Paul Koomey, Ahmed Malabi, Andrew Powell, Hannah Sternadel, Samuel Terwilliger
OmniPen
Executive Summary
Conceptual Design Phase
Background and Mission
The OmniPen is a virtual reality pen that connects to a VR environment to allow the user to draw in a 3D space. The user is able to choose different colors, textures, and line width by pushing the attached buttons on the pen. The design of the pen will be similar to a pen with a diameter of about an inch and a half. The pen will have a slick design with a grip material around the tip of the pen for hand comfort. The pen is comprised of a housing frame, a microcontroller, push buttons, and a battery source. The inputs provided from the pen will be transmitted to the environment via a Bluetooth connection. Depending on the buttons pushed on the pen, the VR environment will either pop up a color/texture/size menu, allow for drawing, or calibrate/fix the orientation of the pen.�
Currently, the virtual reality pens in society are expensive. This leads users to use VR controllers as a substitute. Our goal was to develop a VR pen that would be accessible to all VR drawing hobbyists. The OmniPen will allow users to interact with a 3D virtual environment in an intuitive and easy manner. Users will be able to draw in this virtual space while also being able to change textures and colors using button presses on the pen.
The OmniPen will be the size of a large pen, about an inch and a half in diameter. It will be comprised of a PCB controller with a Bluetooth connection, an internal measurement unit (IMU), a battery, and three push buttons. One of these buttons will be used for drawing with the pen, one will be used for accessing a menu in VR, and the last button will be used for calibrating the pen. All of these components will fit seamlessly inside of a 3D printed casing. The OmniPen will then connect to a virtual reality Unity environment through a Bluetooth connection that will relay orientation and button presses from the pen. There are two IR cameras that are used for tracking the pen’s position and will send XYZ data to the environment over Bluetooth. The headset will be connected to a computer that will be running the virtual environment.
Throughout the design process, our team ran into many issues with our original idea for the pen. We originally planned on using only the IMU to track the pen’s position, but we soon realized IMU tracking would result in a severe drifting problem. These issues led us to add a new source of tracking. Our solution was to add two base stations that would consist of two IR cameras and would track the X, Y, Z position of an IR LED found within pen. The IR cameras added another problem, the cameras were not able to detect the IR LEDs in certain pen positions. We realized the IR LED’s light was not diffused enough. Our solution was to sand the surface of the LED and print out a tip for the pen that would closely wrap around the LED.The porous PLA material allowed proper detecting diffusion.
Figure 1. OmniPen Conceptual Design Goal
Detailed Design Phase
Prototype & Test
The system is comprised of four layers, the Pen Circuit, Pen Housing, VR Environment, and Base Stations.The Pen Circuit is responsible for collecting pen orientation/user input and relaying that information over Bluetooth to the other layers. The Pen Housing is simply responsible for providing a comfortable physical interface between the user and the pen. The VR Environment layer provides visual feedback for the user and is responsible for interpreting data received from the Pen Circuit and Base Station layers. Lastly, the Base Station layer is responsible for providing camera tracking information to the VR Environment layer through the use of IR cameras and a Bluetooth connection.
In the end, the OmniPen has come a long way. The pens current design relatively fits our beginning goals and is a working prototype of what could be a true product in the future but there is still more that could be done. The pen itself is slightly bigger than the design specifications, but still provides a comfortable hand positioning when in use. Overall, despite coming into the project blind, the team has produced a prototype that we can be proud of and have gained experience of interdisciplinary work that can be applied in the future.
Future work: The current design is lacking a few abilities that would be a great addition to the pen, such as an eraser, more colors and textures. An application could also be created for the pen to provide a full immersive experience.
CS and CpE Senior Design
2023 UTA College of Engineering
May 5th, 2023
Figure 2. Detailed Design Specification Diagram
Name | Description and Use |
Pen Circuit | Provides orientation tracking of the pen and user control inputs for drawing |
Pen Housing | 3D printed casing to protect and provide abstraction the circuitry |
VR Environment | Display the users drawing and provide access to a menu in a VR space |
Base Stations | Tracks the X, Y, Z position of the pen and sends the data to the VR environment over Bluetooth to remap location in the VR environment |
Table 1: Describes the minimum requirements for the OmniPen design
Conclusions
Figure 3: Pen schematic, PCB layout, and current prototype
Figure 4: Drawing menu
Figure 5: Base Station Casing
2018 UTA College of Engineering Innovation Day April 16, 2018 Poster ID#