Surgical Robotic Arm Force Detection for Collision and Misalignment
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Solution Overview
Problem
Surgical robotic systems face challenges in detecting undesirable forces on robotic arms, which can lead to collisions and misalignments during medical procedures, potentially affecting the precision and safety of the operation.
Innovation Solution
The system employs torque and position sensors in the joints of the robotic arms to calculate gravity-compensated forces, detect collisions, and misalignments by analyzing force data, providing real-time indications to the user and adjusting the arm positions to prevent further complications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If torque and position sensors are used to detect forces on robotic arms, then collision and misalignment detection capability is improved, but device complexity increases
Solution Approach 1:
The torque sensors and position sensors are integrated into the existing robotic arm joints, serving both their original control functions and the additional function of collision detection. The control system processes sensor data for both normal operation and safety monitoring, making the system multi-functional without adding separate dedicated detection hardware.
Solution Approach 2:
The robotic arm's existing sensors (torque and position sensors) are utilized to detect collisions and misalignments, rather than adding separate dedicated detection sensors. The system uses its own operational sensors for dual purposes: control and safety detection, thereby avoiding additional hardware complexity.
2Reliability
If real-time force analysis is performed to detect collisions, then safety response time is improved, but computational load increases
Solution Approach 1:
The system performs force analysis primarily along the longitudinal axis of the robotic arm, focusing computational resources on the most critical collision detection direction. By concentrating detection efforts on the primary axis rather than analyzing all possible force vectors equally, the system achieves timely collision detection with reduced computational overhead.
3Measurement precision
If gravity compensation is calculated to improve force detection accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The control system calculates gravitational forces acting on the robotic arm based on its current position and configuration, then applies compensatory torques to counteract these gravitational effects. This gravity compensation enables more accurate detection of external forces (such as collisions) by removing the confounding variable of gravitational influence from the force measurements.
Data Source
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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.