Page 16 - EngineerIt June 2021

AUTOMOTIVE ELECTRONICS

ensures that should a passenger be accidentally locked inside premium OEMs for advanced HMI and gesture control, with the
the vehicle, the driver will be immediately notified with the ability optimum location being in the roof console. ToF provides an
to detect the number and age of the passengers. Emergency excellent solution not just for detecting the presence of a child
responders can be provided with additional information before but also their body position. You can see the need for a different
their arrival to an accident when this data is combined with the location of the sensor to enable line of sight to the rear seat (as
emergency call (eCall) system. shown in purple in Figure 3).
A special use case of occupant sensing is child presence With the advances in image sensing technology, ToF
detection, which will become (dependent on the region) a is the depth sensing method of choice for its smaller form
mandatory requirement. factor, wide dynamic range of sensing, and ability to operate
Advanced HMI and gesture control provide enhanced user in direct sunlight. The combination of high resolution distance
experience (see Figure 2). Instead of searching for and pushing measurement and medium resolution intensity image (ambient
a button on the main control area, a gesture can perform simple light insensitive 2D active brightness image) is unique to ToF.
functions such as skipping an audio track. ADI’s ToF sensor has the highest resolution (1 megapixel)
in the market, which enables wider field-of-view cameras.
Although many vision applications can be realised using
2D cameras, the 3D (depth) information offers an additional
level of robustness. For comfort applications this translates
to better user experience, and for safety applications it is the
key differentiator.
Since there will be multiple cameras in the cabin to support
different use cases, it is necessary that cameras support
interference cancellation to reduce errors in depth measurement.
Such challenges must be solved at the system level, and ADI
is actively pursuing this area with a smart mix of hardware and
software elements.
For biometric authentication ToF can provide a very secure
solution, making it very difficult to fool the system, as has been
proven possible with other implementations.
ADI technology in the ToF area includes ToF imagers
Figure 2: Human machine interface (HMI). (ADSD3100), laser drivers (ADSD3000), and power regulators
(ADP5071).

How to address these applications Car camera bus (C B)
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When we look at these applications, be it from their physical For connecting different cameras regardless of 2D imagers or
location (see Figure 3), the comfort vs. safety aspect, or the 3D ToF, ADI also provides a dedicated automotive camera link
solution they need to provide, it becomes evident that a single technology, the car camera bus (C B ). C B is a low-cost solution
TM
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sensing solution cannot address them all. Sensor fusion with to transport up to two megapixel camera data along with control
different sensing modalities is required. The combination of information from cameras installed inside or outside the car.
safety and comfort applications needs to be addressed. Several
technologies need to be combined and work together to reach Impedance sensing
the goals of the increasing safety and comfort requirements. ADI offers several VSM solutions and works closely with software
partners to provide an overall system solution for features
including heart rate variability, stress etc. The AD5941W is an
integrated solution for both HOD and for measuring EDA.
Impedance sensing provides a robust and reliable solution to
not only detect hands on the steering wheel but also the quality
of the grip, which is a key requirement. The location of the hand
on the steering wheel can also be provided. EDA information can
be used to detect the driver’s current stress level.
ADI has significant expertise in this area from working on
Figure 2: Human machine interface (HMI). this technology across multiple industries. The AD5933 high
precision impedance converter is used in cars today for HOD.
The AD5941W supports multiple HOD zones in a single device.
Technologies
Time of flight (ToF) technology Electro-cardiography
A time of flight (ToF) camera is one of the key technologies that Combining impedance sensing components with the AD8232W,
can address several of the previously described applications, a high precision amplifier for electro-cardiography, ADI offers a
providing both image and depth data. complete VSM solution consisting of only two components. ECG
A ToF camera located in the dashboard or roof can be used along with EDA can monitor the driver’s health state, but ECG can
for DMS such as eye tracking. ToF is already in production at also be used to address biometric authentication applications.

EngineerIT | June 2021 | 14