Vehicle Braking Force Control for Stable Coasting Deceleration
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Solution Overview
Problem
In vehicles, the generation of braking force through multiple actuators like alternators and air-conditioners can lead to fluctuating deceleration feelings during coasting states, affecting ride quality and operational stability.
Innovation Solution
A braking force control device that manages the driving force in a coasting state by controlling a first actuator unit that always generates a negative driving force and a second actuator unit that may not always generate a negative driving force. The device includes a target driving force acquisition unit, a minimum driving force acquisition unit, a prediction unit, a detection unit, and a control unit that adjust the driving forces based on predictive and impossible states of the second actuator unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple actuators including alternator and air-conditioner are used to generate braking force, then sufficient deceleration can be obtained, but the negative driving force fluctuates causing poor ride quality and operational stability
Solution Approach 1:
The actuator system is segmented into two distinct units: a first actuator unit (engine brake) that can always generate negative driving force, and a second actuator unit (alternator/air-conditioner) that cannot always generate negative driving force. This segmentation allows the system to maintain stability through the first unit while utilizing the second unit for additional deceleration capability when available.
Solution Approach 2:
The control unit dynamically changes the operating parameters of the actuators based on their capability states. When the second actuator unit cannot generate negative driving force (detected by the detection unit), the control unit adjusts the first actuator unit to compensate, maintaining consistent total negative driving force output and preventing fluctuations in ride quality.
2Power
If the second actuator unit is used to generate negative driving force, then additional braking capability is obtained, but the actuator may become unable to generate negative driving force under certain conditions
Solution Approach 1:
The prediction unit performs preliminary detection to predict when the second actuator unit will become unable to generate negative driving force. Based on this prediction, the control unit proactively adjusts the first actuator unit before the second unit fails, ensuring continuous and reliable braking capability without interruption or fluctuation.
Solution Approach 2:
The detection unit continuously monitors the operational state of the second actuator unit and provides feedback to the control unit. When the second unit cannot generate negative driving force, the feedback triggers the control unit to compensate using the first unit, ensuring reliable overall system performance despite individual actuator limitations.
3Stability of the object's composition
If the first actuator unit always generates negative driving force, then operational stability is improved, but the device complexity increases due to multiple actuator units
Solution Approach 1:
The first actuator unit (engine brake) serves as a universal backup that can always generate negative driving force regardless of the state of the second actuator unit. This multi-functional design allows the same first unit to both provide primary braking stability and compensate when the second unit fails, reducing the need for additional specialized components.
Data Source
AI summary
The braking force control device detects an impossible state where one or some of the actuators are temporarily unable to generate a negative driving force, and a predictive state where one or some of the actuators are predicted to become unable to generate a negative driving force. Every time the coasting state occurs before establishment of the impossible state and after establishment of the predictive state, the braking force control device gradually increases the negative driving force generated by the corresponding one or ones of the actuators. Even when the coasting state occurs in the impossible state, the braking force control device does not cause the corresponding one or ones of the actuators to generate a driving force. Every time the coasting state occurs after the impossible state, the braking force control device gradually decreases the negative driving force generated by the corresponding one or ones of the actuators.