This research aims at using a dynamic model of tractor system to support navigation system design for an automati- cally guided agricultural tractor. This model, consisting of a bicycle model of the tractor system, ha...This research aims at using a dynamic model of tractor system to support navigation system design for an automati- cally guided agricultural tractor. This model, consisting of a bicycle model of the tractor system, has been implemented in the MATLAB environment and was developed based on a John Deere tractor. The simulation results from this MATLAB model was validated through field navigation tests. The accuracy of the trajectory estimation is strongly affected by the determination of the cornering stiffness of the tractor. In this simulation, the tractor cornering stiffness analysis was identified during simulation analysis using the MATLAB model based on the recorded trajectory data. The obtained data was used in simulation analyses for various navigation operations in the field of interest. The analysis on field validation test results indicated that the developed tractor system could accurately estimate wheel trajectories of a tractor system while operating in agricultural fields at various speeds. The results also indicated that the developed system could accurately determine tractor velocity and steering angle while the tractor operates in curved fields.展开更多
An aircraft tractor plays a significant role as a kind of important marine transport and support equipment. It＇s necessary to study its controlling and manoeuvring stability to improve operation efficiency. A virtual...An aircraft tractor plays a significant role as a kind of important marine transport and support equipment. It＇s necessary to study its controlling and manoeuvring stability to improve operation efficiency. A virtual prototyping model of the tractor-aircraft system based on Lagrange＇s equation of the first kind with Lagrange mutipliers was established in this paper, According to the towing characteristics, a path-tracking controller using fuzzy logic theory was designed. Direction control herein was carried out through a compensatory tracking approach. Interactive co-simulation was performed to validate the path-tracking behavior in closed-loop, Simulation results indicated that the tractor followed the reference courses precisely on a flat ground.展开更多
In this paper,the user interface of tractor cab real-time information management system was designed. Based on the principle of "user friendly",it reasonably arranged spatial position of information manageme...In this paper,the user interface of tractor cab real-time information management system was designed. Based on the principle of "user friendly",it reasonably arranged spatial position of information management system according to spatial distribution of tractor cab. Then,it analyzed operation habits and thinking ways of drivers,and formulated design principle meeting demands of drivers. Besides,it used LabView software to design user interface,including interface layout and interface design. User interface includes basic information interface,job information interface,camera monitoring interface,and fault diagnosis interface. Finally,it made evaluation of the user interface from color,indicator lamp,dial,and pointer. Results indicate that the designed user interface layout conforms to cognition mentality and operation habits and easy to get familiar and grasp; graphical interface is vivid and easy to stimulate pleasure of drivers in operation; interface color matching is coordinated; the layout of controls is hierarchical and logic,and operating mode is consistent with Windows system.展开更多
In this study, tractor power output, fuel consumption rate and work performance were indirectly predicted in order to develop an eco driving system. Firstly, equations were developed which could foretell tractor power...In this study, tractor power output, fuel consumption rate and work performance were indirectly predicted in order to develop an eco driving system. Firstly, equations were developed which could foretell tractor power output and fuel consumption rate using characteristic curves of tractor power output. Secondly, with actual engine revolution per minute （rpm） determined by initial engine rpm and work load, tractor power output and fuel consumption rate were forecasted. Thirdly, it was possible to foresee tractor work performance and fuel consumption rate by the speed signals of Global Positioning System （GPS）. Lastly, precision of the eco driving system was evaluated through tractor Power Take-Off （PTO） test, and effects of the eco driving system were investigated in the plowing and rotary tilling operations. Engine rpm, power output, fuel consumption rate, work performance and fuel consumption rate per plot area were displayed on the eco driving system. Predicted tractor power outputs in the full load curve were well coincided with the actual power output of prototype, but small differences, 1 to 6 kW were found in the part load curve. Error of the fuel consumption rate was 0.5 to 3 L/h at the part load curve. It was shown that 69% and 53% of fuel consumption rates could be reduced in plowing and rotary tilling operations, respectively, when the eco driving system was installed in tractor.展开更多
