New materials with unique properties that can be used for 3D printing are always under development, however figuring out how to print with these materials can be complex.
Often, an expert operator must use manual trial-and-error to determine ideal parameters that consistently print a new material effectively. These parameters include printing speed and how much material the printer deposits.
MIT researchers have now used artificial intelligence (AI) to streamline this procedure, developing a machine-learning (ML) system that uses computer vision to watch the manufacturing process and then correct errors in real-time.
The researchers used simulations to teach a neural network how to adjust printing parameters to minimize error, and then applied that controller to a real 3D printer. Their system printed objects more accurately than all the other 3D printing controllers they compared it to.
The work avoids the prohibitively expensive process of printing thousands or millions of real objects to train the neural network. And it could enable engineers to incorporate novel materials more easily into their prints, which could help develop objects with special electrical or chemical properties. It could also help technicians adjust the printing process on-the-fly if material or environmental conditions change unexpectedly.
“This project is really the first demonstration of building a manufacturing system that uses machine learning to learn a complex control policy,” says senior author Wojciech Matusik, professor of electrical engineering and computer science at MIT who leads the Computational Design and Fabrication Group (CDFG) within the Computer Science and Artificial Intelligence Laboratory (CSAIL). “If you have manufacturing machines that are more intelligent, they can adapt to the changing environment in the workplace in real-time, to improve the yields or the accuracy of the system. You can squeeze more out of the machine.”
The co-lead authors on the research are Mike Foshey, a mechanical engineer and project manager in the CDFG, and Michal Piovarci, a postdoc at the Institute of Science and Technology in Austria. MIT co-authors include Jie Xu, a graduate student in electrical engineering and computer science, and Timothy Erps, a former technical associate with the CDFG.
Picking parameters
Determining the ideal parameters of a digital manufacturing process can be one of the most expensive parts of the process because so much trial-and-error is required. And once a technician finds a combination that works well, those parameters are only ideal for one specific situation. She has little data on how the material will behave in other environments, on different hardware, or if a new batch exhibits different properties.
Using a ML system is fraught with challenges, too. First, the researchers needed to measure what was happening on the printer in real-time.
To do this, they developed a machine-vision system using two cameras aimed at the nozzle of the 3D printer. The system shines light at material as it is deposited and, based on how much light passes through, calculates the material’s thickness.
“You can think of the vision system as a set of eyes watching the process in real-time,” Foshey says.
The controller would then process images it receives from the vision system and, based on any error it sees, adjust the feed rate and the direction of the printer.
But training a neural network-based controller to understand this manufacturing process is data-intensive and would require making millions of prints. So, the researchers built a simulator instead.
Successful simulation
To train their controller, they used a process …….
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