Progress 09/01/20 to 12/31/21

Outputs
Target Audience:The focus of this research is the development of a novel planting technology for vegetable, flower and specialty crop growers.Theprimary work of this research is aimed at a solution for small and medium size growers although the core technology is scaleable to large growers. Specifically, the small field system this research supports will be beneficial to part-time growers who often require off-farm income to survive. It will save them time that can be applied to other value added activity. Changes/Problems:Technical objective #3 originally planned to test the portable backpack unit on four surfaces: paved, bare prepared soil seedbed, prepared seedbed with plastic mulch, and an untilled surface simulated a no-till surface.The intent was to test forperformance variations that these surfaces might create.However, because we were not able to achieve a repeatable performance of the system using the Laponite RD material in the lab, an experiment to compare the affect of different surfaces was not viable so we did not conduct this comparison. The primary problem that we identified is that the Laponite RD material's behaviour is unpredictable and is the main cause of the low performance of the system. Typically, when more than one seed is queued to be extruded, the performance is to either extrude more than one seed or to extrude one seed and then skip a seed. Two options for solving this issue were identified:1) an alternative fluid that can be better controlled or 2) a low-cost, non-contact method of detecting the flow of the gel. Also, we change our design from a backpack system to a cart-based system. This was required because the distance the fluid would need to flow from the back of a person to the planting location was too long for the low pressure system to push the gel. If the pressures were raised, we risked the thixotropic gel's viscosity dropping multiple orders of magnitude. What opportunities for training and professional development has the project provided?Our team has learned how to use the BeagleBone Black's programmable real-time units to control the planter's operation with a deterministic processor. We also gained experience working with a non-Newtonian thixotropic fluid. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Commercial vegetable, flower, and specialty crop growers face challenges obtaining labor regardless of the scale of their operation. These challenges make it more difficult for these growers to remain in business and provide fresh, quality products to consumers. The impact of this project isto providea less labor-intensive approach to planting these crops by creating a precision system to germinate and plant germinated seeds. The system can potentially replace or minimize the labor, energy, and capital-intensive process of growing and transplanting seedlings. In addition to labor savings, the systemreduces fossil fuel use and improves soil health by lowering soil compaction with a lighter weight, all-electric approach. In Phase I, our goal is to design and build a proof-of-concept backpack gel planter for small and mid-size farms by completing three essential research objectives. A key aspect of this work is to devise a method for handling wet, growing seeds in a batch, and placing one and only one seed at every planting location. The broader impact of this research project provides the base for solutions that will apply to any scale farming operation. The backpack system will significantly reduce the seasonal labor required to plant these crops. On large-scale farms, a future embodiment of the solution will be an autonomous system that will eliminate planting labor substantially (>90%), reduce the system's weight by 75%, and eliminate the use of on-farm fossil fuels during planting entirely. A method is required to move germinated seeds into the soil that does not damage the living, growing seed.And, further, seeds must be deposited individually at the precise planting location and spacing required for optimal production. The engineering research team considered ergonomic factors such as weight, which can include pumps, valves, power sources, and motors when designing the fluid-seed delivery system. Technical Objective #1: We designed and built a lab-scale platform to test the hypothesis that we could manage the seed-gel fluid flow without using fluid pumps and valves, therefore, lowering the overall system weight. We completed the design and prototype of the test platform, including custom electronic interfaces between air valves, sensors, and switches, and microcomputer platform. Control and data collection software was written in C on the Linux operating system. In addition, we designed and fabricated an index table that rotates Petri dishes into position under the fluid outlet, which synchronized the Petri dishes' positioning with extrusion of discrete samples. The system extruded multiple samples of a concentration of Laponite RD and water into Petri dishes. We weighed each dish to determine the amount of fluid extruded and completed regression analysis on the data to assess the consistency of the fluid amount in each sample. No seeds were in the gel during these tests. Further, our study indicated that sample weight declined with time consistently. Since the gel is non-Newtonian, it exhibits thixotropicproperties, making identifying theprocess values challenging. Therefore, we began to study this fluid more closely and conducted a literature review as an aid. We found limited publications on the Laponite material and sought help from the distributor with minimal success. Our conclusion from examining the data is that we could not predict a uniform gel extrusion every time. This non-uniformity is because the fluid's viscosity within a container varies, and therefore the flow rate of the fluid also varies. However, we observed that we could stop and start the flow of the gel solely using our control approach.Thus, although we did not meet the original test goal of this objective, we learned how to control the fluid flow to meet the needs of the overall solution. Technical Objective #2: We began work on Technical Objective #2 with an existing optical sensor design and collected data from this sensor as the gel-seed mixture passed through the detector sub-assembly. We used a constant concentration of Laponite RD in water and mixed 'Celebrity' tomato variety seeds with it in a 4 ml/seed or 6 ml/seed concentration. We used the test platform developed in Technical Objective #1 to flow the seed-gel mixturepast the original sensor arrangement and the BeagleBone Black microcontroller collected data. The data was loaded into Excel, and basic statistics were calculated on each signal believed to represent a seed. Although the data we collected was promising, the results led us to explore three alternative designs to the sensor arrangement to determine if better signals to identify a seed could be obtained. For these different arrangements, we collected signal data from the sensors and analyzed it for key characteristics that would allow the signal to be designated as a seed. We also began to record videos of the seed-gel flow so that signals could be matched to the data. This matching was completed manually through an onscreen review of the video. We conducted multiple tests and collected multiple sets of data. We also analyzed this data to determine any characteristics that might discern a seed from a bubble. Although we conducted multiple experiments with multiple sensor arrangements, we were not able to obtain a extrusion of only one seed 95% or better. Typically, we reached a success rate in the 65-80% range. We can reliably detect seeds, stop the flow and then plant a single seed. However, the primary issue is with extruding a seed that might come right after the extruded seed. The thixotropic nature of the gel material makes it difficult to predict how long it will take to get it moving again. Consequently, it is not possible to reliably extrude a seed detected while another seed is being extruded without knowing this information. Attempts to use an average delay value did not provide good results. Technical Objective #3 Finally, as the results of technical objectives #1 and #2 were obtained, we began to design the backpack proof of concept to be used for actual field testing in Technical Objective #3. We constructed the backpack and proved it can be built with lighweight components. However, the length of tubing required to flow the seed-gel mixture from a person's back to the ground is too long and the low pressures being used would not result in a seed being output on the soil. Therefore, we modified the design into a cart which shortened the tubing and enabled the system to extrude the seed-gel mixture. The system is still lightweight and portable. However, since the we were not able to reliably extrude only one seed every time, we did not test operation on multiple surfaces as comparing the results would be meaningless. We performed a basic test on a paved surface and learned that the sensor system must be shielded from sunlight to perform properly and that the LED indicators selected for the controls are very visible in bright sunlight. Further the proof of concept system is easy to handle although aligning with the desired planting location can be tricky. Improvements in this area will be required.

