Vehicle Sideslip Angle Estimation with Roll Compensation
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Solution Overview
Problem
Existing methods for estimating a vehicle's sideslip angle, particularly in commercial vehicles, are hindered by the influence of frame roll on yaw rate and lateral acceleration sensors, leading to measurement errors and instability in estimation, especially with varying payload and nonlinear tire characteristics.
Innovation Solution
A method using axle distance, track width, rolling tire radius, and steering wheel angle, with two iterations and a regulation method based on physical constraints, to estimate the sideslip angle and calculate lateral velocity and acceleration parallel to the road surface, ensuring continuous and accurate estimation without cumulative errors or phase delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If frame-mounted sensors (yaw rate and lateral acceleration) are used in commercial vehicles, then vehicle stability control functions can be implemented, but measurement accuracy deteriorates due to frame roll influence
Solution Approach 1:
The patent extracts the harmful frame roll component from the lateral acceleration measurement by introducing a separate roll angle sensor. This allows the system to isolate and remove the frame roll influence from the lateral acceleration signal, thereby recovering the true lateral acceleration value that would otherwise be contaminated by frame motion.
Solution Approach 2:
The roll angle sensor acts as an intermediary that measures the frame roll separately. This intermediate measurement is then used to compensate for the frame roll effect in the lateral acceleration calculation, enabling accurate lateral acceleration determination despite the sensors being mounted on the rolling frame.
2Adaptability or versatility
If iterative non linear closed loop observer is used for sideslip estimation, then estimation can be performed with available sensors, but cumulative errors and instability occur
Solution Approach 1:
The patent implements a feedback mechanism where the estimated sideslip angle and its derivative are continuously refined based on the relationship between lateral acceleration, yaw rate, and vehicle dynamics. The system uses the corrected lateral acceleration (free from frame roll effects) as feedback to maintain estimation accuracy over time and prevent cumulative errors.
Solution Approach 2:
The patent performs preliminary correction of the lateral acceleration signal by removing frame roll effects before using it in the sideslip estimation process. This preliminary action ensures that the input data to the estimation algorithm is accurate and free from systematic errors that would otherwise lead to instability.
3Quantity of substance
If payload varies in commercial vehicles, then vehicle capacity is improved, but inertia and center of gravity position change causing measurement errors
Solution Approach 1:
The patent adopts a dynamic approach by continuously estimating the sideslip angle based on real-time sensor measurements rather than relying on fixed vehicle parameters. This dynamic estimation adapts to changing payload conditions, center of gravity positions, and inertia variations, maintaining accuracy despite the vehicle's varying operational state.
Data Source
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AI summary
The invention refers to a method for estimating a vehicle's, or, in a vehicle trailer combination having a tractor vehicle and a towed trailer, a tractor vehicle's sideslip angle, the method comprising the steps of: a) Gaining the following vehicle parameters from the vehicle: Axle distance, track width, rolling tire radiuses, and steering wheel angle, b) Measuring signals for the longitudinal velocity (19), the steering wheel angle (20) and the yaw rate (14) of the vehicle, where c) the method for estimating operates with two iterations in each processing step, where a processing step is done by a vehicle's onboard integrated processing unit in real time, where c1)a first iteration (21) estimates the vehicle sideslip angle's next value on the basis of the gained vehicle parameters and the measured signals, c2)a second iteration (26) estimates a mass specific cornering stiffness parameter on the basis of the gained vehicle parameters and the measured signals, where c3)between the two iterations, a regulation method (23) is inserted, which is based on constraints, which are originated from physical laws such as continuity or maximum possible adhesion coefficient, where a first regulation step calculates threshold values for the vehicle sideslip angle that are based on kinematical conditions, an a following regulation step investigates that the continuity of the vehicle sideslip angle can be held or not with the calculated maximum and minimum vehicle sideslip angles, and if yes then saturates the first iteration's result.