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Silva Balcanica, 14(1)/2013

CONTROL OF THE WORK PRECISION ΙΝ THE LAND LEVELING MACHINERY

Ploutarchos Kararizos, Euaggelos Karagiannis, Metaxia Kalaitzi

Department of Forest Engineering and Surveying, School of Forestry and Natural Environment, Aristotle University of Thessaloniki

Abstract

Ιn the earth moving procedures, such as land leveling, where crops require-ments are increased, strict control of the work precision, of the appropriate machin-ery and the methods applied is required. In this paper was calculated the leveling precision in two experimental plots, in the area Skoutari in Serrers, with two differ-ent application methods (classical and modern). The results have shown that during the land leveling with laser (modern method), the 84% of the recorded readings (el-evations and coordinates) presented deviation within ±1 to ±3 cm from the desired grade level, whereas during the conventional land leveling, was only 62% during the same deviation.

Key words: land levelling, control of the work precision, grade deviation, land leveling methods

INTRODUCTION

The work precision of earth-moving machinery is generally one of the most important factors that influence greatly the performance, the quality and the low production cost. Particularly, in soil processing works such as its leveling it is ex-ceptionally useful to carry out a strict control of the work precision, the suitable ma-chinery and the application methods, for the utilization of all advantages of modern technology so that the wanted leveling precision is ensured (Tsatsarelis, 2006)

Recently, for the precise land leveling in USA as well as in Europe is broadly used modern machinery equipped with laser devices (Fangmeier et al., 1999) where-as at the same time the classic machinery is also used (graders). The differences, as concerns the precision, between both methods are significant, with the modern methods (laser beams) presenting more advantages in relation to the classic ones. Es-pecially in irrigation with inundation (surface irrigation), where a controlled amount of water is channeled into flat earthen surfaces, the precise land leveling is necessary for obtaining equally-shared distribution of water (Dedrick, 1979)

During the precision leveling (by laser technology) significant advantages but also some disadvantages, may arise such as:

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AdvantagesThe leveling precision degree affects severely the yield per hectare (Williams,

2004);A larger area is cultivated resulting to the bigger production between the em-

bankments in the crops (Ellis, 1982);A significant saving of water is obtained resulting to the reduction of the av-

erage cost production of 6,3% - 15,4% for all cultivations (El-Sahrigi et al., 1993) The cost reduction, as a result of the precision leveling, emerges from the smaller required amount of water and from the more effective usage of herbicides and fertil-izers due to their rational application (Cooke et al., 1996);

The precision leveling improves the uniformity of sowing and the maturity of plants while at the same time it also increases the productivity of plants in compari-son to the classic leveling (Hinz et al., 1978).

DisadvantagesThe disadvantages of the precision leveling by laser technology are also dis-

advantages of the classic leveling method:It is observed a decrease of the soil’s content in nutrients such as K, Na, P,

Zn, Mg, and Ca which are detected in the first 10 cm of the soil, in its deeper layers, whereas at the same time the pH and the proportion of the organic substance is re-duced. The decrease of the overall N is the result of the organic substance in the soil surface (De Sousa et al., 1993);

The compression of the subsoil from the use of heavy vehicles (laser-con-trolled) due to the many courses they run within the field, limits the development of the rooting system resulting to the difficult absorption of nutrients, a fact that affects the yield of plants (Kundu et al., 1997).

What was calculated and compared in this paper was the precision of land leveling in two experimental sites in the area of Skoutari, Prefecture of Serres, with two different application methods (classic and modern).

MATERIALS AND METHOD

In October 2010, two experimental sites of 2.6 and 2.8 ha respectively, were delimitated and established in the area of Skoutari, Prefecture of Serres, where land leveling works were in progress.

MaterialsIn the first experimental site of 2.6 ha the modern laser technology method

with a drag scraper type CAT 140M equipped with electronic settings has been used while in the second one of 2.8 ha the classic method with the same drag scraper has been used. According to the FAO classification 1989/1990 the kind of the soil was Fluvisols (FL).

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For the surveying of both surfaces, is has been used a GPS connected to a computer as well as to electronic settings such as a tripod with laser transmission device and a receiver adjusted to the machine.

