sensors: add initial coverage

sensors/operation.md

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+title = "Operation"
+description = "Sensors for measuring the operational status and conditions of the vehicle."
+date = 2022-11-21T22:50:00+11:00
+template = "docs/page.html"
+sort_by = "weight"
+weight = 30
+draft = false
+
+[extra]
+lead = ""
+toc = true
+top = false
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+
+## Sensors
+
+### Type
+
+- Used for
+- Features
+- [Library]()
+
+### Tested with ArduSub
+- [SensorID type]() (Autopilot)
+
+## Code Usage
+Library -> Flow -> of -> Code

sensors/orientation.md

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+title = "Inertial"
+description = "Inertial orientation/motion sensor types."
+date = 2022-11-21T21:50:00+11:00
+template = "docs/page.html"
+sort_by = "weight"
+weight = 10
+draft = false
+
+[extra]
+lead = "Inertial sensors make measurements of the vehicle orientation and motion without requiring direct access to the surrounding environment"
+toc = true
+top = false
++++
+
+## Sensors
+
+### Magnetometers / Compasses
+
+- Measure magnetic field strength in all directions
+- Can estimate North orientation by strongest magnet direction
+- Calibration allows correcting for _constant_ magnetic effects from vehicle components
+- Subject to error due to magnetic field fluctuations (from nearby changing electrical currents, and going near large magnetic structures)
+- DIFFERENCE??
+- [`AP_...` library]()
+
+### Gyroscopes
+
+- Measure rotation rate about all axes
+- Can be integrated over time to estimate relative rotation angles
+   - Integrated readings continually build error, and need to be corrected for by an absolute reference
+- Faster response than compass
+- [`AP_...` library]()
+- [`AP_Compass` library](https://github.com/ArduPilot/ardupilot/tree/master/libraries/AP_Compass)
+
+### Accelerometers
+
+- Measure acceleration in all directions
+- Can directly estimate gravity direction
+- Can be integrated over short time periods to estimate "airspeed" (speed through the transport fluid)
+   - Integrated readings continually build error, and need to be corrected for by an absolute reference, or not used
+- Can be doubly-integrated to estimate position relative to a starting time
+   - Double integration error grows exponentially, so is impractical to use without frequent corrections
+- [`AP_InertialSensor` library](https://github.com/ArduPilot/ardupilot/tree/master/libraries/AP_InertialSensor)
+
+### Tested with ArduSub
+- [MMC5983 magnetometer]() (Navigator)
+- [AK09915 compass]() (Navigator)
+- [LSM303D accel/mag]() (Pixhawk)
+- [IST8310 magnetometer]() (Pixhawk 4)
+- [ICM-20602 IMU]() (Navigator / Pixhawk 4)
+- [L3GD20H gyro]() (Pixhawk)
+- [MPU6000 accel/gyro]() (Pixhawk)
+- [BMI055 accel/gyro]() (Pixhawk 4)
+- [ICM-20689 accel/gyro]() (Pixhawk 4)
+- [ICM 20602](https://github.com/ArduPilot/ardupilot/blob/master/libraries/AP_InertialSensor/AP_InertialSensor_Invensense.cpp)
+
+
+## Code Usage
+InertialSensor -> InertialNav / NavEKF/2/3 -> AHRS -> AttitudeControl
+

sensors/positioning.md

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+title = "Positioning"
+description = "Positioning sensor types."
+date = 2022-11-21T22:30:00+11:00
+template = "docs/page.html"
+sort_by = "weight"
+weight = 20
+draft = false
+
+[extra]
+lead = "Sensors used for positioning and motion, based on measuring the surrounding environment."
+toc = true
+top = false
++++
+
+## Sensors
+
+### Type
+
+- Used for
+- Features
+- [Library]()
+
+### Tested with ArduSub
+- [SensorID type]() (Autopilot)
+
+## Code Usage
+Library -> Flow -> of -> Code