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1.
Y. G. Ampatzidis S. G. Vougioukas D. D. Bochtis C. A. Tsatsarelis 《Precision Agriculture》2009,10(1):63-72
It is proposed that radio frequency identification (RFID) technology be used to overcome the limitations of existing yield
mapping systems for manual fresh fruit harvesting. Two methods are proposed for matching bins—containing harvested fruits—with
corresponding pairs of trees. In the first method, a long-range RFID reader and a DGPS are mounted on an orchard tractor and
passive low-cost RFID tags are attached to the bins. In the second method, the DGPS is not used and RFID tags are attached
to individual trees as well as bins. An experimental evaluation of the accuracy and reliability of both methods was performed
in an orchard. The first method failed in half of the trials because the tree canopies interfered with the GPS signal. The
RFID reader miss ratio for the detection of the bins was 0.32% for both methods. However, the attachment of RFID tags on suitable
tree branches (to achieve 100% detection), in the second method, is not a well-defined procedure; some trial is demanded to
determine the best positions and orientations of the tree tags in order for the RFID reader to successfully detect them. The
first method seems more promising if robust tractor location under foliage can be achieved. 相似文献
2.
Statistical tools are discussed for the analysis of data collected from tractor guidance systems. The importance of both accuracy and precision is discussed, and statistical tools for analysis are considered which incorporate important features of the data. In particular, accuracy is modelled using a generalized least squares model incorporating autocorrelation, and variances (inverse of precision) using a gamma generalized linear model. The methods are applied to data collected during an experiment conducted with a Trimble receiver used with a Beeline tractor guidance system. Three different scenarios are considered, then compared: a tractor simulating ploughing a field; the tractor pulling a plough with the receivers on the tractor; the tractor pulling a plough with the Trimble receiver on the plough. The change in the precision and accuracy between the scenarios is discussed. Data were recorded over repeated swaths for each scenario. After discussing specific statistical techniques for analysis of this type of data, the collected data are analysed; major conclusions are: The data from the Trimble receiver showed evidence of autocorrelation in the offsets; the plough recorded a variance about three times that recorded by the tractor.This research was completed while the second author was at the University of Southern Queensland. 相似文献
3.
Developing models and estimating model parameters for a tractor and implement system is important for rapid development and improvement of precision implement guidance systems. A dynamic model for a tractor with a towed implement was developed. This model contained a tire lateral force model with several parameters that are varying and difficult to measure accurately. Several field experiments were conducted to collect trajectory data for a tractor with a single axle grain cart. Data from these experiments were used to estimate the tire lateral force model parameters. Three different replicates of the experimental trajectories were collected with each of the step, random and chirp steering inputs. The data was collected at 4.5 m/s forward velocity in two different fields. A two-step optimization process was used to estimate the tire model parameters. First, the experimental data and a set of steady state model equations were used to estimate cornering stiffness parameters. Second, a prediction error minimization method and a dynamic model were used to estimate relaxation length parameters. The parameter estimation process was repeated with each replicate of the experimental data, and the individual estimates were combined using a weighted averaging method. The vehicle model responses with estimated parameters represented the system responses with reasonable accuracy. With the parameters estimated from three different trajectories, the RMSEs for trajectories of tractor and implement CGs varied from 0.05 to 0.83 m. The model-based frequency responses also closely matched with the experimental frequency responses. 相似文献
4.
Accuracy levels achieved with differential global positioning system (DGPS) receivers in agricultural operations depend upon
the quality of the correction signal. This study has assessed differential signal error from a Dedicated Base Station, OmniSTAR
VBS, European Geostationary Navigation Overlay System, European reference frame-IP for internet protocol (EUREF-IP) and radio
navigation satellite aided technique (RASANT). These signals were utilized in guidance assisting systems for agricultural
applications, such as tillage, harvesting, planting and spraying, in which GPS receivers were used under dynamic conditions.
