A rotational speed estimation method for an incremental encoder includes generating a plurality of pulse signals according to a plurality of square waves, detecting a time duration when the pulse signals reach a predetermined amount, and generating a rotational speed of a disc according to the predetermined amount, the time duration, and the total number of pulses corresponding to one rotation of the disc of the incremental encoder.

There is provided an optical encoder with alignable relative positions between elements including an encoding medium, a sensor package and a memory. The sensor package includes a photodiode array and two alignment photodiodes opposite to the encoding medium. The memory records an alignment pattern associated with output signals of the two alignment photodiodes when the encoding medium and the sensor package are at nominal operating positions. When the encoding medium and the sensor package are not at the nominal operating positions, the relative position alignment is performed by adjusting current relative positions between the encoding medium and the sensor package to cause a current pattern associated with output signals of the two alignment photodiodes to be identical to the alignment pattern.

A vehicle system includes a base, a seat rotatably disposed on the base, a magnet generating a magnetic field, and a sensor. The sensor is programmed to measure an angular displacement of the seat relative to the base based at least in part on an orientation of the magnetic field generated by the magnet.

A vehicle system includes a base, a seat rotatably disposed on the base, a magnet generating a magnetic field, and a sensor. The sensor is programmed to measure an angular displacement of the seat relative to the base based at least in part on an orientation of the magnetic field generated by the magnet.

A vehicle system includes a base, a driver seat rotatably disposed on the base, a sensor, and a processor. The sensor is programmed to measure an angular displacement of the driver seat relative to the base and output a displacement signal representing the angular displacement. The processor is programmed to receive the displacement signal and select at least one of a plurality of passive safety devices based at least in part on the angular displacement represented by the displacement signal and only deploy the selected passive safety devices during a collision.

A vehicle system includes a base, a driver seat rotatably disposed on the base, a sensor, and a processor. The sensor is programmed to measure an angular displacement of the driver seat relative to the base and output a displacement signal representing the angular displacement. The processor is programmed to receive the displacement signal and select at least one of a plurality of passive safety devices based at least in part on the angular displacement represented by the displacement signal and only deploy the selected passive safety devices during a collision.

A vehicle system includes a base, a seat rotatably disposed on the base, a sensor, and a processor. The sensor is programmed to measure an angular displacement of the seat relative to the base and output a displacement signal representing the angular displacement. The processor is programmed to receive the displacement signal and deploy at least one passive safety device based at least in part on the angular displacement represented by the displacement signal.

A vehicle system includes a base, a seat rotatably disposed on the base, a sensor, and a processor. The sensor is programmed to measure an angular displacement of the seat relative to the base and output a displacement signal representing the angular displacement. The processor is programmed to receive the displacement signal and deploy at least one passive safety device based at least in part on the angular displacement represented by the displacement signal.

A vehicle system includes a base, a seat rotatably disposed on the base, a sensor, and a processor. The sensor is programmed to measure an angular displacement of the seat relative to the base and output a displacement signal representing the angular displacement. The processor is programmed to receive the displacement signal and deploy at least one passive safety device based at least in part on the angular displacement represented by the displacement signal.

A vehicle system includes a base, a seat rotatably disposed on the base, a sensor, and a processor. The sensor is programmed to measure an angular displacement of the seat relative to the base and output a displacement signal representing the angular displacement. The processor is programmed to receive the displacement signal and deploy at least one passive safety device based at least in part on the angular displacement represented by the displacement signal.