Google is committed to advancing racial equity for Black communities. See how.

Sensor Fusion Box Details

This page provides information on how to purchase or assemble a Sensor Fusion Box. The Sensor Fusion Box is used in the CameraITS sensor_fusion test and multi-camera sync test. It provides a consistent test environment for measuring timestamp accuracy of sensors for Android devices, specifically camera image sensors and gyroscopes. It consists of plastic box components that are laser cut from computer-aided design (CAD) drawings and a Servo Control Box.

You can purchase a Sensor Fusion Box or build your own.

Purchasing a Sensor Fusion Box

We recommend purchasing a Sensor Fusion Box from one of the following qualified vendors.

Building a Sensor Fusion Box

This section includes step-by-step instructions for assembling a Sensor Fusion Box from laser-cut acrylonitrile butadiene styrene (ABS) components (shown in Figure 1).

CAD drawing of Sensor Fusion Box components
Figure 1. Mechanical drawing of Sensor Fusion Box components

Required tools

Before starting, ensure you have downloaded the technical drawings for the Sensor Fusion Box (included in the Sensor Fusion Box zip file) and have the following tools available:

  • Phillips head screwdriver
  • JIS head screwdriver
  • Hex keys
  • Power drill set
  • X-ACTO knife
  • Tape

Step 1: Apply vinyl stickers

After creating the ABS components with a laser cutter, apply vinyl stickers to the plastic box to get the proper color control on the interior of the test box:

  1. Apply vinyl on the smooth side of the ABS as shown in Figure 2. For helpful tips on applying vinyl, refer to wikiHow.

  2. Cut out the necessary holes on the vinyl with the exacto knife.

    ABS pieces
    Figure 2. ABS pieces with vinyl applied on the smooth side (interior of the box)

  3. Using acrylic glue, glue the round ABS pieces onto the four corners of the bottom panel.

    bottom panel
    Figure 3. Bottom panel with round ABS pieces glued to the four corners.

Step 2: Prepare phone mount and attach servo mount

To prepare the phone mount to attach to the servo:

  1. Tap 20 holes on the phone fixture with a 1/4"-20 drill bit.

    Phone fixture holes
    Figure 4. Phone fixture with tapped holes

  2. Make sure you have the ABS cut outs, nylon thumb screws, nylon nuts (for adjusting screw height if necessary), the C1 spline actobotics dual servo arm, 4-40 screws, and compression springs.

    phone mount parts
    Figure 5. Phone mount parts

  3. Apply the 4-40 screws and tighten the servo arm to the back of the phone mount. Using the same screws and 4-40 cap nuts, tighten the phone divider ABS cut out on the front side of the phone mount.

    Servo shaft
    Figure 6. Shaft on the back of fixture, tightened by screws applied from the front

    screws and cap nuts
    Figure 7. 4-40, 3/4" long screws and 4-40 cap nuts

    Phone mount servo arm
    Figure 8. Back (left) and front (right) of the phone mount

Step 3: Attach phone clamps

To attach the phone clamps:

  1. Cut the neoprene sheet according to the shape of the ABS cut-out clamps, but leave one inch shorter from both ends as shown in Figure 9. After cutting the neoprene sheet accordingly, apply the pieces to the ABS cut-out clamps as in Figure 8.

    Clamp with neoprene sheet
    Figure 9. ABS clamp with neoprene sheet applied

  2. Attach nylon thumb screws and spring wire to the clamp. Add nylon nuts to reduce screw length, as needed.

    Clamp with screws, sheet, nuts
    Figure 10. Clamp with neoprene sheet, thumb screws, nylon nuts, and spring wire

  3. Screw the phone clamps' thumb screws into the tapped holes of the phone fixture as shown in Figure 11. You can adjust the location of the phone mounts depending on the size of the phones.

    CAD drawing of phone fixture
    Figure 11. Mechanical drawing of the phone fixture

    Assembled phone fixture
    Figure 12. Assembled phone fixture

Step 4: Assemble sliding door rail

  1. Fix sliding panel rails on the top and bottom of the box toward the front. Figure 13 shows 6-32 screws on pre-tapped holes. Alternatively, you can use self-tapping screws.

    Fixed rail
    Figure 13. Fixed sliding panel rail on top and bottom of box

Step 5: Attach lighting

To attach the light brackets and diffuser:

  1. Stack two handle pieces on top of each other and assemble them using 6-32 screws (or use self-tapping screws).

    Handle pieces and assembly
    Figure 14. Sensor Fusion Box handle pieces and assembly

  2. Prepare four 4-40 screws, nuts, and acorn nuts to fix the mounting bracket from the lighting kit to the wall of the box.

    Screws and bracket on interior wall
    Figure 15. 4-40 screws and light bracket on the interior wall of the box

    Exterior with bolts applied
    Figure 16. Bolts and acorn bolts applied to the screws from the exterior of the box

  3. Cut the light diffuser to an appropriate size to wrap the light strips (not required if the lights come with the diffuser).

    Light strips and diffusers
    Figure 17. Light strips and light diffusers

  4. Wrap the light diffuser around the strip and tape it at the back.

    Strips and diffusers taped from back
    Figure 18. Light strips and light diffusers taped from the back

  5. Snap the lights into the brackets (can be a tight fit).

    Lights on interior wall
    Figure 19. Lights mounted in brackets

Step 6: Attach phone fixture to servo plate

To attach the phone fixture to the servo plate:

  1. Prepare four 6-32 screws and a servo plate to fix the servo onto the wall. Fix the servo onto the interior wall and insert the screws from the inside into the servo plate on the exterior wall.

    Servo and servo plate
    Figure 20. Servo and servo plate held in place with 6-32 screws

  2. Secure the phone fixture onto the servo with nylocks (pushing the center of the shaft into the servo's rotation center).

    Phone fixture on servo
    Figure 21. Servo gear

  3. Using the servo screw that came with the servo, screw the phone fixture onto the servo gear through the servo arm.

    Phone fixture on servo with screw
    Figure 22. Servo arm

Step 7: Final assembly

To complete assembly of the Sensor Fusion Box:

  1. The sensor fusion test rig comes with a one-channel controller. There is also the option of ordering a rack-mount controller, which controls up to four servos. Connect the servo to the servo controller with the connector where the label reads YRB.

    Servo control box on wall
    Figure 23. Single channel servo controller

    Servo control box on wall
    Figure 24. Rack-mount servo controller with four channels

  2. Tape the box together, then screw the parts together (you might need to pre-drill holes in some parts).

    Taped box
    Figure 25. Taped sensor fusion test rig

  3. Print out a colored copy of the checkerboard (included in the Sensor Fusion Box zip file) on A3 (or 11 x 17 inch) paper, and tape it on the opposite wall of the phone fixture.

    Make sure the red dot in the center of the checkerboard is directly facing the camera when placed on the fixture, as shown below.

    Checkerboard
    Figure 26. Checkerboard printed and taped to the opposite wall of phone fixture