Adaptive Electronic Brake Torque Control for Sensor Hysteresis
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Solution Overview
Problem
Conventional electronic braking systems (EBS) in hybrid and electric vehicles face errors and variances in braking torque requests due to low resolution of force sensors and mechanical hysteresis, especially under low force conditions, leading to discrepancies between intended and applied braking forces.
Innovation Solution
An adaptive control method and apparatus that continuously multiplies the travel position-based braking torque request by an adjustable multiplier factor to approximate a force-based braking torque request, using a controller with stored threshold settings and algorithms to adjust the multiplier based on vehicle conditions and acceptable error windows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a brake pedal force sensor is used to detect braking force, then the braking torque request can be determined, but under low force conditions the sensor resolution is insufficient leading to errors and variances in braking torque request
Solution Approach 1:
The patent combines data from two different sensors - a force sensor and a travel position sensor - to determine the braking torque request. The controller selectively uses data from either sensor or both sensors together depending on operating conditions, merging their advantages to overcome the limitations of each individual sensor.
Solution Approach 2:
The patent creates a composite measurement approach by integrating measurements from heterogeneous sensor types (force sensor and position sensor) to form a unified braking torque request determination system that leverages the strengths of each sensor type.
2Measurement precision
If a brake pedal travel position sensor is used to detect braking position, then better resolution at lower pressure ranges is achieved, but mechanical hysteresis in the braking system leads to errors and variances in applied braking torque request
Solution Approach 1:
The controller merges data from the travel position sensor with force sensor data to compensate for hysteresis effects. By combining position information with force information, the system can determine braking torque requests that are more accurate than what either sensor could provide alone.
Solution Approach 2:
The system uses feedback from multiple sensors to continuously monitor and adjust the braking torque request determination, comparing actual sensor readings with expected values and correcting for hysteresis effects through adaptive control algorithms.
3Adaptability or versatility
If an immediate switch between force sensor and travel position sensor is made during low pressure applications, then sensor limitations can be circumvented, but mechanical hysteresis leads to errors and variances in applied braking torque request
Solution Approach 1:
The patent implements dynamic sensor selection and data fusion strategies where the controller adaptively chooses which sensor data to use based on real-time operating conditions. This dynamic approach allows smooth transitions between sensor sources and prevents the hysteresis problems associated with immediate switching.
Solution Approach 2:
The system performs preliminary evaluation of sensor data quality and operating conditions before making sensor selection decisions, preparing transition parameters in advance to ensure smooth, hysteresis-free switching between sensors during low pressure applications.
Data Source
AI summary
A vehicle has a controller with a threshold brake pedal apply force and an algorithm for determining a first braking torque request corresponding to a pedal apply force, a second braking torque request corresponding to a pedal travel position, and a calculated third braking torque request. The third torque request is calculated by multiplying the first torque request by an average percentage variance of the second to the first torque request. An adaptive electronic brake system (EBS) includes force and travel sensors connected to a brake pedal for determining a force-based and travel position braking torque request, and an algorithm for adapting one of the force-based and travel position-based braking torque requests to the other despite variances over time in a force/travel relationship therebetween.