July 10, 2022

BLiM | Lidar-based Blind Spot Monitoring System

 Most of the mishaps with vehicles take place because the driver is unable to see objects around a vehicle in the blind spot zone. Any vehicle traveling in the blind spot is under serious threat as its presence is completely unknown to the driver. Road collision deaths of pedestrians, cyclists, and bikers are intolerably high and amount to most deaths globally.


With the rapid development of vehicle technology and more attention to driving safety, driver assistance systems are making driving easy and safe. With traffic accidents occurring frequently in recent years, safe driving assistance systems have become one of the hottest and most critical technologies. It can improve road transportation efficiency and decrease accidents. Blind Spot Detection Warning (BSDW) is one of the methods through which we can solve the issue.

Blind spot monitoring | Lidar technology

Recently, car manufacturers have started designing blind-spot monitoring systems to avoid collisions due to blind spots. There are many blind spot systems, like radar-based, ultrasonic-based, and camera-based detection systems.

Presently in the Indian auto market, blind spot detection technology is only present in extravagance automobiles with narrow features. Yet, the majority of Indian roads consist of mid-range cars which do not have this technology. As 10-20% of the total road accidents happen due to blind spot crashes, so devising a reliable system that prevents collisions and warns the driver is a necessity of time. Here's where the proposed model solves this problem.

What is a Blind Spot in a vehicle?

A blind spot in a vehicle is an area around the vehicle that cannot be directly observed by the driver while at the controls, under existing circumstances.

Because of the vehicle's blind spot area, especially the rear spot area, and the driver's weak vision, traffic collision accidents easily occur when the driver changes lanes.

What is Blind Spot Lidar Monitoring(BLiM)?

The Blind Spot Monitor using Lidar alerts drivers of vehicles in their blind spot and the rear cross-traffic alert warns drivers of approaching vehicles when backing up. The Blind Spot Monitor enables alerting the driver to the presence of a car that might evade detection in side-view mirrors, improving conviction and helping to optimize safe operation.

Blind-Spot Lidar Monitoring and alert system that is devised to provide an early warning about the proximity of surrounding vehicles to the driver using the Lidar technology.

The presented system is highly accurate and most importantly cost-effective. Such systems are only available in the higher segment vehicles. Most mid-range cars that comprise a central component of vehicular traffic ignore these systems. Thus the system is a solution for the mid-range segment.

The objective of the project

The focus of this project is to identify the causes of automobile collisions, notably the side collision impact caused by the blind spot.

To develop a system that can accurately monitor the rear blind-spot area of the vehicle which is also affordable for normal car users.

So with this system, accidents can be avoided.

System Components

The system mainly consists of 2 parts 

1. Hardware 2. Software,

The hardware component consists of the Lidar sensor, the microcontroller & the Bluetooth module.

A lidar sensor is a light-emitting sensor. That calculates distance using Time of Flight(ToF). So here in this project, the TF Luna Lidar sensor is used which can travel distances up to 8m. It can perform steady, accurate, sensitive, and high-frequency range detection.

The second component is Arduino Uno is a microcontroller other variants of microcontroller Arduino Uno, Arduino Mega, and Arduino Nano can be used and can work perfectly having no issue with latency. But used for single-operator use.

HC-05 Bluetooth Module is an easy-to-use Bluetooth. Enabling the Arduino to exchange data with other Bluetooth devices. It works between baud rate of 9600-115000.

And the software component consists of an application (BLiM) on which the data collected from the Lidar sensor (Distance) will be displayed and seen by the driver.

What is Lidar? How does Lidar work?

Lidar Sensor (Light + Radar) which stands for Light Detection and Ranging. It means a sensor that works on the principle of light. Here we have used the TF Luna Lidar sensor which is a single point ranging sensor that is it is having FOV of 3 degrees. TF Luna Sensor emits infrared waves for detecting objects. It uses the Time of Flight Principle. It calculates time by measuring the phase difference between the original pulse and the reflected pulse and uses that time to get the relative distance.

𝑫 = 𝒄/𝟐  ∗  𝜟𝝋/𝟐𝝅𝒇 


c = Speed of Light

f = Signal Frequency

Δφ = Phase Difference.

The detection range of TF Luna is up to 8m.

