Development Of Three-dimensional Scanning Probe Data Acquisition Card For CNC Gear Measuring Machine

Measurement data acquisition card is the key component of CNC gear measuring machine control system, which has great influence on the overall performance of the measuring machine.In this paper, Three-dimensional scanning probe data acquisition card is designed for the C40 gear measuring machine, and the basic function and performance index of the acquisition card are tested.The design and development of the acquisition card mainly include the design of the PCB circuit and the development of the HDL program. The PCB circuit of acquisition card is mainly composed of probe signal conditioning circuit, analog to digital conversion circuit, bus decoding circuit and servo control feedback circuit. The overall structure of the circuit and the way of working:The probe voltage signal conditioning circuit in three directions via filtering, amplification and other processing are transferred to A/D conversion circuit analog to digital conversion, FPGA as the control core which achieves the control of the analog to digital conversion and the conversion of three-way serial data and probe status information, digital filtering, synchronization latch gating and reading data bus and CAMAC instruction decoding functions. The HDL program of card acquisition mainly uses the top-down design methodology, including four modules,they are the consecutive three-way switch control module, handshaking module and status response module, an instruction decoding module and the read data bus interface module. Specific programs written uses the Verilog HDL and Altera’s Quartus II integrated development environment. The simulation tool uses the Modelsim, and also uses the development tool integrated logic analyzer function real time capture signal to carry on the on-line debugging verification.After the initial adjustment of the acquisition card hardware, on-line debugging is carried out on the debugging platform and C40 gear measuring machine. The test of the function of the data acquisition card and the state switch are made by using the measuring machine diagnosis software.The amplification factor of the amount of floating probe is calibrated in three directions.At the same time, the anti noise performance and the index of the system components of the acquisition card are tested and evaluated.Test results show that the developed three-dimensional scanning probe data acquisition card has reached the design requirements.