Redundant Vehicle Braking Using Motor-Based Wheel Speed Estimation
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Solution Overview
Problem
Existing redundant braking systems in vehicles face challenges in maintaining accurate braking control when the main braking system fails, especially due to the inability to transmit wheel speed data from malfunctioning wheel speed sensors.
Innovation Solution
The proposed solution involves using the electronic control unit of the redundant braking system to calculate wheel speed based on motor speed, eliminating the need for additional hardware and allowing the redundant system to take over braking functions in case of main system failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional redundant wheel speed sensors are installed or a dual-output channel sensor is used, then the redundant braking system can obtain wheel speed data independently, but hardware costs and system complexity significantly increase
Solution Approach 1:
The patent creates a virtual copy of the wheel speed sensor functionality by using the motor speed sensor to generate wheel speed data through calculation. Instead of installing physical redundant sensors, the system copies the speed measurement function through software computation, multiplying motor speed by the transmission ratio to obtain equivalent wheel speed information for the redundant braking system
Solution Approach 2:
The motor speed sensor serves multiple functions: it provides speed data for both the main braking system (through direct use) and the redundant braking system (through calculated conversion). This multi-functional approach eliminates the need for separate redundant sensors, reducing hardware complexity while maintaining reliability
2Reliability
If additional redundant wheel speed sensors are installed or a dual-output channel sensor is used, then the redundant braking system can obtain wheel speed data independently, but hardware costs and R&D costs significantly increase
Solution Approach 1:
The patent creates a virtual copy of the wheel speed sensor functionality by using the motor speed sensor to generate wheel speed data through calculation. Instead of installing physical redundant sensors, the system copies the speed measurement function through software computation, multiplying motor speed by the transmission ratio to obtain equivalent wheel speed information for the redundant braking system
Solution Approach 2:
The patent uses existing, low-cost computational resources within the electronic control unit to perform the speed calculation rather than investing in expensive redundant hardware. The solution leverages inexpensive software processing to achieve what would otherwise require costly additional sensors and hardware modifications
3Reliability
If wheel speed sensors malfunction, then the main braking system cannot obtain accurate wheel speed data, but the redundant braking system also cannot function without wheel speed data
Solution Approach 1:
The patent introduces motor speed as an intermediary parameter to bridge the gap when wheel speed sensors fail. By using the motor speed sensor (which remains functional) as a mediator and applying the transmission ratio, the system reconstructs wheel speed information without directly relying on the failed wheel speed sensors, thus maintaining data availability for the redundant braking system
Solution Approach 2:
The patent changes the measurement parameter from direct wheel speed (obtained through wheel speed sensors) to motor speed (obtained through motor speed sensors), then transforms this parameter through multiplication by the transmission ratio. This parameter substitution and transformation enables the redundant system to obtain wheel speed data through an alternative measurement pathway when the original sensors fail
Data Source
AI summary
A method for braking a vehicle through a redundant braking system includes (i) in response to a fault signal received from the main braking system of the vehicle, obtaining the motor speed, (ii) calculating the wheel speed of the vehicle based on the motor speed, and (iii) generating a braking command based on the wheel speed to control the braking actuators of the vehicle to brake the wheels.