2015 International Conference on Smart Sensors and Systems (IC-SSS)
INS-GPS Enabled Driving Aid Using Doppler Sensor Sudheer Kumar Nagothu
G. Anitha
Research Scholar Division of Avionics Department of Aerospace Engineering, Anna University Chennai MIT campus
[email protected]
Assistant Professor (Sr. Gr.) Division of Avionics Department of Aerospace Engineering, Anna University Chennai MIT campus
[email protected]
Abstract— Now a days Large no of road accidents are happening, which causes loss of life. As life is very precious which can’t be brought back, some preventive measures need to be used to alert the driver to avoid the accidents. Here INS- GPS integrated system is used which will give the present position of the vehicle precisely. The INS- GPS system can be integrated with digital maps which will alert driver when there is scope for accidents such as T junction. In some situations it may necessary to control the speed of the vehicle based upon the geographical position. The position obtained from the integrated ins- gps system is used to limit the speed based upon the condition given by an authorized person. The Doppler sensor is used to alert the driver when his vehicle is approached by another vehicle with more speed. This system is most useful in single lane roads Keywords— INS- GPS system, Doppler sensor, Driving Aid
I. INTRODUCTION Most Number of accidents are happening on the roadways, which causes passengers death. By obtaining the current position of the vehicle some alert can be given to the driver in a dangerous situation. Normally GPS is used to get the position ,but in urban canyon or in hilly Ares GPS signal is affected by Tropospheric Propagation Errors, Multipath Problem, Ephemeris Data Errors etc. to avoid this error INS & GPS are integrated using Kalman filtering, which gives accurate position. There are various ways of alerting the driver such as processing his face images to find it out whether he is drowsy or not etc.
LCD INS& GPS
ARM
Alerts & Warnings
Figure 2 Hardware Kit of Electronic Card
Figure 1 shows the block diagram of card which consists of INS and GPS which is interfaced with ARM microcontroller to vibration motors Figure 2 shows hardware kit of electronic card, which can be minimized to small card by using MEMS technology. II. INTODUCTION TO INS- GPS INTEGRATION AND DOPPLER SENSOR
A. Introduction to INS and GPS Person position can be determined accurately by having accurate acceleration and direction which is provided by an accelerometer and gyroscope. INS is a dead reckoning navigation device, which is self-contained. It will not depend on any external signal for its operation
Power Fig. 1. Block diagram of Electronic Card Fig. 3. Basic principles of inertial navigation.
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In GPS system 24 satellites are used which surround the earth. By using the signals transmitted from the satellite, with trilateration technique the accurate position of the person can be determined. B. Integration of GPS and INS The information from GPS and INS can be combined using Kalman filtering for mutual benefit. For example, in INS the Calibration and correction can be done using GPS The INS can smooth out the step change in the GPS position output, which can occur when switching to another satellite because of the change in inherent errors. In INS as error increases with time some other navigation system is required to correct the error for long journey. As shown in figure 4 Kalman filter applies correction to the INS. The Kalman filter provides an optimum estimate of the inertial navigation system errors taking into account the errors present in the position fixing system. A pattern is shown in figure 5 to indicate the resulting error propagation using a Kalman filter to estimate and correct the INS errors, which is a good improvement. Even Doppler radar velocity sensor, can also be used in conjunction with a Kalman filter to estimate and correct the INS error. The dissimilar nature of the error characteristics of an INS and the various positions (and velocity) aids is exploited by the Kalman filter to achieve an overall accuracy and performance which is better than the individual systems.
Fig. 5 Aided INS with Kalman filter.
. As the INS is integrated with GPS the device can be used either inside the closed structure such as a building or open air. The device is also equipped with Doppler sensor which will give the information about the obstacle which in front of the person. The obstacle can be stationary or moving. Two vibration motors are attached the persons arms, based on the obstacle vibration v=can be given to the respective arm, if the person has to go to right side vibration will be given to right arm, and if he there is no obstacle on left side vibration can be given on left. If he can continue the path in straight line vibration can be given to both the arms C. Doppler sensor The Doppler Effect is a shift in frequency perceived by a receiver from a signal source due to relative movement of the source and/or receiver. Here the frequency of a wave apparently changes as its source moves closer to, or farther away from, an observer. FD= vf/c (1) where FD= frequency difference, v = aircraft velocity, f= frequency of transmission, and C = speed of electromagnetic propagation (3 x 108 meters/second).
