A nongyroscopic inertial measurement unit

This paper describes a concept of a low-cost gyroless inertial measurement unit. By means of an orthogonal triad of rotating or vibrating accelerometers, angular rates are measured along with specific forces. The precise separation of the two signals from the accelerometer readings is described. Apart from its simplicity, the special features of the separation method are that signal bandwidth is not sacrificed, inertial angular rate measurements are essentially drift-free, and dynamical errors due to angular rate and specific force derivatives are reduced to negligible values. A detailed statistical analysis of the error sources, due to dynamical effects, sampling, nonlinearities, and vibration is given. The residual angular rate offset is due to the electronic processor which, with modern CMOS components, is shown to provide a performance level in the 1 n.mi./h class. The possibility of dispensing with the costly gyroscopes, which are essential in conventional designs, indicates a substantial saving in cost.