Brake Control Device Abnormality Handling
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Solution Overview
Problem
Conventional electric parking brake systems face issues with generating excessive load when hydraulic pressure exceeds a predetermined level, leading to inadequate braking force due to sensor abnormalities, which cannot be accurately compensated by existing sensor-based control methods.
Innovation Solution
A brake control device with an abnormality detection unit and actuator control unit that sets a target pressing force based on past sensor output values, even when sensor abnormalities occur, to maintain appropriate braking force without excess or deficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sensor-based control is used to set target pressing force, then braking force can be adjusted according to hydraulic pressure, but the system becomes unreliable when sensor abnormalities occur
Solution Approach 1:
The system stores the output value of the sensor before abnormality occurs as a substitute for real-time sensor data. This preliminary action of saving historical data allows the control system to continue functioning reliably even when the sensor becomes abnormal, avoiding complete system failure.
Solution Approach 2:
Instead of relying on the original sensor output, the system uses a copy of the previously stored sensor value to continue controlling the actuator. This copying approach maintains system operation using historical data when the live sensor signal becomes unreliable.
2Force
If the linearly moving member pushes the piston when hydraulic pressure is high, then braking force is generated, but excessive load is generated in the electric parking brake mechanism
Solution Approach 1:
The control unit continuously monitors the sensor output value representing hydraulic pressure and adjusts the actuator operation accordingly. When hydraulic pressure exceeds a predetermined level, the feedback mechanism reduces or stops actuator operation to prevent excessive load, while still maintaining appropriate braking force through proportional control.
Data Source
AI summary
A brake control device for controlling an electric parking brake may include: a piston capable of pressing a brake pad in accordance with the hydraulic pressure in a cylinder; a linearly moving member that adjusts, by reciprocating in the cylinder, the pressing force applied to the brake pad by the piston; and an actuator that moves the linearly moving member by operating based on a target pressing force, which is a target value of the pressing force corresponding to an output value obtained from a sensor that detects information correlating with the hydraulic pressure. The brake control device is provided with: an abnormality detection unit that detects an abnormality of the sensor; and an actuator control unit that, if an abnormality is detected, controls the operation level of the actuator based on an output value obtained prior to the detection of the abnormality.