Patent ID: 8137047

Claim:
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; and a control system previously storing a first threshold value and a second threshold value for discriminating a positional relationship between the left and right work arms, 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, and to command signals from the operating devices, generates an output signal to swing the swing post, wherein the control system includes: an interference prevention controller constructed such that: when the calculated differential angle is below the first threshold value, the controller defines, as an interference danger area, a differential angle range in which the left and right work arms are likely to come into contact with each other; when the calculated differential angle is larger than the first threshold value and below the second threshold value, the controller defines, as a semi-interference danger area, a differential angle area adjacent to the interference danger area and in which the left and right 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 the calculated differential angle is larger than the second threshold value, 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 between the left and right work arms is present in the semi-interference danger area and the work arms are operated to make relative approaches, the controller outputs a signals to reduce the swinging speed of the swing posts; and a driving signal generator which, on the basis of the output signals from the controller, generates and outputs driving signals to driving units of the swing posts.