Predictive Transmission Shifting for Road Gradient Changes
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Solution Overview
Problem
Automated transmissions frequently shift between gears due to elevation changes, leading to driver annoyance and reduced fuel economy, as they rely solely on current conditions rather than anticipating future road gradients.
Innovation Solution
A predictive shift system that adjusts upshift and downshift thresholds based on future gradient conditions by tracking vehicle parameters and using lookahead distances to determine optimal gear shifts, allowing the vehicle to cruise at lower engine speeds while maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If automated transmission uses current situation information for shift decisions, then the transmission responds quickly to current conditions, but it causes frequent shifting on routes with elevation changes and reduces fuel economy
Solution Approach 1:
The transmission control system performs preliminary actions by determining future gradient conditions in a lookahead distance before actual gear shifts are needed. The system calculates whether future gradient conditions will require gear changes and adjusts shift thresholds in advance, allowing the transmission to shift proactively rather than reactively, thereby avoiding frequent shifting and improving fuel economy
2Use of energy by moving object
If the vehicle cruises at low engine speed to maximize fuel economy, then fuel efficiency improves, but the vehicle may need to shift frequently when encountering elevation changes
Solution Approach 1:
The system determines future gradient conditions in advance within a lookahead distance and uses this information to proactively adjust upshift and downshift thresholds. By knowing upcoming elevation changes before they occur, the transmission can maintain optimal gear selection through the entire gradient sequence, avoiding frequent shifts while keeping the vehicle at efficient low engine speeds during cruising
Solution Approach 2:
The transmission control system dynamically adjusts shift thresholds based on predicted future gradient conditions. Instead of using fixed shift points, the system modifies upshift and downshift thresholds in real-time according to the anticipated road profile, allowing flexible adaptation that maintains both fuel efficiency and smooth operation across varying terrain
3Speed
If the transmission shifts frequently between top gear and lower gear on elevation changes, then the vehicle can maintain speed through gradients, but driver annoyance increases and fuel economy decreases due to torque interruption
Solution Approach 1:
The system determines future gradient conditions in advance and proactively adjusts shift thresholds before the vehicle encounters the gradients. This allows the transmission to select appropriate gears in advance and maintain speed through gradients without frequent shifting, eliminating the harmful effects of driver annoyance and fuel penalty associated with reactive shifting
Data Source
AI summary
A method of shifting an automated transmission in a vehicle comprises tracking vehicle parameters and determining a current gear selection. An upshift threshold can be determined for the current gear selection. Future gradient conditions are determined in a lookahead distance and are processed to determine a first percentage of future conditions that are above a selected gradient threshold. The first percentage of future conditions is compared to a selected first percentage limit to determine that the first percentage of future conditions is within the first percentage limit. The upshift threshold for the current gear selection is adjusted to change the vehicle parameter at which the vehicle transmission shifts from the current gear selection to the adjacent gear. The automated transmission is computer-controlled to shift to the adjacent gear according to the adjusted upshift threshold. A downshift threshold can also be adjusted.