Control system for synchronous rotation of cutter heads, for use in shield machine

A control system for controlling synchronous rotation of a plurality of rotating cutter heads in a multi-cutter shield machine, said rotating cutter heads are generally disposed in the same plane and the distance between the centers of the adjoining rotating cutter heads is larger than the radius but smaller than the diameter of the rotating cutter heads, comprising:

• a plurality of electric drive systems to respectively and independently drive said plurality of rotating cutter heads, each drive system includes a plurality of motors which are coupled to the respective cutter head by means of a pinion and reducing gears;
• a control means for synchronously rotating the adjoining first and second ones of said rotating cutter heads with an allowable deviation angle which will not cause interference between the first and the second cutter head;
• said control means comprising:
• a means for detecting an angle of deviation, or the difference in rotation angle between the first and second rotating cutter heads, and for delivering a deviation angle detected value signal corresponding to the detected angle of deviation;
• a first means for detecting the rotation speed of a master motor in the plurality of motors comprising a first one of said electric drive systems which drives said first rotating cutter head, wherein said first means delivers a rotation speed signal corresponding to the detected rotation speed of the master motor of the first drive system;
• a second means for detecting the rotation speed of a master motor in the plurality of motors comprising a second one of said electric drive systems which drives said second rotating cutter head, wherein said second means delivers a rotation speed signal corresponding to the detected rotation speed of the master motor of the second drive system;
• a speed setting means for setting a speed command to the master motor of each of said first and second drive systems;
• a first speed control means for comparing the rotation speed signal delivered from said first means with the speed command given by said speed setting means, and for adjusting the power supplied to the master motor of the first drive system so that the deviation resulting from the comparison becomes zero;
• a second speed control means for comparing the rotation speed signal delivered from said second means with the sum of said speed command and said deviation angle detected value signal, and for adjusting the power supplied to the master motor of the second drive system so that the deviation resulted from the comparison becomes zero;
• a first torque setting means for detecting the current through the master motor of the first drive system, and for setting a torque command based on a detected current value of the master motor and for providing said torque command to the slave motors in the first drive system;
• a second torque setting means for detecting the current through the master motor of the second drive system, and for setting a torque command based on a detected current value of the master motor and for providing said torque command to the slave motors in the second drive system;
• and
• torque controlling means for adjusting power supplied to the slave motors in the first and second drive system so that the torques generated by the slave motors in the respective drive system are the same as the torques generated by the master motor of the respective drive system.