Introduction

The DOT sensor is a small motion-tracking sensor, which comes in a small box with 5 sensors. The sensor measures 3D angular velocity, 3D acceleration and 3D earth magnetic fields. Currently, the DOT is used in various fields, like sports, health, ergonomics and entertainment. Examples of applications are, for example, rehabilitation therapy, risk control on the work floor, sports analysis, and new fitness technology.

In the box

After opening the box, you will find a container with five small DOT's. This case is not only a good way to store the sensors, it is also used to charge them by plugging a cable into the side of the container. When looking further, you will also find a small envelope with different patches. These patches can be used to 'glue' the sensors to the skin of a user. Another way to attach the sensors is to use the black bandages that can be found in the 'Xsens DOT' box in the Media Lab. It is recommended to use the bandages since these can be used for an unlimited amount of time.

How to get started

The DOT app

The DOT app is developed by Xsens for a quick start with the sensors. Inside the app, the dashboard allows you to connect the sensors, rename them and identify them. Here you can also see the battery status of your sensor. After connecting a sensor, the ‘Measure & Collect’ section allows you to actually use your sensors. Select ‘Real-time Streaming’ to stream the data in real life. The ‘recording’ option allows you to record a session, after which you can download the .csv file for further analysis. Don’t forget to first clear the memory of your DOT sensors.

Connecting to the sensors

1. Make sure the sensors are charged. If not, plug a USB cable connected to a power supply into the container of the DOT sensors. It is also possible to attach a single sensor to the cable, while you're using it.
2. Turn on your Bluetooth and open the App. It will now automatically try to pair with your sensors.
3. Switch on the sensors by toggling the slider. The list elements will now appear orange. By clicking on a sensor in the list, you can view specific information about the sensor. You can also change its name or identify which of your DOT sensors corresponds to the list item.

You can switch off the DOT by pressing the sensor for 3 seconds.

Measuring data

1. Click the 'Measure & Collect' tab on the bottom of the screen
2. This will provide you with two options: a) 'Real-time Streaming' to stream data in real-time, or b) 'Recording' to store the data on your phone.
3. a) For 'Real-time Streaming'. Select the sensors that you want to use. Next the app lets you chose between different measuring modes, which will lead to different combinations of data. The sensor Fusion Mode includes orientation and free acceleration, whereas Intertial Data Mode includes acceleration, angular velocity and magnetic field. In the custom mode option, you can choose options yourselves. For more information about each of the options, check the DOT sensor manual, as referenced at the bottom of this page. After selecting a measuring mode, click 'apply' to start the recording. Graphs will be showing the data that you chose in your settings.
4. b) For 'Recording'. Select the sensors that you want to use. The app will show an overview of the storage space of each of your sensors and provide the option to clear the memory. Next, select 'start recording' to begin your measurement. After this, it is not necessary to maintain a Bluetooth connection between the sensors and your phone anymore. To stop the recording, press the sensor for 1 second or click 'stop recording' in the app. Click the export button in the top right corner to export a CSV file for each of your sensors.

The KineXYZ app

The KINEXYZ app is developed especially for the DOT sensors. It provides a development tool where you can build 3D interactive systems to capture and process the movement of both people, animals and other flexible structures. Inside the app, you can create your model with simple pre-made parts, it’s just a matter of dragging and connecting elements. It is also possible to use (build-in) mathematical models to analyse the structure or to implement a more realistic relationship between each of the elements.

Important: The app can only be used on an Ipad with iOS 13.0 or later.

Below are two examples of what the KineXYZ application looks like: KineXYZ demo and a live demo

The Xsens DOT SDK

1. Download the software here. On the website, enter your mail information and the file will be sent to your mailbox.
2. Extract and open the folder. Open the Xsens DOT SDK Programming Guide for Android. This contains all the information you need to get started with the SDK. The file also contains very useful examples that you can follow to get going with the DOT. The folder also contains a file named Xsens_DOT_SDK_Core_Android.aar.
3. Download Android Studio. Select file > new > new project. From the pop-up select Empty Activity. Provide a name and a location, and check if the minimum SDK is at least 26. Click finish.

4. Import the AAR file from the download into your environment. Select file > new > New Module. When the pop-up opens, scroll to the bottom and select Import JAR/AAR Package, and import the aar. file. If this is not working, refer to the following site
5. Select File > Project structure. In the pop-up, go to dependencies and click on the + plus sign. Here, select the JAr/AAR Dependency option. Now, specify where your aar package is located, and confirm.

6. Your SDK is now correctly set up!

Useful links and documents

The developer page on the Xsens website is a good starting point if you want to develop your own application with the DOT sensor. The website provides a user manual, a download link for the Xsens DOT SDK and useful tutorials to get started with your sensors, with the app, the output data and the SDK environment. More information can be found here, on the Xsens DOT forum

Comparing different motion sensors