Actuator Position Sensing Error Correction
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Solution Overview
Problem
Conventional position sensing systems for actuators, particularly linear actuators, face issues with contact wear and mechanical failures in contact-based methods and lack effective self-detection and correction mechanisms in non-contact methods, limiting their accuracy and practicality, especially when actuators have limited stroke or impractical reference points.
Innovation Solution
A position sensing system comprising a first sensor for detecting the rotational position of a movable portion, multiple second sensors for detecting the translational position, and a controller to calculate and correct positional errors by moving the actuator based on differences in data from these sensors, using Hall-Effect sensors and magnets to provide accurate and repetitive position checking without requiring travel to both ends of the actuator's range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact-based potentiometer is used for position sensing, then position accuracy is maintained, but contact wear and mechanical failures occur over time
Solution Approach 1:
The patent replaces the contact-based mechanical potentiometer with a non-contact sensing system using Hall-effect sensors and magnets. The Hall-effect sensor detects the position of a magnet attached to the actuator shaft, eliminating physical contact and associated wear while maintaining position measurement capability. This substitution resolves the contradiction by preserving measurement precision through magnetic field detection while eliminating contact wear and mechanical failures.
2Device complexity
If non-contact Hall-effect sensor with single reference point is used, then device complexity is reduced, but position error accumulation occurs over time
Solution Approach 1:
The system performs preliminary position verification by checking against a known reference point during actuator operation. When the actuator reaches the reference point, the system compares the measured position with the expected position and corrects any accumulated error. This preliminary correction action prevents long-term error accumulation while maintaining system simplicity.
Solution Approach 2:
The patent implements a feedback mechanism where the Hall-effect sensor continuously monitors actuator position, and the controller compares measured positions with expected positions based on motor commands. When discrepancies are detected, the system generates correction signals to adjust future position calculations, thereby preventing error accumulation while maintaining simple sensor hardware.
3Measurement precision
If actuator travels to both extents for self-correction, then position error is corrected, but productivity is reduced due to extended travel time
Solution Approach 1:
Instead of requiring the actuator to travel to both extreme positions for error correction, the system uses a single reference point located within the normal operating range. The actuator only needs to reach this intermediate reference point periodically for correction, performing a partial correction action that is sufficient to maintain accuracy without the excessive travel time required by full-range correction methods.
4Measurement precision
If actuator travels past reference point for reorientation, then position accuracy is restored, but ease of operation is reduced due to dedicated correction effort
Solution Approach 1:
The system performs self-correction automatically during normal operation without requiring dedicated correction maneuvers or external intervention. The Hall-effect sensor and controller work together to detect position errors and implement corrections autonomously as the actuator passes through the reference point, making the correction process transparent and convenient for the operator.
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 system enables accurate and self-correcting position sensing for actuators, ensuring precise positioning without the need for extensive travel, thus overcoming limitations of stroke and practicality issues, and maintaining accuracy over time.
Implementation Method 1
non-contact sensing technology, such as Hall-effect sensors. In such an arrangement, for example, a rotating magnet located on an actuator shaft of the actuator is used in combination with a Hall-effect sensor
Data Source
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AI summary
An actuator position sensing system for sensing a position of an actuator. The actuator position sensing system includes a first sensor for detecting a position of a first moveable portion of the actuator; a plurality of second sensors each being configured for detecting a position of a second moveable portion of the actuator; and a controller connected to the first sensor and the plurality of second sensors. The controller is configured to calculate a difference between (i) a position of the second movable portion as calculated based upon the data transmitted from the first sensor, and (ii) a position of the second movable portion as calculated based upon the data transmitted from one or more of the plurality of second sensors. A motor is connected to the first movable portion and the controller, and the motor is configured to move the first moveable portion based upon the calculated difference.