Split-Housing Electro-Mechanical Actuator for Fail-Operational Control
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Solution Overview
Problem
In vehicles with fly-by-wire operation, actuators often fail to maintain functionality when a single actuator fails, especially in scenarios where space constraints limit the installation of multiple actuators, leading to potential loss of control and safety issues.
Innovation Solution
The development of an electro-mechanical actuator (EMA) with integrated fail-operational mechanisms, including multiple motors, backup motors, and a controller that ensures continued operation even if one component fails, by redistributing the actuation load and using redundant pathways to maintain control between mounting points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple actuators are installed to provide redundancy, then reliability is improved, but device complexity and space requirements increase
Solution Approach 1:
The patent combines multiple actuators into a single integrated unit with a common housing, control system, and mounting structure. This merging approach provides redundant actuation capability while reducing the overall space required compared to installing separate actuators, and simplifies the control system architecture by having a single controller manage all actuation functions.
Solution Approach 2:
The integrated actuator system is designed to perform multiple functions through its redundant actuator components. The system can operate in normal mode using one actuator and switch to backup mode using the other actuator or both actuators simultaneously, providing multi-functional capability that enhances reliability without requiring separate dedicated systems for each function.
2Reliability
If multiple actuators are installed to provide redundancy, then reliability is improved, but installation space increases
Solution Approach 1:
The patent combines multiple actuators into a single integrated unit with a common housing, control system, and mounting structure. This merging approach provides redundant actuation capability while reducing the overall space required compared to installing separate actuators, and simplifies the control system architecture by having a single controller manage all actuation functions.
3Device complexity
If a single actuator is used to reduce complexity, then device complexity is reduced, but reliability decreases upon failure
Solution Approach 1:
The integrated actuator system employs dynamic switching capability that allows the control system to transition between different operational modes based on real-time conditions. When one actuator fails, the system dynamically reconfigures to use the backup actuator, maintaining operational reliability while keeping the overall system design relatively simple through a single integrated unit.
Solution Approach 2:
The control system acts as an intermediary that monitors the health and performance of the actuator components and automatically switches between actuators when failures are detected. This intermediary function maintains reliability without requiring complex mechanical redundancy, as the control system intelligently manages the transition between actuators based on operational status.
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 EMA with integrated fail-operational mechanisms enables continued actuation and control of vehicle components even if one actuator fails, enhancing safety and reliability by ensuring that the system remains operational, thereby preventing loss of control and damage.
Implementation Method 1
a first motor configured to rotate the first ball nut about an axis of the ballscrew; a second motor configured to rotate the second ball nut about the axis of the ballscrew
Data Source
AI summary
Some embodiments relate to an electro-mechanical actuator that includes a screw, structurally segregated (split) housings, first and second nuts coupled to the screw, a sensor assembly, a plurality of motors, and a controller. The first nut is coupled to a first mounting point, and the second nut is coupled to a second mounting point. The sensor assembly may generate signals indicative of (e.g., relative) positions of left and right units of the actuator or positions of the first nut and the second nut on the screw. The controller controls the motors based on the signals generated by the sensor assembly. The motors may rotate each nut about a screw axis of the screw. This rotation results in one or both nuts moving along the screw. Movement between the first nut and the second nut along the screw adjusts a distance between the first mounting point and the second mounting point.