Navigation systems play an important role in aerospace, in seafaring, in autonomous mobility and in navigation devices for both smartphones and cars. The STARS Laboratory (Laboratory for Sensor Testing and Assessment on a Rotation Simulator) supports the development of highly accurate navigation systems.
The development of a navigation system can be separated into different phases, starting from the requirements definition to the final tests. In the early phases of the development, Software-in-the-Loop Tests (SiL Tests) are used. They allow to adapt the filter algorithm and to verify the performance of the navigation system. An important part of the SiL Test is the mathematical model of the sensors. One task of the GPS/INS Test- and Verification Laboratory is the exact characterization of the sensors. This data provides the foundation for the mathematical sensor model used in the simulations, which turns into a higher accuracy of the navigation solutions.
Later in the development, the simulated sensor data will be exchanged with the real sensor data to verify the performance of the navigation system. These tests are called Hardware-in-the-Loop Tests (HiL Tests). To support the SiL and HiL Tests, the GPS/INS Test- and Verification Facility was build. The lab may also be made available for external customers.
The laboratory is operated by the Department of Guidance, Navigation and Control Systems at the DLR Institute of Space Systems. One of the duties of the department is to design and build navigation systems for spacecrafts. These systems often consist of several accelerometers and gyroscopes which are combined to an inertial measurement unit (IMU); additional sensors (e.g. GPS receivers, star trackers and/or Sun sensors) can be included as well. The characterization of the sensors as well as the determination of mathematical models for the sensors are key-tasks of the laboratory. These models are used in the SiL Tests to create a realistic simulation. The real sensor data is used in the HiL Tests to verify the results from the SiL Tests. For HiL testing, the laboratory offers the possibility of stimulating the sensors using the equipment listed below.
Description of the Equipment
Rotation table ACUTRONIC AC3347
The rotation table in combination with the real time system, provided by the company dSPACE, is used for the stimulation of the different sensors. Through this combination, it is possible to move the sensor using programmed positions, rotation rates or trajectories in real time and collect the synchronized data of the rotation table and sensor. This setup can be used to characterize gyroscopes, accelerometers or IMUs as well as provide measurements for Hardware-in-the-Loop Tests. A set of large doors can be opened to allow an unobstructed view of the night sky for the verification of star trackers.
Specification of the rotation table:
GPS Simulator Spirent GSS 7700
The GPS simulator offers the possibility to test GPS receivers. Additionally, by connecting the GPS simulator to the real-time system and the rotation table, it is possible to test more complex systems.
Specification of the GPS simulator:
Sun Simulator neonsee
The sun simulator can be used in combination with the rotation table to test and characterize Sun sensors.
Specification of the Sun simulator: