Redundancy in autonomous vehicles: Steering, Braking and Power systems

This blog post explains how Einride's autonomous vehicles ensure safety and reliability through redundant systems for steering, braking, and power, particularly crucial for their cabless eBots. It details the implementation of redundant batteries, DC/DC converters, and electro-mechanical steering with dual controllers to eliminate single points of failure and maintain operational capability in critical situations.

Autonomous vehicles necessitate the implementation of redundant architectures within steering, braking, and power systems. Redundancy, defined as the provision of backup systems, is analogous to the human body's dual appendages, where the failure of one necessitates the activation of its counterpart. This principle is of paramount importance specifically for our eBots, with its cabless design.

Imagine a scenario with loss of electrical power or communication bus failure to the steering and braking systems; the vehicle must autonomously transition to a safe state, such as executing a controlled deceleration and pulling onto the shoulder to stop, regardless of the distance. This necessitates the elimination of any single point of failure within critical subsystems.

For dependable backup power, our vehicle design incorporates power redundancy as a critical feature. Our eBots heavily rely on low-voltage DC power distribution networks to energize all the onboard electronic control units (ECUs), which are essential for safety-critical functions. To address this, we've implemented a dual-redundant battery topology coupled with dual-redundant DC/DC converters. This setup ensures that even if one battery fails, the communication protocols and ECUs continue to operate effectively, maintaining vehicle control and safety in all scenarios.

Because of our unique cabless design, we shifted from traditional hydraulic steering, characterized by fluid-based actuation and substantial mass, to a more efficient electromechanical steering (EMS) system. The developed system is built up by a redundant motor set-up, making sure that the requested torque is always transferred to the linear actuator which further controls the steering geometry of the front axle. Dual steering controllers send the steering request at all times to maintain full redundancy, and they constantly perform plausibility checks on each other.

Looking ahead, we believe an industry shift to fully electro-mechanical steering, braking and robust power systems represents the future trajectories, just like we've seen for passenger vehicles. We're continuing to innovate and push the development of these electronically controlled systems as part of our robust safety procedures, as we innovate for tomorrow’s applications of autonomous technology.