| 摘要 |
For each axis, a cyclic transducer has a scale supplied with a sinusoidal signal from a timing unit and a cursor which provides two output signals which are proportional to the sine and to the cosine, within the elementary interval of the transducer. Sin alpha and cos alpha and the corresponding inverted signals are supplied to squaring circuits and logic which generates a three-bit number in a register defining the octant (000 to 111, i.e. 0 to 7) within which the electric angle alpha lies. The three-bit number controls multiplexers each having inputs for quadrants 0 to 7 and feeding respective sample and hold circuits and whose signals are NUM and DEN. An analog-to-digital converter system forms the digital value n=NUM/DEN and n along with the lowest order octant bit address a ROM which outputs the value of alpha within the range of a quadrant. A microprocessor responds to the higher two bits to create the final value of alpha . The microprocessor also keeps count of the integral displacements of elementary intervals. The apparatus enables alpha to be determined instantaneously, thereby eliminating the following error of known apparatuses when alpha is changing. |
