Absolute Photoelectric Encoder and Its Adoption in Fertilizing Corn Machinery in Ridge Planting

Abstract

Absolute photoelectric encoder has the advantages of output data only corresponding to one position, requiring absolute zero position, no need to search for zero position after power failure and restart, and no cumulative error. Firstly, the principle of the traditional absolute photoelectric encoder is analyzed, and the matrix code plate is adopted to complete the production of the 16-bit absolute photoelectric encoder code plate, which reduces the volume of the high digit encoder. Then, K9 glass is chosen for the material of code plate and slit plate, which has good light transmittance and can improve the precision of photoelectric encoder. Giving that that the performance of light source of photoelectric encoder directly determines the accuracy of photoelectric encoder, bullet SE2470 light-emitting diode is selected as the emitting light source. It has a beam angle of 18 degrees and a large operating temperature range, supporting the working wavelength of 880 nm. The receiving light source is set as the bullet photosensitive triode SD2440, which has low power consumption, with 48 degrees of receiving angle, can be directly mounted to the double-sided PCB board. Finally, the designed absolute photoelectric encoder is used in the ridge corn mechanical fertilization system, and the system controller adjusts the opening of proportional valve through the motor speed signal fed back by the photoelectric encoder. In the experiment, the absolute photoelectric encoder is tested with the help of serial debugging assistant. When the encoder does not rotate the serial port, the output data of the assistant does not change. When the encoder rotates, the result change after receiving a lot of data due to the high baud rate. The error of each fertilization tube in the mechanical fertilization system of ridge planting corn is less than 3%, the coefficient of variation is less than 0.05, and thus the economic benefit of fertilization is improved.