Publications

Progress 09/01/20 to 08/31/21

Outputs
Target Audience: Nothing Reported Changes/Problems: Technical Objective #1 provided a greater understanding of the impact of the viscosity fluctuation of the Laponite RD-based mixture. At the start, we expected to extrude a precise fluid volume by turning on the flow for a constant time and not have to determine the flow rate instantaneously. However, results from this work proved this would not be possible without expensive (~$1000) miniature flow meters. Therefore, we had to seek another way to understand the flow rate near instantaneously. After determining a method to approximate the instantaneous flow rate, we recognized this approach as advantageous. It also revealed that the machine could track the variations in flow rate over time and use this information in the control algorithm to adjust its operation to extrude seeds and gel more precisely. Essentially, it will be learning how to manage each unique batch of gel and seeds during planting. This ability is essential as each batch will likely have slightly different characteristics. The results from using our initial optical detector system led us to investigate three alternative approaches that we thought might give better signals for use in our control system. These investigations were in line with our objective to extrude one and only one seed because a definitive identification of seed at a point in space is necessary to extrude a single seed at the right time. After some initial signal analysis, we hypothesized that multiple detectors might better discern seeds from bubbles. We developed mounting arrangements for multiple sensors and took numerous data sets from them using the test platform. These additional experiments helped us determine that multiple detectors and detector geometries were not significantly beneficial in discerning a tomato seed from a bubble. And we also observed that the bubbles are not a significant problem in this fluid. We used clear tubing to transport the seed-gel mixture and learned that over time the clarity of the tubing we were using initially degrades. This discovery led us to contact the manufacturer and obtain samples of a better formulation of this tubing for our application. After several months of use, the clarity is still acceptable. However, we did not suspect the tubing was the problem when the initial issue occurred because its clarity did not appear to have degraded. Therefore, we investigated all aspects of the system as the cause of the test platform's degraded performance. (We could not reliably detect a seed at all when just a week before we had been detecting them at acceptable error rates.) This systematic review revealed a mistake in LED sourcing that was corrected and the addition to our detector circuitry that allows the signals to be tuned more precisely. What opportunities for training and professional development has the project provided?The work has provided an excellent opportunity to learn how to use the BeagleBone Black's programmable real-time unit (PRU) processors and the Texas Instruments' protocol for communication between the PRU and the main processor programs that can run under Linux. The BeagleBone Black uses the Texas Instruments AM355x family of system-on-a-chip (SOC) processors. The main processor runs Debian Linux, and programs run in a non-deterministic mode under Linux, even when given high priority. The non-deterministic program operation results in occasional, unpredictable delays reading sensors and missing seeds in the flow and is unacceptable. The PRU runs programs in a deterministic method and isa solution to this issue. Through self-study using many online resources, we gained knowledge of using the PRU and the detailed configuration of the analog-to-digital-converter (ADC) also in the SOC. This expanded understanding of the various components of the TI AM355x system-on-a-chip (SOC) will significantly benefit future solution development for the planting system. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? The next reporting period will cover the conclusion of this research work. We will complete the control software required to test extruding one and only one seed from the gel-seed batch by incorporating the signals from the detector system to provide the control signals necessary to extrude the seed. This work will complete Technical Objective #2. Finally, the control software will be incorporated into the backpack system, and a field-level test of the backpack system will be conducted as planned to evaluate the ability to extrude one and only one seed from the gel-seed batch under actual field conditions.