A novel data acquisition system was successfully integrated on-board the Massey Ferguson 3,000 series agricultural tractors for measuring tractor-implement performance. A commercial load cell was incorporated into the...A novel data acquisition system was successfully integrated on-board the Massey Ferguson 3,000 series agricultural tractors for measuring tractor-implement performance. A commercial load cell was incorporated into the existing system for the needed tractor-implement performance, measurements. This system is capable of measuring, displaying and recording, in real-time, the tractor＇s theoretical travel speed, the actual travel speed, the engine speed, the fuel consumption rate, and the drawbar pull. Static calibration tests on various associated sensors for the required measurements show excellent linearity with correlation coefficients that are close to 1. The developed system was extensively and successfully field demonstrated for tractor-implement performance with offset disc harrows on dry, undisturbed loamy soils. Under these conditions, a ratio of tractor power to implement width is suggested. The data also show the existence of a linear relationship between fuel consumption per hectare and specific draught, for the 4 to 9 kN m^-1 range, which suggests the possibility of extending the American Society of Agricultural and Biological Engineers model of draught prediction to forecast fuel consumption. The configuration of the tractor-harrow combination, based on the measurement of the draught required under operational conditions, provides the manufacturers with a reliable indication of the recommended power required for each harrow model. With this type of information farmers can make decisions regarding selection of a suitable tractor-implement combination for their farms. As a consequence, there is improved tractor-harrow productivity and field efficiency.展开更多
Electric tractors(ETs)with mounted implements form operating units.There are significant differences in parameters such as shape,firmness,and moisture content of the soil in contact with the tractor and implements whe...Electric tractors(ETs)with mounted implements form operating units.There are significant differences in parameters such as shape,firmness,and moisture content of the soil in contact with the tractor and implements when working in complex terrains such as field stubble,waterlogged silt,and loose/firm terrain.These differentiated dynamics prevent cooperation between ETs and operating implements under independent control,resulting in poor quality operations and low energy efficiency.We propose a control mechanism for ETs and implements to achieve full life cycle management of collaborative control tasks,instantaneous intertask interaction,and a multitask synchronization mechanism.To address the internal redundant communication problems caused by traditional distributed microcontrol units,we break through the underlying technology of unit data processing and interaction and develop an integrated high-performance controller structure with high processing capacity and high-and low-speed communication interfaces.On the basis of hierarchical stepwise control theory,a hierarchical real-time operating system is designed.This system realizes a preemptive kernel response of computational tasks and competitive-collaborative synchronization among tasks;overcomes the low-latency response of collaborative control tasks,instantaneous information interaction,and multitask synchronization problems;and provides system-level support for deep collaborative operation control of units.To demonstrate and validate the proposed collaborative control mechanism,a plowing collaborative operation management strategy is designed and deployed.The experimental results show that the communication delay of collaborative tasks is as low as 83μs,the solution time of complex collaborative equations is as low as 46 ms,the mechanical efficiency of the ET is increased by 9.07%,the efficiency of the drive motor is increased by 9.72%,the stability of the operation speed is increased by 106.25%,and the stability of the plowing depth reaches 94.98%.Our work meets the hardware and software requirements for realizing complex collaborative control of ET units and improves the operational quality and operational energy efficiency in real vehicle demonstrations.展开更多
Aiming at the problem that the draft-position integrated tillage depth control method with fixed comprehensive coefficient of tractor electro-hydraulic hitch system is difficult to adapt to the working environment wit...Aiming at the problem that the draft-position integrated tillage depth control method with fixed comprehensive coefficient of tractor electro-hydraulic hitch system is difficult to adapt to the working environment with large changes in soil conditions,a tractor draft-position integrated tillage depth control method with variable comprehensive coefficient was proposed.A comprehensive coefficient control scheme based on traction resistance was designed and its working principle was clarified.Aiming at the time-varying tillage depth control system,a tillage depth control algorithm based on the sliding mode control with a differential observer was designed.In order to verify the performance of the control scheme,a control system simulation model and a bench test platform were built,and the performance was compared with the draft-position integrated control method with a fixed comprehensive coefficient of 0.5.The results showed that the variable comprehensive coefficient tillage depth control method can automatically adjust the comprehensive coefficient according to the change of soil conditions,and has higher traction efficiency.In the small resistance range,it can better ensure the quality of operation;in the large resistance range,it can ensure the engine performance and protect the tractor from damage.This method is more adaptable to the complex field operation environment,which provides a reference for the research of tillage depth control method.展开更多
