Vehicle Downshift Scheduling via Pedal Rate Analysis
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Solution Overview
Problem
Downshift scheduling in automatic transmissions often results in close pedal spacing between shift points, causing drivers to tip-in and back out of the pedal to find the desired gear, leading to inefficient acceleration and potential hunting for the appropriate gear.
Innovation Solution
A controller in the vehicle is programmed to command a downshift to a downshift gear based on the rate of change of the accelerator pedal position, the last predefined position crossed, and a gears-remaining value, ensuring the difference between the initial and downshift gears exceeds the number of predefined positions crossed, thereby optimizing gear shifts and reducing driver input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If downshift scheduling is based on gear and pedal position with close pedal spacing between shift points, then the transmission can respond to driver demand, but the driver must tip-in and back out of the pedal to hunt for the desired gear
Solution Approach 1:
The controller predicts the driver's desired gear selection by analyzing the rate of change of pedal position and the number of predefined positions crossed, then proactively schedules the downshift before the driver completes the pedal tip-in action. This preliminary action eliminates the need for drivers to hunt for the correct gear by anticipating their intent and pre-positioning the transmission in the desired gear.
Solution Approach 2:
The system continuously monitors pedal position, rate of change of pedal position, and current gear state to dynamically adjust downshift scheduling. By feeding back this information to the controller, the system can determine when a downshift is imminent and schedule it appropriately, preventing gear hunting while maintaining responsive acceleration.
2Adaptability or versatility
If the pedal spacing between shift points is reduced to provide finer control, then more gear options are available, but the driver must make frequent small adjustments to find the desired gear
Solution Approach 1:
By calculating the rate of change of pedal position and the number of predefined positions crossed, the controller predicts which gear the driver intends to select and schedules the downshift in advance. This eliminates the need for drivers to make frequent small pedal adjustments to navigate through multiple gear options, as the system proactively selects the appropriate gear based on the predicted driver intent.
3Productivity
If downshift scheduling is based on multiple parameters including rate of change of pedal position and positions crossed, then gear shifts are optimized, but the control system complexity increases
Solution Approach 1:
The controller uses pre-defined thresholds and calculation methods for rate of change of pedal position and number of positions crossed to predict driver intent. By establishing these preliminary criteria, the system can efficiently determine when to schedule downshifts without requiring complex real-time decision algorithms, thus optimizing gear shifts while managing controller complexity through structured parameter evaluation.
Data Source
AI summary
A vehicle includes an accelerator pedal moveable across a plurality of predefined positions and a controller programmed to, responsive to the pedal reaching a tip-in position, command a downshift to a downshift gear from an initial gear. A difference between the initial and downshift gears exceeds a number of predefined positions crossed upon moving to the tip-in position when a rate of change of pedal position exceeds a predefined threshold.