| 摘要 |
PURPOSE:To enhance resolution at the time of A/D conversion by setting the range for subjecting the output of a turning angular speed sensor to A/D conversion such that it corresponds with the inherent output range of the sensor considering no offset drift. CONSTITUTION:When a vehicle is parked while idling the engine, a differential amplifying section 20 is not fed with an analog value of reference voltage and thereby no corrected gyro output is produced. A multiplexer section 21 outputs a selected gyro 1 output. It is subjected to A/D conversion 23 and fed through a switch SW1 to a reference voltage calculating section 24 where an average value is determined over a predetermined time and stored 25 as a digital value of reference voltage. When a vehicle is running, a switch SW3 is conducted and the digital value of reference voltage being stored 25 is subjected to D/A conversion and fed to the amplifying section 20. The amplifying section 20 subtracts the analog value of reference voltage from the gyro output and the difference is amplified specifically before being delivered as a corrected gyro output. It is then subjected to A/D conversion 23 and delivered to an azimuth operating section through a switch SW2. |
