Force-Sensed Robot Assembly for Snap-Fit Engagement Detection
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Solution Overview
Problem
Automating the assembly of parts with fastener structures, such as clips and snap-fits, is challenging due to difficulties in mechanically determining the correct engagement between the engagement portion and the receiving portion, which can lead to assembly failures and part damage.
Innovation Solution
A robot system equipped with a force sensor to measure forces and moments during the assembly process, allowing the controller to determine the state of engagement and orientation by monitoring changes in force and moment, and performing recovery operations if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If the pressing reaction force is used to determine engagement, then the assembly process can be automated, but manufacturing variations may cause false negatives leading to excessive pressing and part damage
Solution Approach 1:
The system continuously monitors the pressing reaction force during insertion and uses this feedback to determine when engagement has occurred. The controller adjusts the insertion process based on real-time force measurements, stopping the insertion when the characteristic force drop indicating engagement is detected, thereby preventing excessive pressing and part damage.
Solution Approach 2:
The system monitors changes in the pressing reaction force parameter throughout the insertion process. By detecting the characteristic drop in force that occurs when engagement portions interlock, the system can reliably determine engagement status despite manufacturing variations in clearance and geometry.
2Ease of operation
If the male part is pressed into the female part with large clearance, then insertion is easier, but the male part may be inserted obliquely causing interference and assembly failure
Solution Approach 1:
The system monitors the pressing reaction force and moment during insertion to detect oblique insertion conditions. When the moment exceeds a threshold indicating misalignment, the controller can adjust the insertion trajectory or apply corrective forces to realign the parts, ensuring proper engagement despite initial clearance variations.
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 system effectively automates the assembly of parts with fastener structures by accurately determining the engagement state and orientation, preventing excessive pressing and assembly failures, and enabling timely correction of insertion errors.
Implementation Method 1
a force sensor located on the robot to measure a force and a moment acting on the workpiece
Data Source
AI summary
A technique automates robotic assembly of two parts with a fastener structure including an engaging portion and a receiving portion. A robot system includes a robot that grips a workpiece, a force sensor located on the robot to measure a force and a moment acting on the workpiece, and a controller that controls the robot. The controller monitors, while moving the workpiece in a direction along a first axis and inserting the workpiece into a part, a change in a force F in the direction along the first axis and a change in a moment M about a second axis perpendicular to the first axis measured by the force sensor to determine a state of assembly of the workpiece with the part.