Double-arm working machine

A double-arm working machine comprising:

• a lower travel structure with a travel device;
• an upper bodywork that is provided at an upper section of the lower travel structure and includes an operator cabin;
• left and right swing posts provided on front left and right sides of the upper bodywork such that the swing posts each swing in both leftward and rightward directions;
• left and right work arms provided on the left and right swing posts such that the work arms each sway vertically;
• and
• operating devices which each give an operational instruction to the swing posts and the work arms;
• the working machine further comprising:
• angle sensors which each sense a swinging angle of the left or right swing post;
• angle sensors which each sense a vertical pivoting angle of the left or right work arm;
• and
• a control system previously storing:
• reference points set for each of the two work fronts;
• radiuses of first virtual spheres with centers at the reference points respectively;
• and radiuses of second virtual spheres being concentric with and larger than the first virtual spheres respectively, the control system which, pursuant to a differential angle between the left and right work arms that has been calculated from sensor signals sent from the angle sensors, to postures of the work arms, and to command signals from the operating device, generates an output signal to drive the swing posts and the work arms;
• wherein the control system comprises:
• an interference prevention controller constructed such that:
• when any one of the first virtual spheres of one work arm interferes with any one of the first virtual spheres of the other work arm, the controller defines, as an interference danger area, a distance range in which the left and right work arms are likely to come into contact with each other;
• when any one of the second virtual spheres of one work arm interferes with any one of the second virtual spheres of the other work arm, the controller defines, as a semi-interference danger area, a distance range adjacent to the interference danger area and in which both work arms, although kept free from contact under a stopped state thereof, are liable to come into contact when operated to make relative approaches;
• when all of the second virtual spheres of one work arm do not interfere with any one of the second virtual spheres of the other work arm, the controller defines, as a normal area in which the interference between the work arms is unlikely, regardless of their operating states;
• and
• when a positional relationship is present in the semi-interference danger area and the work arms are operated to make relative approaches, the controller outputs signals to reduce the operating speed of the swing posts and the work arms associated with the shortest distance between both work arms calculated using the sensor signals sent from the angle sensors, which is to be reduced;
• and
• driving signal generators which, on the basis of the output signals from the controller, generates and outputs driving signals to driving units of the swing posts and the work arms.