Dynamical analysis and suppression of human hunting in the excavator operation

The paper deals with human hunting phenomena, which is one of the coupled vibration phenomena between the vehicle and the operator on board, appearing at the operation of the small-sized excavator and degrades operativity. This phenomena is related not only to the vehicle dynamical characteristic but also to human-operator's dynamical characteristic. To analyze this phenomenon, it is necessary to consider the vehicle-operator dynamic model. We first derived a mathematical model, which has six degrees of freedom to analyze this phenomenon. Up and down motion of the excavator-boom is simulated, and it agrees with the phenomenon well. The linearized mathematical model shows that some control lever parameters are related to a stability criterion. By simulation, it is confirmed that the proper selected control parameters can suppress the human hunting phenomena.