Gaze Glasses

Gaze Glasses: Optimizing the design of PUPIL eye tracker

PUPIL was an eye tracking hardware and software developed by MIT architectural graduate students for their thesis. PUPIL was relatively low cost, and it was an open source and community driven project with uses ranging from linguistics, human-computer interaction, and marketing. PUPIL utilized two cameras, one camera to track the eye's movement (eye camera) and the other camera that simulated what the eye is seeing (scene camera). Both cameras were connected to the computer via USB. On the PUPIL model, the eye camera was a uncased Microsoft HD-6000 webcam and the scene camera was a uncased Logitech webcam. Both cameras were mounted onto 3D printed frame's that only came in one size. The PUPIL frame was very uncomfortable to wear and required suguru, a self-setting rubber, at points of contact on the head for comfort, especially on the nose piece and on the end of the frame's arms.

Our sponsors operate a research facility at the University of California, San Diego called the Research on Autism and Development Laboratory (RADLab). At RADLab, researchers on autism study autism behavior, and one aspect of their research is using eye tracking to understand where a patient's center of attention is during certain activities. The PUPIL eye tracker allowed our sponsors to pin point the exact location of the patient's vision while undergoing a series of test which include conversation, interactive games, and visual perception tests.

Video demonstrates the PUPIL eye tracker.

Project Goals:

Functional Requirements:

Main priority:

Redesign the PUPIL eye tracker frame to be adaptable to wide range of head sizes and shapes
Reduce the overall weight of the PUPIL in the newer design of the Gaze Glasses
Durability and Robustness of the Gaze Glasses
Adjustable eye camera placement

Secondary priority:

Reduce the size of the camera
Audio capturing enable-ability

Bonus goals:

Make Gaze Glasses wireless.
60 plus frames per second for the eye tracking camera
720p or higher resolution for the scene camera
Must be around ~$100 per headset

Deliverable:

Reproducible final prototype of the Gaze Glasses that meet all the of main priorities
List of parts purchased for Gaze Glasses
Documentation of fabrication instructions, and CAD drawings of 3D printed parts

Design Solution:

Tie-on necessary components to existing commercial glasses frames.

The idea of tie-on pieces solve the problem of discomfort users experienced with the PUPIL eye tracker. With tie-on parts, users can buy glasses that fit and add the pieces onto the glasses. The tie-on method also solve's the problem of different head sizes and shapes of the user since the person can just buy glasses that fit. Another advantage of tie-on approach is if any of the parts malfunctions or break due to long term use, those parts can be replaced.

Key Components:

The final version of the Gaze Glasses incorporates key components that were demeaned necessary or fabricated to achieve the project's requirements. The final design was meant so that parts, other than the ones that are 3D printed, are off-the-shelf items that can be purchased with minimal modifications.

Those components are:

Eye and scene camera
Arm mounts
Camera mounts
Gooseneck tubing
Off-the-shelf glasses frames

1. Eye and Scene Camera

Figure 1. Microsoft LifeCam HD 6000. Stock encased (left) and uncased (right)

Microsoft LifeCam HD 6000 provides the required function for both the eye and the scene cameras. Additionally, the webcams are already compatible with the eye tracking program. The cameras are relatively cheap and light weight (10 grams) with a small form factor.

2. Arm Mounts

Figure 2. CAD images of arm mount for scene camera (left) and the eye camera (right)

The arm mounts for both the eye and scene cameras fastens the arms of glasses by using ties. The small slots on the sides of the mounts are opening for fastening materials, such as cable ties, to fit through, and rap around the mounts in order to bind the pieces together. The grooves cut on the inside of the mounts simulate two L-brackets that encloses around the arms of the glasses. Having a two L-bracket design limits the torsional movement of the arm to provide better stability when tied onto glasses, and also allows for adaptation of different glasses frame sizes.

Both arm mounts contain 4.75 mm clearance holes that act as guides for the gooseneck tubing to fit through. Furthermore, the small hooks at the top of the eye camera mount (Figure 2, right) and at the side of the scene camera mount (Figure 2, left) serve the purpose of directing the wires, that are connected to the webcams, along the same path as the gooseneck tubing. The arm mounts are available in CAD files and are 3D printed out of acrylic.

3. Camera Mounts

Figure 3. CAD images of camera mount for scene camera (left) and the eye camera (middle). Camera is press fitted into the mount (right).

The camera mounts are 3D printed out of acrylic and are designed in such a way that the Microsoft LifeCam HD 6000 can be press fitted by hand into the square slots (Figure 3, right). The clearance holes are designed in such a way that a thicker PVC tube, which is fitted onto the end of the gooseneck tubing as well, can fit and provide a stable connection of the camera mounts. The PVC tube allows for a better fit while letting the cameras rotate without wearing down the acrylic. The hooks coming out from the side of the clearance holes are used to hold the wires coming from cameras. The main difference between the scene and eye camera mounts is that for the eye camera mount (Figure 3, middle) has a slot cut so the infrared LED can illuminate the eye. These camera mounts are available in CAD files.

4. Gooseneck Tubing

Figure 4. Gooseneck tubing (right) and gooseneck ear support (left).

The gooseneck tubing provides enough stiffness to hold the weight of a camera, the camera mount, and wire. Using the gooseneck tubing allows for easy camera adjustments while providing enough stiffness to stay in place after it has been set. The gooseneck tubing is also used to curl behind the ear (Figure 4, left), this helps keep the glasses from slipping off the face and relieves the weight on the nose by distributing the weight towards the ears.

5. Off-the-shelf glasses frames

Figure 5. Generic Wayfarer glasses frames

The tie-on mechanism applies to generic glasses frames that are readily available. Using bought off-the-shelf glasses is advantageous as they can be replaced for a very low cost. The frames are designed to be comfortable when worn for a long period of time. These glasses frames chosen are similar to Wayfarer glasses because they provide a large surface area to work with while being an in style type of glasses.

Assembled Gaze Glasses Headset:

The final assembly of the Gaze Glasses Headset is shown below.

Figure 6. Fully assembled Gaze Glasses Headset

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