Angular Position Error Correction for Continuous Rotation Motors
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Solution Overview
Problem
Continuous rotation motors in timepieces face measurement errors in angular position due to malfunctions such as slowing down, stopping, or changes in direction, which distort the counting of counter-electromotive forces, leading to incorrect angular position determination.
Innovation Solution
A method that measures time intervals between detected instants and compares them to motor-specific reference intervals to determine measurement errors, allowing for the correction of angular position by counting instants of advance or delay, and updating reference intervals regularly to maintain accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the motor is actuated continuously to enable smooth seconds hand movement, then the visual smoothness is improved, but measurement errors occur when the motor slows down or stops momentarily due to external disturbances
Solution Approach 1:
The system continuously monitors the time intervals between zero crossings of counter-electromotive forces and compares them against reference intervals to detect deviations. When a malfunction is detected (time interval exceeds threshold), the system generates a correction signal to reset the angular position counting, ensuring accurate position determination even after disturbances cause momentary stops or speed variations.
2Device complexity
If the counting method is used to determine angular position by integrating speed from back-EMF sign changes, then the measurement simplicity is improved, but the measurement precision deteriorates when voltage becomes too low to detect counter-electromotive force values
Solution Approach 1:
The system pre-establishes reference time intervals between zero crossings during normal operation. These reference intervals are stored and used for comparison when detecting malfunctions. By having the reference data prepared in advance, the system can quickly identify when measurements become unreliable due to low voltage conditions and apply corrections without complex real-time analysis.
Solution Approach 2:
The system introduces an intermediary threshold value that represents the maximum acceptable time interval between zero crossings. When the actual time interval exceeds this threshold, it serves as an indicator that the motor has stalled or reversed, triggering a correction of the angular position count. This intermediary threshold simplifies the detection logic while maintaining measurement accuracy.
3Measurement precision
If reference intervals are updated regularly to maintain accuracy, then the measurement precision is improved, but the energy consumption increases due to continuous monitoring and comparison operations
Solution Approach 1:
The system performs reference interval updates and malfunction checks at periodic intervals rather than continuously. The control unit compares current time intervals against stored reference intervals at discrete moments, and only updates references when necessary. This periodic operation reduces energy consumption compared to continuous monitoring while maintaining adequate measurement precision for timepiece applications.
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 method provides a reliable and energy-efficient means to determine and correct measurement errors in the angular position of continuous rotation motors, ensuring accurate timekeeping even after malfunctions, by characterizing time intervals and correlating them with reference intervals.
Implementation Method 1
The electric current is supplied by an electric source in the coils to generate a magnetic field which actuates the rotation of the rotor by acting on the magnets
Implementation Method 2
The induction of the coils produces a back EMF correlated with each phase
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
The invention relates to a method for determining a measurement error in the angular position of a continuously rotating motor having one or more phases (11, 12, 13), particularly a clockwork motor, characterized in that the method comprises the following steps: - detecting (3) each instant (14) when the value of one of the back electromotive forces is zero, - recording (4) a time corresponding to each detected instant, - measuring (5) several time intervals between two detected instants (14) of the same motor revolution, - comparing (6) the measured time intervals to reference time intervals to deduce which reference intervals they correspond to, and - determining (7) a measurement error in the angular position if the measured intervals do not correspond to expected reference intervals. The invention also relates to a method for correcting the measurement of the angular position.The invention also relates to a determination and correction system for implementing the processes, as well as a timepiece comprising such a system.