Multi-Leaf Collimator Drive Control with Feedforward Compensation
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Solution Overview
Problem
Conventional closed-loop feedback control systems for multi-leaf collimators in radiotherapy introduce movement lags and reduce control precision due to factors like gravity, friction, acceleration, and deceleration, leading to inaccuracies in radiation beam delivery.
Innovation Solution
A method that combines feedforward control with closed-loop feedback control to generate control signals based on target velocities, accelerations, and current angles of the leaves, compensating for motion factors such as gravity, friction, and acceleration, thereby improving control precision and reducing movement lags.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional closed-loop feedback control is used to drive MLC leaves, then the control system can maintain stability, but movement lags occur and control precision is reduced due to gravity, friction, and acceleration factors
Solution Approach 1:
The patent applies feedforward control to calculate and apply compensation signals before the actual leaf movement occurs. By predicting the required compensation based on target position, velocity, and acceleration, the system proactively counteracts gravitational and frictional effects, eliminating movement lags and improving position precision while maintaining system stability
Solution Approach 2:
The patent combines feedforward control with closed-loop feedback control to create a hybrid control system. The feedback component continuously monitors actual leaf position and velocity, comparing them with target values, and adjusts the control signal to eliminate errors, thereby maintaining control stability while improving precision
2Manufacturing precision
If feedforward control is added to compensate for motion factors, then control precision is improved and movement lags are reduced, but the control system complexity increases
Solution Approach 1:
The patent merges feedforward control and closed-loop feedback control into a unified hybrid control system. By combining the predictive capabilities of feedforward control with the error-correcting capabilities of feedback control, the system achieves high precision leaf positioning while managing complexity through integrated control architecture
Data Source
AI summary
A method for driving a leaf of a multi-leaf collimator (MLC) is provided. The method may include obtaining a target position of the leaf; identifying a current position of the leaf; generating a first control signal based on the target position of the leaf and the current position of the leaf; generating a second control signal based on at least one of a target velocity of the leaf, a target acceleration of the leaf, or a current angle of the leaf; generating a third control signal based on the first control signal and the second control signal; and/or causing a drive circuit to generate a driving signal for driving the leaf to move towards the target position by providing the third control signal to the drive circuit.