The AccuGrade Laser is an elevation control system designed for precise grade control with tight tolerances using a laser transmitter and receiver(s). A laser transmitter is set up on the work site and creates a constant grade reference over the work area. A digital laser receiver is mounted on the machine and senses the laser signal as the machine moves across the work site. The system captures elevation information and calculates the blade adjustments necessary to achieve grade. The system makes automatic elevation adjustments typically performed by the operator and provides automatic blade control to one or both sides of the blade. The opera-tor simply steers the machine. The system also calculates cut/fill requirements for manual blade control. When combined with AccuGrade Cross Slope, the single laser system provides automatic blade adjustments to one side of the blade for automatic control of elevation and cross slope. When two laser receivers are used, the system provides automatic elevation control to both sides of the blade for fine grading with tighter tolerances. A laser transmitter is mounted on a tripod so the laser beam can rotate unobstructed above the machine. The laser transmits a plane of light above the work area, which allows several machines to work effectively in any direction using one laser transmitter. An all-new digital laser receiver is mounted on an electric mast above the cutting edge and is used to detect the laser beam. The receiver picks up the position of the laser’s reference plane position relative to finish grade and measures height deviation from the on-grade location to the laser beam strike. The receiver sends blade position information back to the system to calculate necessary adjust-ments. A full 360 degree laser detection range allows the receiver to pick up the laser signal from any direction on the work site while the machine is working. The type of the laser receiver used was LR400-C.

The type of GPS which has been used is Topcon Hiper Pro. The dual fre-quency and GPS features of Hiper Pro, combine to provide a real kinematic (RTK) system accurate for short and long baselines.

MethodBy the assistance of GPS and the electronic settings there have been delimi-

tated and recorded (coordinates and altitudes) 65 spots in the first site and 70 spots in the second site.

For the measurements, the operator of the Grader, using the GPS connected to a computer, has been listing the coordinates inside the experimental site whereas for the altitudes, it has been used the system where the laser transmission device was fit-ted on a tripod outside the experimental site at a height 1.50 cm above ground and the mast with the receiver was adjusted on the machine at the same height. The grader with the laser device was moving cross-wise within the farm taking spots every 20 meters. From the respective altitudes of the spots measured by the assistance of the

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laser, the height of the instrument has not been taken into account and so the altitude difference of spots points from the reference level has arisen. By the statistical analy-sis of the altitude differences their average has come out.

After the leveling of the experimental sites with both methods (modern, clas-sic) there have been recorded by the assistance of GPS and the laser instrument the altitude deviations of the points that were recorded before land leveling, from the average term of the altitude differences, from the reference level. For the safety and the precision of recording the altitude deviations, the same tripod with the laser transmitter was used outside the experimental sites and within the sites the mast with the receiver.

RESULTS AND DISCUSSION

The overall number of points recorded in the first site (2.6 ha) before level-ing with the modern method, was 65 and the aggregate of altitude differences was 330.04 cm. The average of altitude differences would equal to: 330.04:65 = 5.49 cm (Fig. 1). In the same way there have been also recorded the spots in the second site (2.8 ha) before the leveling with the classic method, where the overall number of spots was 70 and the aggregate of altitude differences was 384.25 cm. The average of altitude differences would equal to 384.25:70 = 5.48 cm (Fig. 2). Outlining all spots found to be above the average (Fig. 1, 2) the operator is assisted to determine the most effective way of leveling with the appropriate courses.

5.55 5.52 5.54 5.47 5.47 5.38 5.46 5.54 5.57 5.46 5.47 5.48 5.57

5.62 5.50 5.47 5.52 5.53 5.39 5.49 5.52 5.51 5.53 5.41 5.49 5.52

5.57 5.59 5.66 5.51 5.48 5.45 5.57 5.49 5.43 5.42 5.46 5.47 5.48

5.47 5.45 5.58 5.50 5.53 5.57 5.64 5.59 5.39 5.35 5.39 5.44 5.45

5.59 5.54 5.49 5.47 5.42 5.48 5.59 5.67 5.38 5.44 5.50 5.56 5.57

27.80 27.60 27.74 27.47 27.43 27.27 27.75 27.51 27.28 27.20 27.23 27.44 27.59

Fig. 1. Altitude differences (cm) of spots, from the reference level, before the leveling of the surface with laser technology

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5.58 5.64 5.36 5.51 5.52 5.56 5.54 5.40 5.50 5.54 5.48 5.43 5.51 5,53

5.53 5.53 5.42 5.40 5.50 5.52 5.61 5.46 5.48 5.40 5.53 5.37 5.47 5,60

5.49 5.59 5.47 5.63 5.46 5.44 5.56 5.35 5,44 5.46 5.50 5.41 5.42 5,56

5.44 5.40 5.59 5.55 5.57 5.38 5.47 5.57 5.51 5.60 5.38 5.49 5.46 5,59

5.56 5.42 5.51 5.44 5.65 5.30 5.58 5.34 5.46 5.42 5.45 5.52 5.54 5,36

27.60 27.58 27.35 27.53 27.70 27.20 27.76 27.12 27.39 27.42 27.34 27.22 27.40 27.64

Fig. 2. Altitude differences (cm) of points, from the reference level, before the site leveling with grader

In Fig. 3 and 4 are illustrated the altitude deviations (with both methods) from the average of altitude differences, from the reference level, of the same points which have been recorded.

