Research regarding the possibility to increase the precision farm, using detection sensors and gps in the work technologies

RESEARCH REGARDING THE POSSIBILITY TO INCREASE THE PRECISION FARM, USING DETECTION SENSORS AND GPS IN THE WORK TECHNOLOGIES

CERCETARI PRIVIND POSIBILITATILE DE CRESTERE A PRECIZIEI IN PROCESELE AGRICOLE UTILIZAND SENZORI DE DETECTIE SI ECHIPAMENTE GPS

Abstract: The paper presents the research carried out in the Agricultural Machinery laboratory, regarding the possibilities to increase work efficiency using the sensor for tools guidance and GPS equipments for the geo-reference position in the working process of the agricultural machines.

The tests was developed in order to improve the sensors for displacement and position detection of the tools in the working process. The laboratory tests of the laser and ultrasonic detection sensors and GeoGPS device used for scanning the land offer promising opportunities in order to increase the precision of the agricultural work.

Key words: GPS, laser, detector, test, logger

1. State of the Arts

The precision farming represents the most efficient way for increase the quality and for reduces the operating time for most agricultural works. The electronics revolution of the last several decades has spawned two technologies that will impact agriculture in the next decade. These technologies are Geographic Information Systems (GIS) and Global Positioning System (GPS). Along with GIS and GPS there have appeared a wide range of sensors, monitors and controllers for agricultural equipment such as shaft monitors, pressure transducers and servo motors. Together they will enable farmers to use electronic guidance aids to direct equipment movements more accurately, provide precise positioning for all equipment actions and chemical applications and, analyze all of that data in association with other sources of data (agronomic, climatic, etc). This will add up to a new and powerful toolbox of management tools for the progressive farm manager.

Precision farming should not be thought of as only yield mapping and variable rate fertilizer application and evaluated on only one or the other. Precision farming technologies will affect the entire production function (and by extension, the management function) of the farm.

Some benefits of this concept are exemplified by [ ]:

Yield monitoring instantaneous yield monitors are currently available from several manufacturers for all recent models of combines. They provide a crop yield by time or distance (e.g. every second or every few meters). They also track other data such as distance and bushels per load, number of loads and fields.

Yield mapping with GPS receivers coupled with yield monitors provide spatial coordinates for the yield monitor data. This can be made into yield maps of each field.

Variable rate fertilizer express by variable rate controllers are available for granular, liquid and gaseous fertilizer materials. Variable rates can either be manually controlled by the driver or automatically controlled by an on board computer with an electronic prescription map.

Weed mapping the farmer can map weeds while combining, seeding, spraying or field scouting by using a keypad or buttons hooked up to a GPS receiver and data logger. These occurrences can then be mapped out on a computer and compared to yield maps, fertilizer maps and spray maps.

Variable spraying by knowing weed locations from weed mapping spot control can be implemented. Controllers are available to electronically turn booms on and off, and alter the amount (and blend) of herbicide applied.

Topography and boundaries using high precision DGPS a very accurate topographic map can be made of any field. This is useful when interpreting yield maps and weed maps as well as planning for grassed waterways and field divisions. Field boundaries, roads, yards, tree stands and wetlands can all be accurately mapped to aid in farm planning.

Guidance systems; several manufacturers are currently producing guidance systems using high precision DGPS that can accurately position a moving vehicle within a foot or less. These guidance systems may replace conventional equipment markers for spraying or seeding and may be a valuable field scouting tool.

Records and analyses precision farming may produce an explosion in the amount of records available for farm management. Electronic sensors can collect a lot of data in a short period of time. Lots of disk space is needed to store all the data as well as the map graphics resulting from the data. Electronic controllers can also be designed to provide signals that are recorded electronically. It may be useful to record the fertilizer rates actually put down by the application equipment, not just what should have been put down according to a prescription map. A lot of new data is generated every year (yields, weeds, etc). Farmers will want to keep track of the yearly data to study trends in fertility, yields, salinity and numerous other parameters. This means a large database is needed with the capability to archive, and retrieve, data for future analyses.

Two research directions were connects in order to assure the harvest machines work parameters :

GPS device used for detect the position of agricultural machines and for realized the geo references (digitized) map of the land;

The position sensors used in order to identify the network place of the tools for increase the ability to adjust the kinematics parameters according with the crop conditions.

If this approach represents an usual practice for most European countries, for our conditions the purpose of this approach represent a challenge which must be developed and adapted to our land and technologies conditions.

2. Description of GPS equipment and software applications

For measurement purposes, GPS Pathfinder Pro produced by Trimble was employed. This comprises the following: receiver and antenna, recon with display, handling stick and connection cable (Fig. 1).

