Table Drive Safety Block Prevents Uncontrolled Motion
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Solution Overview
Problem
Conventional patient positioning systems face safety issues due to uncontrolled motion from single point failures in rack and pinion drive assemblies, such as pinion failure, and gear detachment in gear train drive assemblies, leading to potential patient falls and equipment damage, with existing safety devices like fail-safe brakes and redundant brakes increasing system complexity and minimum table height.
Innovation Solution
A table drive system incorporating a safety block mechanism that arrests motion upon failure of drive assembly components, specifically designed for rack and pinion and gear train systems, to prevent uncontrolled movement and ensure patient safety without increasing system size or complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fail-safe brake is added to control uncontrolled motion from pinion failure, then patient safety is improved, but system complexity and device size increase
Solution Approach 1:
A safety block is introduced as an intermediary mechanical component between the rack and the environment. This safety block acts as a passive mechanical stop that prevents uncontrolled motion without requiring active control systems, sensors, or complex braking mechanisms. The safety block simply provides a physical barrier that limits the rack's travel distance, thereby improving patient safety while maintaining system simplicity.
2Reliability
If a redundant second fail-safe brake is added in parallel axis, then patient safety is improved, but longitudinal stroke is reduced and system size increases
Solution Approach 1:
The active braking function is extracted from the drive system and replaced with a passive mechanical stop. By removing the need for redundant brakes and their associated control systems, the longitudinal stroke is preserved and system size is reduced while maintaining safety through the safety block's physical limitation of rack travel.
3Reliability
If fail-safe brakes are added to each stage of ball screw, then vertical movement safety is improved, but minimum table height increases
Solution Approach 1:
Safety blocks are introduced as passive mechanical intermediaries that prevent uncontrolled vertical motion without requiring additional vertical space for brake mechanisms. The safety blocks act as mechanical stops that limit the ball screw's travel, thereby ensuring vertical movement safety while maintaining the minimum table height required for patient access.
4Reliability
If safety devices are added to prevent gear detachment collapse, then patient safety is improved, but system complexity increases
Solution Approach 1:
Safety blocks serve as simple mechanical intermediaries that prevent gear detachment collapse by providing a physical stop that limits the rack's travel distance. This passive mechanical approach improves patient safety without introducing complex sensors, controllers, or active safety systems.
Data Source
AI summary
A table drive system for driving a support table is disclosed herein. The table drive system comprises at least one of a first drive assembly or a second drive assembly or a combination thereof. The first drive assembly is configured for moving the support table in a first direction for example, a longitudinal direction and the second drive assembly is configured for moving the support table in a second direction for example, a vertical direction. The table drive system further includes a safety block in combination with at least one of the first drive assembly or the second drive assembly, the safety block configured to arrest the motion of the first drive assembly or the second drive assembly upon experiencing a predetermined condition such as the failure of at least one of the first drive assembly or the second drive assembly.


