CZ20054U1 - Circuit arrangement of ultrasonic sensor for detecting height of straw material layer while passing though harvester - Google Patents

Description

The technical solution relates to the measurement of the height of the layer of straw materials by means of ultrasonic apparatus. The height of the layer of straw, hay or cut forage can be measured directly at harvest on the harvesting machine at the entrance (collecting device), eventually. outlet (for mower). Continuous scanning of the height of the harvested material allows for immediate yield monitoring and yield map creation.

BACKGROUND OF THE INVENTION

Monitoring crop yield is an integral part of the precision farming system10. Systems operating on the principle of a contact sensor are known for harvesting stalks, especially forage crops. Utility model CZ 17560 U1 describes the possibility of detecting the instantaneous throughput of a material by a mower by sensing the torque on the agitator shaft by a dynamometer. The mower's cutter is in contact with the cut material and its power input is proportional to the amount of material passing through.

Another option is to sense the force exerted on the inclined impact plate by the strain gauge bridges on the plate which is inserted into the path as it passes through the harvesting machine (Kumhála et al. 2007, Computers and Electronics in Agricuíture). Also, continuous weighing of the transfer conveyor on mowers is another possibility of yield mapping during forage harvesting (Demmel et al. 2002, Agricultural Engineering conference (VDI)). However, the mower must be equipped with this conveyor.

However, the use of contact sensors in agriculture proves inappropriate due to the high risk of sensor destruction by foreign objects, most often by stone. Non-contact sensors for determining instantaneous crop yield are more advantageous for this purpose.

Gonigeni et al. 2002, ASAE Paper 021169 describes the possibility of sensing the amount of material passing through the camera and image analysis. Other sensors based on optical principles 25, such as a laser, are published in scientific journals.

The non-contact method of measuring the yield of harvested crops by means of a capacitive sensor, where two parallel plates are connected in the electrical circuit between which the harvested material passes - Martel and Savoie 1999, ASAE Paper No. 1, is possible. 991050, Kumhala et al. 2009, Biosystems Engineering.

The essence of the technical solution

The technical solution consists in arranging the ultrasonic sensing element in the inlet or outlet channel of the harvesting machine, which continuously measures the height of the layer of passing material.

Laboratory measurements showed an exponential dependence of the amount of material, ie the height of the layer passing through the machine during harvesting, on the output voltage of the ultrasonic sensing element. As the height of the material layer increases, the ultrasonic wave passing is reduced and the sensor output voltage is reduced.

According to the calibration curves for a particular harvested material and its moisture content, the instant crop yield can be determined.

Data from the sensor together with information about the exact position of the machine with the GPS module enable creation of yield maps of the whole plot. Data records are recorded in RAM files, from which data can be transferred to a desktop PC after work is finished.

- 2 CZ, Ul

Overview of pictures

Giant. 1. Block diagram of technical solution of sensor wiring.

Example of technical solution

The wiring of the ultrasonic transducer for determining the height of the straw material layer as it passes through the harvesting machine 5 is represented by the block diagram in Fig. 1.

The transmitting piezoelement 2 of the ultrasonic wave and the sensor 4 are located in the input, event. the output channel of the harvester on its opposite walls (piezoelement 2 on the top wall and sensor 4 on the opposite bottom wall). Thus, between the piezolelement 2 and the sensor 4, the harvested material 3 passes in the layer. The ultrasonic wave transmit piezoelement 2 is connected to the winding generator 1. Ultrasonic waves from piezoelement 2 pass through the layer of material 3 and are attenuated according to its size. The transmitted wave is detected by the sensor 4, which is connected to the operational amplifier 5. The signal from the sensor 4 proportional to the intensity of the transmitted ultrasonic wave is amplified in the operational amplifier 5 to the measured output voltage 6.

Laboratory measurements have shown that as the height of the material layer 3 increases, ultrasonic waves are attenuated and thus the output voltage 6 is reduced. The exponential dependence of the amount of material 3 on the output voltage 6 has been demonstrated.

Claims (2)

1. The connection of an ultrasonic sensor for determining the height of a layer of straw materials when passing through a harvesting machine, characterized in that in the inlet channel, event. at the top of the harvester channel, a transmitting piezoelement (2) is mounted on its top wall, which is connected to a wave generator (1), and a receiving sensor (4) for detecting the incident ultrasonic wave is located on the opposite bottom wall. The ultrasonic sensor circuit according to claim 1, characterized in that the receiving sensor (4) is connected to an operational amplifier (5) to amplify its output signal to 25 the total output voltage (6) of the circuit.