Cruise Control Speed Prediction for Fuel Efficiency
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Solution Overview
Problem
Existing vehicle cruise control systems face high processor load demands, especially when handling hilly terrain and varying road conditions, leading to inefficient fuel consumption and unpredictable performance.
Innovation Solution
A method and module that predict vehicle speed using both retarding and accelerating engine torques, comparing these predictions with set limits to determine a reference value for controlling the vehicle's speed, resulting in a consistent processor load independent of road topography and vehicle weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If traditional cruise control maintains constant reference speed equal to set speed, then driver convenience is achieved, but fuel consumption increases on hilly terrain due to unnecessary acceleration and braking
Solution Approach 1:
The system performs preliminary actions by predicting future vehicle speed based on road gradient information before the vehicle actually encounters the hill. It calculates required torque adjustments in advance and applies them proactively, allowing the vehicle to maintain set speed through the hill without excessive acceleration or braking, thereby reducing fuel consumption while preserving driver convenience
Solution Approach 2:
The system dynamically adjusts the reference speed based on predicted road conditions and vehicle state. Rather than maintaining a fixed reference speed, the controller modulates the reference speed profile in real-time according to upcoming gradients, enabling fuel-efficient operation on hilly terrain while keeping the vehicle at the driver's desired set speed under normal conditions
2Use of energy by moving object
If economical cruise control optimizes reference speed to save fuel, then fuel consumption decreases, but processor load becomes unpredictable and varies with road topography
Solution Approach 1:
The system performs preliminary speed predictions and torque calculations based on pre-acquired road gradient data before the vehicle encounters challenging terrain. By preparing the optimal speed profile in advance using stored topographical information, the system avoids sudden, computationally intensive adjustments during operation, thereby maintaining predictable processor load while achieving fuel savings
Solution Approach 2:
The horizon is divided into multiple segments with different gradient characteristics. The system processes each segment independently, calculating speed adjustments for specific road sections rather than treating the entire route as one complex problem. This segmentation reduces computational complexity and makes processor load more predictable by breaking down the optimization into manageable, repetitive tasks
3Speed
If cruise control accelerates over hill crests to maintain set speed, then speed maintenance is achieved, but vehicle speed exceeds set speed and requires braking which increases fuel consumption
Solution Approach 1:
The system detects upcoming hill crests using stored topographical data and applies retarding torque before the vehicle reaches the crest. This preliminary action prevents the vehicle from accelerating over the crest in the first place, maintaining set speed without exceeding it and eliminating the need for subsequent braking, thereby reducing fuel consumption while preserving speed maintenance
Solution Approach 2:
The system applies preliminary anti-action by using retarding torque to counteract the natural acceleration tendency over hill crests before it occurs. By applying a small retarding force in advance, the system prevents the harmful acceleration that would otherwise require corrective braking, thus maintaining speed control while reducing energy consumption
Data Source
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AI summary
The invention relates to a method for determination of at least one reference value which indicates how a vehicle's speed is to be influenced and which may be used to control at least one control system in a vehicle. The invention is characterised by performing the steps of: - making a first prediction vpred _Tnew _ret and a second prediction vpred _Tnew _acc of a vehicle speed along a horizon, said first prediction based on an engine torque Tret which retards the vehicle as compared with a conventional cruise control, and said second prediction based on an engine torque Tacc which accelerates the vehicle as compared with a conventional cruise control; - comparing said respective first prediction vpred _Tnew _ret and second prediction vpred_Tnew _acc of the vehicle speed with a lower limit value vmin and/or an upper limit value vmax which delineate a range within which the vehicle's speed should be; and - determining at least one reference value based on at least one of said respective comparisons and said first prediction vpred _Tnew_ret and second prediction vpred_Tnew_acc of the vehicle speed along the horizon.