Magnetic Field Warping

Introduction

To make sure that our environment is optimal for our Coil Pro setup, we need to check a couple of important things that can affect the Coil Pro's magnetic field.

Before we start

Before moving forward, please make sure you have validated your Coil Pro setup as shown here.

Performance Disruptors - Magnetic Field Warping

Since we are currently using a non-adaptive model perfect magnetic field to estimate position in space for the EMF receivers in the system, things in the recording area that can disturb this field can influence position accuracy.

This can be experienced in multiple ways, but typically our users experience poor signal quality values in the Studio “details” interface, and there is a clear discrepancy between the actual position and the position visualized in Studio.

EMF Signal Quality (Good - above 99% in this image)

What factors can influence a magnetic field:

1. Material Composition: Certain materials in the environment can disrupt magnetic fields. For instance, ferromagnetic materials like iron, nickel, and cobalt can alter magnetic fields due to their ability to become magnetised themselves. Most metals will influence magnetic fields, but to greatly different extents.
2. Physical Obstructions: Physical barriers can block or redirect magnetic fields. For instance, placing a ferromagnetic object between a magnet and its target can shield the target from the magnetic field.

Less likely causes in a Rokoko application/use case:

1. Radiation: High-energy radiation, such as gamma rays or X-rays, can disrupt magnetic fields by altering the alignment of magnetic domains in materials or by affecting the behavior of charged particles.
2. Electric Currents: Electric currents produce magnetic fields, and changing electric currents can disrupt existing magnetic fields.
3. External Magnetic Fields: Strong external magnetic fields can interfere with or distort the original magnetic field. This is why sensitive instruments such as compasses can be affected by nearby magnets. This is not something that is normally observed.

We have seen degraded system performance when:

• There are large chunks of metal or electronics in the space
  • Examples: refrigerator, whiteboards, radiator
• There are large metal frames
  • Examples: ceiling frames (holding panels in), metal window/door frames, large metal bookshelves

What can you do about it:

🟢 A good Coil Pro environment is expected to show the signal quality (EMF residual) that is consistently over 95% or ideally even higher. (Seen in the Studio diagnostics panel)

The easiest way to diagnose that your Coil Pro is being influenced by the environment, is by trying to use it in another location and see if the system performance improves.

When in the new location, check if the "signal quality" value in diagnostics panel seems to be better (green; as close to 100% as possible).

• E.g. have just one glove connected (+ coil), click on the glove to see diagnostics, and then move around in the environment/room (within coil range) to see how the numbers look. You want as much green/close to 100% as possible.

• Eg. In a similar way to using the glove + diagnostics to understand your space, you can also use the Coil Pro as a sort of metal detector to determine the “hotspots” and then based on this general analysis, the the optimal placement for the coil was found.

  Plug in the Coil Pro via an extension cord so you can move around. Then (after initially calibrating it in a space you feel is open and undisturbed), you can hold it up to different furniture / walls, etc. to see where it starts flashing red. The Coil flashes red when the magnetic field is disturbed by external influences, so it gives a good idea of where in the room you might experience warping. Remember to calibrate/power cycle the Coil Pro after this activity before using the product!

As an alternative to testing in another environment, if possible, you can try to optimise your existing environment by removing metallic/electronic objects from the recording area.

What Rokoko is doing about it:

Just because you’ve received the Coil Pro, doesn’t mean our development team has stopped working. We’re listening to your feedback, and are aware of the limitations caused by environmental sensitivity.

The Rokoko team is constantly working on improving the magnetic field model that is the foundation for our system accuracy, and are investigating ways where the Rokoko system can be more adaptive to the environment. These improvements will be pushed to customers in firmware and Studio updates as they are tested and validated by our team of experts.