Patient Support Motion Control With Regenerative Braking
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Solution Overview
Problem
Existing patient support devices in radiation therapy systems face challenges in precise control and safety during power interruptions, as they often rely on less reliable and expensive hydraulic systems, which can lead to inaccurate motion and safety concerns.
Innovation Solution
A patient support device with an electro-mechanical roller screw configuration and a motor control system that includes a brake control module, allowing for controlled motion and braking even when power is interrupted, using a dynamic load module and rectification module to manage speed and energy dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hydraulic systems are used for patient support device motion control, then motion control is achieved, but reliability and precision deteriorate due to safety concerns and inaccurate motion
Solution Approach 1:
The patent replaces hydraulic systems with an electro-mechanical system consisting of a motor, roller screw mechanism, and brake control module. This substitution eliminates the reliability issues and safety concerns associated with hydraulic systems while providing more precise and accurate motion control through direct electrical actuation and electronic braking control.
Solution Approach 2:
The brake control module is designed to automatically activate when power is interrupted, using the motor's own generated voltage during deceleration to engage the brake. This self-service mechanism ensures safe stopping without requiring external power or complex control systems, thereby improving reliability while maintaining simplicity.
2Measurement precision
If brake control module with dynamic load module is used, then motion control precision is improved, but device complexity increases
Solution Approach 1:
The roller screw mechanism serves as an intermediary between the motor and the patient support table, converting rotational motor motion into precise linear table movement. This mechanical intermediary provides accurate position control through the inherent mechanical advantage of the roller screw, eliminating the need for complex electronic position control systems.
Solution Approach 2:
The brake control module incorporates feedback from the motor's generated voltage during deceleration to automatically regulate brake engagement. This feedback mechanism allows the system to self-regulate braking force based on actual motion conditions, achieving precise stopping control without requiring complex external control systems.
3Ease of manufacture
If electro-mechanical system is used instead of hydraulic system, then cost is reduced, but control reliability during power interruption may worsen
Solution Approach 1:
The patent converts the harmful effect of power interruption into a beneficial self-braking mechanism. When power is interrupted, the motor naturally generates voltage during deceleration, which the brake control module detects and uses to automatically engage the brake. This transforms a potential safety hazard into a reliable self-protective feature, ensuring safe stopping even during power failures.
Solution Approach 2:
The system uses its own motor-generated voltage during deceleration to trigger the brake engagement, requiring no external power source or complex backup systems. This self-service approach ensures reliable operation during power interruptions while keeping the system simple and cost-effective.
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 solution provides reliable, accurate, and cost-effective control of the patient support device's motion, ensuring safe and precise positioning during radiation therapy, even in power-off situations, by using an electro-mechanical system that maintains consistent speed and prevents crashes.
Implementation Method 1
a rectification module electrically coupled to the motor and operable to convert AC voltage to DC voltage when the AC voltage reaches a predetermined value
Implementation Method 2
the controller operable to generate a signal to brake the motor when power to the motor is interrupted
Implementation Method 3
a passive dynamic load module electrically coupled to the motor to increase speed of the motor
Data Source
AI summary
A patient support device of a radiation therapy treatment system includes an electromechanical motor and control system for moving the support device. The control system utilizes regenerative braking concepts, converting the motor into a generator as the support device is moved such that no matter the load, the support device will be moved at a constant speed. The control system also allows for moving of the support device in the powered off situation (i.e., when there is no power to the support device).