Study On Measurement And Electrical Control System Hardware Of High-precision Profile Measuring Instrument

Measuring instrument contains two motion axes, that is, X axis, Z axis, and one rotary spindle, using contact probe to measure. The measuring systems of the measuring instrument include grating measuring system and the probe sensor measuring system.Closed-loop AC servo drive and control systems for X axis and Z axis were set up by using Fuji FALDIC-W servo system and the grating measurement system, which is based on computer-controlled and manual-controlled operation methods.The open-loop control system for the rotary spindle drived by a low-speed synchronous motor was set up. The manual operation panel, the power and operation buttons for each axis drive and control systems are designed. The grating measuring systems for X axis and Z axis were set up by using linear displacement gratings and grating reading card, which are used to measure the motion displacement for X axis and Z axis.The limit signals from gratings were used as the control command input of servo amplifier in order to protect the servo system and prevent over travel.The measuring instrument was equipped with total length and LVDT(linear variable differential transformer)sensor probes, and the measuring system of LVDT sensor was primarily studied and designed particularly, which mostly includes signal conditioning circuitry, A/D conversion and data sampling circuit. In order to achieve the purpose converting weak AC voltage signal on behalf of the change of displacement iron core to the±10V bipolar DC voltage signal, which was in proportion to the iron core's displacement and satisfied with the requirement for the input voltage of A/D converter, conditioning circuit was primarily studied and designed particularly. Simultaneously, the bipolar DC power supply, providing for electronic devices in the signal conditioning circuitry, was designed, and it was simulated by Proteus simulation software, and the simulation results showed the correctness of the circuit. To realize the equal angle's sample in the circumference measurement, the sampling /holding circuit before A/D conversion was controled by the output singal of rotary encoder, which was installed on the rotary spindle, and the input of A/D converting circuit is bipolar and 12-bit conversion datas. ISA bus interface control circuit was studied and designed to achieve communicate between peripheral equipment and PC.