Electric Parking Brake Control Using Motor Current Feedback
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Solution Overview
Problem
Existing electric parking brake systems face challenges in accurately controlling the braking force and manufacturing costs due to the need for precise measurement of both motor current and revolutions, which complicates reflecting the current vehicle conditions.
Innovation Solution
A method that controls the electric parking brake by calculating desired braking forces and load torque based on actuator current changes, eliminating the need to measure motor revolutions, and adjusts operations accordingly to ensure reliable braking and releasing functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of revolution of a braking motor and current sensor are measured to control the operation of the braking motor, then the control precision is improved, but the device complexity increases
Solution Approach 1:
The patent extracts and eliminates the position sensor component from the system. Instead of measuring both current and number of revolutions, the invention only uses current sensor measurements to determine actuator state and control the braking motor, thereby reducing device complexity while maintaining control precision through alternative control logic
Solution Approach 2:
The patent replaces the mechanical measurement approach (position sensor for revolution counting) with an electrical measurement approach (current-based state detection). By substituting mechanical revolution measurement with electrical current analysis, the system achieves the same control objective with fewer components
2Measurement precision
If both position sensor and current sensor are included to control the braking motor operation, then the measurement precision is improved, but the manufacturing cost increases
Solution Approach 1:
The patent removes the position sensor from the required component list, eliminating its associated manufacturing cost. The invention achieves sufficient measurement precision using only the current sensor, thereby reducing overall system cost while maintaining functional performance
Solution Approach 2:
The patent employs a simpler, more cost-effective sensing approach by relying solely on the current sensor rather than combining it with an expensive position sensor. This substitution with a cheaper sensing method reduces manufacturing costs while maintaining adequate measurement precision for the application
3Reliability
If the current condition of a vehicle is to be accurately reflected, then the device complexity increases due to multiple sensors, but the reliability of control improves
Solution Approach 1:
The patent implements a feedback mechanism where the current sensor continuously monitors actuator current to determine actuator state, which then feeds back to control the braking motor operation. This closed-loop feedback ensures reliable control by continuously adapting to the current vehicle condition without requiring complex multi-sensor systems
Solution Approach 2:
The system uses the existing current sensor to serve dual purposes: both for basic motor control and for determining actuator state to reflect current vehicle conditions. This self-service approach allows the single sensor to provide comprehensive system monitoring and control, maintaining reliability without adding additional sensors
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
This approach enhances control reliability and reduces manufacturing costs by focusing on current values to manage braking forces effectively without requiring motor revolution measurements.
Implementation Method 1
measuring current of an actuator controlling operation of a braking motor
Data Source
AI summary
A method of controlling an electric parking brake of a vehicle includes calculating a desired braking force based on the vehicle condition at an instruction of applying a braking force, and starting a braking motor of the electric parking brake. The method further includes determining whether a braking force is increasing by measuring current applied to the braking motor, calculating a braking correction value based on the measured current when determined that a braking force is not increasing, calculating a load torque based on the braking correction value and the measured current when determined that a braking force is increasing, and stopping the braking motor when the load torque is greater than the desired braking force.