Cobot Hole-Machining End-Effector With Passive Self-Alignment
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Solution Overview
Problem
Cobot systems face challenges in achieving high precision and repeatability due to their low stiffness and high compliance, especially when working near designed boundary conditions or handling large payloads, which can lead to significant degradation in machining accuracy and increased susceptibility to external disturbances.
Innovation Solution
The implementation of a customized machining end-effector with a linear guiding mechanism and passive self-alignment features, which utilizes the compliance of the Cobot system to generate a reaction torque for precise alignment of the machining bit, and incorporates a displacement sensor and anti-slip mechanisms to ensure accurate and repeatable machining operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Cobot systems are used to perform machining tasks, then flexibility and safety in collaborative workspaces are improved, but machining precision and repeatability deteriorate due to low stiffness and high compliance
Solution Approach 1:
The end-effector is divided into multiple segments: a fixed part attached to the Cobot, a movable part that can translate and rotate, and a workpiece clamping mechanism. This segmentation allows each component to perform its specific function while compensating for Cobot compliance through the passive alignment mechanism between segments.
Solution Approach 2:
The linear guiding mechanism acts as an intermediary between the Cobot and the workpiece. It provides a rigid mechanical guide that compensates for the compliance of the Cobot system, enabling precise positioning and alignment without requiring the Cobot itself to achieve high stiffness.
2Force
If large payloads are handled by Cobot systems, then task capability is improved, but positioning accuracy deteriorates due to increased compliance effects
Solution Approach 1:
The linear guiding mechanism provides counteracting forces through its rigid structure and bearing support. The bearing surfaces and guiding rails create reaction forces that counterbalance the compliance effects caused by heavy payloads, maintaining positioning accuracy even when handling large masses.
Solution Approach 2:
The linear guiding mechanism utilizes curved or rounded bearing surfaces that allow for self-alignment and passive compensation of positioning errors. The cylindrical or spherical contact surfaces enable automatic adjustment to maintain optimal alignment under varying payload conditions.
3Adaptability or versatility
If Cobot systems operate near designed boundary conditions, then task versatility is improved, but repeatability deteriorates significantly
Solution Approach 1:
The end-effector performs preliminary alignment actions through its passive alignment mechanism before the actual machining operation. The linear guiding mechanism pre-establishes the correct positioning and orientation, compensating for boundary condition variations and ensuring repeatable results even when operating near design limits.
Solution Approach 2:
The end-effector uses its own compliance and the compliance of the Cobot system to generate reaction torque for self-alignment. The linear guiding mechanism allows the system to self-correct positioning errors through passive mechanical alignment, improving repeatability without requiring external intervention or complex control systems.
4Ease of operation
If external disturbances and environmental factors affect Cobot systems, then operational flexibility is improved, but output variability increases
Solution Approach 1:
The linear guiding mechanism and bearing support structure provide beforehand cushioning against external disturbances. The rigid mechanical guide and bearing surfaces create a stable reference frame that protects the machining operation from vibrations, shocks, and environmental factors, maintaining output consistency despite operational flexibility.
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 precision and repeatability of machining tasks, achieving standard deviations in machining operation parameters on the order of 0.01 mm, and improves the Cobot system's ability to handle large payloads and work near boundary conditions without compromising accuracy.
Implementation Method 1
The linear guiding mechanism can passively align the machining bit by generating a reaction torque that utilizes a compliance of the Cobot system
Implementation Method 2
incorporates a displacement sensor and anti-slip mechanisms to ensure accurate and repeatable machining operations
Data Source
AI summary
A cooperative robot (Cobot) system can perform multiple machining tasks. For example, a Cobot system can include a machining end-effector. The machining end-effector can include a main part. The main part can include a machining bit extendable from the main part. The main part can also include a motor for rotation the machining bit. The machining end-effector can also include a subpart. The subpart can include a linear guiding mechanism. The linear guiding mechanism can passively align the machining bit by generating a reaction torque that utilizes a compliance of the Cobot system.