Real-time monitoring of the mass flow rate of granular materials in the seeder tube using a piezoelectric sensor

Document Type : Research Paper


1 Department of Biosystems Engineering, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran

2 Department ofBiosystems Engineering, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran

3 Department of Agricultural Machinery Engineering, Faculty of Agricultural, University of Tehran, Karaj, Iran


It is difficult to accurately measure the flow rate of seeds and fertilizers in grain drills, because the granules move in a continuous dense state. The purpose of this research was to monitor the mass flow of granular materials in the fall tube of the drill using a piezoelectric sensor. The laboratory system consisted of a repository box, a fluted roller metering device, a fall tube, and a piezoelectric sensor. To simulate the drill movement in the field, a vibrating stand was designed to oscillate the set-up in two perpendicular directions. The maximum amplitude stand was 8.99 cm according to the peaks and depressions available in a field after plowing. The sensor was evaluated in two static and dynamic modes for wheat seed, alfalfa seed, and triple superphosphate fertilizer with the usual drilling rate. The results showed the output signal of the sensor was proportional to all different mass flow rates in both static and dynamic states. The correlation coefficient was 0.95, 0.99, and 0.98 in static mode and 0.93, 0.86, and 0.98 in dynamic mode for wheat, alfalfa seed, and triple superphosphate fertilizer, respectively. In addition, the piezoelectric sensor could instantaneously monitor the sudden changes in the mass flow according to the reading of the digital scale. The results showed that the developed sensor can be used to monitor the mass flow rate of seeds and fertilizers in drills for calculating the drilling rate in real time.


Main Subjects

Real-time monitoring of the mass flow rate of granular materials in the seeder tube using a piezoelectric sensor




In the modern agriculture, the two key issues determining the economic efficiency of arable land and industrial equipment utilization are the challenge of obtaining a uniform grain distribution over the entire field and the detection of drill tube clogging (Yatskul et al., 2017). Solving both issues allow for increasing the efficiency of food production while reducing the use of herbicides, seeds, fertilizers, and water. Practically, since grains move in a dense state, it is difficult to measure accurate grains flow rate. While optical measurement methods have been used to monitor the mass flow of seeds (Besharati et al., 2019), However, due to the existence of dust inside the drill tube, they are not reliable enough. As an alternative, a piezoelectric sensor can be used to measure the flow rate of seeds or granular fertilizers. Nevertheless, literature review shows that few research works utilized piezoelectric sensors for this purpose (Seminara et al., 2011; Maleki et al. 2008). Therefore, in this study, a measuring system was developed to monitor the mass flow of granular materials in the drill applicator's tube.

Materials and Methods

A laboratory set-up was developed to measure the mass flow of granular materials, avoiding the potential error available under field conditions. It consisted of a piezoelectric impact plate installed beneath a drill tube. To simulate the field condition, a vibratory stand was designed according to the drill oscillating, while traveling across the field. Then triple superphosphate in 5 application rates from 3.42±1.22 to 19.3±0.95 g/s, wheat seed in 8 application rates from 2.65±0.23 to 19.02±0.86 g/s, and alfalfa seed in 7 application rates from 0.42±0.02 to 1.6±0.08 g/s in 30 s time lap were measured in both static and dynamic conditions. The sensor performance in seed flow measurement would be appropriate if changes in obtained voltage data set from the sensor comply with granular grains mass changes measured by the digital scale. The standard deviation index was employed to evaluate the sensor performance in the instantaneous detection of mass flow rates.

Results and Discussion

The results showed that the mass flow was correlated with piezoelectric sensor signals for all examined materials. The sensor could monitor the mass flow rates of wheat (R2=0.98), alfalfa (R2=0.99), and triple superphosphate fertilizer (R2=0.99) both in static and dynamic conditions. According to the results, the sensor could effectively measure the mass flow both under static and dynamic conditions for wheat seeds from 2.65±0.23 to 14.22±0.78 g/s (80.16±11.56 to 430.18±23.59 kg/ha) and for triple superphosphate fertilizer from 3.75±0.42 to 15.14±0.63 g/s (113.44±10.27 to 458.01±18.75 kg/ha) at speed of 7 km/h and 17 cm inter-row spacing.  Also, according to the results obtained, the sensor could effectively measure the mass flow under dynamic condition for alfalfa seeds from 0.42±0.02 to 1.57±0.08 g/s (16.61±0.79 to 62.10±3.16 kg/ha) at speed of 7 km/h and 13 cm inter-row spacing. Since the alfalfa seeds had nearly fine sizes, it was necessary to increase the sensitivity of the sensor, which made it possible to monitor the mass flow well in the static condition, but due to the decrease in the signal-to-noise ratio, the performance of the sensor decreased in the dynamic condition. These results were proved by analysis of variance and compare means test. In addition, the more accurate instantaneous mass flow sensing, the less variation in standard deviation was calculated over the examined time for both sensor and digital scale signals.


The piezoelectric impact sensing system is acceptably used to estimate the seed mass flow rate according to the strong linear relationship between the actual seed mass changes and the system-acquired voltages Results showed that the developed sensor can be used in practical sowing to detect the seed flow rate on grain drills.



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