Provided is a method for controlling a resonance enhanced rotary drill comprising a drilling module and a control system for controlling one or more drilling parameters of the drilling module, which method comprises: (a) employing one or more initial characteristics of the material being drilled, and/or one or more initial drilling parameters to control the drilling module; (b) measuring one or more current drilling parameters to obtain one or more measured drilling parameters; (c) employing the one or more measured drilling parameters as an input in the control system, in order to obtain an output from the control system, which output comprises one or more calculated characteristics of the material being drilled; (d) employing the one or more calculated characteristics of the material being drilled, and/or the one or more measured drilling parameters, as an input in the control system, in order to obtain an output from the control system, which output comprises one or more calculated drilling parameters; (e) optionally applying the one or more calculated drilling parameters to the drilling module; (f) optionally repeating steps (b), (c) (d) and (e).