Flexible Actuator Rigidity Control via Converging Fixing Wire
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Solution Overview
Problem
Continuum manipulators using wire-driven methods are vulnerable to deformation under transverse loads and torques, leading to instability in maintaining desired configurations due to redundant degrees of freedom generated by wire tension, which complicates their use in applications requiring robustness and precision.
Innovation Solution
A flexible drive manipulator design incorporating a proximal portion, joint portions, and a distal portion with parallel drive wires and a converging fixing wire to adjust rigidity, where the joint portions have recessed contact surfaces and inclined fixing wire passages to manage tensile forces and prevent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a wire-driven method is used to drive the continuum manipulator, then the manipulator can achieve continuous curvature and flexibility, but the manipulator becomes vulnerable to deformation under transverse loads and torques due to redundant degrees of freedom generated by wire tension
Solution Approach 1:
The manipulator is divided into multiple rigid link segments connected by joints, rather than using a completely flexible continuous structure. Each joint has controlled degrees of freedom, and the wire-driven mechanism acts on specific joints to produce desired curvature while maintaining structural integrity and resistance to transverse loads.
Solution Approach 2:
The manipulator combines rigid link segments with flexible wire actuators to create a hybrid structure. The rigid segments provide structural stability and resistance to deformation, while the flexible wires enable continuous curvature control through tension adjustments, resolving the contradiction between flexibility and stability.
2Adaptability or versatility
If redundant degrees of freedom are generated by wire tension to achieve continuous curvature, then the manipulator can operate in narrow and curved spaces, but the configuration becomes easily deformed by external forces in directions different from the wire direction
Solution Approach 1:
The manipulator uses dynamic control of wire tensions to adapt its configuration in real-time. By adjusting the tension in individual wires acting on specific joints, the system can achieve desired curvatures for navigating narrow spaces while dynamically maintaining resistance to transverse loads through active control of the rigid link segments.
Solution Approach 2:
The system changes the tension parameters of the drive wires to control the configuration of each joint. By independently adjusting wire tensions, the manipulator can achieve continuous curvature for entering narrow spaces while maintaining adequate stiffness in directions perpendicular to the wire action through coordinated parameter changes.
3Ease of operation
If the manipulator is driven by wire tension to achieve desired configuration, then it can operate with continuous curvature, but the configuration is vulnerable to deformation under transverse direction loads and torques during end effector operations
Solution Approach 1:
The manipulator is segmented into rigid links with controlled joints, where wire-driven mechanisms act on specific joints to produce continuous curvature. This segmentation allows the system to maintain configuration stability under transverse loads while preserving ease of operation through independent control of each joint's curvature.
Solution Approach 2:
The hybrid structure combines rigid link segments with flexible wire actuators enables continuous curvature control through wire tension while the rigid segments provide inherent resistance to transverse direction loads and torques during end effector operations, resolving the contradiction between ease of operation and configuration maintenance.
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 design allows for adjustable rigidity and prevents flexion phenomena, maintaining stability and precision under transverse loads and torques, enhancing the manipulator's robustness and operational reliability.
Implementation Method 1
a pair of drive wires passing through the plurality of joint portions in parallel along the longitudinal axis, the pair of drive wires configured to drive the plurality of joint portions in a rotational direction of rotation with respect to a transverse axis perpendicular to the longitudinal axis
Implementation Method 2
a fixing wire passing through the plurality of joint portions in a shape of converging along the longitudinal axis, the fixing wire configured to adjust rigidity of the plurality of joint portions
Data Source
Figure 1
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AI summary
A flexible drive manipulator according to an example embodiment may include a proximal portion, a plurality of joint portions drivably connected from an end of the proximal portion with respect to a longitudinal axis, a distal portion connected to an end of the plurality of joint portions, a pair of drive wires passing through the plurality of j oint portions in parallel along the longitudinal axis, the pair of drive wires configured to drive the plurality of joint portions in a rotational direction of rotation with respect to a transverse axis perpendicular to the longitudinal axis, and a fixing wire passing through the plurality of joint portions in a shape of converging along the longitudinal axis, the fixing wire configured to adjust rigidity of the plurality of joint portions.