Actuator End-of-Travel Damping by Current Limiting
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Solution Overview
Problem
Existing electro-mechanical actuators in aircraft face inaccuracies and increased complexity in damping movement at the end of their range of motion, leading to excessive loads and operational interruptions, as current methods rely on position sensing and speed control which can result in false alarms and premature slowing of the actuator.
Innovation Solution
The actuator limits current supply to the motor when approaching its end position, increasing mechanical resistance to damp movement without position sensing, using additional resistance mechanisms like springs or friction to control speed, ensuring reliable and accurate damping while preventing slow actuation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If position sensors and speed controllers are used to damp actuator movement, then damping control is achieved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the electrical control system (position sensors and speed controllers) with a purely mechanical damping system. The mechanical resistance element provides automatic damping through its inherent mechanical properties, eliminating the need for electronic sensors and controllers while achieving reliable damping control.
Solution Approach 2:
The mechanical resistance element provides self-regulating damping control without requiring external monitoring or control systems. The system automatically adjusts resistance based on the actuator's position and velocity through mechanical means, making the damping function self-service and eliminating complex monitoring requirements.
2Reliability
If position sensors and speed controllers are used to damp actuator movement, then damping control is achieved, but cost increases
Solution Approach 1:
The patent replaces expensive electronic components (position sensors and speed controllers) with a simple mechanical resistance element, significantly reducing manufacturing cost while maintaining reliable damping control functionality.
Solution Approach 2:
The mechanical resistance element is a simple, inexpensive component that can be easily manufactured and replaced if needed, providing cost-effective damping control compared to expensive electronic control systems.
3Loss of information
If timer and position sensor are used to infer actuator speed, then speed estimation is achieved, but measurement precision deteriorates due to actuator inertia
Solution Approach 1:
The patent replaces indirect speed estimation (which suffers from inaccuracies due to actuator inertia) with direct mechanical speed control. The mechanical resistance element automatically provides damping proportional to the actuator's velocity, eliminating the need for speed estimation and providing accurate speed control.
4Reliability
If mechanical resistance increases to damp movement, then actuator speed reduces, but actuator productivity decreases
Solution Approach 1:
The mechanical resistance element provides localized damping control that activates only when the actuator approaches the end of its travel range. During normal operation, the actuator maintains full speed, but damping automatically engages near the endpoints to prevent excessive loads, thus maintaining productivity while ensuring reliability.
Solution Approach 2:
The mechanical resistance element provides dynamic damping control that automatically adjusts resistance based on the actuator's position and velocity. The damping force increases as the actuator approaches the end of travel and decreases during normal operation, maintaining productivity while preventing end-of-travel shocks.
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 enhances the reliability and cost-effectiveness of actuator damping by determining the increase in mechanical resistance through physical arrangement, reducing the risk of slow actuation and operational interruptions, and maintaining accurate control of the actuator's speed without the need for position sensing.
Implementation Method 1
the actuator comprises a spring configured to resist movement of the actuator body in the first direction when the actuator body is in the first part of the range of motion
Implementation Method 2
a brake portion arranged to increase frictional resistance to movement of the actuator body in the first direction when the actuator body is in the first part of the range of motion
Data Source
Figure 1(a)~1(b)
Figure 2(a)
Figure 2(b)
AI summary
An actuator (12) comprises an actuator body (20) mounted for movement over a range of motion, the range of motion comprising a first part and a second part, the first part being the range of motion extending between an end position and the second part. The actuator (12) comprises a motor (14) coupled to the actuator body (20) to move the actuator body (20) in the first direction and a controller (28) configured to control the supply of current to drive the motor (14). The mechanical resistance to movement of the actuator body (20) in the first direction is higher in the first part of the range of motion than in the second part of the range of motion. The controller (28) is configured such that any additional current supplied to the motor (14) when the actuator body (20) is in the first part of the range of motion is limited thereby causing the speed of the actuator body (20) to reduce as the actuator body (20) approaches the end position.