Vehicle Torque Control Using Split Pedal Maps on Gradients
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Solution Overview
Problem
Conventional powertrain systems in electric vehicles fail to accurately replicate the driving experience of internal combustion engine vehicles by not effectively emulating the resistive torque when the accelerator pedal is released, leading to a non-intuitive driving experience.
Innovation Solution
A controller that determines the position of the accelerator pedal relative to a reference position and adjusts torque output using acceleration and deceleration pedal maps, taking into account vehicle speed, gradient, terrain, and state of charge, to emulate the behavior of an internal combustion engine.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a single accelerator pedal map is used for both acceleration and deceleration, then the control system is simple, but the driving experience does not accurately replicate internal combustion engine behavior
Solution Approach 1:
The accelerator pedal map is segmented into two distinct maps: an acceleration pedal map for when the pedal position exceeds the reference position, and a deceleration pedal map for when it is below the reference position. This segmentation allows each map to be optimized for its specific function, accurately replicating ICE behavior during acceleration and deceleration phases separately.
Solution Approach 2:
The system dynamically switches between acceleration and deceleration pedal maps based on the relationship between the current accelerator pedal position and the reference accelerator pedal position. This dynamic adaptation enables the control system to provide context-appropriate torque responses that mimic ICE vehicle behavior across different driving phases.
2Ease of operation
If resistive torque is not emulated when the accelerator pedal is released, then the powertrain is simple to control, but the driving experience is non-intuitive
Solution Approach 1:
The reference accelerator pedal position is predetermined based on road load conditions, allowing the system to anticipate when deceleration should occur. By comparing the current pedal position against this pre-determined reference, the system can proactively apply resistive torque during deceleration phases, replicating the intuitive feel of ICE vehicle engine braking.
Solution Approach 2:
The system continuously monitors the accelerator pedal position and compares it against the reference position to determine whether to apply acceleration or deceleration torque maps. This feedback mechanism ensures that resistive torque is applied at the appropriate moments during deceleration, creating an intuitive driving experience that mimics ICE behavior.
3Force
If downshifting is used to increase resistive torque in ICE vehicles, then overrun torque is increased, but the mechanism is mechanically complex
Solution Approach 1:
The patent replaces the mechanical downshifting mechanism with an electronic control system that uses software-based acceleration and deceleration pedal maps to generate resistive torque. This substitution eliminates the need for mechanical gear changes while achieving the same effect of increasing overrun torque through electronic torque management.
Solution Approach 2:
The system changes the torque output parameter dynamically by switching between different pedal maps (acceleration vs. deceleration) based on pedal position. This parameter change approach allows the system to vary resistive torque levels without mechanical intervention, effectively replicating the force characteristics of downshifting through software control.
Data Source
AI summary
A controller for a vehicle, the controller being configured to: receive a gradient signal indicative of a gradient of a surface the vehicle is traversing; determine a gradient modifier based at least in part on the gradient signal; modify an acceleration pedal map and a deceleration pedal map based at least in part on the gradient modifier; determine a position of an accelerator pedal with respect to a reference accelerator pedal position; and determine a torque output based at least in part on the acceleration pedal map if the position of the accelerator pedal is greater than the reference accelerator pedal position; or determine a torque output based at least in part on the deceleration pedal map if the position of the accelerator pedal is less than the reference accelerator pedal position.