Test Stand Torque Damping via Estimated Internal Torque
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Solution Overview
Problem
In engine test stands, unadjusted combustion processes excite the test stand natural frequency, leading to unnatural rotational speed curves and making calibration difficult, especially when measuring disturbances like internal combustion torque is challenging due to lack of accurate sensors or high installation costs.
Innovation Solution
A method that estimates internal torque using existing sensors, filters, and feeds back a damping signal into the control loop, accounting for the natural frequency and delay, allowing for effective damping of disturbances without direct measurement, using a Kalman filter and FIFO memory for parameterization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the test stand natural frequency is excited by combustion processes, then resonance occurs leading to unnatural rotational speed curves, but direct measurement of the disturbance is not possible making control difficult
Solution Approach 1:
The patent introduces an intermediary estimation process that uses measurable variables (shaft torque, angular velocity) to indirectly determine the unmeasurable internal combustion torque. This mediator approach allows the control system to work with estimated disturbance values rather than requiring direct measurement, thus resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent replaces the need for direct mechanical measurement of internal combustion torque with a computational estimation system. By substituting physical measurement with mathematical estimation based on available sensor data, the system achieves disturbance detection without adding complex measurement hardware
2Measurement precision
If sensors are installed to measure internal torque directly, then measurement accuracy improves, but installation cost and complexity increase significantly
Solution Approach 1:
The system uses existing sensors and available measurement variables (shaft torque, angular velocity) to self-generate the disturbance estimation without requiring additional measurement equipment. This self-service approach eliminates the need for expensive specialized sensors while maintaining measurement precision through computational estimation
Solution Approach 2:
Instead of directly measuring internal combustion torque, the system creates a computational copy or estimate of the disturbance based on relationships between measurable variables. This copying approach provides accurate disturbance information without the cost of direct measurement hardware
3Device complexity
If existing measurement variables are used as controller input, then device complexity remains low, but control performance deteriorates because these variables already contain natural frequency effects
Solution Approach 1:
The patent applies preliminary filtering and estimation actions to the measurement variables before they are used as controller input. By pre-processing the signals to remove natural frequency components and estimate the true disturbance, the system maintains simplicity while improving control performance through cleaner input data
Data Source
AI summary
The invention relates to a device and to a method for controlling a test stand arrangement having a specimen and having a loading machine, which is connected to the specimen by a connecting shaft. An estimated value (TE,est) for for the internal torque (TE) of the specimen is determined and, from the estimated value (TE,est), while taking into account a natural frequency (f0) and a delay, a damping signal (TDamp) is determined and fed back into the control loop.