Patent attributes
A sensor for measuring yaw rate or roll rate of an automotive vehicle comprises a freely rotating inertial disk and an angular rate sensor responsive to the rotation of the inertial disk relative to a housing. In one embodiment the inertial disk presents an alternating magnetic field at its circumference. The rate and direction of rotation of the inertial disk relative to its housing is determined by three magnetic field sensors such as linear Hall Effect sensors responsive to the field presented by the inertial disk. In another embodiment electronic cameras measure movement of fiducial marks on the inertial disk. Air surrounds the inertial disk and air viscosity gradually brings rotation to a stop. For yaw rate measurement the disk axis is oriented vertically and the inertial disk is supported in the radial direction by low friction bearings such as ball bearings or magnetic bearings and in the axial direction by substantially frictionless bearings such as magnetic bearings. In certain embodiments two magnetic poles operate as both axial and radial bearings. For the purpose of sensing incipient or actual vehicle rollover, the axis of the inertial disk is oriented in the direction of the roll axis of the vehicle. The angle of a recent rotation and rate of rotation of the inertial disk relative to the housing indicate the angle through which the vehicle has recently rotated about its roll axis and the roll rate of the vehicle.
