* add spec for npos320

docs/specs/Navigation/Npos320_guide.md

+## Npos320 Guide
+
+BDStar Navigation NPOS is an integrated INS receiver, which has GNSS receiver and IMU included in the device.
+
+![Npos320 main](images/Npos320_main.png)
+
+### Installation
+
+![Npos320 panel ](images/Npos320_panel.png)
+
+
+### Data Protocol Parse
+Typical data protocols commonly used is `INSPVAXA` ，more detail about data protocol please see NovAtel《[OEM7 Commands and Logs Reference Manual](https://docs.novatel.com/OEM7/Content/PDFs/OEM7_Commands_Logs_Manual.pdf)》 
+
+Npos320 Configration：
+```
+SETIMUEVENT IN EVENT1
+CONNECTIMU SPI INVENSENSE_IAM20680
+SETINSPROFILE LAND_PLUS 
+SETINSTRANSLATION ANT1 0.742 0.660 -0.759 0.05 0.05 0.05
+SETINSTRANSLATION ANT2 -0.398 0.660 -0.759 0.05 0.05 0.05
+
+SETINSROTATION RBV 0 180 0 5 5 5
+SETINSROTATION RBV 0 0 0 5 5 5
+SETINSTRANSLATION USER 0 0 0
+ALIGNMENTMODE AIDED_TRANSFER 
+ALIGNMENTMODE UNAIDED
+SETINITAZIMUTH 180 5
+SAVECONFIG
+
+```
+
+**![warning_icon](images/warning_icon.png) WARNING:** Modify the **<u>SETINSTRANSLATION</u>T** line based on the actual measurement (of the antenna and the IMU offset). ANT1 is for primary antenna which is required, and ANT2 is for secondary antenna and it is optional.
+
+For example:
+
+```
+SETINSTRANSLATION ANT1 -0.05 0.5 0.8 0.05 0.05 0.08
+```
+
+The first 3 numbers indicate the result of the lever arm distance measurement. The last 3 numbers are the uncertainty of the measurement. 
+
+## Disclaimer
+
+This device is `Apollo Platform Supported`
\ No newline at end of file