Brake-to-Steer Longitudinal Compensation via Shift and Torque Control
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Solution Overview
Problem
Brake-to-steer systems in vehicles often cause rapid and unnatural deceleration, leading to an uncomfortable driving experience due to the lack of longitudinal compensation during lateral control maneuvers.
Innovation Solution
Implementing a closed-loop longitudinal control system that adjusts transmission gears or equivalent shifts to optimize engine or electric motor speed and torque based on vehicle speed, combining with brake torque commands to manage deceleration and maintain a natural feel during brake-to-steer operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If brake-to-steer systems apply brakes to steer the vehicle, then lateral control is achieved, but rapid and unnatural deceleration occurs causing uncomfortable driving experience
Solution Approach 1:
The system applies preliminary anti-action by using propulsion torque to counteract the deceleration caused by brake-to-steer before the lateral control maneuver completes. The controller calculates compensation torque based on the brake torque applied and adds it to the propulsion torque request, thereby preemptively offsetting the unwanted speed reduction and maintaining natural deceleration characteristics.
Solution Approach 2:
The system implements feedback by continuously monitoring the brake torque applied during brake-to-steer operations and using this information to dynamically adjust the propulsion torque compensation. The controller receives brake torque requests from the brake-to-steer system and automatically generates compensating propulsion torque commands to maintain desired vehicle speed and deceleration characteristics.
2Ease of operation
If transmission gears are shifted to optimize engine speed and torque, then natural deceleration feel is improved, but system complexity increases
Solution Approach 1:
The controller performs multiple functions using a single integrated system. It simultaneously manages brake-to-steer lateral control, longitudinal speed control, and propulsion torque compensation without requiring separate dedicated systems for each function. This multi-functionality approach maintains natural deceleration feel while avoiding the complexity of additional independent control systems.
Solution Approach 2:
The system merges brake-to-steer control with longitudinal speed control into a unified control architecture. The controller integrates the brake torque commands from brake-to-steer with propulsion torque requests for speed maintenance, combining what could be separate systems into one coordinated control unit, thereby reducing overall system complexity while achieving natural deceleration characteristics.
Data Source
AI summary
A number of illustrative variations may include a system including brake-to-steer algorithms may achieve lateral control of a vehicle without longitudinal compensation but may also force a vehicle to slow down too rapidly before appropriate lateral movement can be achieved and may deliver an unnatural driving experience for vehicle occupants. A more natural feeling deceleration may be achieved by optimally selecting appropriate transmission shifts to allow for optimal engine speed or electric motor speed and torque based on current vehicle speed thereby reducing undesirably longitudinal disturbance.