+3.2 +1.0 -1.5 +1.4 -1.0 +1.0 +0.8 -1.5 -1.0 -1.6 -1.1 -1.5 +1.5

+1.6 +2.3 -1.0 -0.9 -1.0 +0.8 +1.3 -1.8 -1.0 +0.7 +0.5 -3.2 +1.7

+1.5 +2.3 -1.0 +1.3 -1.5 +1.0 +0.6 -2.1 -1.0 +1.5 +2.3 -2.1 +1.2

-1.1 +3.3 +1.5 -2.3 -1.2 +1.0 +1.0 -0.7 -1.8 +3.3 +1.0 -3.8 -3.1

-3.6 +3.2 +1.8 +1.3 +2.3 +1.2 -2.1 -1.1 +3.9 +1.5 +1.3 -3.6 -1.5

Fig. 3. Altitude deviations from the average of altitude differences in the site that was leveled by laser-controlled machinery

+1.5 +2.2 -1.0 -1.0 -0.9 -1.7 -1.0 +2.9 -1.0 -1.9 -1.9 +3.3 +1.1 +1.0

+3.7 +1.9 -3.6 +3.7 +3.8 -3.5 -3.5 +1.5 -3.4 -3.7 +1.5 -3.2 +3.3 +1.5

-3.6 -3.2 +1.7 +1.6 -3.7 +3.1 -1.8 +2.7 -1.3 -1.8 +3.2 -2.1 +1.0 -1.0

-2.5 -3.6 +3.6 +1.5 -1.0 -3.5 +2.6 +1.3 +0.7 +0.7 -3.2 -1.5 +3.7 -3.5

-1.8 -1.0 +1.3 -1.6 +1.4 +1.5 +1.0 +1.5 -3.8 -3.3 -3.8 +2.6 -2.6 +3.2

Fig. 4. Altitude deviations of the points from the average of the altitude differences in the site on which was used the classic leveling method

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For the comparison of the precision of both methods three deviation classes were set (<±1 cm, ±1 to ±3 cm, >±3 cm). From the study of the spots of Fig. 3 and 4, Table 1 and Fig. 5 have arisen.

Table 1. Percentage (%) of precision of the two leveling methods in three altitude deviation classes

Percentage (%) of precision in 3 classesLeveling method <±1 cm ±1 to ±3 cm >±3 cmModern (laser) 32 84 100

Classic 19 62 100

Fig. 5. Percentage (5) of precision of the two leveling methods in relation to the altitude deviation

From the study of data of Table 1 and Fig. 5, it seems that the biggest precision percentage (%) is shown in both leveling methods in third class where the deviation is >±1 cm from the average altitude differences of the spots for leveling. The small-est percentage (19%) is shown in first class of the classic method where the deviation is <±1 cm from the average altitude differences of the spots for leveling.

From Fig. 5 it seems that the difference of the precision percentage of the mod-ern method in respect to the classic method is 13% and 22% for the first (<±1 cm) and the second class (±1 to ±3 cm) respectively. Based on international practice for the minimum accepted quality of leveling, the 80% of the points of leveled surfaces must belong to the second class (deviation ±1 to ±3 cm). From the results of research it arises that the precision of leveling with the modern methods responds to this rule whereas the precision of leveling with the classic method does not respond.

CONCLUSIONS

The modern leveling method with laser technology, due to the great precision, has many advantages because it improves the efficiency which is the most important and necessary factor for the reduction of the production cost.

The sensitivity of laser is more precise than the visual and manual hydraulic

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control of the operator in the classic method and consequently operators with fewer qualifications and less experience may have very good results.

The precision of land leveling depends on the application method, the disper-sion of the spots on the surface before the leveling and the size of fluctuation of the altitude differences. However, in no case thee percentage of precision of the laser technology method is decreased even though the fluctuation of altitude differences is bigger in respect to that of the classic method.

REFERENCES

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Dedrick, A.R.1979. Land – Leveling Precisio Attained with Laser – Controlled Drag Scrapers. ASAE paper, 79 – 2565.

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Fangmeier, D.D, A.J. Clemmens, M. El-Ansary. 1999. Influence of land leveling precision on level – Basin advance and Performance Transactions of the ASAE 42(4),1019-1025.

Hinz, W. W., Halderman A.D. 1978. Laser beam land leveling costs and benefits. Bull. No A 114. COOP. Ext. Ser, Tuscan Arizona, 19-23.

Kundu, D.K., Ladha, J.K. 1997. Effect of growing rice on nitrogen mineralization in flooded soil. Soil Sci. Soc. Am, J. 61, 839-845.

Tsatsarelis, K. A, 2006. Managing of Farm Machinery. Giahoudi-Giapouli Publications. Thessaloniki p. 30-37

Williams, J. 2004. Rice Land Formation, California Rice Production, Workshop, January 2004, p. 4-7

E-mails: pkarariz@for.auth.gr, eakarag@for.auth.gr, xeniakal@for.auth.gr