Dual-Redundant Linear Actuator With Planetary Gear Backup Drive
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Solution Overview
Problem
Linear actuators have failure-prone components that can lead to system failure, and there is a challenge in increasing their reliability.
Innovation Solution
A dual rotary input linear actuator design featuring a planetary gear system with two motors and a braking mechanism that allows either motor to be used as a sole input, providing redundancy and alternating wear to prolong the actuator's life, and a fault detection system to engage brakes in case of power loss or failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single motor is used to drive the planetary gear system, then the device complexity is reduced, but the reliability decreases due to failure-prone components
Solution Approach 1:
The single motor is segmented into two separate motors (first motor and second motor), each capable of independently driving the planetary gear system. This segmentation provides redundancy such that if one motor fails, the other can continue operation, thereby improving reliability while managing the complexity through modular design
Solution Approach 2:
The system changes the operational parameter from single-motor operation to dual-motor operation with the ability to switch between motors. The control system monitors motor health and can switch between the first and second motor based on detected failures or power loss, effectively using parameter changes to maintain reliability
2Duration of action of moving object
If continuous operation with one motor is used, then productivity is maintained, but the duration of action decreases due to component wear
Solution Approach 1:
The system implements periodic action by alternating between the first motor and second motor. The controller can switch between motors based on operational cycles, wear detection, or failure conditions, allowing the actuator to maintain productivity while extending overall lifespan through distributed wear across multiple motors
Solution Approach 2:
The second motor serves as a copy or backup of the first motor, with identical functionality and drive capability. This copying approach allows the system to replace a worn or failed motor with its duplicate, thereby extending the actuator's operational duration without sacrificing productivity
3Reliability
If no brake mechanism is used, then the device complexity is reduced, but the reliability decreases during failure or power loss
Solution Approach 1:
The brake mechanism provides preliminary anti-action by automatically engaging when motor failure or power loss is detected. This preemptive braking prevents uncontrolled movement or damage that could occur during failure conditions, improving reliability while adding a safety-focused component to the system
Solution Approach 2:
The brake acts as an intermediary safety device between the motor and the planetary gear system. During failure conditions, the brake mediates the energy dissipation and prevents damage propagation, thereby improving system reliability during critical failure scenarios
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 dual motor configuration enhances reliability by allowing either motor to be used as a sole input, providing redundancy and prolonging the actuator's life, while the fault detection system ensures continued operation by switching to the alternate motor in case of failure or power loss.
Implementation Method 1
a planetary gear system including a sun gear, a ring gear, and a planet carrier
Implementation Method 2
convert rotary motion into linear displacement
Implementation Method 3
A first brake is coupled to the first motor, and a second brake is coupled to the second motor
Data Source
AI summary
A linear actuator includes a planetary gear system includes a sun gear, a ring gear, and a planet carrier. A linear output mechanism is coupled to the planetary gear system. A first motor is configured to drive a first input shaft, and the first input shaft is coupled to the planet carrier. A second motor is configured to drive a second input shaft, and the second input shaft is coupled to the ring gear. A first brake is coupled to the first motor and is configured to be engaged into a braked position that holds the planet carrier fixed. In the braked position, rotation of the ring gear results in rotation of the sun gear for linear displacement of the linear output mechanism.