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Hyundai Mobis develops dual-mode electronic steering system optimized for autonomous driving

Tier-1 supplier Hyundai Mobis has developed an electric power steering system which uses the redundant control mode that takes advantage of two electronic circuits during autonomous driving to maintain normal steering capabilities under any circumstances. The system is an advanced technology with no case of mass-production as of yet.

The normal operation of the steering system in the autonomous driving environment, in which the vehicle operates on its own without the driver’s control, is a requirement directly related to the safety of passengers. Even if the steering system runs into an unexpected problem while the car is being driven, the system must detect the issue by itself and normally control the steering wheel before stable autonomous driving is possible.

Hyundai Mobis redundantly designed all core electronic components (sensors, ECUs, motors, etc.) of the steering system so that normal steering is possible in any situation.


As two independent electronic circuits are applied to one steering system, even if one circuit breaks down, the other circuit will work normally and maintain stable driving.

In the existing electric power steering system, if the driver turns the steering wheel, the internal sensor will read the torque and the steering angle and send a signal to the electronic control unit (ECU). The ECU computes the input data and moves the motor with an appropriate value to control the vehicle in the direction desired by the driver.

In this case, if the steering system has any problem, the driver will be able to take emergency measures, such as reducing speed and moving the car to a safe place on the road.

However, things will be different in the autonomous driving mode. As the driver is not looking ahead during autonomous driving, if the steering system has any problem, the driver cannot intervene immediately, and the risk of an accident will increase.

To ensure that normal steering capabilities are maintained in this situation, Hyundai Mobis developed two independent electronic circuits. The company ensured a high level of safety using twin systems that watch over each other.

To implement this new technology, the ability to reduce the size of electronic components (HW) and develop software (SW) is essential.

Hyundai Mobis succeeded in reducing the size of the electronic control unit (ECU), utilizing small electronic devices to reduce its size in half while ensuring that it performs the same functions.

Configuring the system redundantly (redundant design) and reducing its size belong to the hardware area, whereas operating the two systems and making them perform belong to the software area.

The two systems watch over each other through high-speed communication, and check if the counterpart is working normally. If a problem is detected, System No. 1 is turned off, and System No. 2 will be activated. This is how the vehicle is controlled. As a result, the vehicle can maintain a normal steering status under any circumstances.

To further advance the technology, Hyundai Mobis is conducting reliability evaluations including road tests. It is planning to finish the verification tests in general driving conditions, such as expressways, downtown and parking, by the end of 2018, and start mass-production in 2020.

According to its technology roadmap for autonomous driving, Hyundai Mobis will proprietarily develop the core technologies in implementing autonomous driving by 2020, such as deploying radars, cameras and Lidar—essentially, all sensors.

Currently, it is developing high-performance economical radars, which detect 360° around the vehicle, through a partnership with two German specialists, and it is also seeking to develop cameras based on Deep Learning, the AI technology, through cooperation with domestic and overseas startups.



Similar redundant e-subsystems will be required on all ADVs to maintain/increase safety in all conditions.


Interesting how many parts manufacturers can offer car makers sub-assembly solutions to many of their engineering requirements, i.e., Bosch offering electrical drive trains and LG Chem offering complete battery systems. The carmaker is becoming more of an integrator/assembler than a developer.

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