Using DFSS and Autonomy to Aid in Brake-to-Steer Vehicle Performance Characterization

As the automotive market continues to welcome autonomous technologies, the development of the corresponding features and system redundancies is becoming critical to the successful adaptation of these advanced innovations. As vehicle manufacturers invest in these critical technologies, the ability to engineer and properly execute the products in a cost-effective manner is a valued concern. CNXMotion has worked closely with its partner companies, Nexteer and Continental Automotive, to develop autonomous system redundancies and safety concepts to better facilitate an affordable transition to the autonomous future. Brake-to-Steer is one such technology that has been developed as a redundancy to allow lateral control of the vehicle when the steering system is unavailable.

This paper will discuss the methods by which CNXMotion approached the concept and testing methods used to identify the main chassis and environmental parameters contributing to the performance of Brake-to-Steer. The team began by using Design-for-Six-Sigma (DFSS) principles. DFSS studies were used to understand the main factors contributing to lateral vehicle movement using brakes. Although the vehicles were limiting the success of this method, the factors identified laid a path to allow for high-fidelity vehicle testing methods made possible by the addition of autonomy.

Once the team understood the main contributing factors to steering the car with brakes, creating a testing method to allow repeatable and consistent results was necessary. By automating a straight path, the team was able to manipulate varying brake inputs to augment the vehicle’s path and compare the lateral movement to the known straight path. This method created a basis for analysis and allowed for metrics to be created. Once the metrics were established, braking algorithm designs commenced and evolved into several iterated designs.

The paper will explain in order:

In summary, the team has extensively tested the interactions of the braking, powertrain, and surface mu and their individual and combined effects on the lateral movement of the vehicle through applying brakes.