Blade Control for Surface Profile Tracking by Heavy-Duty Bulldozers

The bulldozer is a heavy-duty earthmoving machine used in ground surface profiling and soil manipulation. Tracking the desired surface gradients with the hydraulically actuated manipulator while compensating for the mobile base motion is important in high-performance surface grading and traction control. In this paper, we present an approach for surface elevation tracking control for earthmoving work done by bulldozers using inertial measurement units (IMUs) and roof mounted global navigation satellite system (GNSS) antennas. We use mapping between the desired surface profile and hydraulic actuator velocities using the elevation surface and its gradient, the mobile manipulator Jacobian, and mobile base pose estimation by the extended Kalman filter (EKF) framework. With the proposed method, a relatively simple low-level actuator space control scheme can produce sufficient accuracy in varying elevation requirements besides leveling work. In an experimental setup, flat and uneven surface profiles were followed with average errors below 2 cm computed using kinematics. An external GNSS survey gave a coarse verification of the actual surface profile, showing average errors below 4 cm. This paper demonstrates a blade controller on a heavy-duty tracked vehicle with high manipulator inertia, hydraulic dynamics, and body vibrations. The experimental results validate the efficacy of the proposed method, also revealing the needs for further development.