An experimental study has been conducted to investigate the effects of vane-type vortex generators in affecting the flow pattern of the wake region using a 1:20 scale tractor-trailer model. The de Haviland wind tunnel of the University of Glasgow was employed in this study. Surface oil flow visualisation, smoke visualisation and twocomponent time-averaged particle image velocimetry measurements...

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...

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 Bessel beam without an axial gradient can exert a pulling force on an object [A. Novitsky, C. W. Qiu, and H. Wang, Phys. Rev. Lett. 107, 203601 (2011)]. However, it cannot be called a "tractor beam" per se, as long as the light pulling effect is ultrasensitive to the object's material and size, a perturbation of which will make the optical traction go away. In this Letter, we investigate and ...

measurement of the values of forces in tractor arms is of great importance due to draft of agricultural equipment. these values can be used for testing and evaluation of the agricultural machinery, selection of suitable tractor, etc. the tools which are used for measurement of the forces are called dynamometer. the main objective of the present study was to design and evaluate a load cell for i...

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...

There are competing economic goals when plowing a farm field. The rows must be level, to reduce erosion. The rows should also perfectly abut each other, so that no land is wasted on gaps and no fuel is wasted on overlapping areas. With todays GPS-guided tractors, it has become worthwhile to try to produce an optimal tractor path, knowing that a tractor can actually be programmed to follow it. T...

In agriculture, a typical task is to do a coverage operation for a field. Coverage path planning algorithms can be used to create the path for a vehicle. In case of an autonomous agricultural vehicle, the path is provided to the guidance or navigation system that steers the vehicle. In this paper, a four wheel steered tractor is used in autonomous sowing operation. The full size tractor is equi...