Cruise Control Coasting Logic for Target Speed Recovery
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Solution Overview
Problem
Drivers are not well-accepting the automatic commencement of rolling or coasting operations in motor vehicles from an active cruise-control function, particularly in utility vehicles like trucks, leading to underutilization of the automatic freewheel function.
Innovation Solution
A method that calculates a forecast speed profile based on traveling route data to determine a maximum permissible time duration for rolling or coasting operation, ensuring the speed reverts to the cruise-control target speed within this duration, thereby automatically activating or deactivating rolling or coasting operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If automatic freewheel function is activated to enable rolling or coasting operation from cruise-control, then energy efficiency is improved, but driver acceptance deteriorates due to prolonged deceleration
Solution Approach 1:
The control device performs preliminary calculation of the forecast speed profile before activating rolling operation. By predicting whether the vehicle will reach the target speed within the maximum permissible time using route data and current vehicle state, the system avoids activating rolling operation when it would cause prolonged deceleration, thus maintaining driver acceptance while preserving energy efficiency benefits when appropriate.
Solution Approach 2:
The system continuously monitors actual vehicle speed against the forecast speed profile and adjusts rolling operation accordingly. If the actual speed deviates from predictions or the vehicle approaches the target speed faster than expected, the control device can terminate rolling operation early, providing feedback-based control that adapts to real-time conditions and prevents excessive deceleration.
2Loss of energy
If rolling or coasting operation is activated automatically from cruise-control, then fuel consumption is reduced, but vehicle speed control precision deteriorates due to uncontrolled deceleration
Solution Approach 1:
Before activating rolling operation, the control device calculates a forecast speed profile based on route data, vehicle mass, and current operating conditions. This preliminary assessment determines whether the vehicle will reach the target speed within the maximum permissible time, ensuring that rolling operation is only activated when speed control precision can be maintained while achieving fuel savings.
Solution Approach 2:
The system continuously compares actual vehicle speed with the forecast speed profile during rolling operation. If the actual speed deviates from the predicted profile or the vehicle reaches the target speed faster than anticipated, the control device terminates rolling operation, providing real-time feedback control that maintains speed precision while capturing energy efficiency benefits.
Data Source
AI summary
Disclosed is a method for operating a motor vehicle having a drive aggregate and a transmission. If the transmission is torque-transmitting, a cruise-control function is active, and a cruise-control target speed has been specified, then based on travelling route data about a travelling route ahead of the motor vehicle, a forecast speed profile is calculated. A maximum deviation between the cruise-control target speed and the forecast speed profile is determined, and as a function of this maximum deviation, a maximum permissible time duration for rolling or coasting operation is determined. It is checked whether the forecast speed profile would revert to the cruise-control target speed within the maximum permissible time duration, and if so, the rolling or coasting operating mode is activated. If the forecast speed profile would not revert to the cruise-control target speed within the maximum permissible time duration, the rolling or coasting operating mode remains deactivated.