increase or decrease, logistics tractor can increase or decrease in quantity, 7, more field application requirements can ask us, ask: how to combine car number, start stop, to stop station number in order to have the most efficient? The lowest logistics cost?