High Accuracy Robot

Our customer required a very precise pick and place system to apply strain gauges to raw material specimens as part of a high-rate quality verification process. These strain gauges were required to be placed precisely with respect to both location and angle, using an exact amount of adhesive.

Featured Design Challenges

Vacuum Work Holding:

The strain gauges were very small and had a high surface area while weighing almost nothing, so handling them required maintaining positive control at all times. Even a slight breeze could cause them to move unexpectedly. Consistent control was accomplished with a multi-vacuum system. Each strain gauge was individually held on a vacuum tray and then picked up by a custom designed vacuum foot, such that it was always positively held. For the vacuum tray, we leveraged the Ravin material system developed and supplied by Technical Tooling of Tacoma, Washington. The vacuum foot was also challenging to design, as it needed to hold the strain gauge firmly without distorting its shape and conform to the specimen surface during placement to ensure even pressure while the adhesive cured.

Machine Vision:

Machine vision was utilized to ensure precise placement of the strain gauges. Achieving adequate contrast between the strain gauge and its backing material was critical. Lighting and backing materials were tested and iterated on until a solution was found that worked reliably for all use cases.

Adhesive Control:

The adhesive dispensing for this system was also a challenge, as the customer required the use of a one part rapid curing adhesive which begins to cure when exposed to humidity in the air. This makes the process time-sensitive and necessitates a thorough and frequent cleaning procedure. Additionally, with such small specimens, the amount of adhesive needed was correspondingly minuscule, so fine control of the amount dispensed was critical.

Solution

The Perellion team integrated an ABB robot with a custom vacuum pick and place end effector and machine vision package. This project pushed the envelope in terms of machine vision and the robot’s accuracy. We ultimately were able to achieve a positional placement accuracy of ±.010” laterally and 0.2° rotationally.

At Perellion, we’re committed to working with our customers from their initial inquiry all the way to reaching their goals such as meeting production rates and quality standards. In addition to being machine designers, we’re also adept at process development. Our team recognizes the importance of understanding existing manual processes while also being able to determine which parts of those processes will not translate well to automation. Our team strives to provide a full solution to help our customers achieve their goals, including both process and machine design.