Surgical Manipulator Shutdown Logic for Encoder Failure Detection
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Solution Overview
Problem
Existing medical manipulator systems fail to quickly transition to a safe state upon power transmission failure to surgical instruments, leading to potential malfunctions and safety risks.
Innovation Solution
A manipulator system incorporating a power source, sensors, an arithmetic logic unit, a control signal generator, and a cutoff unit to detect and respond to changes in drive quantities, enabling quick shutdown of the power source when certain threshold conditions are met, ensuring safe operation even in the event of power failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the difference between operation quantities detected by respective encoders increases in excess of the threshold value to detect encoder failure, then the detection reliability is improved, but the response time to shut down the surgical instrument is delayed
Solution Approach 1:
The system performs preliminary monitoring of encoder operation quantities and compares them against threshold values before actual failure occurs. By continuously checking whether the difference between encoder readings exceeds the threshold, the system is prepared to detect failure immediately when it happens, rather than waiting for post-failure analysis.
Solution Approach 2:
The system implements feedback by continuously monitoring the difference between operation quantities from multiple encoders and comparing this difference against a predetermined threshold. When the threshold is exceeded, the system immediately shuts down the surgical instrument. This closed-loop feedback mechanism ensures both reliable detection and rapid response to encoder failures.
2Loss of time
If the threshold value for detecting encoder failure is set low to reduce response time, then the shutdown speed is improved, but false detection of normal operation as failure increases
Solution Approach 1:
The system optimizes the threshold parameter by setting it to a specific value that balances two competing requirements: it is low enough to enable rapid shutdown when failure occurs, but high enough to avoid triggering false alarms during normal operation. This carefully selected threshold parameter allows the system to achieve both fast response time and high reliability in failure detection.
Data Source
AI summary
A manipulator system includes arithmetic logic units for calculating an operation quantity per unit time of a power source mounted on a surgical instrument as a first operation quantity and calculating an operation quantity per unit time of the power source as a second operation quantity. A determining unit is used for outputting a shutoff signal for de-energizing the power source if the first operation quantity is smaller than a first threshold value and the second operation quantity is larger than a second threshold value. A cutoff unit is configured to cut off the drive signal output from the output unit to the power source in response to the shutoff signal output for de-energizing the power source from the determining unit.