Orthodontic Archwire Bending with Machine Vision Feedback
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Solution Overview
Problem
Existing machines for bending orthodontic archwires are limited in creating complex shapes due to kinematic constraints, accuracy issues, and inefficiencies in manufacturing, leading to increased costs and wire wastage.
Innovation Solution
A compact bending apparatus with a machine vision system, utilizing two compact manipulators with revolute and prismatic joints allowing six degrees of freedom, and an infrared camera for precise shape monitoring and heat histogram detection to ensure accurate and varied wire bending.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a robot with two characteristic design features (bending cone and rotating cone) is used to bend archwires, then the machine can perform deformation around a main axis within a single bending step, but it requires a sequence of five single bending steps to accomplish complex deformations with six degrees of freedom, and the archwire segment length necessary exceeds the available distance between bracket slots
Solution Approach 1:
The invention divides the complex six-degree-of-freedom deformation task into multiple single-degree-of-freedom bending operations performed sequentially by a robot arm with multiple joints. Each joint performs a specific bending operation (torque, angulation, rotation) on the archwire segment, allowing complex shapes to be created through composition of simpler operations rather than requiring a single complex mechanism.
Solution Approach 2:
The robot arm provides dynamic positioning capability, allowing the grippers to move to different locations along the archwire and adjust the bending orientation dynamically. This enables the same robot mechanism to perform multiple different bending operations (torque, bending, twisting) by changing its configuration rather than requiring fixed dedicated mechanisms for each operation type.
2Ease of operation
If a robot with two characteristic design features is used for bending archwires, then deformation around a main axis can be achieved in a single bending step, but manufacturing inaccuracies of each bending step lead to a relative large error in the whole deformation between two adjacent bracket slots
Solution Approach 1:
The invention incorporates a vision system with cameras positioned to observe the archwire from multiple angles. The vision system captures images of the archwire before and after bending operations, allowing the control system to detect actual positions and orientations of the archwire segments. This feedback information is used to compensate for positioning errors and achieve higher precision in the final archwire geometry.
Solution Approach 2:
The vision system performs preliminary detection and measurement of the archwire position and orientation before bending operations begin. This allows the control system to pre-calculate the exact movements required for each robot joint to achieve the desired archwire shape, compensating for known inaccuracies in advance rather than correcting them after the fact.
3Adaptability or versatility
If a robot with six consecutively arranged rotation axes is used to bend archwires, then the robot can move in six degrees of freedom to bend the wire, but the robot has no effective feedback mechanism for detecting how the wire in fact was bent after a particular bending or twisting operation was performed
Solution Approach 1:
The invention introduces a vision system with cameras that capture images of the archwire from multiple perspectives. These images provide real-time feedback on the actual shape and position of the archwire after each bending operation, enabling the control system to verify whether the desired deformation was achieved and to make necessary adjustments for subsequent operations.
Solution Approach 2:
The invention replaces mechanical measurement devices with an optical vision system. Instead of using mechanical sensors or contact-based measurement tools to detect the archwire shape, the system uses cameras and image processing to non-contactly observe and measure the archwire geometry, providing more accurate and versatile measurement capability.
4Ease of manufacture
If off-the-shelf brackets with standardized prescription values are used, then the brackets can be easily installed, but the archwire must have complex bends designed to move or rotate the teeth in the desired direction, requiring precise manufacturing
Solution Approach 1:
The vision system provides real-time feedback on the actual position and orientation of the archwire during the bending process. This allows the control system to continuously monitor and adjust the bending operations to achieve the precise complex shapes required for customized orthodontic treatment, ensuring that the archwire geometry matches the treatment plan within tight tolerances.
Solution Approach 2:
The system performs preliminary calculation and planning of the bending path and parameters based on the desired final archwire shape and the initial straight wire configuration. This pre-planning allows the robot to execute the complex sequence of bending operations with high precision, creating the necessary torque, angulation, and rotation features in the archwire.
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
The solution enables precise and repeatable bending of orthodontic archwires with a wider range of shapes, reducing manufacturing costs and improving accuracy, while allowing for the use of preformed archwires and other medical devices.
Implementation Method 1
at least one of said first and second vision components includes an infrared camera, said infrared camera being configured to measure intensity of infrared light along the length of a bend in said archwire
Data Source
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AI summary
A machine vision system (1102, 1104) for an apparatus (108) for bending or shaping orthodontic archwires (122) or other medical devices into a complex, patient individual shape is described. The apparatus comprises two moveable, compact, manipulators (112,114) with, in total, at least three revolute joints defining three rotation axes and at least three prismatic joints defining at least three translation axes. Gripping tools (116,118) are provided on the manipulators. The two manipulators are arranged to allow a relative movement in six degrees of freedom. The machine vision system is configured to monitor movements of the manipulators and a shape of said archwire before and after bending.