Surgical Robot Torque Sensor Calibration for Zero Offset and Gain
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Solution Overview
Problem
Robotic surgical systems face challenges in precisely controlling end effectors due to variations in torque sensor readings, particularly in zero offset and gain, which affect the accuracy of motor movements during surgical procedures.
Innovation Solution
A method for calibrating torque sensors involves determining the gain and zeroing torque readings, measuring inertia, and accounting for cross-talk torque, using a controller to create a correction matrix for each motor, ensuring precise control of end effectors by compensating for variations in torque sensor readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If torque sensors are used in IDUs to control motor movements, then motor control capability is improved, but variations in torque sensor readings (zero offset and gain) cause measurement precision deterioration
Solution Approach 1:
The patent applies preliminary action by performing calibration procedures before actual surgical operations. The system determines zero offset and gain values for torque sensors during an initial calibration phase, storing these values for subsequent use. This preliminary calibration eliminates measurement errors during actual motor control operations, resolving the contradiction between having functional torque sensors and maintaining measurement precision.
Solution Approach 2:
The patent changes parameters by determining and applying correction values (zero offset and gain) for torque sensors. The system measures actual torque sensor readings under known conditions, calculates deviation from expected values, and applies compensation parameters to correct future readings. This parameter adjustment restores measurement precision while preserving the motor control capability provided by the torque sensors.
2Measurement precision
If calibration procedures are implemented to correct torque sensor variations, then measurement precision is improved, but device complexity increases due to additional calibration steps and correction matrices
Solution Approach 1:
The patent applies self-service by enabling the system to perform its own calibration automatically. The controller executes calibration routines that determine zero offset and gain values without requiring external calibration equipment or manual intervention. The system self-diagnoses torque sensor variations and self-corrects by applying calculated compensation parameters, reducing operational complexity despite the added calibration functionality.
Solution Approach 2:
The patent implements feedback mechanisms where the controller continuously monitors torque sensor readings and applies real-time corrections based on pre-determined calibration parameters. The system uses feedback from position sensors and motor current measurements to verify calibration accuracy and adjust correction values as needed. This automated feedback loop manages complexity by making the calibration system adaptive and self-regulating.
Data Source
AI summary
A method of calibrating a torque sensor for a motor with a controller includes determining a gain of the torque sensor, zeroing a torque reading of the torque sensor, accelerating the motor at a known rate, and determining an inertia of the motor in response to accelerating the motor. Zeroing the torque reading occurs when the motor is in an unloaded and unactivated condition and accelerating the motor occurs when the motor is in an unloaded condition.