Electric Vehicle Steering System: 3 Trends and Challenges in the Era of Intelligent Driving

I. Electric Vehicle Steering System Development Trends

The automotive steering system market is undergoing a rapid evolution from traditional mechanical structures to intelligent, electronically controlled systems. Electric Power Steering (EPS) has become the mainstream technology, and as autonomous driving levels advance, Steer-by-Wire (SBW) is emerging as the future direction of steering innovation.

Key trends shaping the future of Steer-by-wire technology include:

• Latency Reduction:
  Current SBW communication latency stands at 15–20 ms. With ongoing technological advancements, latency is expected to be reduced to under 5 ms by 2025, significantly enhancing both driving experience and system safety.
• Weight Reduction:
  Today’s steering systems typically weigh between 4.8–5.2 kilograms. Through the use of lightweight materials and structural optimization, manufacturers aim to reduce system weight to below 4 kilograms by 2025, supporting overall vehicle lightweighting.
• System Integration:
  While current steering systems largely operate independently, by 2025, steering systems are projected to achieve integrated domain control, working collaboratively with braking, suspension, and other chassis systems to improve overall vehicle intelligence and performance.

II. An Overview of Steer-by-Wire (SBW) Systems

Building upon EPS technology, Steer-by-Wire system eliminates the mechanical connection between the steering wheel and the steering actuator. The system primarily consist of a road feel simulator, steering actuator, electronic controllers, and an array of sensors.

Given safety concerns, SBW systems incorporate dual-redundancy designs, with critical components like motors, control circuits, torque/angle sensors, and power supplies duplicated to ensure secure and reliable operation.

Key Features of SBW Systems:

1. Enhanced Driving Dynamics:
   SBW dynamically adjusts the steering ratio based on factors such as vehicle speed and traction control. Lower steering ratios at low speeds enable smaller turning radii, while higher ratios at high speeds improve straight-line stability.
2. Improved Road Feel Simulation:
   Without mechanical linkages, road feel is electronically simulated to provide customizable tactile feedback, catering to diverse driver preferences.
3. Superior Comfort:
   The elimination of hard mechanical connections prevents road surface imperfections and wheel imbalance vibrations from being transmitted to the driver, reducing fatigue and increasing legroom.
4. Personalized Driving Experience:
   Software-controlled settings allow the customization of steering ratios and feedback torque, adapting the driving behavior to meet individual preferences and diverse driving environments.

Challenges Facing SBW Adoption:

• Safety Concerns:
  Due to limited mass deployment and validation, especially in areas involving upper-level perception algorithms, ensuring safety remains a critical priority.
• High Cost and Complexity:
  SBW development involves expensive and complex electronic control systems. Without large-scale production, manufacturing and maintenance costs remain high, posing a significant barrier to widespread adoption.

III. The Impact of Intelligent Driving on Steering System Evolution

As the pursuit of higher precision, faster response, and increased safety intensifies, intelligent driving demands that steering systems eliminate mechanical connections wherever possible. Commands are transmitted via electrical signals, making true SBW systems indispensable for vehicles reaching Level 3 (L3) autonomous driving capabilities and beyond.

In traditional vehicles, steering depends on driver input, with hydraulic or electric motors assisting the process. In contrast, SBW systems autonomously perform steering operations. Power transmission between the steering wheel and actuator is achieved via electrical cables, not mechanical linkages.

To meet L3 autonomous driving standards, steering systems must achieve an electronic failure rate comparable to aviation standards (approximately 10 failures per billion hours). This necessitates rigorous redundancy designs, involving dual electronic control units (ECUs), motors, and sensors to guarantee operational reliability even under extreme conditions.

As autonomous driving technology matures, steering system strategies face new challenges in environmental adaptability, reliability, and safety. Achieving fully autonomous driving in complex road conditions, recognizing failure modes, and implementing fault-tolerant controls will become critical research and development areas for next-generation Electric Vehicle Steering Systems

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