Downhill Speed Control via Automatic Drivetrain Opening
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Solution Overview
Problem
Existing downhill speed control systems for motor vehicles, such as HADC, rely on driver intervention to adjust the transmission state, which can be inconvenient and dangerous in low-grip or steep conditions, especially when the transmission is not partially open.
Innovation Solution
A method that automatically adjusts the traction chain opening or closing based on external environment information, such as from cameras, radars, or GPS, to reduce the target descent speed below the minimum predefined value, ensuring stability and safety without driver intervention, using a complementary loop that considers slope severity and vehicle behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the transmission is kept closed to maintain engine braking, then the vehicle can maintain higher descent speed, but the driver cannot achieve speed reduction below the minimum predefined value in difficult conditions
Solution Approach 1:
The system automatically detects difficult conditions (low grip, steep slopes) and autonomously opens the transmission to reduce descent speed below the minimum predefined value, eliminating the need for driver intervention. The control computer monitors sensor data and autonomously decides when to open or close the transmission based on environmental conditions and vehicle state.
Solution Approach 2:
The system uses feedback from multiple sensors (wheel speed, slope angle, grip conditions) to continuously monitor the descent situation. This feedback loop enables the control computer to automatically adjust the transmission state, opening it when speed reduction is needed and closing it when engine braking is sufficient, thereby resolving the contradiction between maintaining speed and enabling speed reduction without driver action.
2Reliability
If the transmission is opened to reduce target speed below minimum predefined value, then speed control improves in low grip conditions, but the driver must intervene which causes inconvenience and potential delay
Solution Approach 1:
The system performs preliminary detection of difficult conditions using sensors that monitor grip levels and slope angles before the driver would need to act. By anticipating the need for transmission opening based on pre-detected conditions, the system prepares and executes the opening action proactively, eliminating any delay that would occur if waiting for driver recognition and response.
Solution Approach 2:
The control computer autonomously manages the transmission opening/closing decisions based on real-time sensor data, performing the action that would otherwise require driver intervention. This self-service capability ensures immediate response to changing conditions, improving both reliability of speed control and eliminating the time loss associated with manual driver action.
3Measurement precision
If the minimum speed threshold is lowered below predefined value, then control precision improves in low grip conditions, but the transmission must be opened which requires driver action in manual gearboxes
Solution Approach 1:
The control computer serves multiple functions: it monitors sensor data, determines difficult conditions, controls the transmission opening/closing, and manages the minimum speed threshold adjustment. This multi-functionality allows the system to handle both manual and automated transmissions through a single control unit, reducing the practical complexity despite the sophisticated control logic required for precise speed management in low grip conditions.
Data Source
Figure 1~2
AI summary
The invention relates to a method for controlling the downhill speed of a motor vehicle provided with a power train (26). Said method comprises the automatedly controlling the switching-on of the power train and of an "ESP" function for controlling the stability of the vehicle. Said method limits the speed of the vehicle to a target speed during downhill movement, by controlling the brakes of the wheels (24). Said method is characterized in that, in certain conditions where there is a risk of losing control of the speed, particularly due to the slope (8) or to the grip of the wheels, the method automatically controls at least partially switching-on the power train (26) then lowering the target speed below the predefined minimum value determined by the speed ratio involved and the minimum rotational speed of the engine to avoid the stalling thereof.