By integrating sensors into rotating mechanisms, engineers can build smart hinges that recognize when a door is open, or gears in motors that tell mechanics how fast a machine is rotating. Engineers at MIT have developed a way to easily integrate sensors into these types of mechanisms using 3D printing.
Advances in 3D printing have enabled rapid manufacturing of rotating mechanisms, but integrating sensors into designs remains notoriously difficult. Due to the complexity of rotating parts, sensors are typically manually implanted after the device has already been manufactured.
However, manually integrating sensors is not an easy task. Embedding it inside the device can cause wires to get tangled in the rotating part or impede rotation, while attaching an external sensor can increase the size of the mechanism and limit its movement.
Instead, a new system developed by MIT researchers allows manufacturers to 3D print sensors directly onto the moving parts of mechanisms using conductive 3D printing filaments. This allows the device to sense angular position, rotational speed, and rotational direction.
The company’s system, called MechSense, allows manufacturers to use multi-material 3D printers to produce rotating mechanisms with built-in sensors in a single pass. These types of printers use multiple materials simultaneously to manufacture devices.
To streamline the manufacturing process, the researchers created a plug-in for computer-aided design software SolidWorks that automatically integrates sensors into models of mechanisms. This plugin can be sent directly to a 3D printer for manufacturing.
MechSense allows engineers to rapidly prototype devices with rotating parts such as turbines and motors, while incorporating sensing directly into their designs. This can be particularly useful for creating concrete user interfaces for augmented reality environments where sensing is essential to track user movements and interactions with objects.
“A lot of the research we do in our lab involves taking manufacturing methods created by factories and professional institutions and making them available to people. Tools you can afford to have at home.So how do we give the average author the tools they need to develop these types of interactive mechanics? It revolves around that goal,” says Marwa AlAlawi, a mechanical engineering graduate student and lead author of the paper on MechSense.
AlAlawi’s co-authors include former postdoc at the MIT Computer Science and Artificial Intelligence Laboratory (CSAIL) and current assistant professor at Aarhus University, Michael Wesely. Her senior author, Stefanie Mueller, is Associate Professor in the Department of Electrical Engineering, Computer Science, and Mechanical Engineering at the Massachusetts Institute of Technology, and a member of CSAIL. So do other members of MIT and her Accenture Labs collaborators. The research will be presented at her ACM CHI conference on Human Factors in Computing Systems.
Built-in sensing
To incorporate the sensor into the rotating mechanism in a way that doesn’t interfere with the device’s movement, the researchers leveraged capacitive sensing.
A capacitor consists of two plates of conductive material with an insulating material sandwiched between them. If the overlap area or distance between the conductive plates is changed, possibly by rotating the mechanism, the capacitive sensor can detect the resulting change in the electric field between the plates. For example, you can use that information to calculate speed.
“With capacitive sensing, you don’t necessarily have to touch two opposing conductive plates to monitor changes in a particular sensor. .
A rotating mechanism usually consists of a rotating element placed above, below, or next to a fixed element. It’s like a gear rotating on a static shaft in a plane. A spinning gear is a rotating element and the flat surface underneath it is a stationary element.
The MechSense sensor contains three patches of conductive material printed on a fixed plate, each patch separated from adjacent patches by a non-conductive material. His fourth patch of conductive material with the same area as his other three patches is printed on the rotating plate.
As the device rotates, patches on the rotating plate, called floating capacitors, overlap each patch on the fixed plate in turn. As the overlap between the rotating patch and each fixed patch changes (from fully covered to half covered to completely uncovered), each patch experiences a resulting change in capacitance. separately.
Floating capacitors are not connected to the circuit, so wires cannot get tangled in rotating parts.
Rather, the fixation patch is wired to electronics that use software researchers have developed to convert raw sensor data into estimates of angular position, rotational orientation, and rotational speed.
Enabling rapid prototyping
To simplify the sensor integration process for users, researchers built a SolidWorks extension. When the manufacturer specifies the rotating and stationary parts of the mechanism and the center of rotation, the system automatically adds sensor patches to the model.
“The design doesn’t change at all. We just replace part of the device with a different material, in this case a conductive material,” says AlAlawi.
Researchers have used the system to prototype several devices, including a smart desk lamp that changes light color and brightness depending on how the user rotates the bottom or middle of the lamp. They also made planetary gear trains, like those used in robotic arms, and wheels that measure distance as they roll on surfaces.
While building the prototype, the team also conducted technical experiments to fine-tune the sensor design. They found that reducing the patch size increased the amount of error in the sensor data.
“In order to produce electronic devices with very little e-waste, we want devices that have a smaller footprint and perform well. Then I think we can use the same geometry and scale it down with less error,” she says.
In addition to testing different materials, AlAlawi and her collaborators are exploring ways to make sensor designs more robust against external noise and developing printable sensors for other types of locomotion mechanisms. are also planning.
Original: 3D printed rotating device can sense how you move
Than: Massachusetts Institute of Technology Computer Science and Artificial Intelligence Laboratory
