Actuator Zero Point Initialization via Optical Marker Detection

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Solution Overview

Problem

Conventional actuator initialization methods using mechanical stops limit the range of motion, fail to differentiate between initialization and jamming, and complicate the removal and replacement of actuator packages, leading to reliability concerns and increased costs.

Innovation Solution

An actuator with a detent structure that provides resistance to rotation without stopping, allowing for full 360° rotation and enabling differentiation between initialization and jamming, and allowing for removal and replacement without disassembling the entire system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a mechanical stop is used to initialize the actuator, then the actuator can be positioned at a specific location, but the range of motion is limited and cannot exceed 360° rotation

Engineering Contradiction:
Improveinitialization position accuracyVSAvoidrange of motion
Core Design Contradiction:
Measurement precisionVSLength of moving object

Solution Approach 1:

The patent replaces the mechanical stop system with an optical detection system. A marker is placed on the actuator shaft, and an optical sensor detects the marker's position to determine initialization. This substitution allows full 360° rotation while maintaining precise position detection, as the optical sensor can identify the marker anywhere in the rotational cycle without physical blocking.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a marker as an intermediary element between the actuator shaft and the detection system. This marker serves as a visual reference that can be detected optically, allowing the system to identify position without requiring direct mechanical contact or physical stops that would limit rotation.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If a mechanical stop is used to initialize the actuator, then the actuator can be positioned at a specific location, but the system cannot differentiate between initialization stop and physical jamming

Engineering Contradiction:
Improveposition detection accuracyVSAvoidfault detection reliability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent implements a feedback system where the optical sensor continuously monitors the marker position and provides information to the controller. The controller analyzes this feedback to distinguish between normal initialization (marker detected at expected position) and abnormal jamming (marker not detected or detected at unexpected position), enabling reliable fault differentiation.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

By replacing the mechanical stop with an optical detection system, the patent eliminates the ambiguity between mechanical stop contact and jamming. The optical sensor detects the marker's position independently of mechanical forces, allowing the controller to identify whether the actuator is properly initialized or genuinely jammed based on position information rather than force feedback.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If a hardware-based indication is incorporated on interface parts to determine orientation, then the position can be verified, but the fabrication cost increases and universality is reduced

Engineering Contradiction:
Improveorientation verification accuracyVSAvoidfabrication cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces complex hardware-based indication features with a simple optical marker and sensor system. The marker can be a simple visual element printed or attached to the shaft, eliminating the need for precision-machined interface features. This substitution significantly reduces fabrication costs while maintaining orientation verification capability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The optical marker and sensor system provides a universal solution that can be applied to various actuator types and configurations without requiring custom interface features for each application. The same basic principle works across different shaft sizes and mounting arrangements, enhancing universality and reducing the need for application-specific modifications.

Inventive Principle:
Principle #6Universality (Multi-functionality)

4Measurement precision

If the entire valve assembly is removed to visually verify valve element position, then the position can be confirmed, but the procedure becomes expensive and time-consuming

Engineering Contradiction:
Improvevalve element position verification accuracyVSAvoidmaintenance time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the need for physical visual inspection with an optical detection system that observes the marker through the existing transparent or translucent valve body. This substitution allows position verification without disassembly, eliminating the time-consuming removal and reassembly process while maintaining accurate position confirmation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The optical marker serves as an intermediary that makes internal valve element position visible from the outside. By placing the marker on the valve stem or related component, the system translates internal position information into an externally observable signal, eliminating the need to open the system for verification.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP2269298A1Actuator with zero point initialization
Publication Date: 2011.01.05 WOODWARD HRT INC

AI summary

The actuator has a shaft having a starting resistance portion, and a low resistance portion. The actuator has a motor configured to rotate the shaft, the motor outputting a current feedback signal to indicate current exiting the motor. The actuator has a interference portion disposed on a fixed member adjacent the shaft, the interference portion configured to facilitate a resistance to shaft rotation when the shaft rotates, the resistance to shaft rotation causing a magnitude of the current signal to be greater when the starting resistance portion passes in front of the interference portion than when the low resistance portion passes in front of the interference portion.