Surgical Robotic Arm Torque Sensing for Collision Detection
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Solution Overview
Problem
Surgical robotic systems face challenges in detecting undesirable forces on robotic arms during medical procedures, which can lead to collisions or misalignments, potentially causing unintended forces on steerable instruments within patients.
Innovation Solution
The system employs a robotic arm with torque sensors and position sensors to measure and differentiate between gravitational and applied forces, determining if a collision or misalignment has occurred by comparing measured forces against thresholds, and providing feedback to the user.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If torque sensors are used to detect forces on robotic arms, then collision detection capability is improved, but device complexity increases
Solution Approach 1:
The robotic arm is divided into multiple linkages with torque sensors placed at specific joints (e.g., between linkages). This segmentation allows localized force detection without requiring sensors throughout the entire structure, improving collision detection while controlling complexity.
Solution Approach 2:
Torque sensors serve as intermediary devices that indirectly detect collisions by measuring torque at joints rather than directly detecting contact forces at the instrument tip. This intermediary approach enables collision detection while using simpler sensor components.
2Measurement precision
If multiple sensors are installed on robotic arms, then measurement precision is improved, but device complexity increases
Solution Approach 1:
Torque sensors are strategically placed at specific joints where they can most effectively detect collisions, rather than uniformly distributing sensors throughout the robotic arm. This localized approach optimizes measurement precision while minimizing the total number of sensors required.
3Reliability
If real-time force monitoring is implemented, then safety is improved, but use of energy increases
Solution Approach 1:
The system implements real-time force monitoring with feedback mechanisms that continuously measure torque at joints and compare it against threshold values. This feedback loop enables safety monitoring while allowing the system to operate efficiently by only triggering alerts when actual collisions are detected, rather than requiring constant high-energy processing.
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
This approach enhances the safety and precision of surgical robotic systems by promptly detecting and indicating collisions or misalignments, preventing harm to patients and ensuring accurate instrument positioning.
Implementation Method 1
at least one torque sensor configured to detect torque between the at least two linkages
Implementation Method 2
the second torque value indicative of a gravitational component of the torque between the at least two linkages
Data Source
AI summary
Certain aspects relate to systems and techniques for detection of undesirable forces on one or more surgical robotic arms. In one aspect, there is provided a system including a robotic arm, including: two linkages, a joint, a torque sensor, and an instrument device manipulator (IDM). The system may further include a processor configured to measure a first torque value at the joint based on an output of the torque sensor and determine a second torque value at the joint based on a position of the robotic arm. The second torque value may be indicative of a gravitational component of the torque between the two linkages. The processor may be further configured to determine a force at the IDM based a difference between the first and second torque values and determine whether the robotic arm has collided with an object or misaligned based on the force at the IDM.