Increasing requirements for coordinate systems necessitates the development of new principles of navigation. In particular, one of the conditions dictated by modernity was the introduction of relatively independent means of measuring the location of target objects. These capabilities are provided by an inertial navigation system that eliminates the need for signals from radio beacons and satellites.
Technology overview
Inertial navigation is based on the laws of mechanics, allowing you to fix the parameters of the movement of bodies relative to the established frame of reference. For the first time, this principle of navigation began to be applied relatively recently in ship gyrocompasses. With the improvement of measuring instruments of this type, arosea technique that determines the measured parameters based on the accelerations of bodies. The theory of the inertial navigation system began to take shape closer to the 1930s. From that moment, researchers in this area began to pay more attention to the principles of stability of mechanical systems. In practice, this concept is quite difficult to implement, so for a long time it remained only in theoretical form. But in recent decades, with the advent of special equipment based on computers, inertial navigation tools have been actively used in aviation, water engineering, etc.
System Components
Mandatory elements of any inertial system are blocks of sensitive measurement devices and computing devices. The first category of elements is represented by gyroscopes and accelerometers, and the second one is computer equipment that implements certain calculation algorithms. The accuracy of the method largely depends on the characteristics of the sensitive devices. For example, reliable data make it possible to obtain inertial navigation systems only with precision-type gyroscopes in conjunction with accelerometers. But in this case, the technical equipment has a serious drawback in the form of the high complexity of the electromechanical filling, not to mention the large size of the equipment.
How the system works
The method of determining coordinates using the inertial system is to process data on the acceleration of bodies, as well as theirangular speeds. For this, again, sensitive elements installed directly on the target object are used, thanks to which information is generated about the meta-position, course of movement, distance traveled and speed. In addition, the principle of operation of the inertial navigation system makes it possible to use means for stabilizing and even automatically controlling an object. For such purposes, linear acceleration sensors with gyroscopic equipment are used. With the help of these devices, a report system is formed that works relative to the trajectory of the object. According to the generated coordinate system, the angles of inclination and rotation are determined. The advantages of this technology include autonomy, the possibility of automation and a high degree of noise immunity.
Classification of inertial navigation systems
Basically, the considered navigation systems are divided into platform and strapdown (SINS). The former are also called geographic and may contain two platforms. One is provided by gyroscopes and is oriented in the inertial field, and the second is controlled by accelerometers and stabilizes relative to the horizontal plane. As a result, the coordinates are determined using information about the relative position of the two platforms. SINS models are considered more technologically advanced. The strapdown inertial navigation system is devoid of disadvantages associated with limitations in the use of gyroplatforms. Speed andthe locations of objects in such models are shifted to digital computing, which is also capable of recording data on the angular orientation. The modern development of SINS systems aims to optimize computational algorithms without reducing the accuracy of the initial data.
Methods for determining the orientation of platform systems
Do not lose relevance and systems that work with platforms to determine the initial data on the dynamics of the object. At the moment, the following types of platform inertial navigation models are successfully operated:
- Geometric system. Standard model with two platforms, which was described above. Such systems are distinguished by high accuracy, but they have limitations in servicing highly maneuverable vehicles operating in outer space.
- Analytical system. It also uses accelerometers and gyroscopes, which are stationary relative to the stars. The advantages of such systems include the ability to effectively serve maneuverable objects like missiles, helicopters and fighters. But even in comparison with a strapdown inertial navigation system, analytical systems demonstrate low accuracy in determining the parameters of an object's dynamics.
- Semi-analytical system. Provided by one platform, continuously stabilizing in the space of the local horizon. This base houses a gyroscope and an accelerometer, and the calculations are organized outside the working platform.
Features of inertial satellite systems
This is a promising class of integrated navigation systems that combine the advantages of satellite signal sources and considered inertial models. Unlike popular satellite systems, such systems make it possible to additionally use data on angular orientation and form independent positioning algorithms in the absence of navigation signals. Obtaining additional geolocation information allows us to technically simplify the models of sensitive elements, refusing expensive equipment. The advantages of the inertial satellite navigation system include low weight, small size and simplified data processing schemes. On the other hand, the instability of MEMS gyroscopes causes the accumulation of errors in data determination.
Fields of application of inertial systems
Among the potential consumers of inertial navigation technology are representatives of various industries. This is not only astronautics and aviation, but also automotive (navigation systems), robotics (means of controlling kinematic characteristics), sports (determining motion dynamics), medicine and even household appliances, etc.
Conclusion
The theory of inertial navigation, the concept of which began to form in the last century, today can be considered as a full-fledged section of mechatronics. However, recent advances suggest that the future mayappear and more progressive discoveries. This is evidenced by the close interaction of inertial navigation systems with computer science and electronics. New ambitious tasks appear, expanding the space for the development of related technologies, also based on theoretical mechanics. At the same time, specialists in this direction are actively working on optimizing technical means, the basic among which are micromechanical gyroscopes.
