Work transport control method

A method of controlling a transport system for transporting a work from one station to another, said transport system comprising a plurality of stations arranged in a substantially circular row, a transport robot assembly disposed generally coaxially of the circular row of the stations and including two manipulator arms, a main controller for controlling the transport system in its entirety relative to the transport robot assembly, and a robot controller for controlling sequential operation of the transport robot assembly, said method comprising the steps of:

• a) transmitting from the main controller to the robot controller a transport command for causing the robot assembly to transport the work, said transport command including the number of one of the stations from which the work is to be transported and the number of another one of the stations to which the work is to be transported;
• b) prior to the work being picked-up, calculating angles of swivel of each of the manipulator arms in first and second directions opposite to each other about the robot assembly, said angle of swivel being required for each manipulator arm to swivel from a current position to said one of the stations from which the work is transported;
• c) selecting one of the manipulator arms and one of the first and second directions for which the angle of swivel that has been calculated is minimum;
• d) driving the selected manipulator arm in the selected direction an angular distance corresponding to the calculated minimum angle of swivel to cause the selected manipulator arm to assume said one of the stations;
• e) subsequent to the work having been picked-up from said one of the stations, calculating the angle of swivel in each of the first and second directions required during transport of the work from said one of the stations to said another one of the stations;
• f) selecting the direction of swivel which is assumed during transport of the work, for which the required angle of swivel attains a minimum value during the transport of the work;
• and
• g) driving the selected manipulator arm in the selected direction an angular distance corresponding to the calculated minimum required angle of swivel for the transport of the work;
• wherein all of said method steps are borne by the robot controller.