Photoelectric encoder in the application of the car

Photoelectric encoder is by means of optical and electrical signal output shaft mechanical geometry and displacement quantity again into pulse or digital sensor, is now the most sensors, photoelectric encoder device is grating plate, combined with the photoelectric detection device in the photoelectric encoder, has its unique application circuit, so that it has good performance, at the time of measuring angles and distance can have a very strong anti-jamming capability, but also make it a stable pulse signal, therefore, the pulse signal after statistics can be converted to used to measure the digital signal. A lot of vehicle driving simulator, also can choose photoelectric encoder as the sensor, it can measure the rotation of the steering wheel Angle, the output circuit is the collection electrode is open type, there is a certain output resolution, because the car steering wheel is a two-way, clockwise and counterclockwise rotation, before counting need to identify its phase encoder output signal. When the photoelectric encoder clockwise rotation, channel output waveform leading channel B output waveform 90 degrees, D flip-flop output Q ( Waveform W1) For the high level, Q ( Waveform W2) As the low level, the nand gate open, counting pulse through ( Waveform W3) , sent to the two-way counter 74 ls193 plus pulse input CU, in addition to count; At this point, the nand gate closed, the output of high level ( Waveform W4) 。 When counterclockwise photoelectric encoder, channel A output waveform than the channel delay output waveform 90 B & deg; D flip-flop output Q ( Waveform W1) For the low level, Q ( Waveform W2) As the high level, the nand gate closed, the output of high level ( Waveform W3) ; At this point, the nand gate open below, the counter pulse through ( Waveform W4) , sent to the two-way counter 74 ls193 pulse input reduction CD, to count by subtraction. When the car steering wheel clockwise and counterclockwise, the maximum rotation Angle are two and a half circle, choose a resolution of 360 pulse encoder/circle, its maximum output pulse number is 900; Actual use of the counting circuit with three pieces of 74 ls193 in initialization when the system is powered on, first to reset ( The CLR signal) , and then its initial value is set to 800 h, 2048 ( LD signal) ; So, when the steering wheel clockwise, counting circuit output in the range of 2048 ~ 2948, when the steering wheel counterclockwise, counting circuit output in the range of 2048 ~ 1148. Counting circuit of data output D0 ~ D11 sent to the data processing circuit. When we actually use the encoder, the steering wheel clockwise and anti-clockwise rotation frequently, because there are errors in some detail aspects, after a period of time after work, the wheel back when counting circuit output is not 2048, but there are several digital deviation; If you want to solve the deviation, we added a steering wheel in the back to the encoder detection circuit, after system of processing, the data of the simulator is not running, under the condition of system to detect the circuit in the back, the steering wheel in the back, and counting circuit data output is not 2048, can be reset to the counting circuit, and to set the initial value.