Continuum Robot Contact Detection via Screw Motion Deviation
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Solution Overview
Problem
Current robotic systems, particularly continuum robots, lack a unified framework for fully characterizing interactions with the environment, including collision detection and contact location estimation without prior knowledge of environmental constraints, which is crucial for safe and precise surgical procedures like Natural Orifice Transluminal Endoscopic Surgery (NOTES).
Innovation Solution
A general framework for collision detection and contact location estimation in multi-segment continuum robots using Screw Motion Deviation (SMD) based on nominal forward kinematics and exteroceptive sensory information, allowing for single- and multi-collision detection at multiple segments, and enabling the robot to act as a sensor and surgical intervention platform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If passive compliance of continuum robots is used, then safety of interaction is improved, but payload carrying capability and position accuracy deteriorate
Solution Approach 1:
The system dynamically switches between passive compliance mode (for safety during exploration) and active control mode (for precision tasks). The controller actively regulates contact forces when needed while maintaining the ability to passively comply during uncertain interactions, resolving the contradiction between safety and performance.
Solution Approach 2:
The system changes the compliance parameter dynamically based on task requirements. During surgical exploration, high compliance is maintained for safety. During precision manipulation tasks, the compliance is reduced to improve position accuracy and payload carrying capability, allowing the robot to adapt its mechanical properties in real-time.
2Difficulty of detecting and measuring
If additional sensory devices such as robotic skins are added, then contact detection capability is improved, but device complexity increases
Solution Approach 1:
The continuum robot uses its own elastic deformation as the sensing mechanism. The robot's flexible structure naturally deforms when contacting objects, and this deformation is measured by standard sensors to detect contact location and force. This self-service approach eliminates the need for additional robotic skin sensors while maintaining contact detection capability.
Solution Approach 2:
The robot's flexible structure serves dual purposes: it enables the continuum motion required for navigating tortuous anatomical paths and simultaneously acts as the sensing element for contact detection. This multi-functionality eliminates the need for separate sensing devices, reducing overall system complexity.
3Measurement precision
If a priori knowledge of environmental constraint geometry is required, then control accuracy is improved, but adaptability to unknown environments deteriorates
Solution Approach 1:
The system continuously measures the robot's actual configuration using sensors and compares it with the expected configuration from forward kinematics models. This feedback loop enables the system to detect deviations caused by environmental constraints and adapt its control in real-time, allowing accurate operation in unknown environments without requiring prior knowledge of constraint geometry.
Solution Approach 2:
The system performs preliminary exploration phases where the robot autonomously navigates and maps the environment before performing precision surgical tasks. During this preliminary phase, contact events are detected and used to build an understanding of environmental constraints, which then informs subsequent high-precision operations.
Data Source
AI summary
A robotic system and methods for manipulation of multi-segment continuum robots. The methods relate to contact detection and estimation of contact location along a multi-segment continuum robot.