Everything You Need to Know About Inertial Navigation Systems (INS)
It’s hard to imagine our life without GPS these days. It seems like even our kitchen appliances need a GPS receiver so that we can easily find them when needed. I wish my earphone had one.
Generation Z is dependent on GPS more than anyone else. Can you imagine driving your car in an unknown location without an incorporeal voice instructing your “Turn left in 100m”? I will end up hitting a wall on a blind alley for sure.
Before GPS, people would physically navigate a map, ask people around or assume the roads.
It had a few drawbacks. If you aren’t local, there is a language barrier and the risks of getting robbed. With GPS, now you can roam around in a foreign location like a local.
GPS has several factors that can obscure reliable mapping. Moreover, satellite floating above the earth does not always provide a clear line of sight.
Commercial industries need something more than GPS, something that can provide them with their velocity, acceleration, and position of a moving vehicle, and that is where the Inertial Navigation System comes in.
Inertial Navigation System (INS) uses Gyroscope (Rotation Sensor), accelerometers (Motion Sensors) for continuous calculation of the speed and direction of an object.
INS provides excellent resistance against tampering or hacking as there is no transmission required to any external sources such as GLONASS, GPS, etc. They feed on the data gathered from the Gyroscope and Accelerometers to calculate the navigational data.
INS is commonly used in GNSS solution for calculation of the positioning information in blind spots where satellite reception is absent such as caves and tunnels.
INS Explained
INS is available in a variety of shapes and sizes. The only thing that is common in all of them is their components. All the INSs contains a CPU that is used for calculating the data coming from the inertial sensors. An INS can contain several sensors on each side depending on the type.
GPS will tell you your position measurement by providing you with your Latitude and Longitude coordinates. The information is accurate and updated.
Whereas, in INS, the information is relative to the initials. INS can’t detect your present Longitude and Latitude. But what it can detect is the distance you have moved since you turned it on.
Why You Need INS?
GPS can tell you your current location but it can’t tell you how far you have travelled. With GPS, you will be lost in the sea, underwater, and missiles would never know how far to go. INS helps submarines, spaceships, missiles, and aircraft to reach their location by providing them with data that shows how far they have travelled exactly.
How INS works?
INS comprises two major parts that are the IRU (Inertial Reference Unit) which is also known as the IMU (Inertial Measuring Unit). This part comprises of gyros, accelerators for calculating the angular velocity and acceleration measurements. The second part is known as the navigation computer which outputs the relative position by calculating the data gathered from IMU/IRU.
There are two varieties of navigation computers used primarily. One is the strap down navigators and the other is known as stabilized platforms.
The strap-down navigators have fixed gyroscope and known as microelectromechanical systems. The gyros inside a strap down navigator can also be called angular rate sensors for their immobility.
On the other hand, the stabilized platform navigators have independent moving gyros. So, when the inertial navigation rotates, the stabilized platform inside it remains fixed. Using which the system can learn about the orientation and use the accelerometers for measuring the distance.
Stabilized platforms have gimbal lock, mechanical complexities and are costly, just the opposite of strap down navigators.
Apart from the structure, the tracking approach of both devices is different as well. Strapped down systems transfer signal into global coordinates using three accelerometers and then amalgamate it with orientation values that are generated through the MEMS gyroscopes.
Each of the sensor’s axes must be placed on a 90º angle to each other for deriving measurement from all the three directions, This is what helps the vehicle to understand the rotation and movement of the vehicle.
Inertial Navigation System provides mapping quality that is better than any other technique available today. It can position the feature of interest and the location of the vehicle while it is moving.
