General Information

• Ordering information
• Sirius series architecture
• Xsens Sirius series product variants
  • Xsens Sirius IMU
  • Xsens Sirius VRU
  • Xsens Sirius AHRS

This document provides information on the usage and technical details of the Xsens Sirius series. The Xsens Sirius series robust trackers (S#X##A or S#X##B) are rugged (IP68) devices which can be connected to a host through RS232, RS422, CAN or CAN-FD interface, or through USB using the USB connection cable(included in the Sirius series Development Kit).

The Family Reference Manual supplements this document. It reports generic information on the Xsens generic products, such as output definitions, algorithm details and installation tips.

The Xsens Sirius series Hardware Integration Manual supplements this document. In this document, notes on typical application scenarios, printed circuit board (PCB) layout, origin of measurement reference system, stress related considerations, reference designs and handling information can be found.

For testing and prototyping, Xsens provides the Devlopment Kits (DK) for the robust tracker. Technical details of the Development Kit and its usage can be found in the Xsens Sirius series DK User Manual.

The MT Low Level Communication Protocol document provides a complete reference for the protocols used to communicate with Xsens Motion Trackers on a low-level basis. The MT Low Level Communication Protocol document also describes the synchronization messages and settings in detail.

Ordering information

Sirius series architecture

Xsens Sirius series module diagram

The diagram in the figure above shows a simplified architecture of the Sirius series motion tracker. The Xsens Sirius series motion tracker contains a 3-axis gyroscope, 3-axis accelerometer, 3-axis magnetometer, a high-accuracy crystal and a low-power micro-controller unit (MCU). The MCU applies calibration models (unique to each sensor and including orientation, gain and bias offsets, plus more advanced relationships such as non-linear temperature effects and other higher order terms) and runs the Xsens optimized strapdown algorithm, which performs high-rate dead-reckoning calculations up to 10 kHz, allowing accurate capture of high frequency motions and coning & sculling compensation. The Xsens sensor fusion engine combines all sensor inputs and optimally estimates the orientation at an output data rate of up to 400 Hz. The output data of the Xsens Sirius series is easily configured and customized for an application’s needs and can be set to use one of various filter profiles available within the Xsens sensor fusion engine. In this way, the Xsens Sirius series limits the load and the power consumption on the user application’s processor. The user can communicate with the module by means of three different communication interfaces; RS232 or RS422 and CAN(-FD)[1]. The USB interface is available using the USB connection cable which comes with a Development Kit or by using third party equipment (e.g. RS232 to USB converter). 

Xsens Sirius series product variants

The Sirius Robust Tracker is a fully tested self-contained module available as an:

• Inertial Measurement Unit (IMU),
• Vertical Reference Unit (VRU),
• Attitude and Heading Reference System (AHRS)

It can output 3D orientation data (Euler angles, rotation matrix or quaternions), orientation and velocity increments (∆q and ∆v), and calibrated sensor data (acceleration, rate of turn, magnetic field and pressure). Depending on the product variant, output options may differ.

Xsens Sirius IMU

The Xsens Sirius IMU Robust Tracker is an IP68 rated IMU that outputs calibrated 3D rate of turn, 3D acceleration, 3D magnetic field. The S1M43A/S1M43B also outputs coning and sculling compensated orientation increments and velocity increments (∆q and ∆v). Advantages over a simple gyroscope-accelerometer combo-sensor are the inclusion of synchronized magnetic field, on-board signal processing and the easy-to-use synchronization and communication protocol. The signal processing pipeline and the suite of output options allow access to the highest possible accuracy at any output data rate up to 2000 Hz. Moreover, the testing and calibration is already performed by Xsens and results in a robust and reliable sensor module, which enables a short time to market for the users.

Xsens Sirius VRU

The Xsens Sirius VRU Robust Tracker is a 3D VRU. On top of the functionality of the Xsens Sirius IMU, its algorithm computes 3D orientation data with respect to a gravity referenced frame: drift-free roll, pitch and unreferenced yaw. Although the yaw is unreferenced, it is superior to only gyroscope integration as a result of advanced on-board sensor fusion. The 3D acceleration is also available as so-called free acceleration, which has the local-gravity subtracted. The drift in unreferenced heading can be limited by using the Active Heading Stabilization (AHS) functionality. See Signal processing and algorithms  for more details. The raw sensor signals are combined and processed at a high frequency to produce a real-time data stream with the device’s 3D orientation (roll, pitch and yaw) up to 400 Hz.

Xsens Sirius AHRS

The Xsens Sirius AHRS Robust Tracker supports all features of the Xsens Sirius IMU and VRU, and, in addition, is a full magnetometer-enhanced AHRS. In addition to the roll and pitch, it outputs a yaw (heading) output that is referenced to the Earth's magnetic field and calibrated sensor data: 3D acceleration, 3D rate of turn, 3D orientation and velocity increments (∆q and ∆v) and 3D magnetic field data. The raw sensor signals are combined and processed at a high frequency to produce a real-time data stream with the device’s 3D orientation (roll, pitch and yaw) up to 400 Hz.

[1] RS232 and RS422 are available depending on the model, but a model with RS232 will not have RS422, and vice versa.