Vehicle Speed Control After Manual Acceleration Override
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Solution Overview
Problem
Current speed control systems in vehicles often require unnecessary switching to coasting or braking modes to maintain target speed after temporary driver acceleration, which can be inefficient in terms of comfort and fuel consumption.
Innovation Solution
A speed control system that detects the completion of a manual acceleration request and initiates a sailing operation if the current speed exceeds the target speed, ensuring deceleration behavior matches the desired behavior and can be maintained for a defined time, thereby using sailing mode to return to the target speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the control unit switches to coasting or braking mode to maintain target speed after temporary driver acceleration, then the target speed is maintained, but comfort and fuel consumption are worsened
Solution Approach 1:
The system changes the deceleration parameter by selecting different deceleration sources (coasting, engine braking, service braking) based on the magnitude of speed excess. Instead of always using strong braking, the system adjusts the deceleration profile to match the situation, using gentle coasting when speed excess is small and stronger braking when speed excess is large, thereby improving comfort while maintaining speed control reliability
2Reliability
If the control unit switches to coasting or braking mode to maintain target speed after temporary driver acceleration, then the target speed is maintained, but fuel consumption efficiency is worsened
Solution Approach 1:
The system optimizes energy usage by dynamically changing the deceleration strategy parameter. When the speed excess is within a certain threshold, the system selects coasting mode which consumes minimal fuel. Only when the speed excess exceeds the threshold does the system switch to engine braking or service braking, thereby minimizing fuel consumption while ensuring reliable target speed maintenance
Solution Approach 2:
The system converts the harmful effect of excess kinetic energy (which would otherwise require energy-intensive braking to dissipate) into a beneficial coasting phase. By allowing the vehicle to coast and naturally decelerate using aerodynamic drag and rolling resistance, the system transforms what would be wasted energy into a fuel-efficient deceleration period, reducing overall fuel consumption
3Reliability
If the control unit initiates deceleration to reduce speed back to set speed after override, then the target speed is restored, but comfort is worsened due to unnecessary coasting or braking
Solution Approach 1:
The system applies partial action by using only the necessary deceleration force required to restore target speed. Instead of always applying full braking force, the system calculates the exact deceleration needed based on current speed vs. target speed difference and applies only that amount, using coasting when possible and minimal braking only when necessary, thereby restoring target speed while maintaining comfort
Data Source
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AI summary
The invention relates to a speed control system for controlling the speed of the vehicle to a predetermined target speed, wherein in order to achieve and maintain the target speed, the control unit transmits corresponding control signals to a drive unit or a brake unit, and wherein the control unit is configured, during active speed control, to detect the end of a manually triggered temporary acceleration request, to detect the actual speed at the end of a manually triggered temporary acceleration request and to generate a signal to initiate a coasting mode if, after the ending of the manually triggered temporary acceleration request, the actual speed is greater than the predetermined target speed.