Multi-Leaf Collimator Drive Control for Motion Lag Compensation
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Solution Overview
Problem
Conventional closed-loop feedback control systems for multi-leaf collimators (MLCs) in radiotherapy are prone to movement lags due to factors like gravity, friction, acceleration, and deceleration, leading to reduced control precision and accuracy.
Innovation Solution
A method combining feedforward control with closed-loop feedback control to generate compensation signals based on target and current positions, velocities, and angles of the leaves, reducing the impact of motion factors and improving control precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional closed-loop feedback control is used to drive MLC leaves, then the system structure is relatively simple, but movement lags occur due to gravity, friction, acceleration, and deceleration, reducing control precision
Solution Approach 1:
The patent applies preliminary action by calculating and compensating for motion factors (gravity, friction, acceleration, deceleration) in advance before the leaves move. The compensation signal is generated based on predicted motion parameters rather than reacting to errors after they occur, thereby improving control precision without requiring complex real-time feedback mechanisms
Solution Approach 2:
The patent changes the control approach from pure feedback control to a hybrid system that incorporates feedforward compensation based on motion parameters. By introducing compensation signals that account for gravity, friction, acceleration, and deceleration, the system adjusts the control parameters proactively to maintain precision while managing complexity
2Measurement precision
If compensation for motion factors is introduced to improve control precision, then control accuracy improves, but the control system complexity increases
Solution Approach 1:
The patent introduces an intermediary compensation signal that mediates between the simple feedback control system and the desired high precision control. This compensation signal acts as a bridge, incorporating motion factor calculations to improve accuracy while maintaining a relatively simple overall system structure by building upon the existing feedback control framework
Data Source
AI summary
A method for driving a leaf of a multi-leaf collimator (MLC) mounted on a collimator that is mounted on a gantry is provided. The method may include obtaining an electrical current of an actuator of the leaf; generating a target control signal based on the electrical current of the actuator; and causing a drive circuit to generate a driving signal for driving the leaf to move by providing the target control signal to the drive circuit.