Simulations of agricultural operations on different days and at different time slots and simultaneously recording the tractor′s
geo-position from a DGPS receiver and the tractor′s geo-position from a real-time kinematic (RTK) GPS allowed the comparison
of the GPS correction signals. The hardware used for tractor guidance was a lightbar (Trimble model EZ-Guide Plus) system.
ANOVA statistics showed a significant difference between the accuracy of the correction signals from different sources. GPS
correction signal recommendations to farmers depend upon the accuracy required for the specific operation: (a) Yield monitoring
and soil sampling (<1 m) are possible with all the GPS correction signals accessed in any time slot. (b) Broadcast seeding,
fertilizer and herbicide application (<0.5 m) are possible for 80% of time with OmniSTAR VBS, 40% of time with RASANT and
EUREF-IP and 100% of time with a dedicated base station. (c) Transplanting and drill seeding (<0.04 m) are not possible with
the accuracy correction provided by any one of the systems used in this study. 相似文献
5.
介绍了拖拉机仿真机组控制系统的组成、作用和工作原理。它是一个由中央监控系统和多个子系统组成的、响应有滞后的分布式控制系统，对这样的控制系统，串行通信控制是一种有效的控制方法。在控制系统中，上下位机的信息交换通过串行口完成，可靠地传输控制信号和准确地执行控制命令是实现控制目的的关键。在VC＋＋6.0环境下利用MSComm控件，制定了具体的通信协议，编程实现了和80C196KC单片机串行通信的分布式综合控制。试验结果表明，控制效果很好，具有一定的实用意义。 相似文献
6.
A vision sensing system for the measurement of auto-guidance pass-to-pass and long-term errors was implemented to test the steering performance of tractors equipped with auto-guidance systems. The developed test system consisted of an optical machine vision sensor rigidly mounted on the rear of the tested tractor. The center of the drawbar hitch pin point was used as the reference from which to measure the deviation of the tractor's actual travel path from its desired path. The system was built and calibrated to a measurement accuracy of better than 2 mm. To evaluate the sensor, two auto-guidance systems equipped with RTK-level GNSS receivers were tested and the results for different travel speeds compared. Pass-to-pass and long-term errors were calculated using the relative positions of a reference at a collocated point when the tractor was operated in opposite directions within 15 min and more than 1 h apart, respectively. In addition to variations in speed, two different auto-guidance steering stabilization distances allowed for comparison of two different definitions of steady-state operation of the system. For the analysis, non-parametric cumulative distributions were generated to determine error values that corresponded to 95% of the cumulative distribution. Both auto-guidance systems provided 95% cumulative error estimates comparable to 51 mm (2 in.) claims and even smaller during Test A. Higher travel speeds (especially 5.0 m/s) significantly increased measured auto-guidance error, but no significant difference was observed between pass-to-pass and long-term error estimates. The vision sensor testing system could be used as a means to implement the auto-guidance test standard under development by the International Standard Organization (ISO). Third-party evaluation of auto-guidance performance will increase consumer awareness of the potential performance of products provided by a variety of vendors. 相似文献
7.
The quality of work and the output of a tractor-implement combination relies heavily upon the concentration and skill of the operator. Electronic systems are used increasingly to control tractor sub-systems, i.e. engine, transmission, implement hitch, external hydraulics, and driveline, and to monitor or control certain implements. However, current systems operate autonomously, relying entirely upon the operator for coordination. An integrated hierarchical control system could potentially monitor operating parameters pertinent to both the tractor and attached implements and use this information to control relevant tractor and implement sub-systems in a coordinated manner, thereby improving machine performance. Potential opportunities for the application of real-time, integrated, hierarchical control techniques to certain cultivation and crop establishment implements currently in use on European farms are reviewed. Specific implements (and their parameters) considered include primary cultivation machinery (control of working depth and working width), secondary cultivation machinery (control of working depth and seedbed quality) and crop establishment machinery (control of seeding depth and seed rate). Outline control strategies are proposed for these applications, and sensors and other hardware required to implement the control systems are identified. It is speculated that the agronomic and economic benefits which are likely to result from the implementation of the proposed technology, will enable economic justification of the proposed control systems in two to four operating seasons. These savings are likely to result from greater operational efficiency and more precise control of agronomic inputs. 相似文献
8.