Rollover and jack-knifing of tractor semi-trailer are serious threats for vehicle safety, and accordingly active safety technologies have been widely used to reduce or prevent the occurrence of such accidents. However...Rollover and jack-knifing of tractor semi-trailer are serious threats for vehicle safety, and accordingly active safety technologies have been widely used to reduce or prevent the occurrence of such accidents. However, currently tractor semi-trailer stability control is generally only a single hazardous condition (rollover or jack-knifing) control, it is difficult to ensure the vehicle comprehensive stability of various dangerous conditions. The main objective of this study is to introduce a multi-objective stability control algorithm which can improve the vehicle stability of a tractor semi-trailer by using differential braking. A vehicle controller is designed to minimize the likelihood of rollover and jack-knifing. First a linear vehicle model of tractor semi-trailer is constructed. Then an optimal yaw control for tractor using differential braking is applied to minimize the yaw rate and lateral acceleration deviation of tractor, as well as the hitch articulation angle of tractor semi-trailer, so as to improve the vehicle stability. Second a braking scheme and variable structure control with sliding mode control are introduced in order to achieve the best braking effect. Last Fishhook maneuver is introduced to the active safety simulation and the active control system effect verification. The simulation results show that multi-objective stability control algorithm of semi-trailer could improve the vehicle stability significantly during the transient maneuvers. The proposed multi-objective stability control algorithm is effective to prevent the vehicle rollover and jackknifing.展开更多
In response to the problems of excessive greenhouse-gas and particulate emissions and the low traction efficiency of conventional diesel tractors in the field,a purely electric wheel-side drive tractor was studied,inc...In response to the problems of excessive greenhouse-gas and particulate emissions and the low traction efficiency of conventional diesel tractors in the field,a purely electric wheel-side drive tractor was studied,including an electric motor drive system,a battery ballast system,and an electro–hydraulic suspension system.This paper develops a dynamics model of an electric tractor-ploughing unit under complex soil conditions,leading to the proposal of an active control method for drive wheel torque and a joint control method for the traction force of the suspension system and the front-and rear-axle loads of a tractor.Finally,the tractor is prototyped and assembled,and ploughing tests are carried out.The ploughing results show that the active torque-distribution control method proposed in this study reduces the tractor slip by 14.83%and increases the traction efficiency by 10.28%compared with the average torquedistribution mode.Compared with the conventional traction control mode,the joint control method for traction and ballast proposed in this paper results in a 3.7%increase in traction efficiency,a 15.05%decrease in slip,and a 4.9%reduction in total drive motor energy consumption.This study will help to improve the operation quality and traction efficiency of electric tractors in complex soil conditions.展开更多
A new type continuous variable transmission device, a hydro-mechanical continuously variable transmission （HMCVT） for agricultural tractors is developed, which is composed of a single planetary gear differential tra...A new type continuous variable transmission device, a hydro-mechanical continuously variable transmission （HMCVT） for agricultural tractors is developed, which is composed of a single planetary gear differential train, a hydraulic transmission system consisted of variable displacement pump and fixed displacement motor and a multi-gear fixed step radio transmission. Based on the analysis of types of hydrostatic mechanical transmission （HMT） and styles of hydraulic transmission, the general drive scheme for HMCVT is obtained. The method of selecting mechanical parameters and hydraulic units is explained, and the stepless speed regulation characteristic of HMCVT is analyzed. This paper also specializes the calculating method of transmission efficiency. It shows that tractors assembled with HMCVT can obtain a continuously variable speed and achieve high drive efficiency.展开更多
During oil-gas well drilling and completion, downhole tools and apparatus should be conveyed to the destination to complete a series of downhole works. Downhole tractors have been used to convey tools in complex wellb...During oil-gas well drilling and completion, downhole tools and apparatus should be conveyed to the destination to complete a series of downhole works. Downhole tractors have been used to convey tools in complex wellbores, however a very large tractive force is needed to carry more downhole tools to accomplish works with high efficiency. A novel serial active helical drive downhole tractor which has significantly improved performance compared with previous work is proposed. All previously reported helical drive downhole tractors need stators to balance the torque generated by the rotator. By contrast, the proposed serial downhole tractor does not need a stator; several rotator-driven units should only be connected to one another to achieve a tractive force multifold higher than that was previously reported. As a result, the length of a single unit is shortened, and the motion flexibility of the downhole tractor is increased. The major performance indicators, namely, gear ratio, velocity, and tractive force, are analyzed. Experimental results show that the maximum tractive force of a single-unit prototype with a length of 900 mm is 165.3 kg or 1620 N. The analysis and experimental results show that the proposed design has considerable potential for downhole works.展开更多
