Master-Slave Robotic Alignment Control With Haptic Translation Lock
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Solution Overview
Problem
In master-slave robotic systems, particularly in laparoscopic surgery, alignment differences between the master and slave instruments can lead to a loss of tactile feedback, making it difficult for operators to control the slave instrument effectively when the rotational alignment exceeds a certain threshold, resulting in a disconnect between the handle and end effector movements.
Innovation Solution
A method is implemented where the robotic control system provides haptic feedback to impede translational movement of the handle when a rotational alignment difference exceeds a disablement criterion, while allowing rotational movement, and enables translational movement when the alignment meets an enablement criterion, by calculating and adjusting the end effector position and orientation based on current and previous handle positions and orientations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the robotic system allows free translational movement of the handle, then the ease of operation is improved, but the reliability deteriorates when rotational alignment difference exceeds the threshold
Solution Approach 1:
The system dynamically adjusts the movement constraints of the handle based on the real-time rotational alignment difference between the master and slave instruments. When alignment is within the threshold, full translational and rotational movement is permitted. When alignment exceeds the threshold, the system dynamically transitions to a constrained mode where only rotational movement is allowed, automatically adapting the degree of freedom based on operational conditions.
Solution Approach 2:
The system continuously monitors the rotational alignment difference between the master handle and slave end effector and uses this feedback to determine whether to enable or disable translational movement. The haptic feedback mechanism provides tactile cues to the operator about the alignment state, and the control system uses this information to automatically adjust movement permissions, creating a closed-loop control system that maintains reliability while preserving ease of operation when conditions permit.
2Reliability
If the system disables translational movement to maintain alignment, then the reliability is improved, but the ease of operation deteriorates
Solution Approach 1:
The system applies different movement constraints to different degrees of freedom of the handle. When alignment exceeds the threshold, only translational movement is constrained while rotational movement remains fully enabled. This selective constraint approach allows the operator to still adjust the orientation of the end effector through rotational movements, maintaining operational capability in the dimensions that remain reliable while only restricting movements that would compromise alignment.
3Reliability
If the system provides haptic feedback to impede movement, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The haptic feedback mechanism serves as an intermediary between the alignment monitoring system and the handle movement control. Rather than directly blocking translational movement through mechanical constraints or software locks, the system uses haptic feedback to provide resistive forces that guide the operator's natural movements. This intermediary approach maintains reliability by preventing unintended movements while avoiding the complexity of direct mechanical or software-based movement blocking mechanisms.
Data Source
AI summary
A method of operating a robotic control system comprising a master apparatus in communication with an input device having a handle and a slave system having a tool having an end effector whose position and orientation is determined in response to a position and orientation of the handle. The method involves producing a desired end effector position and a desired end effector orientation of the end effector, in response to a current position and a current orientation of the handle. The method further involves causing the input device to provide haptic feedback that impedes translational movement of the handle, while permitting rotational movement of the handle and preventing movement of the end effector, when a rotational alignment difference between the handle and the end effector meets a first criterion. The method further involves re-enabling translational movement of the handle when the rotational alignment difference meets a second criterion.