Electro-Mechanical Brake Calibration for Stable Brake Force Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electro-mechanical brakes face challenges in accurately measuring brake force due to the high cost and positional inaccuracies of force sensors, and calibration issues under varying conditions such as low friction coefficients and regenerative braking, leading to irregular control and sudden brake force changes.
Innovation Solution
A control method for electro-mechanical brakes that uses a wheel speed sensor to determine vehicle stoppage during travel, adjusts piston, brake pad, and wheel disk positions based on brake force command intervals and estimated values, and generates readjustment commands when differences are within preset limits, reducing sudden force changes and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a force sensor is used to measure brake force, then measurement accuracy is improved, but device cost and complexity increase
Solution Approach 1:
The patent extracts the measurement function from a dedicated force sensor and relocates it to the existing motor component. The motor's current sensor and position sensor are repurposed to estimate brake force by monitoring motor current and piston position, eliminating the need for a separate force sensor while maintaining measurement capability
Solution Approach 2:
The patent creates a virtual model (force map) that copies the relationship between motor position and brake force. By establishing a correspondence table during calibration that maps piston positions to brake force values, the system can estimate brake force without direct sensing, effectively copying the measurement function through computational modeling
2Measurement precision
If calibration is performed frequently to maintain accuracy, then brake force estimation precision is improved, but system reliability deteriorates due to irregular operation under certain conditions
Solution Approach 1:
The patent implements dynamic calibration conditions that adapt to operating circumstances. The system determines whether calibration is appropriate based on real-time assessment of brake force command values, vehicle speed, and operational context, allowing calibration to proceed only when conditions are favorable and preventing calibration during unsuitable conditions like ABS operation or low-friction scenarios
Solution Approach 2:
The system incorporates feedback mechanisms to monitor calibration results and system state. By continuously comparing estimated brake force with actual brake force command values and detecting deviations, the system can determine when calibration is needed and verify calibration success, creating a closed-loop control that improves reliability through adaptive decision-making
3Productivity
If calibration is performed quickly to minimize driver waiting time, then productivity is improved, but measurement precision may deteriorate due to insufficient calibration time
Solution Approach 1:
The patent performs preliminary assessment of calibration conditions before initiating the calibration process. The system evaluates whether current operating conditions are suitable for calibration and pre-determines the optimal calibration timing, ensuring that calibration is launched only when conditions favor both speed and accuracy, thus avoiding the trade-off between quick calibration and accurate calibration
4Measurement precision
If the brake force command is adjusted frequently to match actual brake force, then control precision is improved, but stability deteriorates due to sudden brake force changes and noise
Solution Approach 1:
The patent applies partial adjustment by only modifying brake force commands when deviations exceed predetermined thresholds. Rather than continuously adjusting the brake force command to match estimated values, the system selectively intervenes only when necessary, preventing excessive control actions that would cause instability and noise while still maintaining adequate control precision
Solution Approach 2:
The system performs preliminary checks to determine whether brake force adjustment is actually needed before executing control actions. By assessing the magnitude and significance of deviations between commanded and estimated brake force, the system prevents unnecessary adjustments that would disrupt stability, applying corrections only when they will meaningfully improve accuracy without causing instability
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method ensures accurate brake force detection and reduces driver discomfort by preventing sudden brake force changes and noise during calibration, enhancing brake control stability and reliability.
Implementation Method 1
an actuator driven by a motor is mounted on a brake caliper. The electro-mechanical brake presses the wheel disk using motor, gear box, screw, piston
Implementation Method 2
The brake pads press the wheel disks so that the brake force is generated
Data Source
AI summary
Disclosed are electro-mechanical brake and control method thereof.According to an embodiment of the present disclosure, there is provided a control method of electro-mechanical brake in which a piston is moved by driving a motor to bring a brake pad into close contact with a wheel disk, the method includes determining whether the vehicle is in a stopped state while traveling by using a wheel speed sensor; in response to a determination that the vehicle is stopped while traveling, determining whether a set brake force command value is included in a preset brake force command interval according to a degree of stroke of a brake pedal; in response to a determination that the brake force command value is included in the preset brake force command interval, determining whether the positions of the piston, the brake pad, and the wheel disk are readjusted; in response to a determination that the positions of the piston, the brake pad, and the wheel disk are not readjusted, determining whether the brake force command value changes within a preset change rate for a preset time; detecting a piston position-based estimated brake force value based on a position detector that detects the position of the piston; in response to a determination that the brake force command value is changed within the preset change rate, determining whether a difference between the brake force command value and the piston position-based estimated brake force value is within a preset value; and in response to a determination that the difference is within the preset value, controlling positions of the piston, the brake pad, and the wheel disk by providing a readjustment command for readjustment of the positions.