Standard Disk Plough(SDP)is the integral element of traditional farming system in Middle and Northern Sudan.In SDP,the tilt angle between the planes of the cutting edge of the disk which is inclined to a vertical line...Standard Disk Plough(SDP)is the integral element of traditional farming system in Middle and Northern Sudan.In SDP,the tilt angle between the planes of the cutting edge of the disk which is inclined to a vertical line may be altered according to the field conditions.Tractor drivers usually use an angle close to maximum in order to decrease the tillage depth,consequently decreasing power requirements,without considering the tillage quality and the impact on the soil properties.This experiment was conducted at the College of Agricultural Studies farm of Sudan University of Science and Technology to study the effects of three tilt angles(15°,20°and 25°)on soil bulk density,mean weight diameter,wheel slippage,work rate(or effective field capacity)and soil volume disturbed using mounted disk plough.The nature of soil on the farm found to be light clay.The theoretical forward speed was maintained at 6 km/h.The results showed that increasing tilt angle of the plough significantly(p<0.05)increased the bulk density,mean weight diameter and field capacity while significantly decreasing the tractor wheel slippage and soil volume disturbance.展开更多
In this study we mainly focus on the attitude control problem of a quad tilt rotor aircraft with respect to unknown external disturbance. We propose a class of control methods based on a novel logarithmic fast non sin...In this study we mainly focus on the attitude control problem of a quad tilt rotor aircraft with respect to unknown external disturbance. We propose a class of control methods based on a novel logarithmic fast non singular terminal sliding surface a new fast reaching law and extended state disturbance observer. A logarithmic non singular terminal sliding surface is used owing to its convergence in finite time and significant robustness. A fast reaching law with two order characteristics of the sliding mode is designed. This reaching law can be used reduce the convergence time of traditional reaching law. In addition the extended state disturbance observer is utilized for online estimation and to compensate for system disturbance. The simulation experiment results show that the control strategy proposed in this paper outperforms the traditional non singular fast sliding mode control.展开更多
基金Thanks for the financial support from The National Maize Industry Technology R&D CenterMechanized corn(CARS-02)production system optimization technology and equipment research demonstration projects(200903059).
文摘Standard Disk Plough(SDP)is the integral element of traditional farming system in Middle and Northern Sudan.In SDP,the tilt angle between the planes of the cutting edge of the disk which is inclined to a vertical line may be altered according to the field conditions.Tractor drivers usually use an angle close to maximum in order to decrease the tillage depth,consequently decreasing power requirements,without considering the tillage quality and the impact on the soil properties.This experiment was conducted at the College of Agricultural Studies farm of Sudan University of Science and Technology to study the effects of three tilt angles(15°,20°and 25°)on soil bulk density,mean weight diameter,wheel slippage,work rate(or effective field capacity)and soil volume disturbed using mounted disk plough.The nature of soil on the farm found to be light clay.The theoretical forward speed was maintained at 6 km/h.The results showed that increasing tilt angle of the plough significantly(p<0.05)increased the bulk density,mean weight diameter and field capacity while significantly decreasing the tractor wheel slippage and soil volume disturbance.
文摘In this study we mainly focus on the attitude control problem of a quad tilt rotor aircraft with respect to unknown external disturbance. We propose a class of control methods based on a novel logarithmic fast non singular terminal sliding surface a new fast reaching law and extended state disturbance observer. A logarithmic non singular terminal sliding surface is used owing to its convergence in finite time and significant robustness. A fast reaching law with two order characteristics of the sliding mode is designed. This reaching law can be used reduce the convergence time of traditional reaching law. In addition the extended state disturbance observer is utilized for online estimation and to compensate for system disturbance. The simulation experiment results show that the control strategy proposed in this paper outperforms the traditional non singular fast sliding mode control.
