In inertial navigation (INS), Altitude refers to the vertical position of an object or device relative to sea level (or a reference datum). It is the measure of the object’s height above the Earth’s surface, typically expressed in meters (m) or feet (ft).
Role of Altitude in Inertial Navigation:
- Part of Positioning Information:
- In an inertial navigation system (INS), altitude is one of the components that define the object’s spatial position, often provided alongside latitude and longitude for a complete 3D position. It helps in accurately determining the location of the object.
- Monitoring Vertical Movement:
- Inertial sensors, especially accelerometers, detect changes in vertical acceleration, which can be used to estimate changes in altitude. For example, as an object ascends or descends, the accelerometer can integrate the acceleration to estimate the altitude change.
- Impact on Heading and Attitude:
- In aviation and aerospace, altitude is crucial for the accuracy of the navigation system. Changes in altitude may affect the error accumulation in the inertial navigation system, which is why altitude is often cross-referenced with other sensors (such as barometric altimeters or GPS) for better altitude estimation.
Common Types of Altitude:
- Altitude Above Sea Level:
- Refers to the object’s height relative to sea level. This is commonly used for both ground and airborne vehicles’ positioning, often used in conjunction with latitude and longitude.
- Relative Altitude:
- Refers to the height difference between an object and a specific reference surface. For example, an aircraft’s altitude relative to the runway or a drone’s height relative to the ground.
Relationship with Other Parameters in Inertial Navigation:
In inertial navigation, altitude is not directly measured by inertial sensors. Accelerometers and gyroscopes provide data for horizontal position (latitude and longitude) and attitude, but accurate altitude estimation typically requires auxiliary systems (such as barometric pressure sensors or GPS) to provide additional altitude information.
