More and more people own cars nowadays. As roads become more populated, the chance of accidents also increases. With the rising trend of global road accidents per annum, it poses a tremendous concern among stakeholders ranging from car manufacturers to consumers. The damage caused by road accidents are considered a “global tragedy” where millions of people die, and thousands remain disabled every year. In this paper, it is reported that a mind-blowing 1.17 million deaths occurs due to road accidents each year. Therefore, for automotive industries, passengers’ safety has become a key factor in designs to ensure the safety regulations can meet to reduce the road accidents and casualties and enhance pedestrian safety. To commit to this, car manufactures are constantly upgrading and offering their latest fail-safe safety technologies to protect passengers and pedestrians.
Automotive Radar Sensors Using Millimeter Waves
Taking advantage of available millimeter wave frequency spectrum at 24 GHz and 76 GHz to 81 GHz together with advanced mixed-signal semiconductors, the automotive radar sensors can be built into compact modules and become part of future car safety features.
So why millimeter wave? Why is it important to utilize millimeter wave? This is due to a few factors. Firstly, mm waves have short wavelength, this translates into smaller sizing as the required size of the module becomes smaller when the wavelength is shorter. This factor is especially important due to the number of radars on the car without compromising the aesthetic of the car design itself. With shorter wavelength, antennas required for the radar modules will be shorter, thus minimizing space taken in the car design.
Next, mm wave has the benefit of high accuracy. With wavelength in the millimeter range, this means that the distance measurement and movement detection can have millimeter range of accuracy. In other words, the radar module is significantly more sensitive to proximities and distances unlike radar modules of the pass who usually operates in the meter or centimeter wavelength. This allows millimeter radar systems to transmit signals reflected from small obstacles in its path and by capturing the reflected signal, it can determine the range, velocity and angle of the objects.
There 3 types of radar sensors available:
- Short range Radar — track object or movement of person up to 30m from the vehicle
- Mid-range Radar — operate at a range of 100–150m from the vehicle
- Long range Radar — Detect objects situated in a wide geographical area in a range of 10–200m from the vehicle
These radar sensors can be implemented to mitigate crashes/accidents and limit the damage/injuries caused to the driver, passengers, and pedestrians by electrically looking ahead, behind, and around corners. The figure below illustrates the advance driver-assistance systems (ADAS) features offered by automotive industries which can enable the “cars of the future” capable of autonomous driving.
Based on the Society of Automotive Engineers (SAE), there are five levels of autonomous driving definition. It can be divided into two big groups; human perform from level 0 to level 2 and system perform from level 3 to level 5.
- Level 0: No automation (Driver) — full time driver performs the dynamic driving task
- Level 1: Assisted (Feet-off) — driver performs the dynamic driving task with driving mode-specific execution by a driver assistance system (steering or acceleration/deceleration)
- Level 2: Partial automation (Hands-off) — driver must monitor the system at all times for some driving modes
- Level 3: Conditional automation (Eyes-off) — driver does not need to monitor the system at all times for some driving modes
- Level 4: High automation (Eyes-off and mind-off) — driver is not required during defined use case; the car can pull over safely by guiding system
- Level 5: Full automation (Mind-off) — no driver required during the entire journey
This future megatrend of autonomous driving car cannot be possible without automotive radar sensor technologies. To achieve level 5 automation, multiple radar sensors will be needed. As part of the rapidly advancing vehicular electronic safety systems, these radar sensors will be mounted on the front, rear, and sides of a vehicle for object detection up to a distance of 200m.
With the advancement of material, test and measurement, it is believed that affordable ADAS vehicles will be available not only in developed countries but also in developing countries not far in the future. The “cars of the future” is coming soon and it comes hand in hand with the “not so far away” 5G services.
Originally published at http://filpal.wordpress.com on December 26, 2021.