Impacts
What was accomplished under these goals? Commercial vegetable, flower, and specialty crop growers face challenges obtaining labor regardless of the scale of their operation. These challenges make it more difficult for these growers to remain in business and provide fresh, quality products to consumers. The impact of this project isto providea less labor-intensive approach to planting these crops by creating a precision system to germinate and plant germinated seeds. The system can potentially replace or minimize the labor, energy, and capital-intensive process of growing and transplanting seedlings. In addition to labor savings, the systemreduces fossil fuel use and improves soil health by lowering soil compaction with a lighter weight, all-electric approach. In Phase I, our goal is to design and build a proof-of-concept backpack gel planter for small and mid-size farms by completing three essential research objectives. A key aspect of this work is to devise a method for handling wet, growing seeds in a batch, and placing one and only one seed at every planting location. The broader impact of this research project provides the base for solutions that will apply to any scale farming operation. The backpack system will significantly reduce the seasonal labor required to plant these crops. On large-scale farms, a future embodiment of the solution will be an autonomous system that will eliminate planting labor substantially (>90%), reduce the system's weight by 75%, and eliminate the use of on-farm fossil fuels during planting entirely. A method is required to move germinated seeds into the soil that does not damage the living, growing seed. And, further, seeds must be deposited individually at the precise planting location and spacing required for optimal production. The engineering research team considered ergonomic factors such as weight, which can include pumps, valves, power sources, and motors when designing the fluid-seed delivery system. Technical Objective #1: We designed and built a lab-scale platform to test the hypothesis that we could manage the seed-gel fluid flow without using fluid pumps and valves, therefore, lowering the overall system weight. We completed the design and prototype of the test platform, including custom electronic interfaces between air valves, sensors, and switches, and microcomputer platform. Control and data collection software was written in C on the Linux operating system. In addition, we designed and fabricated an index table that rotates Petri dishes into position under the fluid outlet, which synchronized the Petri dishes' positioning with extrusion of discrete samples. The system extruded multiple samples of a concentration of Laponite RD and water into Petri dishes. We weighed each dish to determine the amount of fluid extruded and completed regression analysis on the data to assess the consistency of the fluid amount in each sample. No seeds were in the gel during these tests. Further, our study indicated that sample weight declined with time consistently. Since the gel is non-Newtonian, it exhibits thixotropicproperties, making identifying theprocess values challenging. Therefore, we began to study this fluid more closely and conducted a literature review as an aid. We found limited publications on the Laponite material and sought help from the distributor with minimal success. Our conclusion from examining the data is that we could not predict a uniform gel extrusion every time. This non-uniformity is because the fluid's viscosity within a container varies, and therefore the flow rate of the fluid also varies. However, we observed that we could stop and start the flow of the gel solely using our control approach.Thus, although we did not meet the original test goal of this objective, we learned how to control the fluid flow to meet the needs of the overall solution. Technical Objective #2: We began work on Technical Objective #2 with an existing optical sensor design and collected data from this sensor as the gel-seed mixture passed through the detector sub-assembly. We used a constant concentration of Laponite RD in water and mixed Celebrity tomato variety seeds with it in a 4 ml/seed concentration. We used the test platform developed in Technical Objective #1 to flow the seed-gel mixture past the various sensor arrangements, and the BeagleBone Black microcontroller collected data. The data was loaded into Excel, and basic statistics were calculated on each signal believed to represent a seed Although the data we collected was promising, the results led us to explore three alternative designs to the sensor arrangement to determine if better signals to identify a seed could be obtained. For these different arrangements, we collected signal data from the sensors and analyzed it for key characteristics that would allow the signal to be designated as a seed. We also began to record videos of the seed-gel flow so that signals could be matched to the data. This matching was completed manually through an onscreen review of the video. We conducted multiple tests and collected multiple sets of data. We also analyzed this data to determine any characteristics that might discern a seed from a bubble. Although technical objective #2 was not completed at the end of this reporting period, through these various experiments, we have determined using a single sensor works sufficiently for the proof of concept and that bubble detection is not a requirement at this time. Technical Objective #3 Finally, as the results of technical objectives #1 and #2 were obtained, we began to design the backpack proof of concept to be used for actual field testing in Technical Objective #3. Many of the components were obtained off the shelf, and custom components were designed and printed using a 3D PLA printer.

Publications