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In-line testing using robots reduces human error and generates high ROI for sensor manufacturer

A collaborative robot from Universal Robots and an easy-to-use adaptive gripper from Robotiq have given sensor manufacturer Elobau an off-the-shelf solution for quality testing on finished goods.

Level management, machine safety systems, and operator controls are the core components produced at elobau.

 

 

Elobau is a leading manufacturer of operator controls, non-contact sensors, and safety devices. It has a large portfolio of components and systems primarily for commercial vehicles, machine safety, and level measurement.

Lately, engineers and product and systems developers at the company have been working on new ways to improve their quality control by implementing a robotic system to perform different in-line production tests. To do so, they have transformed their manufacturing lab so that it can run their first automated quality testing cell.

Elobau was looking for a robot and gripper with advanced grasping and force sensing combined in one simple solution.

 

 

Application background
The joystick bases and control sticks are a main product group manufactured by Elobau that must go through a wide variety of qualitative and quantitative test procedures. These are sold by Elobau as a principal control device for vehicles, and it is a critical component for their customers. The quality-assurance team has to verify the conformance of the electronic and mechanical components before they get to final packaging.

The quality-control team in the past used to test their production manually, which allowed the workers to adapt their verification tasks to dozens of different joystick models, including custom configurations. The goal was to monitor the performance, full functionality, and sensitivity of the joystick components.

With everything being done manually, the company strove to minimize the work in progress at the different workstations, but didn't want to jeopardize its quality by implementing random sampling. Over the long term, they couldn't afford to assign more workers or increase the production pace, which might lead to worker fatigue and increased mistakes. These non-value-added operations within their quality-control functions represented the perfect opportunity for their quality and engineering team to automate their testing through the addition of a robot and gripper.

Key application components

• Limited quality-control capacity;
• Critical non-value-added tasks in production;
• Lack of standardization in their work in progress for testing;
• Time pressure that could lead to worker fatigue and mistakes.

The challenge
For quality assurance, an automated quality system seemed to be the perfect solution. Elobau could easily verify every single part and fully control the output of their quality workstations. However, the engineering team could easily have become lost among the different robot solutions available to achieve their goals. Their current manual processes were expensive, but they did provide a fast response feedback during production for any defective parts.

Elobau also wanted to keep the flexibility of the manual process. Ultimately, the whole process needed to be fast enough to fully monitor the wide variety of in-line testing tasks, as well as retain the capability of being proactive with preceding operations.

Cycle time is certainly a key factor directly affecting the output performance of the quality workstation, but this becomes less critical once the quality-control issues are addressed with an industrial robot. The time spent by the current workers to go through their physical testing on control sticks was generally split equally between the indexing time and the physical testing for every component.

Elobau selected the 3-Finger Adaptive Gripper 85 mm for its dexterous manipulation features offering unlimited grasping possibilities for their automated testing processes.

 

 

One of the most challenging parts of their project was to perform all of the quality tests with one end-of-arm solution using only one robot gripper with a force torque sensor. The gripper needed to be fully adaptive, as it must apply repeatable forces on pushbuttons, as well as grab control sticks of different sizes and shapes throughout the quality-control processes.

The project architects also knew that the automated quality-control system was going to be susceptible to a great number of environmental factors on the shop floor. More specifically, electronic measuring devices like a force torque sensor can be affected by industrial noise. In this environment, a high signal-to-noise ratio sensor should be used to control the testing tasks. The engineers at Elobau also expected to have the robot working with different controlled forces, valued under 100N, and the sensitivity feedback they were seeking needed to be measured from three different axes, so as not to limit the end-of-arm tool position when the force is applied.

The robot movements involved in the application required a standard precision range. The quality team was looking to work with a robot repeatability of 0.1 mm. The same general specs would apply to the gripper.

As far as the robot and gripper speed are concerned, most of the cycle time is spent on the movements required to reach the parts and take up the right position for testing. In this case, the focus needed to be more on the robot speed specs than on the gripper speed specs.

