Vehicle Speed Reference Control Module for Adaptive Cruise Systems
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Solution Overview
Problem
Conventional cruise control systems lack the ability to adapt to varying road conditions and driver preferences, such as fuel efficiency and journey time, as they do not utilize knowledge of the road ahead, limiting driver control options to only two modes and not optimizing speed adjustments for hilly terrain.
Innovation Solution
A module and method that predict vehicle speed based on engine torque, comparing these predictions with defined lower and upper limit values to determine a reference value, allowing the driver to choose a driving mode that influences speed control, enabling more flexible and efficient speed management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional cruise control maintains constant reference speed equal to set speed, then driver control is simple, but fuel efficiency on hilly terrain deteriorates
Solution Approach 1:
The system performs preliminary actions by predicting road gradient ahead and pre-adjusting the reference speed before the vehicle encounters hilly terrain. The prediction unit forecasts upcoming gradients, and the reference speed determination unit proactively modifies the reference speed trajectory to optimize fuel consumption before the actual terrain change occurs, rather than reacting after the fact.
Solution Approach 2:
The system transitions from static constant reference speed control to dynamic reference speed adjustment. The reference speed determination unit continuously adapts the reference speed based on predicted road gradients, vehicle state, and driving mode, creating a dynamic control system that responds to changing terrain conditions while maintaining driver-friendly operation.
2Use of energy by moving object
If reference speed is allowed to differ from set speed for fuel saving, then fuel efficiency improves, but driver acceptance deteriorates
Solution Approach 1:
The system implements feedback through the driving mode determination unit that continuously monitors driver behavior and vehicle state. When the driver activates cruise control or selects economical driving mode, the system feedback-adjusts the reference speed to allow fuel-saving deviations. The mode determination unit uses feedback from accelerator pedal position, brake status, and gear selection to dynamically adjust how much the reference speed can differ from set speed.
Solution Approach 2:
The system changes parameters by introducing multiple driving modes (normal mode and economical driving mode) that alter the relationship between set speed and reference speed. In economical mode, the reference speed is allowed to deviate more from set speed to optimize fuel consumption, while in normal mode, it stays closer to set speed for driver comfort. This parameter change approach allows flexible adjustment of fuel efficiency vs. driver acceptance.
3Device complexity
If only two driving modes are provided, then system complexity is low, but adaptability to different driver preferences deteriorates
Solution Approach 1:
The system applies local quality by providing different levels of economical driving within the two modes. Rather than uniform behavior across all settings, the reference speed determination unit adjusts the degree of reference speed deviation from set speed based on local conditions such as predicted gradient, current vehicle state, and selected mode. This allows nuanced adaptation to driver preferences within each mode.
Solution Approach 2:
The system achieves universality through the driving mode determination unit that integrates multiple functions: detecting driver intent from various inputs (accelerator pedal, brake status, gear selection), selecting appropriate driving modes, and adjusting reference speed behavior. This multi-functional unit allows the simple two-mode system to adapt to diverse driver preferences and driving conditions.
4Measurement precision
If cruise control brakes downhill to maintain set speed, then speed control precision is maintained, but fuel consumption increases
Solution Approach 1:
The system applies preliminary anti-action by predicting downhill gradients ahead and proactively reducing the reference speed before the vehicle encounters the downgrade. This prevents the vehicle from accelerating excessively and needing aggressive braking, thereby reducing energy waste. The prediction unit forecasts the downhill section, and the reference speed determination unit preemptively adjusts the reference speed trajectory to counteract the upcoming gravitational acceleration.
Data Source
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AI summary
A method arranged for determination of at least one reference value, which at least one reference value indicates how a vehicle's speed is to be influenced, and may be used to control at least one control system in a vehicle, which method is characterised by performing the steps of: - making a mode choice from at least two selectable driving modes each comprising a unique set of settings which influence the calculation of the at least one reference value; - 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 vpreil_ 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 said mode choice and 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 so that the at least one reference value is within a range bounded by the lower and upper limit values vmin and vmax.