Development of a New High-Resolution Angle-Sensing Mechanism Using an RGB Sensor

A new high-resolution angle-sensing mechanism using a color sensor is presented in this paper. This scheme is based on a red-green-blue (RGB) sensor that measures the radiant-intensity variation of the light reflected off a colored surface. The propagation mechanism for the output of an RGB sensor due to the reflected light´s intensity on the cylindrical color track printed with the designated RGB codes from a light-emitting-diode source is discussed. The angle discrepancies due to color-printer characteristics and paper roughness are compensated for by a quarter-error compensation formula and the reference angles using a precision potentiometer. Through the performance verification of the new angle-sensing mechanism with a rotary position-control test bed in frequency and time domains, the feasibility of this new cost-effective noncontact angle-sensing mechanism is demonstrated. The bandwidth of 4.42 kHz, resolution of 0.08°, and nonlinearity of 6.63% are achieved.