Lead Screw Backlash Measurement for Precise Landing Gear Control
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Solution Overview
Problem
Existing drive systems for maglev transportation systems, such as those used in landing gear, suffer from inaccuracies due to backlash, which affects the precise extension and retraction of landing gear, essential for maintaining vehicle height and stability, especially in the presence of external influences like track faults or bumps.
Innovation Solution
A drive system that includes a motor with a rotatable output shaft coupled to a lead screw via a transmission, equipped with a position sensor and a controller, which measures and accounts for backlash by calculating the difference between theoretical and actual lead screw positions, allowing for accurate calibration and control of the lead screw's position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a transmission system is used to convert rotary motion to linear motion, then the drive system can control landing gear extension and retraction, but backlash in the transmission causes positioning inaccuracies
Solution Approach 1:
The system employs a position sensor to continuously monitor the actual position of the lead screw and feeds this information back to the controller. The controller compares the actual position with the commanded position and adjusts the motor output accordingly to compensate for backlash, thereby maintaining positioning accuracy despite the presence of backlash in the transmission system.
Solution Approach 2:
The system dynamically changes the control parameters by adjusting the motor's rotational commands based on the detected backlash. The controller modifies the rotation amount and direction to account for backlash variations, transforming the control approach from fixed to adaptive, thereby maintaining precision across different operating conditions.
2Measurement precision
If backlash compensation is implemented through sensing and calculation, then positioning accuracy is improved, but the system complexity increases
Solution Approach 1:
The system performs self-diagnosis and self-correction by using the position sensor to detect actual lead screw position and automatically calculating the backlash compensation. The controller autonomously adjusts for backlash without requiring external intervention or complex additional hardware, allowing the system to service itself and maintain accuracy.
Solution Approach 2:
Instead of using complex mechanical backlash elimination mechanisms such as preloaded nuts or dual-screw systems, the patent substitutes a sensor-based detection and controller-based calculation approach. This replaces mechanical complexity with electronic sensing and computational compensation, achieving the same goal with reduced mechanical complexity.
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 system enables precise and timely extension and retraction of the landing gear, improving the accuracy of the maglev vehicle's height control and stability by accounting for backlash, thereby enhancing the overall performance and reliability of the maglev transportation system.
Implementation Method 1
a lead screw operably coupled to the transmission, wherein the transmission converts rotary output of the motor into linear translation of the lead screw
Data Source
AI summary
A drive system includes a motor having a rotatable output shaft that is operably coupled to a lead screw by a transmission that converts rotary output of the motor into linear translation of the lead screw. The drive system further includes a position sensor configured to sense a position of the lead screw. A method for determining a backlash of the drive system includes the steps of sensing an initial position and driving the lead screw in a first direction to a calculated second position by controlling the motor to rotate the output shaft an amount that corresponds to a distance between the initial position and the calculated second position. The method further includes the steps of sensing an actual second position of the lead screw; and determining a backlash value according to a difference between the calculated second position and the actual second position.