An Electro-hydraulic loading system is designed based on a test-bed of tractor's hydraulic steering by-wire. To simulate the steering resistance driving tractor in many kinds of soils and roads,the loading force i...An Electro-hydraulic loading system is designed based on a test-bed of tractor's hydraulic steering by-wire. To simulate the steering resistance driving tractor in many kinds of soils and roads,the loading force is controlled to make proportional and continuous variable by an electro-hydraulic proportional relief valve. A steering resistance loading test-bed is built to test three kinds of steering resistance including constant,step and sine style. Tire lateral resistance is also tested under different steering conditions. The result shows that the electro-hydraulic loading system has high stability and following performance. Besides,the system's steady state error is lower than 3. 1%,and it meets the test requirement of tractor's hydraulic steering by-wire.展开更多
The ITER （international thermonuclear experimental reactor） tractor is an in-cask remote handling equipment, its tilting and lifting mechanism is important for the tractor operated with forty-five-ton plug in front ...The ITER （international thermonuclear experimental reactor） tractor is an in-cask remote handling equipment, its tilting and lifting mechanism is important for the tractor operated with forty-five-ton plug in front of the ports of Hot Cell and VV （vacuum vessel） successfully. In order to better analyse the movement of this mechanism and decide the key design parameters accurately, a mathematical model of 7-1ink complicated plane mechanism was built up, and the calculation of design and kinematics simulation were implemented. The established mathematical model was proved to be valid by comparing the calculated result with that of kinematics simulation. Finally, the structure analysis and the optimization of its key part, tilting and lifting frame, were performed to guarantee the frame＇s strength in bearing the heavy load of plug.展开更多
Due to the non-standardization and complexity of the farmland environment,it is always a huge challenge for tractors to achieve fully autonomy(work at Self-driving mode)all the time in agricultural industry.Whereas,wh...Due to the non-standardization and complexity of the farmland environment,it is always a huge challenge for tractors to achieve fully autonomy(work at Self-driving mode)all the time in agricultural industry.Whereas,when tractors work in the Tele-driving(or Remote driving)mode,the operators are prone to fatigue because they need to concentrate for long periods of time.In response to these,a dual-mode control strategy was proposed to integrate the advantages of both approaches,i.e.,by combing Self-driving at most of the time with Tele-driving under special(complex and hazardous)conditions through switching control method.First,the state switcher was proposed,which is used for smooth switching the driving modes according to different working states of a tractor.Then,the state switching control law and the corresponding subsystem tracking controllers were designed.Finally,the effectiveness and superiority of the dualmode control method were evaluated via actual experimental testing of a tractor whose results show that the proposed control method can switch smoothly,stably,and efficiently between the two driving modes automatically.The average control accuracy has been improved by 20%and 15%respectively,compared to the conventional Tele-driving control and Self-driving control with low-precision navigation.In conclusion,the proposed dualmode control method can not only satisfy the operation in the complex and changeable farmland environment,but also free drivers from high-intensity and fatiguing work.This provides a perfect application solution and theoretical support for the intelligentization of unmanned farm agricultural machinery with high safety and reliability.展开更多
For further understanding reliability and serviceability of tractor and to furnish scientific and technical theories, based on the promotion and application of it, the following experiments and statistical analysis on...For further understanding reliability and serviceability of tractor and to furnish scientific and technical theories, based on the promotion and application of it, the following experiments and statistical analysis on reliability （reliability and MTBF） serviceability （service and MTTR） of Donfanghong-1002 and Dongfanghong-802 were conducted. The result showed that the intervals of average troubles of these two tractors were 182.62 h and 160.2 h, respectively, and the weakest assembly of them was engine part.展开更多
基金Project supported by the National Natural Science Foundation of China (No. 30270773)the Teaching and Research Award Program forOutstanding Young Teachers in Higher Education Institutions of MOE,Chinaand the Natural Science Foundation of Zhejia
文摘This research aims at using a dynamic model of tractor system to support navigation system design for an automati- cally guided agricultural tractor. This model, consisting of a bicycle model of the tractor system, has been implemented in the MATLAB environment and was developed based on a John Deere tractor. The simulation results from this MATLAB model was validated through field navigation tests. The accuracy of the trajectory estimation is strongly affected by the determination of the cornering stiffness of the tractor. In this simulation, the tractor cornering stiffness analysis was identified during simulation analysis using the MATLAB model based on the recorded trajectory data. The obtained data was used in simulation analyses for various navigation operations in the field of interest. The analysis on field validation test results indicated that the developed tractor system could accurately estimate wheel trajectories of a tractor system while operating in agricultural fields at various speeds. The results also indicated that the developed system could accurately determine tractor velocity and steering angle while the tractor operates in curved fields.
