Satellite navigation systems undergo drastic development and are sure to have wide application range in the future. Enhanced precision of movement parameters control and precise localization of the object represent the key factors of satellite navigation development. Efficiency of such systems is further increased in the case if they are integrated into various measurement processes.
Among major application spheres of satellite navigation one should mention satellite vehicle control, which is represented by a system for moving objects control based on satellite navigation, instruments and technologies of cellular communication and digital maps. Vehicle satellite monitoring is used for addressing logistics tasks in transportation control systems and automated lorry fleet control.
Operating principle is based on control and analysis of vehicle’s dimensional and time coordinates. On the vehicle there is installed a portable module consisting of the following parts: satellite signal receiver, modules for coordinates data storage and transfer. The data received is analyzed and sent to operator in text form along with cartographic data. The portable module should be based on satellite signals receivers operating in accordance with GLONASS standards.
However, the satellite signals received by means of the portable module do not allow to control processes related to minor (within 10 cm) displacement of the controlled object. Besides, when the controlled object moves for considerable distance, it is often necessary to define some dynamic characteristics related to the speed of movement. In this case one should use inertial measurements allowing to promptly obtain information independently of the external data sources. One of the most widely used inertial measuring instruments is represented by accelerometers.
Accelerometer is a device which measures constant component of object’s acceleration. Modern accelerometers allow to measure acceleration in three planes. The accelerometer can be used for measurement of absolute linear acceleration projection as well as for measuring of indirect gravitational acceleration projection. This very feature is used for development of tilt meters. In this particular system accelerometers BC 201 are used. They are capacitive accelerometers that can be used as linear acceleration and displacement sensors that measure both alternating and constant component of the acceleration signal. ВС 201 accelerometer perfectly suits for high-precision inertial measurements. When used together with ADC conversion module ZET 220 (equipped with active aerial and GLONASS receiver), sensor BC 201 forms a compact system with a large range of functions. Possibility of connecting ZET 220 module to PC (laptop) for further data exchange as well as offline mode operation of ADC board with signals recording to the integrated memory and power supply from batteries module contribute to universal features of the system.
In order to detect rail gauge variations and their non-conformance to the applicable norms, one can use a system consisting of one or more ADC converters ZET 220, equipped with GLONASS receiver and two or more accelerometers. Sensors BC 201 are mounted on the truck (one sensor per each truck) in horizontal direction in transverse axis to the direction of train’s movement. Then the sensors are connected to corresponding modules ZET 220. To establish communication with GLONASS network, aerials are mounted at the surface of train sections (the aerials are further connected to corresponding modules of ZET 220).