Light distribution measuring device and method for crop canopy

[0039] Example

[0040] refer to figure 1 , in this embodiment, since the light sensor is to be placed on the surface of the plant leaf, it is also important to reduce the weight of the sensor while ensuring the measurement accuracy. It has high precision, but when measuring the light distribution in the field, it is easy to cause the light intensity to exceed the range. Therefore, a filter is added to the sensor. Because of the filter, it is necessary to measure the light intensity of different intensities The filter coefficient is determined to restore the collected signal to ensure that the system outputs the correct light intensity value. After measurement, the weight of a single sensor plus an optical filter is 11.90g.

[0041] Due to the limitation of data transmission, each line only allows 8 sensors, and each line is equipped with a notebook (receiving unit) to record data, and the sensors are connected by data lines with low quality, and the data lines are equipped with 15cm, 20cm and 30cm There are three lengths, the weight of the data line is 6.09g (15cm long data line) to choose in practical applications, and the data transmission protocol is the I2C bus protocol;

[0042] When measuring the crop leaves to be tested, the following steps are included:

[0043] According to the crop leaves to be measured, design the shape of the light frame and the way of fixing the frame: firstly, determine the main shape of the crop leaves for which the light distribution is to be measured. Taking corn as an example, select the corn leaves for which the light distribution is to be measured, and use a digitizer Measure the shape of its veins, select an aluminum strip of a certain length (that is, a metal strip with a weight of 0.3g/cm) to process it into a vein curve shape, the front end of the aluminum strip has 10cm to spare, and the rear end has about 80cm (according to the specific The distance between the tip of the crop blade and the ground is determined). The front end of the aluminum bar is inserted into the gap between the leaf sheath and the stem of the crop leaf to be tested and is bound and reinforced with a rope, and the rear end is inserted into the ground. The fixed aluminum bar is consistent with the shape of the leaf, and a light sensor can be placed on it. Multiple light sensors are evenly placed on the aluminum strip.

[0044] Design the measurement environment according to the specific crop growth environment: one end of the line needs to extend a sky sensor to the top of the canopy of the leaves of the crop to be measured to measure the light intensity outside the canopy, and the external sensor should be kept horizontal. The other end of each line is extended to the outside of the canopy and connected to the notebook through the data conversion port. Since the experiment needs to continuously observe the light distribution of the canopy, the notebook needs to be placed in a box to prevent excessive temperature caused by long-term sunlight exposure. There needs to be a certain distance from the measurement group to reduce the influence of the box on the light distribution of the canopy.

[0045] refer to figure 2 , Restoration of light intensity measurement data: The light intensity received by the light sensor is the light intensity filtered by the optical filter. In order to obtain the actual light intensity at the measurement position, the measured light intensity needs to be restored. Experiments have shown that the filter changes linearly for different intensities of light intensity, so the reduction formula is determined to be L=6600.0×Va, where Va is the actual measured value of the sensor, and L is the actual measured light intensity (in lux).

[0046] The sensor on the measuring device records and stores data every 3 seconds, so the measuring device can continuously detect the light intensity at the designated position of the crop canopy. The measured data can be used to verify the crop canopy simulation method, and can also be used to analyze the continuous change of the light intensity of the designated organ of the crop.