So called automatic guidance systems are becoming more common in agricultural tractors, so that a driver does not need to steer the vehicle. The systems are mostly relying on GPS with correction. However, these systems usually steer only the tractor itself, despite the fact that the implement is the one that has to be run side by side with the previous swath. With towed implements, or trailers,...

Original scientific paper The slip, the resistance to rolling and pulling force are interconnected. The influence of tyre wear on the tractor pulling force and slip on three different grounds was observed. The tangential force was measured by dynamometers fixed to tractor driving half-axle. The pulling force on the pulling rods was measured by dynamometer fixed to the pulling force. The tractor...

Tractor overturning remains a serious problem in agricultural activities. A detailed analysis of problems and causes leading to a tractor overturn have revealed that by improving tractor’s static stability we can positively infl uence the safety as early as during the concept phase. We designed a mathematical model and a numerical simulation of the static stability of a tractor with an oscillat...

Accurate guidance of towed implements is important for performing agricultural field operations and for gaining the ultimate benefit from an agricultural automatic guidance system. The study of open and closed loop system responses can be helpful in the design of practical guidance controllers. A dynamic model of a tractor and a towed implement system was developed. Open loop analysis of the ki...

An optimal reconfiguration control scheme based on control allocation CA is proposed to stabilize the yaw dynamics of the tractor-semitrailer vehicle. The proposed control scheme is a twolevel structure consisting of an upper level of sliding mode yaw moment controller SMYC and a lower optimal brake force distributor BFD . The upper SMYC is designed to follow the tractor yaw rate and the combin...

Low-cost GPS receivers provide geodetic positioning information using the NMEA protocol, usually with eight digits for latitude and nine digits for longitude. When these geodetic coordinates are converted into Cartesian coordinates, the positions fit in a quantization grid of some decimeters in size, the dimensions of which vary depending on the point of the terrestrial surface. The aim of this...

A capture-mark-recapture study was conducted in crop fields in Morogoro, Tanzania, to investigate how the population dynamics of multimammate field rats, Mastomys natalensis, was influenced by the commonly practised land preparation methods and cropping systems. Two land preparation methods (tractor ploughing and slash and burn) and two cropping systems (mono-cropping with maize and inter-cropp...

This article documents the extent of children's involvement in tractor operations among a representative sample of Kentucky children living and working on family farms. Specifically, we describe children's exposures to tractor-related work activities, profile their use of the tractor (number of days worked), and assess compliance with generally recommended safety measures, such as using tractor...

This paper presents a method to develop a system, which will enable an autonomous agricultural vehicle to follow a leading vehicle with a given lateral and longitudinal offset. With the aid of the RTK GPS systems the position of the leading tractor was obtained every 500 ms with accuracy in the range of centimeters. To provide the target position for the guidance of the following agricultural v...

Power hop is a “porpoising” type of pitch/bounce oscillation superimposed on the forward motion of tractors equipped with pneumatic tires. It is most often observed with tractors having two powered axles pulling towed implements in moderate to high draft field operations on dry soils. As power hop begins, the tractor exhibits gradually increasing vibration amplitudes until the operator, of nece...