Hybrid Vehicle Shift Control Using Terrain Data
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Vehicles with step ratio automatic transmissions experience frequent shifts, which can be annoying to occupants, as they often require shifting between speed ratios in response to changing conditions without considering upcoming terrain.
Innovation Solution
The vehicle controller utilizes terrain information from GPS or similar sources to adjust shift scheduling, employing modified shift curves based on upcoming terrain to minimize shifts by supplementing engine power with the traction motor and managing battery energy accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the transmission shifts between speed ratios in response to changing conditions, then the engine can operate at optimal speeds for power generation, but the frequency of shifts increases causing annoyance to vehicle occupants
Solution Approach 1:
The controller uses GPS and database information to predict upcoming terrain conditions (hills, grades) before the vehicle encounters them. Based on these predictions, the controller proactively adjusts shift scheduling and battery charge state management in advance, preventing frequent shifts by preparing the powertrain system ahead of time to handle upcoming terrain changes smoothly
Solution Approach 2:
The system dynamically adjusts transmission shift points and battery charge state targets based on predicted terrain conditions. The controller modifies shift curves in real-time according to upcoming hills or grades, and adjusts battery charge management strategy dynamically - charging during downhill sections and discharging during uphill sections - to maintain optimal engine operation without frequent shifts
2Adaptability or versatility
If the transmission frequently shifts between speed ratios, then the engine can adapt to varying vehicle speeds and load conditions, but fuel efficiency decreases due to repeated shifting events
Solution Approach 1:
The controller predicts upcoming terrain conditions using GPS and database information, then proactively manages battery charge state in advance. During predicted downhill sections, the system charges the battery by operating the traction motor as a generator, storing energy for upcoming uphill sections. This preliminary energy management allows the engine to maintain optimal operating conditions without frequent shifts, improving fuel efficiency
Solution Approach 2:
The system changes operational parameters dynamically - specifically adjusting transmission shift curves and battery charge state targets - based on predicted terrain conditions. The controller modifies shift points to prevent frequent shifting during upcoming hills or grades, and adjusts battery charge management strategy to support engine operation during varying terrain conditions, thereby maintaining fuel efficiency
3Device complexity
If the vehicle uses only present state information for shift scheduling, then the control system remains simple, but it cannot anticipate upcoming terrain changes leading to frequent shifts
Solution Approach 1:
The vehicle's existing GPS unit and database systems, originally designed for navigation and information display to drivers, are repurposed to provide terrain prediction data for transmission control. The controller integrates these existing multi-functional components into the shift scheduling algorithm, allowing the system to anticipate upcoming terrain conditions without adding dedicated hardware, thus maintaining simplicity while improving shift scheduling efficiency
Solution Approach 2:
The controller continuously receives feedback from the GPS unit about current position and uses this information alongside database information about upcoming terrain to predict future conditions. This feedback loop enables the controller to adjust shift scheduling proactively based on predicted terrain changes, improving productivity without significantly increasing system complexity since it uses existing sensor and communication infrastructure
Data Source
AI summary
A method of controlling a hybrid vehicle having a step ratio transmission is disclosed. The method utilizes terrain data to reduce the number of shift events. The method comprises receiving data indicative of a grade profile of an anticipated route, identifying a forecast shift sequence comprising a forecast downshift event and an adjacent forecast upshift event, and adjusting the shift criteria based on the time between the forecast shift events, the road grade between the forecast shift events, and the state of a storage battery.