Continuum Arm Robot Joint With Intermeshing Gear Teeth for Reduced Deflection
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Solution Overview
Problem
Continuum arm robots suffer from joint deflection under load, reducing positional accuracy and necessitating additional sensor systems due to the spring-like nature of their joints, which are sensitive to external forces and the weight of the arm and payload, and hard stops limit their flexibility.
Innovation Solution
A joint section design featuring intermeshing gear teeth on connecting rods at pivot points, allowing for improved rigidity and reduced deflection, with actuator cables passing through channels or conduits, and potentially using motors or pulleys for independent joint control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If spring-like joints are used in continuum arm robots, then flexibility and ease of manipulation are improved, but joint deflection under load increases reducing positional accuracy
Solution Approach 1:
The joint section is divided into multiple rigid segments (first joint section, second joint section, third joint section) connected by connecting rods with gear teeth. This segmentation allows each segment to maintain rigidity while the gear mechanisms provide controlled flexibility, resolving the contradiction between overall flexibility and local rigidity for accurate positioning.
Solution Approach 2:
The patent changes the mechanical parameter of the joint from spring-like (flexible) to gear-based (rigid with controlled movement). The gear teeth on connecting rods provide a fixed degree of movement between segments, eliminating unwanted deflection while maintaining the ability to achieve desired positions through coordinated gear engagement.
2Reliability
If hard stops are installed in joint sections to prevent overextension, then reliability is improved, but flexibility and achievable shape are limited
Solution Approach 1:
The joint sections use dynamic gear engagement where connecting rods with gear teeth can rotate relative to adjacent joint sections within a fixed degree of movement. This dynamic mechanism provides inherent mechanical limits (replacing hard stops) while allowing continuous adjustment of the arm's shape and flexibility through controlled gear rotation.
Solution Approach 2:
The patent changes the constraint mechanism from static hard stops to dynamic gear-based rotational limits. The fixed degree of movement in gear teeth provides reliable mechanical boundaries preventing overextension, while the ability to rotate through controlled angles maintains flexibility and achieves various arm configurations.
3Ease of operation
If spring-like joints sensitive to external forces are used, then ease of manipulation is improved, but additional sensor systems are required increasing device complexity
Solution Approach 1:
The gear-based joint sections provide inherent mechanical feedback through their rigid structure and fixed degree of movement. The gear teeth naturally limit and define the range of motion between segments, eliminating the need for external sensors to detect joint positions or prevent overextension. The mechanism serves its own measurement and control functions.
Solution Approach 2:
The patent replaces sensor-based detection systems with a purely mechanical solution. The gear teeth and connecting rods provide inherent mechanical constraints and positional definition, substituting the need for electronic sensors and complex control systems while maintaining ease of manipulation through mechanical advantage.
4Measurement precision
If rigid connecting rods with gear teeth are used instead of spring-like joints, then positional accuracy is improved, but device complexity increases
Solution Approach 1:
The connecting rods with gear teeth serve multiple functions simultaneously: they provide rigid structural support, enable controlled rotation between joint sections, define the fixed degree of movement, and prevent overextension. This multi-functionality achieves high positional accuracy without proportionally increasing complexity, as a single component performs multiple critical roles.
Solution Approach 2:
The patent merges the functions of structural support, actuation, and positioning control into integrated connecting rods with gear teeth. Rather than separate components for each function, the gear mechanism combines rigidity, movement control, and mechanical limiting in a single unified structure, achieving accuracy without excessive complexity.
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
Enhances positional accuracy and reduces the need for complex actuator systems, minimizing deformation and damage risk while maintaining flexibility, thus requiring fewer sensors and lowering operational costs.
Implementation Method 1
each of the first and second connecting rods have a plurality of gear teeth at their opposing ends, the gear teeth intermeshing at a central point of the joint section between the first and second pivot point
Implementation Method 2
the joint section has an annular cross-section with a hole at the centre of the joint section and a plurality of channels pass around the outside edge of the joint section for actuator cables of the continuum arm robot to pass through
Implementation Method 3
the joint section comprising a pair of pivot points at a first and second end of the joint section, the joint section further having a first connecting rod pivotable about the first pivot point of the pair of pivot points
Data Source
Figure 1a~1b
Figure 2
Figure 3
AI summary
A section of a continuum arm robot comprising a pair of pivot points at a first and second end of the joint, the section further having a first and second connecting rod connected to the section and joining at the centre of the section, the connecting rods has a plurality of gear teeth at the peripheral ends of the connecting rod that intermesh at a central point on the section.