Active Rejection of Ground Disturbances for Efficient Payload Haul by Mining Loaders

Abstract

Existing teleoperated mining LHD excavators are able to drive along mining galleries with little operator involvement. However, current LHD machines cannot prevent rock fragments from falling of the bucket nor avoid rock fragments on the ground that have fallen from other machines in the convoy. This causes machines running over the fragments to drop more material and slows down underground mining operations. This work proposes an approach to reduce disturbances induced by the terrain which are propagated to excavator or loader arms through the wheels of the machine, by maintaining the LHD buckets levelled during haul even when the machine drives over a bump, mound or pothole, thus reduce the spilling of material and the consequent slowdown of mining operations due to increased maintenance efforts. The active rejection of ground disturbances combines feed-forward with an ADRC (active disturbance rejection control) feedback controller. The proposed approach was evaluated through simulations and using a semi-autonomous Caterpillar Cat®262C compact skid-steer loader provided with inclination and inertial sensors. The simulation results and experimental confirm the effectiveness of the proposed strategy. Disturbances propagated to the payload when travelling over uneven terrain can be reduced by at least 10%, depending on the size of the disturbances and the traveling speed of the machine. A comparison of the system without disturbance rejection and using basic PID control is also included to demonstrate that the combined ADRC feedback controller and the feedforward strategy are critical to an effective reduction of the ground disturbances.