Motor Rotor Position Determination Using Hall-Effect Sensor Fingerprints
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Solution Overview
Problem
LIDAR devices face challenges in accurately determining the angular position of a rotating mirror due to imperfections in motor construction, such as unevenly spaced conductive coils and Hall-effect sensors, which affect the precision of distance and texture measurement.
Innovation Solution
A method and device that utilize Hall-effect sensors to generate a 'fingerprint' of the motor's non-uniform time sequence, allowing for correlation of reference angular positions to reference times and subsequent data to determine the angular position of the rotor with improved precision, even in imperfect motors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional motor construction with evenly spaced coils and Hall-effect sensors is used, then manufacturing is simpler, but measurement precision of angular position deteriorates due to construction imperfections
Solution Approach 1:
The system performs preliminary calibration by rotating the rotor through multiple revolutions and recording the actual activation times of coils and Hall-effect sensors. This creates a reference time sequence that captures the specific non-uniform spacing characteristics of the motor construction. By establishing this reference profile beforehand, the system compensates for manufacturing imperfections during subsequent angular position measurements without requiring re-manufacturing or repositioning of components.
2Ease of manufacture
If non-uniform spacing of coils and sensors is accepted, then manufacturing is easier, but the time sequence data becomes non-uniform requiring complex correction
Solution Approach 1:
The motor's own operational data serves as the calibration reference. During initial calibration, the system records the actual activation times of coils and Hall-effect sensors as the rotor completes full revolutions. This self-generated reference time sequence inherently contains the non-uniform spacing characteristics of that specific motor unit. The system then uses this self-captured profile to correct and interpret subsequent position measurements, eliminating the need for external calibration standards or complex theoretical correction models.
3Measurement precision
If dynamic calibration method is implemented, then angular position accuracy improves, but processing time and computational requirements increase
Solution Approach 1:
The system performs calibration during idle periods or initial startup phases, rotating the rotor through multiple revolutions to capture the reference time sequence of coil and sensor activations. Once this reference profile is established and stored in memory, subsequent angular position determinations during operational sweeps require only comparison against the pre-stored reference data, significantly reducing processing time and computational burden during actual LIDAR scanning operations.
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 accurate and precise determination of the rotor's angular position, enhancing the accuracy of distance and texture measurements in LIDAR systems by accounting for motor imperfections and providing a dynamic method for continuous calibration.
Implementation Method 1
A non-transitory computer-readable medium having instructions stored thereon that when executed cause a computing device to rotate a rotor of a motor... The motor includes a plurality of coils and a plurality of Hall-effect sensors... receiving from the Hall-effect sensors data representative of which coils in the plurality of coils are active
Data Source
AI summary
Methods and systems are provided for determining a position of a rotor in a motor at a particular time based on the non-uniform (imperfect) angular position of coils in the motor. In one example, a method may be implemented for light detection and ranging (LIDAR) applications. The method may involve rotating a rotor of a motor at a substantially constant angular velocity, receiving from Hall-effect sensors in the motor data representative of which coils in the plurality of coils are active during the substantially constant rotation of the rotor, correlating a reference angular position of the rotor, receiving subsequent data from the Hall-effect sensors indicating which coils are active at a particular time, correlating the particular time to a position of the rotor in the substantially constant rotation of the rotor, and determining an angular position of the rotor at the particular time.