Moving Light Fixture Position Control Without Homing Noise
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Solution Overview
Problem
Moving light fixtures with stepper motors face challenges in homing operations, which are time-consuming and produce noise, especially in theatrical environments. Additionally, existing solutions like optical quadrature encoders provide only relative position feedback, limiting accuracy and compatibility with restricted movement scenarios.
Innovation Solution
The implementation of a combination of magnetic absolute encoders and optical sensors with a quadrature or indexer system enhances the positional accuracy of moving light fixtures. This setup allows for absolute position determination and precise adjustment, enabling faster and quieter operation, even in restricted spaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If homing operation is performed to establish reference position for stepper motors, then positional accuracy is improved, but operation time increases and noise is generated
Solution Approach 1:
The magnetic absolute encoder continuously maintains knowledge of the current position without requiring periodic homing operations. The system performs the position measurement action continuously in the background, eliminating the need for time-consuming homing sequences before each operation or during interruptions.
Solution Approach 2:
The patent replaces the mechanical homing mechanism with an electronic solution using magnetic absolute encoder. Instead of mechanically moving to a reference position, the system uses magnetic field detection to continuously know the absolute position, substituting mechanical action with electronic measurement.
2Measurement precision
If homing operation is performed to establish reference position, then positional accuracy is improved, but harmful noise is generated
Solution Approach 1:
The patent replaces the mechanical homing mechanism that generates audible noise with an electronic magnetic sensing system. The magnetic absolute encoder detects position through magnetic fields without mechanical movement, eliminating the harmful noise generated by motor operation during homing.
Solution Approach 2:
The magnetic field acts as an intermediary between the motor position and the control system. Instead of directly measuring position through mechanical means that generate noise, the system uses magnetic field detection as an intermediate step to obtain position information silently and continuously.
3Measurement precision
If optical quadrature encoders are used for position feedback, then relative position measurement is enabled, but absolute position determination is not achieved
Solution Approach 1:
The patent replaces optical quadrature encoders that provide only relative position feedback with magnetic absolute encoders. The magnetic encoder directly measures absolute position through magnetic field orientation, providing complete position information without requiring reference to a starting point or accumulation of incremental movements.
4Measurement precision
If homing operation is required for stepper motors, then positional reference is established, but operation in restricted spaces is prevented
Solution Approach 1:
The magnetic absolute encoder continuously maintains position information without requiring preliminary homing operations. This allows the system to immediately operate from any position within its range, including restricted spaces where full movement to a reference position is not possible.
Solution Approach 2:
The patent changes the fundamental parameter for position measurement from relative displacement (requiring homing) to absolute magnetic field orientation. This parameter change enables operation from any absolute position without needing to return to or establish a reference point, making the system adaptable to restricted installation spaces.
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
The proposed solution significantly improves the positional accuracy and operational efficiency of moving light fixtures, reducing noise and enabling seamless operation in tight spaces, thus enhancing their usability in theatrical and other applications.
Implementation Method 1
a magnetic position encoder configured to transmit a first position signal indicating an angular position of the housing about the axis of rotation
Implementation Method 2
an optical sensor configured to transmit a second position signal indicating a position of the indexer about the axis of rotation
Data Source
AI summary
A moving light fixture and methods for controlling the position of the moving light fixture. The moving light fixture includes a housing, a motor operably coupled to the housing to rotate the housing about an axis of rotation, and an indexer configured to rotate in conjunction with the housing. A magnetic position encoder transmits a first position signal indicating an angular position of the housing, and an optical sensor transmits a second position signal indicating a position of the indexer. An electronic controller receives a target position for the moving light fixture, determines an angular position of the housing based on the first position signal, determines a position of the indexer based on the second position signal, determines a current position of the housing, and drives the motor to move the housing from the current angular position to the target position based on the position of the indexer.