基金Harbin Technological Innovation Research Fund(NO:2012RFXXG039)
文摘An aircraft tractor plays a significant role as a kind of important marine transport and support equipment. It＇s necessary to study its controlling and manoeuvring stability to improve operation efficiency. A virtual prototyping model of the tractor-aircraft system based on Lagrange＇s equation of the first kind with Lagrange mutipliers was established in this paper, According to the towing characteristics, a path-tracking controller using fuzzy logic theory was designed. Direction control herein was carried out through a compensatory tracking approach. Interactive co-simulation was performed to validate the path-tracking behavior in closed-loop, Simulation results indicated that the tractor followed the reference courses precisely on a flat ground.
基金Supported by Science and Technology Support Program of Jiangsu Province(Agriculture)(BE2012384)Special Fund for Conversion of Scientific and Technological Achievements in Jiangsu Province(BA2010055)
文摘In this paper,the user interface of tractor cab real-time information management system was designed. Based on the principle of "user friendly",it reasonably arranged spatial position of information management system according to spatial distribution of tractor cab. Then,it analyzed operation habits and thinking ways of drivers,and formulated design principle meeting demands of drivers. Besides,it used LabView software to design user interface,including interface layout and interface design. User interface includes basic information interface,job information interface,camera monitoring interface,and fault diagnosis interface. Finally,it made evaluation of the user interface from color,indicator lamp,dial,and pointer. Results indicate that the designed user interface layout conforms to cognition mentality and operation habits and easy to get familiar and grasp; graphical interface is vivid and easy to stimulate pleasure of drivers in operation; interface color matching is coordinated; the layout of controls is hierarchical and logic,and operating mode is consistent with Windows system.
文摘In this study, tractor power output, fuel consumption rate and work performance were indirectly predicted in order to develop an eco driving system. Firstly, equations were developed which could foretell tractor power output and fuel consumption rate using characteristic curves of tractor power output. Secondly, with actual engine revolution per minute （rpm） determined by initial engine rpm and work load, tractor power output and fuel consumption rate were forecasted. Thirdly, it was possible to foresee tractor work performance and fuel consumption rate by the speed signals of Global Positioning System （GPS）. Lastly, precision of the eco driving system was evaluated through tractor Power Take-Off （PTO） test, and effects of the eco driving system were investigated in the plowing and rotary tilling operations. Engine rpm, power output, fuel consumption rate, work performance and fuel consumption rate per plot area were displayed on the eco driving system. Predicted tractor power outputs in the full load curve were well coincided with the actual power output of prototype, but small differences, 1 to 6 kW were found in the part load curve. Error of the fuel consumption rate was 0.5 to 3 L/h at the part load curve. It was shown that 69% and 53% of fuel consumption rates could be reduced in plowing and rotary tilling operations, respectively, when the eco driving system was installed in tractor.