Now, why didn't we use an ultrasonic sensor over lidar in this project because,

Ultrasonic-based systems are relatively inexpensive, while their detection range tends to be fairly short, and they take more time to detect cars when in use, their resolution is also quite low.

Speed of Light = c = 3x108 m/s

Speed of Sound = 343.2 m/s

Disadvantages of Ultrasonic sensor:

  • Air temperature has the greatest impact on the measuring accuracy of an ultrasonic sensor.
  • Noise can also affect the performance
  • Dust rain snow

Overall Look of the system:

TF Luna | Arduino Uno | HC-05 | Power bank

The hardware devices are on the left with a wired connection and on the right is the software BLiM opened in Mobile which is connected wirelessly. 

On the left In the hardware section. There is a box containing Arduino and HC-05. Beside it is the Lidar(TF Luna) sensor and connecting to it there is a power source.

All this hardware is having wired connection. But the BliM app connects it wirelessly via Bluetooth and the output can be displayed.

Working on the system

If we go in-depth into the topic then thought must have appeared in the mind that how will this system work?

Blind spot monitoring kit | Lidar sensor

The system starts when the car running above 20 kph with the detection of the vehicle in the blind spot zone by a LIDAR sensor, on detecting the vehicle sends the signal to the microcontroller. Further, this data is sent from the Arduino microcontroller wirelessly to the application (BLiM) on which the alert is shown via the HC-05 Bluetooth module.

The data is then processed and displayed on the BLiM App and displayed in front of the driver. If the approaching is at a critical distance then the driver will get an alert sound will be activated and the distance will be shown in red on the distance dial.

Working on App BLiM

The App comes into the picture when data is received. The App is named BliM(Blindspot Lidar monitoring). Having a clean user interface. When we enter the Application We come across the Start interface where user can set their minimum, moderate and maximum values as per their convenience. Where the minimum distance is critical and rest is safe.

Then connection Bluetooth is done connecting with hardware so that we can receive the data.  Then we land on the main interface. Here there are two main components the color dial which is having red, green, and blue and the other is the real-time distance.  The red color is for minimum distance blue is moderate and green is maximum safe.

Now whenever the car is approaching our car the Lidar sensor placed will detect the range of the approaching car. And send it to App. Then the App segregates whether the distance is in minimum moderate or maximum if it is minimum then it is considered as a critical range and in that case, the color dial will be red with the distance highlighted in red and a chime will sound (beeping) will be activated and as the projected car goes far away (outside the blindspot area) then the color on the dial will be green or blue and the buzzer will stop Beeping.

What if the car is in the critical range (Red) for a long time?

If the car is in the critical range (Red) for a long time then there is an off button on the header of the app. By pressing it in the Red area, the buzzer will stop for an instant and it will automatically turn ‘ON’ when the distance will be i.e. when it reaches the green and blue areas. The buzzer sound stops and the driver will be less irritated.

The reason behind making the app was to show the output wirelessly to the driver. Instead of having the led display with the tangled wire.

Advantages of the System

Of all the existing research covered, many systems using the Ultrasonic sensor were found to be less accurate during bad weather conditions. It also has less detection range (2-4m) & is not good at detecting fast-moving objects.

A lot of existing systems warned the driver through audio (buzzer) & a very basic visual aid (Led) which lacked in providing the driver with sufficient information.

System installation on car

Lidar sensor application | Blindspot Monitoring App

The sensor was placed above the fuel tank lid of the car (Wagon-R). The horizontal viewing angle of the sensor as noticed from the top was about 45°. The sensor’s detection zone is 8m to 9m. The flat distance from the bottom to the sensor was 104 cm. The absolute arrangement of the LIDAR sensor and also the screen on which the warning would be displayed i.e., the BLiM Application in the mobile placed on the dashboard is pictured in the above image. 


The proposed system is highly accurate and most importantly cost-effective. Such systems are only available in the higher segment vehicles. However, most mid-range cars that form a major component of vehicular traffic skip these systems. Thus the system is a solution for this segment.

This project model is Patented under Indian Patent and has a Research Paper published in Journal of the Institution of Engineers, Series C [Springer Journal] (Scopus Index) (UGC approved)

To read more details about this system the entire Research Paper is available on the springer website [Click Here]

This was our Final year Project model of Engineering. Please let me know about it in the comments below.

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