Evaluation of agronomic and economic benefits of using RTK-GPS-based auto-steer guidance systems for peanut digging operations 总被引：1，自引：0，他引：1
B. V. Ortiz K. B. Balkcom L. Duzy E. van Santen D. L. Hartzog 《Precision Agriculture》2013,14(4):357-375
Increasing the peanut (Arachis hypogea L.) digger efficiency by accurate placement over the target rows could minimize damaged pods and yield losses. Producers have traditionally relied solely on tractor operator skills to harvest peanuts. However, as peanut production has shifted to new growing regions in the Southeast US, producers face difficulties digging peanuts under conventional and new management schemes. The present study aimed to: (i) determine the effect of row deviations (RD) of the digger from the target row on peanut yield and quality, and (ii) determine the economic value of using RTK auto-steer guidance systems to avoid tractor deviations during peanut harvest. The study consisted of a randomized complete block design of tillage [conventional (CT) and strip tillage (ST)], row patterns [single (SR) and twin (TWR)] and row deviation (RD0 mm, RD90 mm, and RD180 mm). The RD90 mm and RD180 mm treatments exemplify manual driving deviations compared to using an RTK auto-steer guidance system (RD0 mm). Higher yields and higher net returns resulted from using the RTK auto-steer guidance system. Data showed that for every 20 mm row deviation, an average of 186 kg ha?1 yield loss can be expected. Overall, yield was higher for the conventional tillage and twin row pattern treatments compared to the other treatments. Yield losses for the SR-CT treatment were higher as the row deviation increased compared with the TWR-CT treatment. In contrast, higher yield losses for TWR-ST compared to SR-ST were observed when deviations of 180 mm occurred instead of digging using the RTK auto-steer guidance system. While a farmer using an RTK auto-steer guidance system with an accuracy within 25 mm (RD0 mm treatment) could potentially expect additional net returns of between 94 and 404 $ ha?1 compared to those from row deviations of 90 mm, higher net returns of between 323 and 695 $ ha?1 could be perceived if the guidance system is used instead of having row deviations of 180 mm. Therefore, the use of RTK auto-steer guidance system will allow growers to capitalize on the increases in yield potential by implementing changes in tillage and row patterns as those evaluated in this study. 相似文献
9.
H.L Dijksterhuis L.G Van Willigenburg R.P Van Zuydam 《Computers and Electronics in Agriculture》1998,20(3):185-197
High quality and sustainable agricultural production in the open field will be supported by centimetre-precision guidance of agricultural implements. In this paper, a complete guidance system is proposed and simulated using real sensor data obtained from a real time kinematic (RTK) differential global positioning system (DGPS). This type of the satellite navigation system became available commercially in 1997 and is claimed to reach cm accuracy. It uses real time kinematics to improve the accuracy of a position fix by phase comparison of the carrier signal. The simulation primarily aims to investigate the accuracy of the guidance system that can be obtained with RTK DGPS. Using real DGPS measurement errors the simulated system showed a tracking error less than 0.005 m when the PID-controller had settled. 相似文献
10.
