Abstract— Safety of man, machines and freight
is of significant concern in modern automobiles. Sensors used for advanced
driver assistance systems, helps the driver during dangerous situations,
thereby ensuring high safety standards. Proximity Sensor used in Parking
Assistance Systems, are some of the key feature in the Sensors Used for
Advanced Driver Assistance Systems. The system uses sensors like Ultrasonic Systems
and Electromagnetic Systems inputs and Microcontrollers in calculating
positions and navigating vehicles. This paper will give overviews of various
sensors used for Advanced Driver Assistance Systems with their respective
references and describes the state of the art for Sensors Used for Advanced
Driver Assistance Systems and future technological development, with focus on Ultrasonic
Systems of the Proximity Sensor and will give an overview of proximity sensors
and applications of the ultrasonic system.
The demand for Sensors used for Advanced
Driver Assistance Systems are needed has a result of the need to manufacture
safer vehicles in order to reduce the number of road accidents. Today, Advanced
Driver Assistance Systems uses input data from sensors like proximity sensors,
radar sensors, laser sensors, blind spot monitor sensors, gps sensors and
pressure sensors, etc to work in real time by giving warnings to drivers or by
taking charge of the control systems immediately. This technologies are
controlled by complex real time embedded systems.
There are different sensors used for advanced driver
assistance systems, each of these sensors provide different functions to the
user. Most of these sensors are paramount to the safety of the driver while
others makes it possible for the driver to be able to avoid minor accidents
without difficulty (see Table 1).
Sensors used for advanced driver
assistance systems, should be able to reliably and accurately detect the
environment as a type of “attentive passenger”. Proximity sensors are mostly
used in Parking Assistance Systems.
The sensors are designed
for vehicles, to alert drivers of close obstacles in their part while parking
without any physical contact with the obstacles 1. Proximity sensors makes
use of (see Figure 1) either Ultrasonic System or an Electromagnetic Systems:
which works by searching for differences in electromagnetic fields that are
emitted during the process and then, returns a signal. An example of this type
of system, is the “Electromagnetic induction (EMI) sensor”. A scientific paper
written by L.D. Landau and E.M. Lifshitz, illustrates the working principle of the
electromagnetic induction (EMI) sensor 2.
proximity sensors are mostly used in vehicles, to calculate and determine a
change in position, level measurement and detect the distance to nearby
objects. Ultrasonic proximity sensors, emits acoustic pulses and has a control
unit which calculates the propagation time of (see Figure 2) each reflecting
signal 3. This process ensures that the sensors are able to detect object
independent of its color rendering, the design and surface type 4. It is
possible to correctly detect even materials such as transparent objects, glass,
etc. One of the disadvantages of ultrasonic sensors is that; they do not have a
very good sensitivity towards dirt and can be easily affected by environmental
thermometers and thermocouples are the two conventional methods of measuring
temperature. This methods are used as a result of wave proagation
changes that significantly occur
openly to all parameters with temperature.
Other principles are used when measuring pressure in a process this is
as a result that, ultrasound can not directly measure pressure.
Level and Distance Measurement
Ultrasonic sensors emits acoustic pulses, radiation or beam
patterns, which are relative to the sensitivity of a transducer as a function
of spatial angle 6. Ultrasonic sensors always generate a different beam
pattern from that of its transducer. A technique used for realizing level and
distance measurement is the ultrasound reflection technique. Two different
types of distance and level instruments are used: binary and continuous
instruments. A scientific paper written by M.B. Gitis
and A.S. Khimunin, illustrates the working principle of the technique used in
realizing level and distance measurements with an example on collision
avoidance and monitoring of empty parking lots 7.
Before selecting an
ultrasonic sensor to use, it is necessary and important to check how the
acoustical fundamentals will affect the echo being produced; as there are many
different ultrasonic sensor available with different frequencies and with
different radiation angles 8. The right selection of ultrasonic sensor
parameters, will lead to better optimization of the system performance.
I found that real-time embedded system technology has become a
major target for safty in automotive systems. The use of the right and
efficient sensors and powerful processors will enable these diminutive systems provide
great benefits to vehicle operators. The ongoing systems in development, are
heading towards highway networks of driverless smart vehicles and automated
parking (AVs). Ultrasonic sensor systems are very good when parking in narrow
places but can easily be affected by environmental factors. They are more
expensive when compared with electromagnetic system sensors. Equipped with an
understanding of sensors operations, automotive designers can easily select
efficient and powerful sensors for advanced driver assistance systems while
delivering maximum performance.