Kinematically Induced Excavation by Backhoe Excavator

The paper deals with kinematically controlled excavation process performed by a commonly applied backhoe excavator. It is assumed that all three hydraulic actuators which are driving the arms of the machine may work simultaneously. This creates a unique relationship between - bucket's motion as a rigid body and the actuators action. After discussing kinematic relationship containing constraints arising from limited lengths of actuators, the static constraints at each point of working space are presented. They are defined by maximum possible forces in actuators and by the stability of the excavator. In the case of statics, relationship between two components of teeth force and three forces exerted by actuators are not unique. That fact causes a need for constructing a polygon of feasible forces at the dipper's teeth. The last part of the paper is devoted to the hydraulic flow circuit coupled with a processor. The main idea of the system consists in proper distribution of oil volume and assurance of appropriate pressure in all three actuators. Presented solution allows to dig the soil along assumed path.