Vehicle Torque Map Modification for Curve Entry
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Solution Overview
Problem
Drivers face challenges in gauging appropriate entry speeds for curves, especially blind curves, leading to increased lateral acceleration, as existing yaw control methods often intervene reactively and may not account for obstructed views or varying road conditions.
Innovation Solution
An electronic horizon system integrated with a vehicle's control system, which receives inputs on vehicle state and curve data, downshifts the transmission and modifies the accelerator pedal map to reduce positive drive torque, anticipating and mitigating excessive lateral acceleration by utilizing engine braking and predictive modeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the vehicle speed increases in a curve, then the travel time through the curve decreases, but the lateral acceleration on the vehicle increases
Solution Approach 1:
The electronic horizon system predicts upcoming curves and their characteristics in advance, allowing the controller to preemptively adjust transmission gear and torque request maps before the vehicle enters the curve. This preliminary action enables the vehicle to maintain lower speeds through curves without requiring reactive speed reduction, thereby reducing lateral acceleration while still achieving efficient curve traversal.
Solution Approach 2:
The system dynamically modifies transmission shift schedules and torque request map parameters based on predicted curve characteristics. By changing these control parameters in advance according to the electronic horizon data, the system optimizes the relationship between vehicle speed and lateral acceleration, allowing faster curve passage while keeping lateral forces within acceptable limits.
2Stability of the object's composition
If existing yaw control methods are used to reduce lateral acceleration, then vehicle stability improves, but driver control and response time are reduced
Solution Approach 1:
Rather than reactively intervening when lateral acceleration exceeds thresholds, the system uses the electronic horizon to predict curves in advance and preemptively adjusts transmission and torque parameters. This approach maintains vehicle stability through proactive control while preserving the driver's ability to respond naturally to road conditions, avoiding the reactive delays associated with traditional yaw control methods.
Solution Approach 2:
The electronic horizon system acts as an intermediary that provides advance information about upcoming curves to the controller. This intermediary layer enables the controller to make informed decisions about transmission and torque adjustments without directly interfering with driver input, thereby maintaining stability while preserving driver control and intent.
3Force
If the transmission is downshifted and torque request map is modified to reduce positive drive torque, then lateral acceleration is reduced, but fuel efficiency may deteriorate
Solution Approach 1:
The system performs transmission downshifts and torque map modifications in advance of curve entry based on electronic horizon predictions. By preparing the powertrain in advance rather than making reactive adjustments during the curve, the system minimizes unnecessary torque reductions and maintains optimal fuel efficiency while still achieving the required lateral acceleration control through strategically timed gear and torque changes.
Data Source
AI summary
A vehicle has an accelerator pedal in communication with a prime mover, a transmission, and a controller. The controller is configured to, in response to receiving a first input indicative of a vehicle state and a second input indicative of a curve along a vehicle path within a predetermined time interval, downshift the transmission and modify a driver torque request map associated with the accelerator pedal to reduce a percentage of pedal travel associated with positive drive torque. A method of controlling a vehicle includes downshifting a transmission and modifying a driver torque request map associated with an accelerator pedal to reduce a percentage of pedal travel associated with positive drive torque when a vehicle state and a curve from an electronic horizon system predict a vehicle lateral acceleration in the curve being above a first threshold value.