One of MIT

MIT Design Allows Anyone to Create a Custom 3D Printed Robotic Hand – 3D Printing Industry

Researchers from the Massachusetts Institute of Technology (MIT) created a design pipeline to streamline the process of building a custom robotic hand with touch sensors.

Users don’t need any specialized knowledge to run the new design pipeline, which would be much faster than the traditional trial-and-error process of designing a custom robotic manipulator. Once users have adapted their designs, the manipulator is 3D printed and the sensors are incorporated into a knitted glove that fits over the robot’s hand.

“One of the most exciting things about this pipeline is that it makes design accessible to a general audience,” said Lara Zlokapa, lead author of the study and a student at MIT.

“Rather than spending months or years working on a design and investing lots of money in prototypes, you can have a working prototype in minutes.”

MIT has been involved in a number of innovative 3D printing projects over the years. This year alone, the university teams have developed a new method of integrating information into physical objects via 3D printing invisible to the naked eye, and to propose a new technique for 3D printing objects that change their appearance depending on the angle from which you look at them.

More recently, researchers from MIT and University of Calgary have developed a new type of robotic cube transformed using 3D printing technology. Called ElectroVoxels, the self-configuring robot blocks can assemble themselves into all sorts of shapes using a built-in electromagnet as an actuation mechanism.

The anatomy of a single ElectroVoxel. Photo via MIT.

The integrated design pipeline

Typically, robotics experts can spend months manually designing a custom robotic manipulator through trial and error techniques. Additionally, each design iteration may require new parts that must be designed and tested from scratch.

The MIT team sought to drastically reduce the time and complexity of this process by creating an integrated design pipeline to allow users without specialist knowledge to quickly create a custom 3D printable robotic hand.

Described as similar to building with digital Lego blocks, a designer can use the team’s intuitive interface to design their own custom robotic manipulator from a set of 15 modular components that are guaranteed to be 3D printable. After mixing and matching components in a 3D design space, the designer can adjust the palm and fingers of the robotic hand to suit a specific task before integrating touch sensors into their final design.

The interface is based on a set of production rules known as the graph grammar, which control how users can combine different components.

“If we think of this as a Lego kit where you have different building blocks that you can put together, then the grammar might be something like ‘red blocks can only go on blue blocks’ and ‘blue blocks can’t go over the top. of green blocks,” Zlokapa said. “Graph grammar is what allows us to ensure that every design is valid, which means it makes physical sense and you can make it.”

After creating the structure of the manipulator, the user can then deform the components to further customize them for a specific task, such as creating fingers with thinner tips for handling office scissors, or curved fingers capable of gripping bottles . To do this, the software surrounds each component with a digital cage that can be stretched and bent, but movements are limited to ensure that the parts still fit together properly and can be manufactured.

Once the design is finalized, the MIT software automatically generates 3D printing and machine knitting files to produce the manipulator. The touch sensors are then integrated into the robot through a knitted glove that fits snugly in the hand and allows it to perform complex tasks like picking up objects or using tools.

One of MIT's custom 3D printed robotic hands.  Photo via MIT.
One of MIT’s custom 3D printed robotic hands. Photo via MIT.

Integrate sensors

Once the user has designed, customized and 3D printed their robotic manipulator, they can then choose the desired locations for the touch sensors. The sensors are embedded in a knitted glove that fits securely around the manipulator and is formed of two layers; one with horizontal piezoelectric fibers and another with vertical fibers.

The piezoelectric material produces an electrical signal when pressed, and when the horizontal and vertical fibers intersect, they convert the pressure stimuli into electrical signals that can be measured and form tactile sensors.

Zlokapa and his team chose to integrate the sensors into gloves because they are easy to install and replace in case the sensors need repair.

To test the effectiveness of their design pipeline, the MIT researchers 3D printed four custom manipulators for a variety of different tasks, including picking up an egg, cutting paper with scissors, pouring water from a bottle and screw in a wing nut.

Each of the manipulators performed their tasks adequately, with some even exceeding the team’s expectations. However, the researchers observed that the sensors created a lot of noise due to the uneven weave of the knitted fibers, which hampered their accuracy. The team is now working on creating more reliable sensors that could improve the performance of manipulators.

Zlokapa and his team are also exploring the use of autonomous manufacturing, where algorithms could search the design space to determine optimal configurations for a task-specific robotic hand without human intervention.

“Now that we have a way for a computer to explore this design space, we can work on answering the question, ‘Is the human hand the optimal shape for performing everyday tasks?’ Maybe there is a better shape? Zlokapa added. “Or maybe we want more or fewer fingers, or fingers pointing in different directions?

“This research does not fully answer that question, but it is a step in that direction.”

One of MIT's custom 3D printed robotic hands capable of cutting paper with scissors.  Photo via MIT.
One of MIT’s custom 3D printed robotic hands capable of cutting paper with scissors. Photo via MIT.

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Featured image shows one of MIT’s custom 3D printed robotic hands. Photo via MIT.

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