Vehicle Sideslip Angle Estimation Using Centrifugal Force Feedback
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Solution Overview
Problem
Existing sideslip angle estimation methods face accuracy issues due to cumulative errors from integral calculus and modeling errors, particularly in non-linear vehicle behavior conditions, making it difficult to accurately estimate the sideslip angle, especially during critical vehicle operations.
Innovation Solution
A sideslip angle estimation apparatus that detects accelerations in two directions and calculates the sideslip angle based on the angle between the direction of centrifugal force and the lateral direction of the vehicle body, using a linear two-input observer and feedback compensation to correct for errors, thereby enhancing estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If integral calculus operation is used to estimate sideslip angle, then estimation can be performed using vehicle speed, yaw rate, and lateral acceleration, but cumulative errors occur reducing estimation accuracy
Solution Approach 1:
The patent employs a feedback mechanism where the estimated sideslip angle is continuously fed back to correct the integral calculus operation. A feedback gain is applied to the product of the estimated sideslip angle and vehicle speed, which is then subtracted from the lateral acceleration before integration. This feedback loop compensates for cumulative errors and improves estimation accuracy throughout the vehicle's operation.
Solution Approach 2:
The patent replaces the conventional direct integral calculus method with a corrected integration approach that accounts for the sideslip angle's effect on lateral acceleration. By substituting the simple integration of lateral acceleration with an adjusted integration that removes the centrifugal force component, the system eliminates cumulative errors while maintaining computational feasibility.
2Adaptability or versatility
If vehicle model is used to estimate sideslip angle, then estimation can be performed based on state quantities, but modeling errors occur reducing accuracy especially in non-linear conditions
Solution Approach 1:
The patent introduces the estimated sideslip angle as an intermediary variable that mediates between the vehicle model output and the final accurate estimation. The sideslip angle serves as a feedback signal that corrects the lateral acceleration measurement, bridging the gap between the simplified vehicle model and the actual vehicle dynamics, especially under non-linear conditions.
3Measurement precision
If time constant of integral calculus is adjusted based on vehicle model output, then some error compensation is achieved, but complexity increases and accuracy remains insufficient under critical conditions
Solution Approach 1:
The patent changes the parameter being adjusted from the time constant to the feedback gain applied to the sideslip angle correction term. This parameter change simplifies the control strategy while maintaining effectiveness, as the feedback gain directly compensates for the centrifugal force error without requiring complex time constant adjustments across different operating conditions.
Data Source
AI summary
In order to enhance the accuracy of estimation of a vehicle's sideslip angle, a sideslip angle estimation apparatus calculates an angle between the direction of centrifugal force acting on the vehicle body during cornering and the lateral direction of the vehicle body based on accelerations exerted on the vehicle body and acting in two different directions. A sideslip angle between the longitudinal direction of the vehicle body and the direction of travel of the vehicle is calculated based on the estimated angle.