A. W. Reid

Longwall Shearer Cutting Force Estimation

Longwall mining is an underground coal mining method that is widely used. A shearer traverses the coal panel to cut coal that falls to a conveyor. Operation of the longwall can benefit from knowledge of the cutting forces at the coal/shearer interface, particularly in detecting pick failures and to determine when the shearer may be cutting outside of the coal seam. It is not possible to reliably measure the cutting forces directly. This paper develops a method to estimate the cutting forces from indirect measurements that are practical to make. The structure of the estimator is an extended Kalman filter with augmented states whose associated dynamics encode the character of the cutting forces. The methodology is demonstrated using a simulation of a longwall shearer and the results suggest this is a viable approach for estimating the cutting forces. The contributions of the paper are a formulation of the problem that includes: the development of a dynamic model of the longwall shearer that is suitable for forcing input estimation, the identification of practicable measurements that could be made for implementation and, by numerical simulation, verification of the efficacy of the approach. Inter alia, the paper illustrates the importance of considering the internal model principle of control theory when designing an augmented-state Kalman filter for input estimation.

Swing Trajectory Control for Large Excavators

There is a strong push within the mining sector to automate equipment such as large excavators. A challenging problem is the control of motion on high inertia degrees of freedom where the actuators are constrained in the power they can deliver to and extract from the system and the machine’s underlying control system sits between the automation system and the actuators. The swing motion of an electric mining shovel is a good example. This paper investigates the use of predictive models to achieve minimum time swing motions in order to address the question what level of performance is possible in terms of realizing minimum time motions and accurate positional control. Experiments are described that explore these questions. The work described is associated with a project to automate an electricmining shovel and whilst the control law discussed here is a much simplified form of that used in this work, the experimental study sheds considerable light on the problem.