The Characterisation and Emulation of Rotary Mechanical Machines

Abstract

Typically machine control software is tested using software blocks to replace the physical machines. It is often beneficial to further test the controllers and drive hardware before using physical systems since unavailability or potential damage cost due to failure may make this impractical. The design of a physical machine emulator was investigated that ‘pretends’ to be a (single-shaft) machine or machine component. In addition to this the ‘test-rig’ was designed to characterise a machine connected to it. A set of models could then be compiled and used in isolation or in combination to form machines of arbitrary complexity that could be emulated. Models suitable to represent machines and components of the test-rig are examined, in particular system classification, continuous and discrete-time systems, linear and nonlinear systems and their behaviour. Control strategies are proposed and theoretical and practical performance tests conducted. PID control is employed and implemented using a sampled data system incorporating a DSP. Further control strategies such as velocity feedback and feedforward are combined where applicable to enhance the test-rig control. The subject of system identification and parameter estimation is summarised, and the relevant methods are applied to identify and parameterise machine structures. Practical tests are conducted on physical machines constructed specifically for the purpose of characterisation. The design and construction of these machines and the test-rig is explained and practical performance tests conducted.