Fault-Tolerant Electromechanical Actuator with Torque Sensing Adaptive Control
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Solution Overview
Problem
Existing actuators, particularly electric ones, face reliability issues due to susceptibility to heat and water damage, and wear and tear in their components, leading to potential failures that can cause hazardous conditions.
Innovation Solution
A fault-tolerant electromechanical actuator with a torque sensing adaptive control system that monitors motor module torque and disengages faulty motor modules to prevent failure, using a roller nut mechanism with a ramp and lock mechanism to ensure seamless operation even if one or more motor modules fail.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If electric actuators are used to replace hydraulic actuators, then weight and design complexity are reduced, but reliability deteriorates due to susceptibility to heat, water damage, and wear
Solution Approach 1:
The actuator is divided into multiple independent motor modules (first motor module, second motor module, third motor module) that can operate independently. Each module has its own drive mechanism, allowing the system to segment functionality and isolate failures to individual modules rather than the entire system.
Solution Approach 2:
Different motor modules are positioned at different locations within the actuator housing, with each module having localized components (roller nuts, threaded rollers, disengagement mechanisms) that can be independently monitored and disengaged based on local torque conditions.
2Reliability
If multiple motor modules are used to provide redundancy, then reliability is improved, but device complexity increases
Solution Approach 1:
Multiple motor modules are merged into a single integrated actuator assembly with a common output ram and housing. The modules share common structural elements (housing, output ram, control system) while maintaining independent drive mechanisms, combining redundancy with structural efficiency.
Solution Approach 2:
Each motor module is designed with universal functionality to perform the same drive operation, allowing any module to compensate for the failure of another. The modules can independently drive the output ram, providing multi-functional capability within a unified system architecture.
3Reliability
If torque monitoring and automatic disengagement systems are implemented, then reliability is improved by preventing failure, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The actuator system continuously monitors torque levels in each motor module before complete failure occurs. The control system is pre-programmed with torque thresholds and automatically initiates disengagement procedures when abnormal torque conditions are detected, preventing catastrophic failure before it happens.
Solution Approach 2:
A control system acts as an intermediary between the motor modules and the output ram. It receives torque feedback from each module, processes the information, and mediates the disengagement process by activating disengagement mechanisms in specific modules based on real-time torque conditions.
4Reliability
If disengagement mechanisms are added to motor modules, then fault tolerance is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The disengagement mechanism is nested within each motor module assembly. The ramp and lock mechanism is integrated into the motor module structure, with the cam feature formed as part of the motor module housing or mounting structure, creating a compact nested arrangement that minimizes additional space requirements.
Solution Approach 2:
The disengagement mechanism uses dynamic elements including a spring-loaded plunger that can move between engaged and disengaged positions. The ramp and lock mechanism provides dynamic response to torque conditions, automatically transitioning from locked to unlocked state when torque thresholds are exceeded.
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 actuator provides reliable redundancy, preventing failures and potentially hazardous conditions by disengaging faulty motor modules and ensuring continuous operation, thus enhancing safety and reliability.
Implementation Method 1
the roller nut is configured to rotate in response to magnetic fields created about the armature by the stator
Implementation Method 2
magnetic fields created about the armature by the stator
Implementation Method 3
the roller nut comprising one or more biasing devices to bias the threaded rollers radially inward and into contact with threads of the output ram
Implementation Method 4
move tapers of the ramp and lock mechanisms under corresponding taper sections of the threaded rollers to lift the threaded rollers away from the output ram
Data Source
Figure 1
Figure 1A
Figure 2~2A
AI summary
An electromechanical actuator (EMA) is provided. The EMA includes a threaded output ram connectable to a mechanical component and at least one motor module engageable with the output ram for controllably translating the output ram along a linear axis of the output ram. The actuator further includes a torque sensing adaptive control (TSAC) system for monitoring torque within the motor module. The TSAC generates a disengagement command signal when the TSAC system determines torque within the motor module is outside an allowable motor module torque range. The disengagement command signal initiates disengagement of the motor module from the output ram.