Surgical Robot Torque Limits for Collision Safety
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Solution Overview
Problem
Surgical robotic arms face safety risks due to excessive contact forces applied during medical procedures, which can injure patients or damage equipment, and may inadvertently move when colliding with stationary arms, leading to unintended tissue damage.
Innovation Solution
Implementing a surgical robot system with a processor that applies a first torque limit to joints during active movement and a second, greater torque limit when the arm is stationary, allowing the stationary arm to resist collisions and maintain its position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a robotic arm applies high torque to maintain position during stationary state, then stability is improved, but risk of excessive contact force increases
Solution Approach 1:
The system dynamically adjusts torque limits based on the operational state of the robotic arm. When the arm is stationary, a higher torque limit is applied to maintain position stability. When the arm is moving, a lower torque limit is applied to prevent excessive contact forces. This dynamic adjustment resolves the contradiction by making the torque limit adaptive to the current state rather than fixed.
Solution Approach 2:
The torque limit parameter is changed based on the operational state (stationary vs. moving). The processor monitors the state of the robotic arm and switches between different torque limit values. This parameter change allows the system to optimize for stability during stationary periods while preventing harmful contact forces during movement.
2Object-affected harmful factors
If a robotic arm applies low torque limit during movement, then patient safety is improved, but ability to resist external interference deteriorates
Solution Approach 1:
The torque limit is made dynamic rather than static. During movement, a lower torque limit protects the patient from excessive contact forces. During stationary state, a higher torque limit provides robust resistance to external interference such as accidental collisions. The system transitions between these states based on real-time monitoring.
Solution Approach 2:
The system prepares for potential external interference by maintaining the ability to apply higher torque limits when stationary. The processor continuously monitors the state and can quickly switch to a higher torque limit regime if external interference is detected during stationary operation, while having already established protective lower limits during movement phases.
3Stability of the object's composition
If a stationary robotic arm applies high torque to resist collision, then position maintenance is improved, but risk of tissue damage from inadvertent movement increases
Solution Approach 1:
The torque limit parameter is adjusted based on the operational state. During stationary operation, a higher torque limit enables the arm to resist collisions and maintain position. During movement, a lower torque limit prevents inadvertent tissue damage. The processor switches between these parameter values based on state detection.
Solution Approach 2:
The system uses feedback from state monitoring to adjust torque limits appropriately. The processor detects whether the arm is stationary or moving and adjusts the torque limit accordingly. This feedback mechanism ensures that high torque is only applied when the arm is stationary and position maintenance is the priority, while low torque is applied during movement to prevent tissue damage.
Data Source
AI summary
A surgical robot includes an end effector driven by a plurality of joints located along a robotic arm of the surgical robot. Additionally, the surgical robot includes a processor communicatively coupled to the robotic arm, the processor configured to apply a first torque limit to at least one of the plurality of joints when the robotic arm is actively moving, and apply a second torque limit to at least one of the plurality of joints when the robotic arm is in a stationary state, wherein the second torque limit is different from the first torque limit.