ESA GNC Conference Papers Repository
Development, Parameterization and Verification of a Generic Gyro Model
Gyros play an important role in spacecrafts, either for high accuracy pointing or for coarse Safe Mode control. Different types of gyros exist, characterized according to their measurement principles. In a gyro simulation model the performance should be expressed by a common group of parameters which are independent of the gyro type but with individual values for individual gyros. This investigation focuses on the implementation of a generic gyro model including parameterization covers various gyro types and is suitable for use as a building block for different AOCS simulators. Thus, an individually tuned model accurately represents the functions of a gyro to be used for attitude control development in space technology. The model is verified by comparing it with the data obtained in a hardware test under defined input conditions. The model development process starts with analyses of the real inputs in order to match characteristics of the simulated model environment with physical inputs. For a test on Earth, for example, the sensor axes measure parts of the Earths rotation vector as a function of the latitude of the gyro position with reference to Earth. Common characterization parameters of a gyro, such as Bias, Scale Factor and Noise (plus the so-called Angular Random Walk) were added accordingly. After implementing the model and applying a test procedure to the hardware, an initial statement about the model accuracy has been made by comparing the model output and the data obtained from the real gyro. A further evaluation applies statistical methods (such as the Allan variance) to the characterization of specific parameters from the hardware measurements and compares them with the corresponding model parameters.