文摘A novel data acquisition system was successfully integrated on-board the Massey Ferguson 3,000 series agricultural tractors for measuring tractor-implement performance. A commercial load cell was incorporated into the existing system for the needed tractor-implement performance, measurements. This system is capable of measuring, displaying and recording, in real-time, the tractor＇s theoretical travel speed, the actual travel speed, the engine speed, the fuel consumption rate, and the drawbar pull. Static calibration tests on various associated sensors for the required measurements show excellent linearity with correlation coefficients that are close to 1. The developed system was extensively and successfully field demonstrated for tractor-implement performance with offset disc harrows on dry, undisturbed loamy soils. Under these conditions, a ratio of tractor power to implement width is suggested. The data also show the existence of a linear relationship between fuel consumption per hectare and specific draught, for the 4 to 9 kN m^-1 range, which suggests the possibility of extending the American Society of Agricultural and Biological Engineers model of draught prediction to forecast fuel consumption. The configuration of the tractor-harrow combination, based on the measurement of the draught required under operational conditions, provides the manufacturers with a reliable indication of the recommended power required for each harrow model. With this type of information farmers can make decisions regarding selection of a suitable tractor-implement combination for their farms. As a consequence, there is improved tractor-harrow productivity and field efficiency.
基金supported by the National Key Research and Development Plan of China(2022YFD2001202)the National Natural Science Foundation of China(32301719 and 52272444)the 2115 Talent Development Program of China Agricultural University.
文摘Electric tractors(ETs)with mounted implements form operating units.There are significant differences in parameters such as shape,firmness,and moisture content of the soil in contact with the tractor and implements when working in complex terrains such as field stubble,waterlogged silt,and loose/firm terrain.These differentiated dynamics prevent cooperation between ETs and operating implements under independent control,resulting in poor quality operations and low energy efficiency.We propose a control mechanism for ETs and implements to achieve full life cycle management of collaborative control tasks,instantaneous intertask interaction,and a multitask synchronization mechanism.To address the internal redundant communication problems caused by traditional distributed microcontrol units,we break through the underlying technology of unit data processing and interaction and develop an integrated high-performance controller structure with high processing capacity and high-and low-speed communication interfaces.On the basis of hierarchical stepwise control theory,a hierarchical real-time operating system is designed.This system realizes a preemptive kernel response of computational tasks and competitive-collaborative synchronization among tasks;overcomes the low-latency response of collaborative control tasks,instantaneous information interaction,and multitask synchronization problems;and provides system-level support for deep collaborative operation control of units.To demonstrate and validate the proposed collaborative control mechanism,a plowing collaborative operation management strategy is designed and deployed.The experimental results show that the communication delay of collaborative tasks is as low as 83μs,the solution time of complex collaborative equations is as low as 46 ms,the mechanical efficiency of the ET is increased by 9.07%,the efficiency of the drive motor is increased by 9.72%,the stability of the operation speed is increased by 106.25%,and the stability of the plowing depth reaches 94.98%.Our work meets the hardware and software requirements for realizing complex collaborative control of ET units and improves the operational quality and operational energy efficiency in real vehicle demonstrations.
基金National Key Research and Development Plan of China(Grant No.2022YFD2001202)The Open Project of the State Key Laboratory of Intelligent Agricultural Power Equipment(SKLIAPE2023019)The Postgraduate Research and Practice Innovation Program of Jiangsu Province,China(Grant No.KYCX22_0716).
文摘Aiming at the problem that the draft-position integrated tillage depth control method with fixed comprehensive coefficient of tractor electro-hydraulic hitch system is difficult to adapt to the working environment with large changes in soil conditions,a tractor draft-position integrated tillage depth control method with variable comprehensive coefficient was proposed.A comprehensive coefficient control scheme based on traction resistance was designed and its working principle was clarified.Aiming at the time-varying tillage depth control system,a tillage depth control algorithm based on the sliding mode control with a differential observer was designed.In order to verify the performance of the control scheme,a control system simulation model and a bench test platform were built,and the performance was compared with the draft-position integrated control method with a fixed comprehensive coefficient of 0.5.The results showed that the variable comprehensive coefficient tillage depth control method can automatically adjust the comprehensive coefficient according to the change of soil conditions,and has higher traction efficiency.In the small resistance range,it can better ensure the quality of operation;in the large resistance range,it can ensure the engine performance and protect the tractor from damage.This method is more adaptable to the complex field operation environment,which provides a reference for the research of tillage depth control method.
