Machine Vision Application.

Robot positioning and quality check application in the automotive industry.

(Photos taken during commissioning)

In this application a robot is equipped with a automatic screw feed unit.

A moulded plastic case is automatically screwed together.

The plastic moulding varies in size and because of heat distortion. The variations in the component make it impossible to position every moulded component with the required accuracy for robot assembly.

To ensure that the screws are inserted into holes with no fail a Cognex InSight 3400 vision system with remote camera head is utilised to operate in conjunction with the robot.

Initially, the robot is automatically calibrated with the camera.

This function can and is automatically called up by the robot PLC process program if required.

The robot positioned the camera to begin of the robot cycle over one of the screw holes. The camera is locating the hole and the robot PLC is extracting the offset coordinates via Ethernet I/P communication from the Cognex InSight.

If the hole is within set tolerance of the last setting the robot proceeds with the last obtained hole coordinates. If the hole is not within the set tolerance then the robot drives over a second hole and extracts the hole position from the Cognex InSight. The robot then adjusts the hole pattern with the obtained offset data.

If the screw feeding system detects via the torque sensor that a screw has not been fitted properly, the camera is positioned over hole and the PLC can establish if the hole is present and if the hole is in the specified position or if a screw head is present.

If the hole is detected without the screw head the robot will simply attempt to fit another screw. In case the screw head is detected the robot will complete the assembly but will indicate to the operator that a specific screw has failed.

The component will be locked in the jig until the operator confirms via the user interface that the problem has been addressed. 

The Cognex vision system is checking several sections of the assembled plastic mouldings for specific features and that components are installed as per specification. 

The robot PLC extracts the information that determines which features are present via the Ethernet I/P connection ensuring that the desired component configuration is produced. 

A SOP is displayed during the assembly process providing the operator with the information in what order, and how the parts are assembled.

The engineering staff can log onto the equipment with their PCs via the Ethernet during the production runs and extract production data. The SOP can be update remotely during production run.  

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