Evaluation of the Position Accuracy of the Excavator Tool

The automation and robotics for earth moving machines were introduced to reduce labor cost and increase machines performances, the increment of position accuracy of the excavator bucket obtained by laser and/or automatic control systems meets both objects. Experimental tests and simulations have shown excavating accuracy to be about two centimeters, the excavating accuracy depends on position accuracy of excavator boom prevalently, and also a simulation of the boom dynamic system has shown it, in fact, during the precision excavation the arm is near the vertical position. The excavator, or the basic machine, is used also as loader, forklift, pipe-layer, drill and more, therefore we consider right to value the position accuracy of all excavator linkages and complete equipment, and the design problems of the control system. The accuracy evaluation of the complete arm is made by simulation, the evaluated system includes the dynamics of the linkages, hydraulic and power system (hydraulic cylinders, valves, pumps, engine) and the operator. An important task is made by the operator, he is at the same time the feedback and controller of the machine, the use of the human model in the simulation doesn’t prejudice the generality of the problem, because the excavator should became a telerobot probably, while it is less probable that it could become a complete autonomous robot. The simulation is made using the dimensions and measure values of a microexcavator used as scale model.