The described GPS equipment has as operating systems Windows Mobile. In order to do preliminary setting of the equipment as well as the measurements itself TerraSync

software application from Trimble is used. This application allows some simple operations, prior and subsequent to measurements, finally result a new file in a format compatible and acceptable within GIS. Graphic user interface (GUI) of TerraSync main window application, having few measured points is shown in figure 2.

The file format generated by TerraSync application is then imported to ArcView software application from ESRI. This format allows marking of an electronic map, geo referenced in any wanted geographical coordinates system. On this map precise dimensions and positions of measured points could be read.

Measurement itself carried out using GPS equipment are preceding by main working parameters setting: coordinates system, measurement zone, altitude measurement checkpoint etc. Within this preliminary stage data dictionary file is set, this being the file that stores the effective data measured using GPS equipment.

After preliminary setting the measurement are done, the file is saved, visualization and eventual data sorting being done, all followed by file conversion for import in ArcView software application. Operations diagram described above is shown in figure 3.

The accuracy of the GPS position set was verified using a simple evaluation of five points arbitrary considered and a zero reference point. Two devices were used for measure the distance between the references point and the other five's considered points: the Trimble GPS and a metric wheel (conventional measurement). The differences between two measuring method used are presented in table no.1.

For relative error calculation the following relation was used:

                              (1)

where V_conv is the value measured by conventional means and Vgps is the value measured by GPS equipment means.

Table 1. Comparative values of measured data.

From the previously carried out experiments we can see that GPS equipment can get the utility in the harvest machine position mapping. In the absences of the yield mapping, this device it is bale to offer the basic information regarding the coordinate of the land and assure also the geo references of the machine in the crop process.

3. Sensors used in the harvest process

In order to evaluate the possibilities for an automatic management of the harvest machines work process, different sensor was tested in the laboratory conditions.

One of the most promising sensor for harvest application is the L-Gage sensor (fig. 4).  The L-GAGE LT3 sensor uses "time-of-flight"technology for precise, long-distance gauging at the speed of light. The microprocessor-controlled laser distance-gauging sensor features a unique design for exceptional accuracy and range at a much lower cost than competitive laser-gauging devices. Precise performance make the LT3 an ideal solution for a variety of precision inspection applications. Important technical characteristics are:

. Available in accurate diffuse-mode models with ranges to 5 m and retroreflective models with a 50 m range;

• Emits one million pulses per second;
• Reliably detects angled targets;
• Sensing Ranges: 1 2 3 4 5 . . . 50 m;
• Diffuse models with white targets: 0.3 - 5 m;
• Retroreflective models with retroreflector: 0.5 - 50 m;
• Diffuse models with gray targets: 0.3 - 3 m;
• Radiant power 0.15mW; 10ns PULSE, 1MHz 650 - 670 nm;

The sensor was tested in laboratory conditions in order to identify the time response in accordance with the work conditions for harvesting machines. One of the first test was carried out for evaluate the sensor possibilities to work with a logger interface in order to achieve data from the measurements and for find the time response according with kinematics parameters of the harvest process.

Using a voltage supply and an oscilloscope HM 507, the laboratory tests confirm the initial considerations regarding the sensor capability to identify with high precision the distance, in real time response.

Some possibilities for use the laser sensor in the harvest process are presented in table 2.

Table 2. Application of the laser sensor in the harvest process

The possible applications are:

A - control of the header position in the harvest process, according with the cutting device type and the yield conditions. In this respect, the sensor sensitivity assures the possibility to adjust the header highest in real time;

B - grain tank load detection represents a parameter which offers information regarding the quantity crop and the average production rate of the land;

C - regarding the combine speed detection, some conditions of the work process must be considered: the yield shape, the harvest machine speed and the weeds uncutted which decrease the resolution of the detection. In this respect, ultrasonic sensor is more appropriate for use;

D - other application consist in the straw detection as a possibility to evaluate the harvest process efficiency.

Conclusions

The precision farming represents a challenge for all specialists in this field. The various industrial sensors designed with different technical parameters cover several applications for manage the harvest process.

The three step connection: sensor - GPS - logger interface, assure a real time harvest control and the possibility to adjust in real time the harvest machine work conditions.

The tests carried out in the Harvest machines laboratory of our faculty will be developed in order to evaluate also the ultrasonic and radar sensor as a possible devices for assure the most efficient work conditions for the combines.

Other application of the tested sensor regarding the precision farming purpose will be developed in the future, according with the farmer needs.

References

[1]. Coldea, C., Filip, N. The GPS used for precision detection. In the volume V, Acta Technica Napocensis, pag. 235, Cluj - Napoca, 2007.

[2]. Filip, N., Masini Agricole de Recoltat. Editura Todesco, Cluj - Napoca, 2003.

[3]. Raj Khosla, Sensor in Yeld Monitoring, In Agronomy News revue of Colorado State University, volume 22, USA, 2002.

[4]. * * * Turck Industrial Automotion. Product catalogues and technical documentation, 2006.