Vehicle Motion Control Under Traction-Limited Longitudinal Force
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Solution Overview
Problem
Existing vehicle motion control systems face challenges in efficiently adjusting acceleration to match target values due to limitations in the controllable range of longitudinal force, leading to excessive control amount fluctuations and increased convergence time when requests exceed or fall below the available force range.
Innovation Solution
A vehicle motion controller that includes a feedback controlling unit, a request outputting unit, and an obtaining unit to adjust the control amount based on the difference between target and actual acceleration, while prohibiting increases or decreases when the request longitudinal force exceeds or falls below the controllable range, and considering traction control, anti-lock brake control, anti-skid control, and frictional member temperature to maintain stable feedback control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If feedback control is continued when the requested longitudinal force exceeds the controllable range, then the control system attempts to eliminate the acceleration difference, but the control amount excessively increases and convergence time increases
Solution Approach 1:
The patent implements feedback control by continuously comparing target acceleration with actual acceleration and adjusting the longitudinal force accordingly. The controller calculates the difference between target and actual acceleration, then adjusts the longitudinal force within the controllable range to eliminate this difference, ensuring stable convergence without excessive control amounts.
Solution Approach 2:
The patent dynamically adjusts the longitudinal force within the controllable range based on real-time vehicle state and actuator availability. When the requested force exceeds the controllable range, the system adapts by applying maximum available force in the desired direction, preventing control amount saturation and enabling faster convergence.
2Measurement precision
If the control amount is adjusted to match target acceleration, then acceleration control accuracy improves, but the control amount may excessively increase or decrease when the request exceeds controllable range
Solution Approach 1:
The patent obtains the controllable range of longitudinal force and actuator availability in advance before executing feedback control. By pre-acquiring the maximum and minimum longitudinal forces that can be generated, the controller prepares the boundaries for safe control adjustments, preventing excessive control amounts before they occur.
Solution Approach 2:
The patent introduces the controllable range as an intermediary constraint between the target acceleration request and the actual control output. This intermediary layer ensures that control adjustments remain within physically achievable limits while still pursuing target acceleration, simplifying control amount management by preventing saturation.
3Speed
If the longitudinal force is increased to meet high acceleration requests, then acceleration response improves, but the actuator may exceed its controllable range and cannot generate the requested force
Solution Approach 1:
The patent applies partial action by adjusting the longitudinal force to the maximum or minimum available within the controllable range when the requested force exceeds capabilities. Instead of attempting to apply the full requested force that cannot be achieved, the system applies the greatest possible force in the desired direction, maintaining acceleration response while ensuring reliable force generation.
Data Source
AI summary
A vehicle motion controller includes a feedback controlling unit that executes feedback control in which a difference between a target acceleration corresponding to a request value from a driver assistance device and an actual acceleration of a vehicle is an input, thereby calculating a control amount used to reduce the difference, a request outputting unit that calculates a request longitudinal force based on the control amount, the request longitudinal force controlling an actuator, and an obtaining unit that obtains, as information that indicates availability, information indicating whether traction control is executed, the availability being a controllable range of the longitudinal force, wherein the feedback controlling unit prohibits the control amount from increasing when the traction control is executed.