Nexteer Automotive and Continental have announced a new JV, CNXMotion, with Brake-to-Steer (BtS) technology that they say provides driver safety through an additional layer of directional control for highly automated and autonomous vehicles.
In highly automated vehicle applications, steering systems feature multiple protective layers to ensure the steering safety net is always on. In addition, BtS adds yet another layer by using the electronic brake system to safely steer the vehicle while simultaneously controlling its speed. In a fully autonomous vehicle with no steering wheel present, BtS will negotiate a commanded path until a safe pull-over can be achieved.
“Perhaps the most critical challenge in highly automated and autonomous driving is ensuring the robustness of system redundancies to keep drivers, passengers and road users safe,” explained Alan Davis, general manager of CNXMotion. “CNXMotion’s Brake-to-Steer technology offers another steering safety layer for a wide range of automated driving conditions.”
CNXMotion’s BtS technology offers a cost-effective way for automakers to achieve safety needs by leveraging the vehicle’s existing braking and steering systems.
“As we progress toward higher levels of automation in vehicles, secondary and tertiary redundancy becomes crucial in executing successful minimum risk maneuvers. This helps keep vehicle occupants and road users safe,” said Hiren Desai, Head of Strategy, Autonomous Mobility and Safety, Continental North America. “Cross-domain functionalities such as Brake-to-Steer are enabled by, and housed on, existing hardware, like Continental’s MKCx brake-by-wire systems, eliminating the need for additional, costly components.”
“While steering traditionally manages the lateral control of a vehicle, Brake-to-Steer enables braking to contribute to lateral control as well,” said Robin Milavec, Senior Vice President, Executive Board Director, Chief Technology Officer (CTO) and Chief Strategy Officer (CSO), Nexteer Automotive. “When combined with advanced steering systems like Nexteer’s High Availability Electric Power Steering or Steer-by-Wire, Brake-to-Steer gives an additional layer of redundancy – further enhancing the safety net.”
How Brake-to-Steer Works
The BtS function resides in the Motion Control System (MCS), which acts as an intermediary between the vehicle’s path planner (the automated driving system) and the actuators (steering, brakes and powertrain) to determine the best path forward.
Integrated with a Performance Manager, the vehicle’s intended path is compared to the system’s ability to steer the vehicle via BtS, while constantly negotiating the safest route ahead.
In the event that BtS needs to engage, BtS reacts in one of three ways:
- Continues on the intended path before ultimately moving to the first or second option,
- Performs a minimum risk maneuver, such as slowing and braking to steer the vehicle to the side of the road, or
- Stops in the lane.
Originally developed for steering redundancy in Level 4+ autonomy, the feature can be adapted to assist a driver in multiple scenarios for lower levels (Lane Keep, Obstacle Avoidance, etc.) while a driver is still present, following the intentions provided from the driver’s steering input.