Engine Torque Estimation Using Non-linear Kalman Filter
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Solution Overview
Problem
Existing engine torque estimation methods face challenges in achieving high accuracy due to the limited measurement resolution of crank angle pulse width, resulting in phase delays and reduced accuracy of estimated indicated torque.
Innovation Solution
An engine torque estimation device and method that utilize a non-linear Kalman filter, incorporating both crank angle and crank angle speed estimation errors to derive a more accurate estimated engine torque, with the crank angle speed being calculated through smoothing processing to reduce noise and improve estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional crank angle measurement methods are used, then the measurement process is simple, but the measurement precision is limited due to pulse width resolution constraints
Solution Approach 1:
The patent introduces crank angle speed as an intermediary parameter to improve measurement precision. By calculating crank angle speed from crank angle measurements and using it as an additional input to the Kalman filter, the system achieves higher precision torque estimation without directly enhancing the crank angle sensor resolution
Solution Approach 2:
The patent replaces direct mechanical measurement limitations with computational processing. Instead of improving the physical sensor resolution, the system uses mathematical models (Kalman filter) and signal processing to extract more precise information from the existing measurement data
2Measurement precision
If traditional torque estimation methods are used, then the calculation process is simple, but the estimated torque accuracy is reduced due to phase delays
Solution Approach 1:
The patent implements feedback by using the calculated crank angle speed as feedback input to the Kalman filter. The estimated torque and crank angle speed are continuously updated based on the difference between measured and estimated values, creating a closed-loop system that reduces phase delays and improves accuracy
Solution Approach 2:
The patent performs preliminary calculation of crank angle speed from crank angle measurements before using it in the torque estimation process. This preliminary action allows the system to anticipate and compensate for phase delays by having the speed information available before the final torque calculation
3Measurement precision
If crank angle speed calculation is added to the system, then the estimation accuracy is improved, but the calculation complexity increases
Solution Approach 1:
The patent replaces complex hardware solutions with computational methods. Instead of adding physical sensors or mechanical measurement devices, the system uses software-based differentiation and smoothing algorithms to calculate crank angle speed, reducing hardware complexity while improving measurement precision
Data Source
AI summary
An engine torque estimation device includes: a memory; a processor coupled to the memory and the processor configured to, acquire a measured value of a crank angle that is a rotation angle of a crank shaft of an engine, derive, based on the measured value of the crank angle, a calculated value of a crank angle speed, and derive an estimated value of an engine torque, based on a non-linear Kalman filter using a first estimation error that is a difference between the calculated value of the crank angle speed and the estimated value of the crank angle speed.