Linear Synchronous Motor Load Characterization via PRBS Injection
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Solution Overview
Problem
Motion control systems with linear drive systems face challenges in characterizing the performance of movers due to varying loads, friction, and changing center of gravity, which affect speed and efficiency along different track segments over time.
Innovation Solution
A method and system that utilize segment controllers to generate a pseudo-random binary sequence (PRBS) injection signal, which is added to the control module to sample and record the motion of movers, allowing for the determination of frequency responses to identify resonant operating points and harmonic content, enabling characterization of loads and optimizing performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional motion control methods are used without load characterization, then the system operation is simpler, but the performance and efficiency vary unpredictably due to varying loads, friction, and changing center of gravity
Solution Approach 1:
The system performs load characterization by injecting test signals and measuring frequency responses before normal operation to identify resonant frequencies and system parameters. This preliminary characterization enables the control system to compensate for varying loads, friction, and center of gravity changes, ensuring consistent mover performance without requiring complex real-time adjustments during operation.
Solution Approach 2:
The system uses sensors to measure actual mover position and velocity, compares these measurements with commanded values, and uses the error signals to update the frequency response characterization. This feedback mechanism allows the system to adapt to changing loads and conditions by continuously refining the load characterization data, improving performance consistency while maintaining manageable control complexity.
2Measurement precision
If load characterization is performed to identify resonant operating points and harmonic content, then the motion control precision is improved, but the measurement and detection difficulty increases
Solution Approach 1:
The system uses periodic test signals with known frequency content to excite the mover and measure its frequency response. By using periodic excitation signals rather than random inputs, the system can systematically sweep through different frequencies to identify resonant points and harmonic content. This approach improves measurement precision by providing clear, repeatable excitation patterns that are easier to analyze than random disturbances.
Solution Approach 2:
The system introduces an intermediary test signal (injection sequence) that mediates between the control system and the mover. This test signal serves as a known reference input that interacts with the mover's mechanical properties, allowing the system to extract frequency response information without requiring direct measurement of complex dynamic behaviors. The intermediary signal simplifies the measurement process by providing a controlled excitation source.
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 allows for precise characterization of mover performance, identifying resonant operating points and harmonic content, thereby optimizing motion control and maintaining efficiency across varying loads and track segments, improving system stability and reliability.
Implementation Method 1
Successive activation of the coils establishes a moving electromagnetic field that interacts with the movers and causes the mover to travel along the track
Implementation Method 2
The track is made up of a number of track segments that, in turn, hold individually controllable electric coils. Successive activation of the coils establishes a moving electromagnetic field that interacts with the movers
Implementation Method 3
An injection sequence is generated within the segment controller, where the injection sequence is a pseudo random signal generated such that it exhibits behavior of a random signal and also includes harmonic content across a range of frequencies to be evaluated
Implementation Method 4
The frequency response may be utilized to identify a resonant operating point or to determine if the harmonic content in the sampled data exceeds a predefined maximum threshold for operation of the mover
Data Source
AI summary
A method and system for characterizing performance of a mover operating in a linear drive system is disclosed, where the linear drive system includes multiple track segments and where each track segment includes a segment controller. Each segment controller is configured to obtain an in-system frequency response for a mover present along the track segment. An injection sequence is generated within the segment controller, where the injection sequence includes harmonic content across a range of frequencies to be evaluated. The injection sequence is added to a control module within the segment controller, and the segment controller samples and records motion of the mover in response to the injection sequence. A frequency response corresponding to the recorded motion of the mover resulting from the injection sequence is obtained, and may be utilized to identify a resonant operating point or an undesirable level of the harmonic content present in the sampled data.