Fig. 4 Block diagram of aided IN system with Kalman filter. Fig. 6 Constant o/p of 2 volts when there no vehicle is approaching
Set the speed limits for particular geographical area
Calculate the speed of the vehicle and vehicle position
Current speed > set speed (geographical area) NO YES
Warning indicator
Fig. 7 The voltage variations when a vehicle is approaching
The voltage value depends upon the speed at which the obstacle object is coming towards / moving away from the vehicle. III. LIMITATIONS IN EXISTING METHOD So many navigation aids to such people have been evolved which normally uses GPS. Here INS is integrated with GPS to eliminate the problems associated with GPS such as Tropospheric Propagation Errors, Multipath Problem, and Ephemeris Data Errors etc. Even if Inertial Navigation System is used independently it will develop an error which gets accumulated with time. These problems can be avoided by integrating IBNS with GPS. Thus here a hybrid system is used to develop precise navigation aid to help the driver. IV. PROPOSED METHOD Here an aid for the driver is proposed using integrated INS-GPS. The accurate location obtained from the INS-GPS module is used to point out the vehicle precisely in google maps. It will alert the driver when there are accident prone areas is going to arrive A. Setting the speed and range limits Based upon the geographical locations the speed limit will be set by an authorized person. Based upon the difference between the current speed of the vehicle and the speed limit a warning is indicated (red when the difference is more than 5 km/hr. and yellow when the difference is 2-5 km/hr.) Two Doppler sensors are attached at the front end and rear end of the vehicle which are used to find the speed of the following vehicle and the approaching vehicle with respect to the current vehicle respectively. By integrating speed, distance can be obtained. If the distance is less than 10 meters an oral warning can be given to alert the driver. It is also possible to reduce the fuel flow to the engine in order to reduce the speed of the vehicle so that collision can be avoided B. Processing of data A flowchart has been shown in figure 5 to show the flow of data.
YES
Whether any T junctions or cross junction exists (Using current position of the vehicle in google maps) NO YES
Distance between the current vehicle and other vehicle is < 10 m (Using Doppler sensor) NO
Fig.8 Flow chart
Initially speed limits for the vehicle in a particular area will be fixed by the person who is responsible for the safety of people who are travelling in the vehicle. The precise position from the INS- GPS module is obtained. This data can be checked with restored position data. Here the following formulae are used to find the difference between the present position and pre-defined position. 1 1 a sin 2 ( 2 ) cos(2 ) * cos(1 ) sin 2 ( 2 ) 2 2 a d 2 * RE * a tan 2( ) (1 a ) Where 1,λ1 is latitude & longitude of present position ,
2,λ2 is latitude & longitude of pre-defined position and RE is Earth's radius (approximately 6371000 meters), and all angles are in radians. Distance in meters is given by d. At a position where the distance is less than 20 m the speed limits for the pre-stored position is used. When the speed of the vehicle reaches more than the prescribed limit, a warning will be issued in terms of light or buzzer. With respect to the difference between the prescribed speed and current speed warning can be displayed for Eg. Red when there is high difference The precise position can also be used to alert the driver when there are T – junctions or cross junction ahead of the driver as shown in figure 5. As these type of junctions cause severe accident cases based upon the alerts driver can drive the vehicle with the utmost care
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[5] Fig.9 Example of a T – junctions
V. CONCLUSION As the driver can’t maintain full concentration throughout his driving some means of alerting the driver need to be used to aid the driver when accident prone areas arrives while he is traveling, or when he is traveling with more speed than particular limit. So here a navigation aid using INS-GPS and Doppler sensor is developed to alert the driver. With accurate position obtained from INS-GPS module it became to point the vehicle precisely in google maps and an alert to the driver when accident prone area occurs such as cross junction etc., can be given. Based upon the speed limits set by the authorized person, if the vehicle reaches more speed than limits the driver will be alerted. The Doppler sensor is also able to give alerts when another vehicle is approaching. REFERENCES [1]
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