Design and implementation of ISA card for rotary inductosyn signal processing based on AD2S1210 and CPLD

The rotary inductosyn is widely used as an angle measuring instrument in a control system. In order to obtain the absolute angle from the original output signals of the inductosyn, an ISA card for inductosyn signal processing based on the resolver-to-digital converter AD2S1210 and CPLD is designed and implemented in this paper. The sinusoidal oscillator and some other circuits, such as the one for adjusting the bandwidth, are integrated within AD2S1210. Therefore, the excitation generation circuit could be gotten rid of and few peripheral circuits would be adopted. This reduces the design complexity and improves the circuit integration. Meanwhile, a binary counter in the range of 360 degrees is implemented by CPLD to calculate the integer angle value, and a zero position sensor is set to obtain the absolute angle. Finally, the ISA card is tested with an industrial computer. The results indicate the real-time angle curve is smooth and the angle value is accurate. Consequently, the practicability and stability are verified. Compared with the traditional method of adding another one-pair pole resolver, the proposed approach simplifies the structure as well as reduces the costs of the system. The circuit is suitable for application requiring high resolution and fast conversion speed in industrial automation.