基金supported by Open Research Fund of State Key Laboratory of Automobile Dynamics Simulation, China (Grant No. 20101103)National Natural Science Foundation of China (Grant No. 51075176)
文摘Rollover and jack-knifing of tractor semi-trailer are serious threats for vehicle safety, and accordingly active safety technologies have been widely used to reduce or prevent the occurrence of such accidents. However, currently tractor semi-trailer stability control is generally only a single hazardous condition (rollover or jack-knifing) control, it is difficult to ensure the vehicle comprehensive stability of various dangerous conditions. The main objective of this study is to introduce a multi-objective stability control algorithm which can improve the vehicle stability of a tractor semi-trailer by using differential braking. A vehicle controller is designed to minimize the likelihood of rollover and jack-knifing. First a linear vehicle model of tractor semi-trailer is constructed. Then an optimal yaw control for tractor using differential braking is applied to minimize the yaw rate and lateral acceleration deviation of tractor, as well as the hitch articulation angle of tractor semi-trailer, so as to improve the vehicle stability. Second a braking scheme and variable structure control with sliding mode control are introduced in order to achieve the best braking effect. Last Fishhook maneuver is introduced to the active safety simulation and the active control system effect verification. The simulation results show that multi-objective stability control algorithm of semi-trailer could improve the vehicle stability significantly during the transient maneuvers. The proposed multi-objective stability control algorithm is effective to prevent the vehicle rollover and jackknifing.
基金supported by the National Key Research and Development Plan of China(2022YFD2001201)the Beijing Postdoctoral Research Foundation(2023-ZZ-112)+1 种基金the National Natural Science Foundation of China(52272444)the Natural Science Foundation of Jiangsu Province(BK20230548).
文摘In response to the problems of excessive greenhouse-gas and particulate emissions and the low traction efficiency of conventional diesel tractors in the field,a purely electric wheel-side drive tractor was studied,including an electric motor drive system,a battery ballast system,and an electro–hydraulic suspension system.This paper develops a dynamics model of an electric tractor-ploughing unit under complex soil conditions,leading to the proposal of an active control method for drive wheel torque and a joint control method for the traction force of the suspension system and the front-and rear-axle loads of a tractor.Finally,the tractor is prototyped and assembled,and ploughing tests are carried out.The ploughing results show that the active torque-distribution control method proposed in this study reduces the tractor slip by 14.83%and increases the traction efficiency by 10.28%compared with the average torquedistribution mode.Compared with the conventional traction control mode,the joint control method for traction and ballast proposed in this paper results in a 3.7%increase in traction efficiency,a 15.05%decrease in slip,and a 4.9%reduction in total drive motor energy consumption.This study will help to improve the operation quality and traction efficiency of electric tractors in complex soil conditions.
基金Fund of Henan Innovation Project for University Prominent Research Talents (2002KYCX010) Youth Scientific Research Foundation of Henan University of Science and Technology (2004QN030)
文摘A new type continuous variable transmission device, a hydro-mechanical continuously variable transmission （HMCVT） for agricultural tractors is developed, which is composed of a single planetary gear differential train, a hydraulic transmission system consisted of variable displacement pump and fixed displacement motor and a multi-gear fixed step radio transmission. Based on the analysis of types of hydrostatic mechanical transmission （HMT） and styles of hydraulic transmission, the general drive scheme for HMCVT is obtained. The method of selecting mechanical parameters and hydraulic units is explained, and the stepless speed regulation characteristic of HMCVT is analyzed. This paper also specializes the calculating method of transmission efficiency. It shows that tractors assembled with HMCVT can obtain a continuously variable speed and achieve high drive efficiency.
基金Supported by Sichuan Provincial Science and Technology Program of China(Grant Nos.2013GZ0150,2014GZ0121)Research Project of Key Laboratory of Fluid and Power Machinery of Ministry of Education,Xihua University,China
文摘During oil-gas well drilling and completion, downhole tools and apparatus should be conveyed to the destination to complete a series of downhole works. Downhole tractors have been used to convey tools in complex wellbores, however a very large tractive force is needed to carry more downhole tools to accomplish works with high efficiency. A novel serial active helical drive downhole tractor which has significantly improved performance compared with previous work is proposed. All previously reported helical drive downhole tractors need stators to balance the torque generated by the rotator. By contrast, the proposed serial downhole tractor does not need a stator; several rotator-driven units should only be connected to one another to achieve a tractive force multifold higher than that was previously reported. As a result, the length of a single unit is shortened, and the motion flexibility of the downhole tractor is increased. The major performance indicators, namely, gear ratio, velocity, and tractive force, are analyzed. Experimental results show that the maximum tractive force of a single-unit prototype with a length of 900 mm is 165.3 kg or 1620 N. The analysis and experimental results show that the proposed design has considerable potential for downhole works.
