The monitoring systems emergency detector which is based on modern MEMS sensors

Actually, to control the road traffic the most useful is GLONASS/GPS monitoring systems. The main purpose of the introduction of GLONASS in passenger transport is necessary to increase the safety of passenger traffic, first of all using monitoring compliance with speed limits, rapid response in case of accident and other emergency situations. Municipalities also will have an opportunity to control the implementation of licenses which are obtained by carriers. This is necessary for normal organization of passengers’ traffic and transport situation in the cities.

The modern monitoring systems GLONASS are able not only to locate and speed up controlled object, but also to check whether the controlled object adheres to the specified route of road traffic or not, whether it is in traffic or not. In addition, due to the analytical calculations we can get information about mileage, travel time, idle time, fuel consumption etc. All monitoring tasks seem to have already been solved, but actually systems do not provide us with the information about the dynamic parameters of moving objects.

There is a car accident detector for this work. It can be integrated to existing monitoring systems GLONASS and it will allow to register such common traffic situations as: hit in front, behind, from the left, from the right sides; upheaval forward, backward, to the left, to the right, on the roof; hard acceleration and slowdown; skidding in speed; falling. If there is a car detector in case of accident a service worker will be informed about this fact and about the reason automatically. For example, in winter time it is possible for: skidding in speed -> hit from the right -> upheaval on the left side. This message will go to the controller remote.

The modern transport monitoring systems become an integral part of the market passengers’ services and cargo. Widespread and adoption of these systems made it possible due to their low market price. Besides low-market price, we point out a large number of firms engaged in the development of motor transport monitoring systems, and as a result trucks are equipped with various devices often without common or standardized interfaces for communication with external sensors or other peripherals. The foregoing characteristics of the motor transport monitoring systems were taken into developing the project, as follows:

• -    emergency detector is a system which are integrating to existing motor transport monitoring system GLONASS;

• -    The developing device should have a comparatively low market price (it should be less expensive than the motor transport monitoring system);

• -    The device must have an interface allowing communication with existing monitoring transport devices

A necessary condition is performed as using universal communication interface based on RS-485 standard. The reason of selecting a standard RS-485 is existence of it the present motor transport monitoring systems. The universal interface is provided with the capability to change the protocol depending on the hardware monitoring system.

Creating a device with a low market price can be possible when using modern chips: sensors MEMS (micro electromechanical systems) [2].

Electrical diagram of the developing sensor is shown in the 1st picture.

Picture 1 – electrical diagram.

Definition of emergencies are based on the data processing which can be removed from the three axis MEMS accelerometer, magnetic compass and three-axis MEMS gyroscope. The data is processed by the microcontroller with the core Cortex-M0. There are raw data from the sensors on the 2nd picture. After preprocessing (filtering, alignment sensor coordinate system) the data are analyzed by the developed algorithm to determine an emergency. The algorithm of determining emergency is threshold algorithm [1] and requires calibration for a specific car and driving style. In the case of determining any emergency-AM DAS transfers the data to the main controller monitoring system by using communication interface with external devices.

Picture 2 – Data from sensors

It is shown at the picture that sensors data are very noisy. The filter used was alpha-beta filter , this filter is characterized by ease of implementation, small computational cost.

Evaluating tolerance in the determination of emergency is rather trivial task and requires further research. The authors evaluated tolerance subjectively to carry out tests on the car, simulated the situation of hard braking, acceleration, skidding. As a result, device demonstrates the accuracy of determining 10 of 10, and also should be noted that initial calibration with a driving style has influence the precision of instrument.

"Экономика и социум" №2(15) 2015