We investigate experimentally and numerically suppression of drill-string torsional vibration while drilling by using a sliding mode control. The experiments are conducted on the novel experimental drill-string dynamics rig developed at the University of Aberdeen (Wiercigroch, M., 2010, Modelling and Analysis of BHA and Drill-string Vibrations) and using commercial Polycrystalline Diamond Compact (PDC) drill-bits and rock-samples. A mathematical model of the experimental setup, which takes into account the dynamics of the drill-string and the driving motor, is constructed. Physical parameters of the experimental rig are identified in order to calibrate the mathematical model and consequently to ensure robust predictions and a close agreement between experimental and numerical results for stick–slip vibration is shown. Then, a sliding mode control method is employed to suppress stick–slip vibration. A special attention is paid to prove the Lyapunov stability of the controller in presence of model parameter uncertainties by defining a robust Lyapunov function. Again experimental and numerical results for the control cases are in a close agreement. Stick–slip vibration is eliminated and a significant reduction in vibration amplitude has been observed when using the sliding controller.

This paper presents the design and the initial experimental results of a novel impact oscillator rig developed by the Centre of Applied Dynamic Research at the University of Aberdeen. In this rig, the excitation force is generated electromagnetically and it acts directly on the mass in contrast to the most of the experimental set-ups where the excitation passes through the structure. This significantly enhances flexibility of the system allowing to observe subtle phenomena. The evolution of the design from an initial concept to the finalised rig is discussed in details where a special attention is paid to the instrumentation and parameter identification which are important for the mathematical modelling. The initial experimental results demonstrate potentials of this rig to study fundamental impact phenomena, which have been observed in various engineering systems. They also indicate that this new rig can be a good platform for investigating nonlinear control methods.