Building a Flexible Vision System for Brake Pad Inspection
"With NI vision products and LabVIEW software,
we managed to build a highly flexible and robust
vision system for the SBS brake pad production line. "
- Jan Reinholdt Mohrdieck, SBS Friction A/S
Developing a flexible vision system for a line that produces more than 1,200 different brake pad combinations so that an operator can easily configure the system and create the vision inspection template from scratch depending on the product under test.
Using NI vision tools and LabVIEW software to build a highly flexible and robust vision system for the Scandinavian Brake System (SBS) brake pad production line that has zero maintenance stops per day, which saves a huge amount of operation time.
SBS Custom-Made Brake Pads
SBS, established in 1964, manufactures braking system parts for all sorts of vehicles and rotating systems from racing motorcycles to wind turbines. SBS does not mass produce, but instead specializes in high quality and custom brake pads for its customers.
It is a well known saying that SBS motorcycle brake pads are the “Choice of Champions.” SBS is one of the most preferred brands with the world’s top riders as titles are distributed in the world of Supersport 600 and Superbike. Systematic, sustained product development that focuses on creating the optimum combination of performance, durability, and safety makes SBS braking pads popular. Knowledge, experience, and enthusiasm motivate our R&D department to constantly set new standards and always fulfill the demands of the best riders.
Custom-made brake pads challenge the production line because of changing materials, shapes, and sizes. The production line must be extremely flexible and adapt different product types fast. Therefore, a well-designed vision system is the key to designing a good automated production line. Before using a vision-based approach, the production line needed one pickup tool per brake pad, which required a huge storage and maintenance facility. This resulted in unacceptable overhead both in time and manpower to simply acquire and keep tabs on these thousands of pickup tools.
With a vision system, these tools became obsolete as the vision algorithm tells the robot where to pick up the brake pad with a simple suction cup. The vision algorithm ensures fast and reliable geometric matching, which greatly increases throughput. Teaching the new matching patterns is easy and intuitive so the staff on the production line can do it without assistance from R&D, which frees up manpower and increases productivity.
Figure 1. SBS Brake Pads Waiting for Testing
Figure 2. SBS Brake Pads
Figure 3. Robot Arm With Vision System Picking Brake Pads
Vision Inspection System Architecture
Because of the complexity of the vision system, we used CIM Industrial Systems A/S, an NI Alliance Partner in Denmark, to design the architecture and deliver a highly flexible and easy-to-use solution. CIM’s expertise using NI tools made the company a good partner for this project.
We based the vision inspection system architecture on a modular event-based, producer-consumer architecture. Event-based architecture keeps the system tight and minimizes polling overhead. Upon message from the robot, the system generates the events required to capture an image, processes the image, sends the positions of brake pads to the robot, and displays the information on the GUI. The architecture is purely reactive to outside stimuli, which simplifies the design greatly and focuses on speed for superior throughput.
Figure 4. Tile With Brake Pads
Ready to Future Needs
We selected NI tools and consulting services from CIM because it was the only highly flexible system available. Our own technicians can easily and quickly create inspection templates at production if needed. The other systems could not handle that in a flexible way. We can also easily scale this system to cover even more production steps in the future. We are confident that by using these tools together with CIM’s knowledge, we can meet any future requirements and challenges.
We designed the application with scalability in mind and expect that many of the routines used can directly transfer to other similar applications within SBS in the future. The learn geometric pattern tool from NI combined with the CIM interface most likely must be exactly the same to ensure that the operator is familiar with the system and can go directly from one production station to another without a steep learning curve.
Direct resuseability of the code can also make the new applications much less expensive to code. Because the code is reused, the modules have already been tried and tested, which drastically cuts down on implementation overhead.
A Flexible and Robust Vision System for the Brake Pad Production Line
With NI vision products and LabVIEW software, we managed to build a highly flexible and robust vision system for the SBS brake pad production line. The new system has zero maintenance stops per day, which saves a huge amount of operation time. The system is completely autonomous, which means that if templates are already known from previous tests, no action is needed from the operator at all. The operator simply enters the production code in the main system and this information is relayed to the vision application. Using the modern and well-tested vision matching algorithm, the system has a near 100 percent match rate. The algorithm only fails when the brake pads are very dirty or broken.
The vision application causes virtually no downtime, which means SBS can focus on optimizing more failure-prone systems in its production line. All in all, this creates an overall more robust and cost-effective production line.
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