Introduction

The regulation of driving shafts, e.g. in CNC machines, is achieved with programmable control units. In order to test the control algorithm in the laboratory we constructed an electronic shaft, which simulates the behaviour of a mechanical one.

The rotation of the shaft is shown by AB-signals (two square-wave signals positioned in a 90 angle). The AB-signal impulses are generated by an incremental position measuring device. The impulse frequency is linear to the spin. The mechanical attributes and the time behaviour of the shaft were modelled and described in the hardware language VHDL.

Results

We implemented two electronic driving shafts into an ALTERA Flex 10k70. The digitized output of the controller is used as an input signal generating the AB-signals. The time-behaviour of the shaft is described with an 2nd order IIR filter.To simplify the settings of the driving shaft we programmed an application software (Win95). This enables the communication with the FPGA through a serial interface. Additionally the positioning can be displayed and altered online.

We achieved the given task in modelling an electronic shaft. Now it's possible for the designer to optimise his controlling software wherever he likes.