Smart Sensing in Steering and Chassis Applications: a Digital Torque and Absolute Angle Sensor

This paper describes the operation of an advanced CMOS opto-ASIC used in a digital torque and angle sensor. Its purpose is to resolve the relative and absolute angular position of two bar-coded disks rotationally coupled by a stiff torsion bar. The resulting digital output of the sensor comprises two absolute angle measurements with up to 18-bit accuracy, and a torque measurement calculated from the difference of the two angular measurements. The measurement of torque and absolute angle in a single sensor eliminates the need for additional steering angle sensors for other vehicle dynamic systems such as dynamic stability control (DSC) or intelligent cruise control (ICC).