基金Supported by National Natural Science Foundation of China(51175269)Jiangsu Provincial Science and Technology Support Program(Agriculture)(BE2012384)
文摘An Electro-hydraulic loading system is designed based on a test-bed of tractor's hydraulic steering by-wire. To simulate the steering resistance driving tractor in many kinds of soils and roads,the loading force is controlled to make proportional and continuous variable by an electro-hydraulic proportional relief valve. A steering resistance loading test-bed is built to test three kinds of steering resistance including constant,step and sine style. Tire lateral resistance is also tested under different steering conditions. The result shows that the electro-hydraulic loading system has high stability and following performance. Besides,the system's steady state error is lower than 3. 1%,and it meets the test requirement of tractor's hydraulic steering by-wire.
基金design of the ITER transfer casks system(ITER International Team),ITA 23-01-CN
文摘The ITER （international thermonuclear experimental reactor） tractor is an in-cask remote handling equipment, its tilting and lifting mechanism is important for the tractor operated with forty-five-ton plug in front of the ports of Hot Cell and VV （vacuum vessel） successfully. In order to better analyse the movement of this mechanism and decide the key design parameters accurately, a mathematical model of 7-1ink complicated plane mechanism was built up, and the calculation of design and kinematics simulation were implemented. The established mathematical model was proved to be valid by comparing the calculated result with that of kinematics simulation. Finally, the structure analysis and the optimization of its key part, tilting and lifting frame, were performed to guarantee the frame＇s strength in bearing the heavy load of plug.
基金supported in part by the Independent Innovation Project of Agricultural Science and Technology of Jiangsu Province(CX(20)3068)Modern Agricultural Machinery Equipment and Technology Demonstration and Promotion Project of Jiangsu Province(NJ2021-37)+1 种基金National Foreign Experts Program of China(G2021145010L)Science and Technology Project of Suzhou City(SNG2020039)。
文摘Due to the non-standardization and complexity of the farmland environment,it is always a huge challenge for tractors to achieve fully autonomy(work at Self-driving mode)all the time in agricultural industry.Whereas,when tractors work in the Tele-driving(or Remote driving)mode,the operators are prone to fatigue because they need to concentrate for long periods of time.In response to these,a dual-mode control strategy was proposed to integrate the advantages of both approaches,i.e.,by combing Self-driving at most of the time with Tele-driving under special(complex and hazardous)conditions through switching control method.First,the state switcher was proposed,which is used for smooth switching the driving modes according to different working states of a tractor.Then,the state switching control law and the corresponding subsystem tracking controllers were designed.Finally,the effectiveness and superiority of the dualmode control method were evaluated via actual experimental testing of a tractor whose results show that the proposed control method can switch smoothly,stably,and efficiently between the two driving modes automatically.The average control accuracy has been improved by 20%and 15%respectively,compared to the conventional Tele-driving control and Self-driving control with low-precision navigation.In conclusion,the proposed dualmode control method can not only satisfy the operation in the complex and changeable farmland environment,but also free drivers from high-intensity and fatiguing work.This provides a perfect application solution and theoretical support for the intelligentization of unmanned farm agricultural machinery with high safety and reliability.
基金Supported by Education Department of Heilongjiang Province (9551022)
文摘For further understanding reliability and serviceability of tractor and to furnish scientific and technical theories, based on the promotion and application of it, the following experiments and statistical analysis on reliability （reliability and MTBF） serviceability （service and MTTR） of Donfanghong-1002 and Dongfanghong-802 were conducted. The result showed that the intervals of average troubles of these two tractors were 182.62 h and 160.2 h, respectively, and the weakest assembly of them was engine part.
