Actuator Position Detection via DC Motor Commutation Artifacts
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Solution Overview
Problem
Existing methods for determining the position of actuators in internal combustion engines, such as flaps and valves, are costly due to the need for position sensors and limit temperature range and vibration resistance.
Innovation Solution
A method using the number of commutation artifacts from a DC motor to determine the position of an actuator, where the control unit recognizes end positions independently of the number of commutation artifacts and resets the count, allowing for cost-effective and robust position determination without complex sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If position sensors (such as Hall sensors) are provided on the actuator to detect the position, then the position detection accuracy is improved, but the cost (material and assembly) increases and the temperature range and vibration resistance are limited
Solution Approach 1:
The patent extracts the position detection function from separate position sensors and integrates it into the existing DC motor control system by utilizing commutation artifacts already present in the armature current. This eliminates the need for additional position sensors while maintaining position detection capability.
Solution Approach 2:
The system uses its own operational characteristics (commutation artifacts in the armature current) to perform position detection. The DC motor's own commutation process provides the measurement signal, making the system self-sufficient and eliminating external sensing requirements.
2Measurement precision
If position sensors are provided on the actuator, then the position detection accuracy is improved, but the temperature range and vibration resistance are limited
Solution Approach 1:
The patent removes vulnerable position sensors from the system and extracts position detection capability from the inherent commutation artifacts in the DC motor's armature current, which are immune to temperature and vibration effects.
Solution Approach 2:
The patent replaces mechanical/electronic position sensors with an electrical signal processing approach, analyzing commutation artifacts in the armature current to determine actuator position. This substitution eliminates components susceptible to environmental stress.
3Device complexity
If the position is determined using the number of commutation artifacts, then the cost is reduced and robustness is improved, but the measurement accuracy may be affected by measurement errors
Solution Approach 1:
The patent employs feedback mechanisms where the control unit continuously monitors commutation artifacts, compares the actual number against expected values, and corrects positioning errors by identifying end positions and recalibrating the commutation count. This feedback loop compensates for measurement errors.
Solution Approach 2:
The system performs preliminary calibration by identifying end positions and resetting commutation counts before normal operation. This preliminary action establishes accurate reference points that prevent error accumulation during subsequent position determination.
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 accurate and reliable position determination of actuators in internal combustion engines, reducing costs and improving robustness by utilizing existing current measurements and eliminating the need for sensitive sensors.
Implementation Method 1
measuring the current profile of the direct-current motor and determining the position of the actuator from the current profile
Data Source
Figure 1~2
Figure 3~4
AI summary
A method for determining the position of an actuator (24) of an internal combustion engine (10), in particular a control flap, a swirl flap, or a valve actuated by a DC motor (26), comprises the following steps: a) measuring the current waveform (38) of the current supplied to the DC motor (26), b) detecting commutation artifacts (42) in the measured current waveform (38), c) determining the number of detected commutation artifacts (42) by a control unit (30), d) determining the position of the actuator (24) based on the number of commutation artifacts (42) by the control unit (30). An actuator assembly is also shown.