Moving Light Fixture Position Control Using Magnetic Encoder

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Solution Overview

Problem

Conventional moving light fixtures with stepper motors face challenges in achieving full positional feedback, leading to the need for time-consuming homing operations and undesirable noise, especially in restricted environments, due to the use of relative position sensors like optical quadrature encoders or expensive absolute position sensors.

Innovation Solution

The implementation of a moving light fixture with a stepper motor, a magnetic position encoder, and an electronic controller that determines the angular position and micro steps to accurately position the light fixture, allowing it to move from a current position to a target position without the need for homing operations, using magnetic position encoders to provide absolute positional feedback.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If optical quadrature encoders are used with stepper motors, then relative positional feedback is provided, but homing operation is still required and full positional feedback is not achieved

Engineering Contradiction:

Improvepositional feedbackVSAvoidhoming operation requirement

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces optical quadrature encoders with magnetic position encoders that provide absolute positional feedback. This substitution eliminates the need for homing operations while delivering full positional feedback, directly resolving the contradiction between measurement precision and device complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If DC servo motors are used, then full positional feedback is provided, but the cost becomes extremely expensive and prohibitive

Engineering Contradiction:

Improvepositional feedbackVSAvoidcost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent employs magnetic position encoders with stepper motors as a cost-effective alternative to expensive DC servo motors. This approach provides the necessary full positional feedback at a fraction of the cost, making the system economically viable while maintaining measurement precision.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent changes the fundamental parameter of the positioning system by using magnetic position encoders that provide absolute position data, eliminating the need for expensive DC servo motors while maintaining full positional feedback capability.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If homing operation is performed, then known reference position is established, but time is consumed and noise is produced in theatrical environments

Engineering Contradiction:

Improvereference positionVSAvoidhoming time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The magnetic position encoder provides absolute positional feedback from the moment of power-up, eliminating the need for preliminary homing operations. The system immediately knows its position without requiring time-consuming homing sequences, thus reducing loss of time while maintaining reliability.

Inventive Principle:

Principle #10Preliminary action

4Reliability

If homing operation is performed, then known reference position is established, but the moving light fixture requires full unencumbered movement which is not available in restricted environments

Engineering Contradiction:

Improvereference positionVSAvoidrestricted movement capability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent replaces the mechanical homing process with an electronic solution using magnetic position encoders. This substitution allows the system to establish known reference positions electronically without requiring physical movement, enabling operation in restricted environments where full movement is not available.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution enables precise and quiet operation of moving light fixtures in restricted spaces without the need for homing, reducing noise and setup time, while providing cost-effective full positional feedback.

Implementation Method 1

a magnetic position encoder configured to provide full positional feedback about a position of the moving light fixture

Methodology Applied

Scientific EffectMagnetic field sensing: Magnetic Field

Data Source

PatentUS10274175B1Systems and methods for controlling the position of a moving light fixture

Publication Date: 2019.04.30 ELECTRONIC THEATRE CONTROLS INC

AI summary

Moving light fixture and method for controlling the position of a moving light fixture. In one example, the moving light fixture includes a housing, light sources, a stepper motor, a magnetic position encoder, and an electronic controller. The stepper motor rotates the housing. The magnetic position encoder is configured to transmit a position signal indicating an angular position of the housing. The electronic controller determines the angular position of the housing based on the position signal. The electronic controller also determines a full step of the stepper motor based on the angular position of the housing, and a micro step of the stepper motor. The electronic controller also determines a current position of the moving light fixture based on the full step and the micro step. The electronic controller drives the stepper motor to move the moving light fixture from the current position to a target position.