Robot Guided Vehicle Wheel Assembly Using Matched Point Cloud Data

When Bluewrist were approached by an automotive OEM to automate wheel assembly there were a number of challenges to address when designing the application solution that would improve performance, process, and quality. The challenges related to both the rotors and the processes involved in the fitting of the tires. The OEM was previously using a manual assembly system that required four workers to pick-up and mount each tire on the rotor; two workers would work on each side of the wheel during the installation process.

Over 60 different rims were being used on the assembly line with different types of surfaces (dark, matte, glossy), making 2D camera systems difficult to implement because of the effect of lighting solutions on the different types of surfaces.

The bolts, preinstalled on each router, had a small surface area meaning a 3D high-resolution vision system was essential to accurately locate the point cloud for each bolt cap.

During installation, the rotor had a random rotation, meaning that the bolts were in a different position for each installation requiring a solution that identified bolt location. The rotor can rotate up to 15 degrees in both directions along the car so the solution also needed to be able to achieve 3D matching.

A cycle time of just 3.5 seconds was available for the full point cloud grab and process.

Robot Guidance Solution

Bluewrist implemented the 3D Vision Robot Guidance solution using two Fanuc robots with a seven-axis linear slide and high-resolution blue structure light snapshot 3D cameras. Using ScanXtream and comXtream software point clouds of the wheel and the rotor are matched to the corresponding CAD model with great accuracy. The implimented vision system can achieve +/‒ 0.3 mm accuracy in XYZ and +/‒ 0.3 degrees in WPR.

The Bluewrist solution is scalable from a few hundred to thousands of cars per day as required by a manufacturer’s production requirements. The current production of the installed system run rate is 250 cars per day, and the wheel installation system consistently achieves 99.5% uptime.

The application can pick up the wheel and install it onto the rotor with multiple features covering the functionality required to process different surfaces, fitting positions, and bolts.

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