DSP algorithm for the extraction of dynamics parameters in CNC machine tool servomechanisms from an optical incremental encoder

Machine-tool axis dynamics is an important factor that has influence in the machining finishing and interferes with wear machine and actuators. The parameters that describe this dynamics are: position, speed, acceleration, and jerk: these parameters are useful to make decisions on the trajectory planning, control, and machine performance. The contribution of this work is the development of a dynamics reconstruction method that consists of a combination of finite differences and a filter based on the application of discrete wavelet transform, where Daubechies function basis is used. The method objective is to obtain the dynamics parameter from a machine-tool axis, starting from an encoder for a sensorless approach. Results of the simulations and experimentation applied to computerized numerical control (CNC) lathe show the efficiency of the method, since the axis dynamics reconstruction of the machine tool is achieved by processing the position signal generated from the encoder. (C) 2008 Elsevier Ltd. All rights reserved.