A system for computer control of a turning lathe

Blaž Hostnik (2008) A system for computer control of a turning lathe. EngD thesis.

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Abstract

The following paper details the development of a system which enables the computer control of a turning lathe. The proposed system allows a computer to access lathe electronics through the use of registers. Lathe electronics consist of electric motors, sensors and switches. The following work concentrates mainly on the interface between the computer and the lathe, while mechanical adjustments of the lathe and software control are left for user. In the second chapter, following the introduction, the problem of mechanical adjustments of a lathe is introduced – what needs to be controlled and what devices are required. In order to do mechanical work, brushed DC electric motors are used. For control, they require feedback information, which is obtained from a device called an impulse generator. This system is based on a closed loop principle. In the third chapter, the concept of the system is introduced: essentially a circuit that does low level operations, giving total control to a computer through registers. The basic functions and required performance calculations of the system are also given here. The fourth chapter discusses available technologies and also the chosen combination – development board Raggedstone1, which is based on Spartan-3 FPGA and has PCI interface for communication with a computer. The fifth chapter describes the implementation of the system. The functionality of individual modules in VHDL is described. Also described are problems with the PCI protocol and their solutions. An additional circuit module is introduced, which is used alongside Raggedstone1 plate for protection, optical isolation and voltage translation of signals. The last part of this chapter presents usability of the system through a user manual – where and how to connect in/out signals, through which registers to access them etc. There is also an example of system usage on an operating system Linux at the end of the chapter.

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