Adaptive Brake Feeling Curve for Commercial Vehicle Deceleration Control
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Solution Overview
Problem
Existing brake systems in commercial vehicles face challenges in accurately determining driver deceleration demand due to temperature-dependent spring characteristics and external influences, leading to inconsistent brake pressures for the same brake pedal operation, which can result in unintended braking effects.
Innovation Solution
The method involves determining an operating variable from the brake pedal displacement, using a mass-dependent feeling curve to associate the driver's deceleration demand with actual vehicle deceleration, and adapting this curve with a scaling factor to create an adaptation feeling curve that accounts for external influences, ensuring accurate and reliable brake pressure adjustment for adaptive control of vehicle deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed feeling curve is used to convert brake pedal displacement to brake pressure, then the brake system structure is simple, but the braking behavior becomes inconsistent under different temperature and load conditions
Solution Approach 1:
The feeling curve is transformed from a fixed static mapping to a dynamic adaptive mapping that automatically adjusts its parameters based on detected operating conditions (temperature, vehicle load). The control unit continuously adapts the feeling curve parameters to maintain consistent braking behavior across varying conditions, directly resolving the contradiction between structural simplicity and behavioral consistency.
Solution Approach 2:
The system changes the parameters of the feeling curve (scaling factors, offset values) based on detected operating conditions such as temperature and vehicle load. By dynamically adjusting these parameters, the system maintains accurate translation of driver input to brake pressure despite environmental variations, solving the reliability issue without complicating the core brake system structure.
2Device complexity
If temperature-dependent spring characteristics are not compensated, then the control system is simple, but the brake pressure becomes inconsistent for the same brake pedal operation under different temperatures
Solution Approach 1:
Temperature sensors provide feedback about the operating temperature to the control unit, which then compensates for temperature-dependent spring characteristic changes by adjusting the feeling curve parameters. This feedback loop ensures that the same brake pedal operation produces consistent brake pressure across different temperatures, resolving the measurement precision issue while keeping the control system relatively simple.
Solution Approach 2:
Instead of using complex mechanical compensation mechanisms for temperature effects, the system substitutes a electronic control approach where the control unit calculates and applies compensation factors based on temperature sensors. This replaces potential mechanical complexity with simpler electronic sensing and computation, maintaining brake pressure accuracy without significantly increasing device complexity.
3Ease of operation
If external influences are not compensated, then the system operation is simple, but the association between driver deceleration demand and actual vehicle deceleration becomes inaccurate
Solution Approach 1:
The control unit uses feedback from vehicle sensors (acceleration, load, temperature) to continuously adapt the feeling curve and compensate for external influences. This feedback mechanism maintains accurate translation of driver input to actual vehicle deceleration despite varying operating conditions, resolving the measurement precision issue while keeping system operation straightforward through automated compensation.
Solution Approach 2:
The brake control system performs self-adjustment by automatically detecting operating conditions and adapting its own control parameters (feeling curve) without requiring manual intervention. This self-service capability maintains accurate deceleration demand translation across different conditions while keeping the system easy to operate, as the compensation happens automatically based on sensor inputs.
Data Source
AI summary
A method for the adaptive control of a driver operation-dependent actual vehicle deceleration in a commercial vehicle includes determining an operating variable that indicates a displacement of a brake pedal of a brake valve demanded by the driver as well as an assistance deceleration demand, providing a mass-dependent feeling curve that associates a driver's deceleration demand with the operating variable, adapting the mass-dependent feeling curve if there is no assistance deceleration demand so that the determined operating variable is associated with an actually prevailing actual vehicle deceleration, specifying a target vehicle deceleration depending on a driver operation-dependent driver's deceleration demand determined from the corresponding feeling curve and the assistance deceleration demand if there is an assistance deceleration demand, and actuating a brake pressure corresponding to the target vehicle deceleration for adaptively adjusted, driver operation-dependent control of the actual vehicle deceleration.