Master-Slave Robotic Alignment Control With Haptic Motion Constraint
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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 maintain alignment, which can result in the end effector not feeling fundamentally linked to the master handle's motion.
Innovation Solution
The system provides haptic feedback to impede translational movement of the handle when a rotational alignment difference exceeds a threshold, while enabling rotational movement, and allows translational movement when the alignment difference 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
1Adaptability or versatility
If the end effector is allowed to move freely in response to handle movement, then the operational flexibility and range of motion are improved, but the alignment between handle and end effector deteriorates, causing loss of tactile feedback
Solution Approach 1:
The system continuously monitors the rotational alignment between the handle and end effector, and provides haptic feedback forces to the handle when misalignment is detected. This closed-loop feedback mechanism maintains reliable alignment while allowing operational flexibility, as the haptic feedback guides the operator to maintain proper alignment without restricting the overall range of motion.
Solution Approach 2:
The system dynamically adjusts the control mode based on alignment conditions. When alignment is maintained, full motion freedom is permitted. When misalignment is detected, haptic feedback is activated to guide realignment. This dynamic adaptation resolves the contradiction by allowing high versatility during proper operation while ensuring reliability during alignment deviations.
2Reliability
If haptic feedback is provided to impede handle movement, then the alignment between handle and end effector is improved, but the ease of operation deteriorates due to restricted movement
Solution Approach 1:
The haptic feedback is applied selectively and locally - it is activated only in the specific condition when rotational misalignment exceeds a threshold. When properly aligned, the handle moves freely without haptic resistance. This localized application of haptic feedback maintains ease of operation during normal use while ensuring alignment reliability when needed.
3Reliability
If the system disables end effector movement when misaligned, then the safety is improved, but the productivity deteriorates due to interruption of surgical workflow
Solution Approach 1:
The system applies haptic feedback forces to the handle to prevent misalignment before it can cause unsafe conditions. By proactively guiding the operator to maintain alignment through haptic cues, the system prevents the need to disable end effector movement, thereby maintaining safety while avoiding workflow interruptions.
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 solution enhances the operator's ability to maintain alignment by providing intuitive feedback and control, ensuring that the end effector moves in sync with the handle, thereby improving the precision and safety of surgical procedures.
Implementation Method 1
causing the master apparatus to provide haptic feedback that impedes translational movement of the handle, while permitting rotational movement of the handle
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.