This paper presents the automatic guidance system of an agricultural tractor and the side shift control of the attached row crop cultivator using electro-hydraulic actuators. In order to simulate the dynamic behaviour...This paper presents the automatic guidance system of an agricultural tractor and the side shift control of the attached row crop cultivator using electro-hydraulic actuators. In order to simulate the dynamic behaviour of the tractor along with the attached cultivator, the modified bicycle model was adopted. Steering angle sensor, fibre optic gyroscope （FOG） and RTK-DGPS technologies are assumed for measurements of the steering angle, yaw rate and the lateral position of the tractor, respectively. The kinematics model was used for the implement. In this study four cascade controllers were designed and simulated for tractor guidance which consists ofPD, PD, P and PID controllers. Other PI and PID controllers also had been designed for implement side shifting purpose. Then, these two systems were combined and the performance of the whole system was evaluated through the simulation results. According to the results tractor reaches the desired path after less than 10 seconds. Simulations showed that the maximum deviation of the tractor from the desired path was about 5 cm within this period. And the cultivator blades would follow the predetermined path with steady state error of about 5 cm too.展开更多
In this paper, we study the Mei symmetry which can result in a Lutzky conserved quantity for nonholonomic mechanical system with unilateral constraints. The definition and the criterion of the Mei symmetry for the sys...In this paper, we study the Mei symmetry which can result in a Lutzky conserved quantity for nonholonomic mechanical system with unilateral constraints. The definition and the criterion of the Mei symmetry for the system are given. The necessary and sufficient condition under which the Mei symmetry is a Lie symmetry for the system is obtained. A Lutzky conserved quantity deduced from the Mei symmetry is gotten. An example is given to illustrate the application of our results.展开更多
Smart grids are expected to become an essential component of the future energy system. The technical potential of smart grids is far reaching and increasingly well understood, and smart grids are now in the early phas...Smart grids are expected to become an essential component of the future energy system. The technical potential of smart grids is far reaching and increasingly well understood, and smart grids are now in the early phases of market deployment in several regions, particularly, in Europe and the US. Less understood than the technical aspects is how and to what degree end users （i.e. the customers） are willing and able to embrace smart grid technologies and the changes in mindset associated with this transition. This article reports the main findings from an lEA （International Energy Agency）-DSM （demand side management） project addressing the role of customers in a smart grid deployment scheme, specifically how customer behavior may restrict the technical potential of smart grids from being realized. With a model of household energy behavior as the theoretical point of departure, the research builds on experiences from various smart grid pilot studies, together with consumer research within similar domains, to identify behavioral challenges that are likely to hamper adoption of＂smart grid behaviors＂. Based on this insight, a set of recommendations to minimize customer resistance to smart grid deployment is suggested.展开更多
文摘This paper presents the automatic guidance system of an agricultural tractor and the side shift control of the attached row crop cultivator using electro-hydraulic actuators. In order to simulate the dynamic behaviour of the tractor along with the attached cultivator, the modified bicycle model was adopted. Steering angle sensor, fibre optic gyroscope （FOG） and RTK-DGPS technologies are assumed for measurements of the steering angle, yaw rate and the lateral position of the tractor, respectively. The kinematics model was used for the implement. In this study four cascade controllers were designed and simulated for tractor guidance which consists ofPD, PD, P and PID controllers. Other PI and PID controllers also had been designed for implement side shifting purpose. Then, these two systems were combined and the performance of the whole system was evaluated through the simulation results. According to the results tractor reaches the desired path after less than 10 seconds. Simulations showed that the maximum deviation of the tractor from the desired path was about 5 cm within this period. And the cultivator blades would follow the predetermined path with steady state error of about 5 cm too.
文摘In this paper, we study the Mei symmetry which can result in a Lutzky conserved quantity for nonholonomic mechanical system with unilateral constraints. The definition and the criterion of the Mei symmetry for the system are given. The necessary and sufficient condition under which the Mei symmetry is a Lie symmetry for the system is obtained. A Lutzky conserved quantity deduced from the Mei symmetry is gotten. An example is given to illustrate the application of our results.
文摘Smart grids are expected to become an essential component of the future energy system. The technical potential of smart grids is far reaching and increasingly well understood, and smart grids are now in the early phases of market deployment in several regions, particularly, in Europe and the US. Less understood than the technical aspects is how and to what degree end users （i.e. the customers） are willing and able to embrace smart grid technologies and the changes in mindset associated with this transition. This article reports the main findings from an lEA （International Energy Agency）-DSM （demand side management） project addressing the role of customers in a smart grid deployment scheme, specifically how customer behavior may restrict the technical potential of smart grids from being realized. With a model of household energy behavior as the theoretical point of departure, the research builds on experiences from various smart grid pilot studies, together with consumer research within similar domains, to identify behavioral challenges that are likely to hamper adoption of＂smart grid behaviors＂. Based on this insight, a set of recommendations to minimize customer resistance to smart grid deployment is suggested.
