A practical operator support scheme and its application to safety-ensured object break using dual-arm machinery

A practical operator support system for disaster response work using construction machinery is applied to object-break operations using a dual-arm machine. An object-break operation, which separates an object into two different parts by applying massive pulling force, requires skillful force and trajectory controls. Operators typically have trouble visually perceiving the movement of the manipulator because the target object is strongly restrained. As a result, after the object has been separated into two pieces, the operator may continue performing lever operations because of unavoidable perception reaction time and the manipulator may collide with the surrounding environment. A control input cancellation system based on object-break identification is proposed to reduce the time difference between the object break and operation stoppage. A support system for disaster response situations must be safe and efficient and accommodate operators with various skill levels; thus, common physical phenomena related to the object breakage should be exploited. The system cancels control inputs to stop the movement of the manipulator when an object-break flag is detected, which is defined as a situation where the force applied to each joint of a manipulator decreases rapidly when a lever operation and load on the inside of the grapple are detected. Demolition experiments were conducted using a hydraulic dual-arm system. The results indicate that the displacement of the end-point after the object breaks is greatly decreased and the completion time of the task is reduced as well.