Joystick bases and control sticks are a main product group manufactured by elobau that must go through a wide variety of test procedures.

 

 

Elobau also expected the robot to perform all the quality testing without workers. Nevertheless, they still preferred to give access to the robot environment to every worker without restriction. Thus, a workstation without protective guards would be a great advantage for the new production layout.

Key application challenges

• High mix of control-stick sizes and shapes;
• Advanced grasping and force sensing combined in one simple solution;
• Adaptive gripper for dexterous testing;
• Force sensor featuring a high noise immunity;
• Force control precision throughout the different force ranges under 100N.

Finding the right balance
Beyond the solution, the quality-control team knew that they needed to keep the right balance between automated and manual quality-assurance processes. It was decided to take time to integrate the new automated workstation in two phases. The first-phase goal was to select the right robotic hardware and software and review the extensive list of tasks that would have to be done by the robot.

The second phase included the full integration of the automated system into the production line. The quality team expected to run their automated testing routines outside the production line for a while, while they restructured the quality-control process. Once done, the integration and switch with the robot was easier to organize along with job reassignments. Selecting a robot, a gripper, and a sensor that are easy to use is an important criteria for the workers. In the end, the current quality-control employees most wanted to be able to operate the robot system with ease.

Other key components for the solution were flexibility and precise control. Elobau selected the Robotiq 3-Finger Adaptive Gripper (85 mm) for its dexterous manipulation features that offer unlimited grasping possibilities for automated testing processes.

Collaborative robot and workers in the same environment was another part of the solution.

 

 

They selected the digital force torque sensor, the Robotiq FT 150, for its ease of use with a Universal Robots collaborative robot, but also due to the high-quality, low-noise signal. They were confident that when they hit a pushbutton or moved the joystick with the gripper, it would always perform as they had tuned it.

For example, they knew they would get the right corresponding response just like musicians get the right sound with a precise stroke on a keyboard. They wanted a fast integration for the second phase of the project, so getting easily understandable software for their robotic hardware left more time to work on the quality-control output rather than spending a lot of time programming every single task involved in their vigorous testing processes. Having the option to work with the Robotiq end-of-arm solution that is purpose-built for collaborative robots helped Elobau to prove their design concept for an affordable in-line testing system using robots.

Key application solution

• Collaborative robot and workers in the same environment;
• Robotiq bundle with 3-Finger Adaptive Gripper 85 mm and FT 150 force sensor;
• Robotiq gripper and sensor software developed for the Universal Robots controller;
• Easy force monitoring with the digital FT 150 sensor from Robotiq;
• Flexible end-of-arm tools to test buttons and control sticks.

End result: Success
Elobau has taken a huge step to improve their production costs by tremendously reducing the manual tasks that have been affecting their quality testing output rate. In the beginning, they didn't expect to achieve such a smoothly integrated solution that can be so easily operated by their workers.

The end result for this owner-run family business is that this easy-to-use solution allows the employees to take on a new role in robotic quality testing by keeping the focus on their own products and processes rather than spending several hundred hours on robotic development and analysis.

The quality-control employees are able to operate the robot system with ease.

 

 

At the beginning of the project, the company needed to quickly validate the concept with a Universal Robots UR5 robot. They are continuing to evaluate other collaborative robot options, because they realize that in the future they may need a longer reach and 10-kg payload to fully meet all the required flexibility and specs that they are looking for.

Much of the development effort is now focused on a complete panel checkout and product tracking system, because elobau's goal is to integrate everything in their production processes. However, the design concept of using the collaborative robot and end-of-arm solution from Robotiq has proven to be able to be quickly integrated and offers a greater projected ROI over time. In-line testing using robots will reduce human error and allow quality-control operators to spend more time on high-value tasks for production while doing less repetitive manual work.

Want more information? Click below.

Universal Robots
Robotiq

Published September 2015

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