Towards optimal force distribution for walking excavators

This paper presents the successful implementation of force control strategies on a 12 ton walking excavator to optimize the ground reaction force distribution for better stability, less terrain damage and to reduce the operation complexity. Using cleverly arrange standard industrial valve components to separately control in- and out-flow of the hydraulic cylinders, we achieve accurate and fast joint torque control purely based on pressure feedback. On the full system level, we realize an automated force distribution to adjust the center of pressure and to level out the cabin of the machine. While the operator has still full control over the excavator, this assistance system guarantees permanent ground contact and ideal force distribution among the all four wheels independent of the level of the terrain. The proposed method significantly improves operability of the walking excavator in rough terrain.