While the automatic detection of MTw trackers in the MVN Awinda is great for including any MTw tracker you'd want to your system, it can also cause a small challenge when you want to connect a specific set of tracker to one Awinda station, and use a second Awinda station for another set of trackers. When you want to do a multiperson setup with 2 MVN Awinda systems, this will be the case. Therefore, this article will describe how to set this up.
In Xsens MVN there are 4 tabs for MVN systems on the left side of the configuration window; 1 for each subject/actor. For each tab, the settings from the previous use are remembered (like name, system type, scenario, body dimensions and props). This can be useful when you are capturing the same subjects multiple times. With this setting it will also be easy to work with a multi-person setup, because you can link each subject to a specific tab, including the appropriate settings.
Connecting 2 MVN Awinda systems:
- In a multiperson setup with 2 MVN Awinda systems it is important to first only switch on the trackers of 1 complete MVN Awinda system. Keep the trackers of the second MVN Awinda system switched off for now. Plug in the Awinda station of the first system.
- Connect the first MVN Awinda system in the software and check (or alter) the radio channel (see figure below).
- Click OK in the configure session window and proceed with the Npose+Walk (or Tpose+Walk) calibration for this first system. Apply the calibration and make sure that you initialize the system properly by walking around and waving the arms a bit in the first 20 seconds of the live connection.
- Now, setup the second MVN system by connecting the second Awinda station and switch on the accompanying trackers. Make sure to choose a radio channel that is at least 2 channels apart of that of the first Awinda station, to avoid wireless cross talk between both systems.
- Continue to calibrate also this system.
Aligning the 2 MVN systems:
by sharing the same coordinate frame in terms of both orientation and position
For both MVN systems to share the same coordinate frame (=same orientation) in MVN 2018 there are 2 options:
- After processing the calibration the software will prompt you to apply the calibration. At the moment of clicking apply (see figure below), let your subject face a certain direction. This direction will become your X axis when you hit "Apply". Do this after the calibrations of both systems.
- work with 2 calibrated (and proper initialized) live systems. Have your subjects stand next to each other or one standing behind the other one, and have them face to the same direction. A third person clicks Task > Axis Reset (CRTL+ALT+A, see figure below).
For correct position data between both MVN systems, you need reset both avatars to the origin. When moving the character to the origin, the origin is placed underneath the back of the right heel. Therefore, your subjects need the put the back of their right heels together. At that time, click Tasks > Move Character to Origin (CRTL+0, see figure above). Also, see this tutorial on setting Character to Origin.