Cardan Shaft Moment Estimation via Torsional Oscillator Chain
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Solution Overview
Problem
Existing methods for estimating cardan shaft moments in vehicle drive trains are either complex and costly for real-time measurement or provide non-real-time calculations, making them unsuitable for series production and practical use.
Innovation Solution
A method using state space modeling and a Kalman filter to estimate cardan shaft moments in real-time by modeling the drive train as a torsional oscillator chain, connecting drive machine and wheel inertia moments with spring-damper elements, and reducing drive moments when load limits are exceeded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If measurement technology specially designed for detecting cardan shaft moments is used, then measurement precision is improved, but device complexity and cost increase significantly making it unsuitable for series production
Solution Approach 1:
The patent introduces a Kalman filter as an intermediary computational layer that processes readily available sensor data (torque, angular velocity, braking moment) to estimate cardan shaft moments. This mediator transforms inexpensive, standard sensor inputs into precise moment estimates without requiring complex dedicated measurement hardware, thereby resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent replaces physical mechanical measurement devices (such as torque sensors on cardan shafts) with a computational/mathematical model approach. By using a state space model with Kalman filtering that processes electrical sensor signals, the system substitutes complex mechanical measurement systems with simpler computational algorithms, achieving precise moment detection while reducing device complexity and cost
2Measurement precision
If off-line simulations are used to calculate cardan shaft moments, then measurement precision is improved, but real-time availability is lost
Solution Approach 1:
The patent performs preliminary actions by pre-defining the state space model structure, state vectors, and system matrices during the design phase. The Kalman filter parameters and model coefficients are predetermined, allowing the system to execute only efficient parameter updates during real-time operation rather than performing full simulations, thus achieving both precision and real-time performance
Solution Approach 2:
The patent transforms the static off-line simulation approach into a dynamic real-time estimation system. By using a dynamic state space model with time-varying state vectors and recursive Kalman filter updates, the system adapts continuously to changing operating conditions while maintaining computational efficiency. The recursive nature of the Kalman filter allows real-time adaptation without re-running full simulations, resolving the contradiction between precision and speed
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables real-time detection and management of high loads on axle shafts, allowing for precise component design and protection against excessive loads, such as during 'misuse kick-down' maneuvers, by providing estimated axle shaft torques to control units.
Implementation Method 1
estimating, in real time via a Kalman filter, a respective axle shaft torque assigned to the respective axle shaft
Implementation Method 2
The respective drive machine inertia moment is connected by a respective spring-damper element to the respective wheel inertia moment
Implementation Method 3
selecting the physical model as a torsional oscillator chain
Implementation Method 4
A movement equation system is provided for the torsional oscillator chain by means of the principle of angular momentum
Data Source
AI summary
A method for estimating cardan shaft moments in a vehicle includes performing a state space modelling of a physical model for force transmission in at least one drive train The at least one drive train is formed with at least one drive machine, at least one axle and at least two axle shafts each with a respective wheel. The method further includes selecting the physical model as a torsional oscillator chain in which a respective drive machine inertia moment is assigned to the respective drive train and a respective wheel inertia moment is assigned to the respective wheel. The respective drive machine inertia moment is connected by a respective spring-damper element to the respective wheel inertia moment of the respective wheel which is connected to the respective axle shaft. A vehicle mass is connected by a respective spring-damper element to the respective wheel inertia moment of the respective wheel.

