Abstract This paper describes a method which determines the parameters of an object orientation in 3D space. The rotation angles calculation bases on the signals fusion obtained from the inertial measurement unit (IMU). The IMU measuring system provides information from a linear acceleration sensors (accelerometers), the Earth’s magnetic field sensors (magnetometers) and the angular velocity sensors (gyroscopes). Information about the object orientation is presented in the form of direction cosine matrix whose elements are observed in the state vector of the non-stationary Kalman filter. The vector components allow to determine the rotation angles (roll, pitch and yaw) associated with the object. The resulting waveforms, for different rotation angles, have no negative attributes associated with the construction and operation of the IMU measuring system. The described solution enables simple, fast and effective implementation of the proposed method in the IMU measuring systems.

The article considers the step and impulse response of second-order linear systems with a positive zero. A particular parameterization of the system equations is proposed which enables good assessment of the influence of its parameters on transients. Expressions missing in the literature are derived for step response parameters such as the values of undershoot, overshoot, time of inverse response, rise time and settling time, as well as of impulse response. Based on them, a precise time-domain approach to design feedforward, feedback and mixed feedback– feedforward control structures for nonminimum phase objects is presented that considers both setpoint tracking and disturbance rejection.