Judul: Rancang Bangun Sistem Kemudi Otomatis Traktor Pertanian Berbasis Navigasi GPS (Global Positioning System)
Abstrak: Research about the application of automatic navigation system on agricultural tractors has become one of the important research topics in the last two decades especially in the developed countries where the issue of ‘Precision Farming’ application is considered. GPS has been commonly used as the navigation system of vehicles including tractors. The objective of the research was to develop smart tractor that would work automatically based on GPS navigation for cultivation activity in precision farming. Mechatronic navigation control system for agricultural riding tractor including tractor steering, accelerator, clutch, brake system, and hydraulic control had been successfully developed using microcontrollers. GPS interfacing and data processing were also developed using Visual Basic 6.0 and functioned as the main control system. Field test was done on 40 x 20 m area with tractor velocity 0.6 m/s. The average error of control system was 17.9 cm.
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Judul: Modification of automatic navigation system on controlling tractor for dry land tillage
Abstrak: This is the advanced research concerning to the development of automatic steering system on tractor with Global Positioning System navigation (Rahman, 2013). The purpose of this research is to improve algoritm from the previous research (Rahman, 2013) for the automatic navigation following the dry land tilling trajectory. The field test has been carried out in two steps, they are test of straight line without using implement and dry land tilling test using rotary tiller. Result of the straight line test without any mechanical component changes and without using implement, shows the average error 8.62 cm and maximum error 16.77 cm, this result is much better than the previous one by Rahman (2013) because of 28.17% average error decrease. Operation by rotary tiller following the dry land tilling trajectory produces the average error of straight line 6.9 cm and maximum error 31.64 cm, this result shows that the average error has 61.45% decrease compared to Rahman’s research (2013). In this research, it has been developed a new mechanisms of onwards and backwards transmition to support the tractor movement following the new trajectory and to separate the right and left brake mechanism which the work result of 1.5 m turning radius.
Keyword: tractor., automatic navigation, algoritm

Judul: Karakteristik Kimia Kayu Reaksi Ulin (Eusideroxylon zwageri T. et B.)
Abstrak: Reaction wood which formed in hardwood generally has a lower klason lignin content, higher acid soluble lignin content, and higher syringil unit than opposite wood. Ulin wood (E. zwageri) contains high klason lignin and low acid soluble lignin contents which closed to lignin characteristic of softwood. This experimental aimed to study the difference of chemical characteristic of reaction wood (klason lignin content, acid soluble lignin content, and lignin monomer composition) and polysaccharides content which formed in E. zwageri stem. Visually, the reaction wood part was formed in upper side of leaning stem. Klason lignin content in reaction wood part was lower (32.71%) than opposite wood part (33.74%). However, the lowest lignin content was found in the side wood part (28.15%). Lignin of E. zwageri was composed by syringyl and guaiacyl monomer with average of syringil to guaisyl ratio 0,2. Acid soluble lignin content in E. zwageri was very low (0.69%) that positively correlated with the proportion of syringil unit in lignin. Polysaccharide content of reaction wood part (63.66%) was higher than opposite wood part (62.88%), but the highest content polysaccharides presented in the side wood part (64.19%).
Keyword: Polisaccharide, syringil-guaiasyl ratio, lignin, E. zwageri, reaction wood