Surgical Robot Camera Calibration Using Dual-Camera Hand-Eye Alignment
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Solution Overview
Problem
Existing methods for hand-eye and geometric calibration in medical robotics are time-consuming, prone to errors, and require manual user input, which is unsuitable for precise surgical procedures.
Innovation Solution
An automated calibration method using two cameras, one mounted on the robot (eye-in-hand) and one externally (eye-on-base), with a control unit to perform sequential or simultaneous calibrations, minimizing errors and eliminating the need for manual intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If manual calibration methods are used, then the calibration process can be performed with simple equipment, but the calibration time is excessive and error-prone
Solution Approach 1:
The calibration system performs self-calibration automatically without requiring manual user input. The control unit executes calibration algorithms that autonomously process images from both cameras, calculate transformations, and update calibration parameters, eliminating the need for manual intervention while maintaining high precision
Solution Approach 2:
The system performs preliminary positioning of the robot flange to specific poses before calibration measurements are taken. The control unit pre-calculates required positions and orientations, then automatically moves the robot to these predetermined poses to ensure optimal calibration conditions are met before data collection begins
2Productivity
If automated calibration is implemented, then calibration speed and precision are improved, but the device complexity increases
Solution Approach 1:
The control unit serves multiple functions: it controls the robot arm movements, processes images from both cameras, executes calibration algorithms, and manages data storage. By consolidating these functions into a single multi-functional control system, the patent avoids the need for separate dedicated devices for each task, thereby limiting the increase in overall system complexity while maintaining high calibration efficiency
Solution Approach 2:
A calibration pattern serves as an intermediary object that facilitates the calibration process. This pattern with known geometry is captured by both cameras and used as a reference to calculate transformations. The intermediary pattern simplifies the calibration task by providing easily detectable geometric features that bridge the coordinate systems of the two cameras and the robot
3Measurement precision
If two cameras are used for calibration, then calibration accuracy is improved, but the cost and device complexity increase
Solution Approach 1:
The patent merges the functions of the two cameras into a unified calibration process. The first camera (on the robot) and the second camera (external) are combined through coordinate transformation calculations that integrate their respective views. By merging the calibration data from both cameras into a single hand-eye calibration solution, the system achieves higher accuracy without requiring each camera to operate independently, thereby limiting the increase in complexity
4Reliability
If manual calibration handling is used, then the equipment requirements are simple, but the calibration is prone to errors and lacks precision
Solution Approach 1:
The calibration system incorporates feedback mechanisms where the control unit continuously monitors the calibration process, validates detected calibration patterns, and adjusts robot positions based on measurement results. The system provides feedback on calibration quality metrics and can automatically retry measurements that fall below precision thresholds, thereby enhancing reliability while maintaining ease of operation through automated error correction
Data Source
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AI summary
The disclosure relates to a calibration method for the automated calibration of a robot camera (10) in relation to a medical robot (2), more particularly a surgical robot, the robot camera (10) being movably guided on a robot flange (6) of a robot arm (4), which is connected to a robot base (26), and for the automated calibration of an external camera system, which has at least one external camera (16), in relation to the medical robot (2), comprising the steps of: moving the robot camera (10) by means of the robot arm (4) during sensing and capturing (A) by the robot camera (10); detecting, on the basis of the capturing (A), a position of a predefined optical calibration pattern (22) and/or of an external tracker, each having a predefined transformation to a position of the external camera (16), and/or detecting, on the basis of the capturing (A), a position of the external camera (16); determining, on the basis of the ascertained position of the external camera (16), a transformation between the robot camera (10) and the external camera (16), and determining a field of view of the external camera (16); moving the robot flange (6), more particularly with at least one tracker (12) fastened on the robot flange (6), into at least three different positions in the field of view of the external camera (16), and sensing the at least three positions of the robot flange (6), more particularly the at least three positions of the tracker (12), by means of the external camera (16), and simultaneously sensing a transformation between the robot base (26) and the robot flange (6); and carrying out, on the basis of the at least three sensed positions and the at least three sensed transformations, a hand-eye calibration, more particularly with determination of a transformation from the robot flange (6) to the robot camera (10) and/or of a transformation from the external camera (16) to the robot base (26). In addition, the disclosure relates to a surgical assistance system and a computer-readable storage medium according to the additional independent claims.