Actuator Soft Reference Positioning via Load Step Detection
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Solution Overview
Problem
Existing actuators in applications like automotive air conditioning systems face precision and resilience issues due to vibrations and thermal variations, leading to needle valve position deviations and increased mechanical wear, with recalibration methods either increasing wear or being costly.
Innovation Solution
A method and actuator system that controls the electric motor to move the actuating element towards a soft reference position, overtraveling it to detect load changes and update the position, reducing wear and allowing for precise, constant positioning without explicit calibration steps, using load steps and torque thresholds to identify mechanical resistance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If recalibration is performed on an absolute mechanical end stop, then positioning precision is improved, but mechanical wear increases
Solution Approach 1:
The patent introduces a soft reference position as an intermediary calibration point between the absolute mechanical end stop and the operational range. This soft reference position is detected through load step detection rather than mechanical contact, serving as a mediator that provides calibration functionality without the severe mechanical wear associated with repeated end stop contact.
Solution Approach 2:
The patent replaces the mechanical end stop contact-based calibration method with a load detection-based soft reference position method. Instead of relying on mechanical contact and force feedback from the absolute end stop, the system uses torque or load sensor data to detect load steps and identify the soft reference position, thereby substituting mechanical wear-prone calibration with a sensor-based approach.
2Measurement precision
If position sensors are introduced for recalibration, then positioning precision is improved, but system cost increases
Solution Approach 1:
The patent enables the actuator system to perform its own calibration using existing load sensors and control algorithms. The microcontroller detects load steps during normal operation and automatically updates the soft reference position without requiring external calibration equipment or additional position sensors. This self-calibration capability eliminates the need for expensive external positioning sensors while maintaining precision.
Solution Approach 2:
The patent makes the existing load sensor serve multiple functions: it is used both for normal actuator operation control and for calibration through load step detection. By extracting calibration information from the same sensor used for operational monitoring, the system avoids the need for separate position sensors, reducing overall system cost and complexity.
3Measurement precision
If the actuator approaches the absolute mechanical end stop for calibration, then positioning precision is improved, but the actuator is stressed and wear increases
Solution Approach 1:
The patent uses partial action by detecting the soft reference position through load step detection before the actuator reaches the absolute mechanical end stop. The calibration process identifies a reference point in the intermediate range where load changes indicate the soft reference position, avoiding the need to fully traverse to and contact the extreme end stop position, thereby reducing mechanical stress while maintaining calibration accuracy.
4Measurement precision
If recalibration is performed frequently, then positioning precision is maintained, but operational time is lost
Solution Approach 1:
The patent enables continuous calibration functionality during normal operation by detecting load steps in real-time as the actuator moves through its range. The soft reference position is updated dynamically based on detected load changes, allowing the system to maintain positioning precision without interrupting operational cycles for separate calibration events. The calibration process becomes integrated into the continuous operational flow.
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
This approach enables precise and constant positioning of needle valves over the actuator's service life without recalibration interruptions, reducing mechanical wear and operational costs by using soft reference positions to adapt to thermal and mechanical changes.
Implementation Method 1
an actuator (10) comprising an electric motor (24, 40) and an actuating element (14) coupled to the electric motor (24, 40)
Implementation Method 2
detecting the load of the actuator (10) and updating the registered soft reference position on the basis of the detected load
Data Source
AI summary
A method of controlling an actuator comprising an electric motor and an actuator coupled to the electric motor, the method comprising controlling the electric motor to move the actuator in a direction towards an absolute mechanical end stop until a last registered soft reference position has been reached and then to overtravel the last registered soft reference position by a predetermined distance, detecting the load of the actuator, and updating the registered soft reference position on the basis of the detected load.