This article presents a new kind of navigation system for agricultural machines. The focus is on trajectory control where a Nonlinear Model Predictive path tracking for tractor and trailer system is presented. The experiments of the proposed method are carried out by using real agricultural machines in real environments.The agricultural objective is to drive so that swaths are exactly side-by-side, without overlapping or gaps. Hence, the objective of this research was to control the lateral position of the towed implement and to keep it close to the adjacent driving line. The adjacent driving line was recognized locally by using a 2D laser scanner. The local measurement and global position information was merged with the help of an Extended Kalman Filter (EKF). The measurement of the heading by GPS was improved by using an inertial measurement unit and a separate EKF filter. The position of the implement was controlled by steering the tractor and by the use of a hydraulically controlled joint. Because there were two actuators which affected the position of the implement, the problem was a multivariable control problem. Nonlinear Model Predictive Control (NMPC) was used to accomplish the navigation task.The goal was to build a system, which is able to have at least the same accuracy as a human driver. The sufficient accuracy requirement was at most 10 cm lateral error at a speed of 12 km/h. The results presented in the article show that the goal was met and NMPC is a feasible method for accurate path tracking. Further investigation is, however, needed to adapt the method to other kinds of agricultural machines. 相似文献
11.
《Computers and Electronics in Agriculture》2007,56(2):161-173
In order to investigate and understand drift from field sprayers, a steady state computational fluid dynamics (CFD) model was developed. The model was developed in 3D in order to increase the understanding of the causes of drift: a deviation in the wind direction cannot be captured by a 2D approach, the wake behind a wind screen is not symmetrical, the effects of a changed nozzle orientation may not be symmetrical. The model's accuracy was validated with field experiments carried out according to the international standard ISO 22866. A field sprayer with a spray boom width of 27 m and 54 nozzles (Hardi ISO F110-03 at 3 bar) was driving at 2.22 m/s over a flat pasture. During the experiments the wind direction was perpendicular to the tractor track. The model explained the variation in drift replicates during each single field experiment through varying boom height (0.3–0.7 m), wind velocity (1.3–2.5 m/s), wind deviation (−18° to +18°) from the direction perpendicular to the tractor track and injection velocity of the droplets (17–27 m/s). Boom movements had the highest impact on the variations in drift values (deviations in drift deposits of 25%), followed by variation in wind velocity (deviations in drift deposits of 3%) and injection velocity of the droplets (deviations in drift deposits of 2.5%). Wind deviation from the direction perpendicular to the tractor track had a reducing effect on the drift values (deviations in drift deposits of 2%). Small variations in driving speed had little influence on drift values. Near drift (<5 m) is predicted well by the model but the increased complexity compromised the predictions at greater distances. The model will be further developed in order to improve far drift prediction. Dynamic simulations will be performed and the model for turbulent dispersion will be optimized. The model did not require calibration. 相似文献
12.
基于GNSS航向微分和MEMS陀螺仪的农机轮角测量方法 总被引：1，自引：0，他引：1
【目的】设计一种农机前轮转角测量方法,代替安装复杂的连杆式轮角传感器。【方法】采用GNSS天线测量航向和速度,MEMS陀螺仪测量车身和车轮的合转动速率,计算MEMS陀螺仪与GNSS航向微分差值,获得车轮转动速率;设计自适应卡尔曼滤波器进行信息融合和校正,获得车轮转向角,并进行性能验证和田间应用试验。【结果】与连杆式轮角传感器测量结果对比,轮角测量方法的拖拉机在偏离航线2.5和1.5 m进行上线时,平均绝对误差(MAE)分别为1.13°和0.87°,均方根误差(RMSE)分别为0.90°和0.68°,上线时间分别为29.4和23.5 s;以4 km/h田间导航应用时,MAE为0.44°,RMSE为0.87°,满足拖拉机旱地作业要求。【结论】GNSS航向微分和MEMS陀螺仪轮角测量方法与连杆式轮角传感器测量性能相当,能够替代轮角传感器用于较低速农业机械导航。 相似文献
13.
The accuracy and interaction among global positioning system (GPS) horizontal accuracy, differential GPS (DGPS) sampling frequencies and machine delay times of a hypothetical variable rate applicator for nitrogen (N) fertilizer application based on an application map in Florida citrus were studied. Parameters studied included: five GPS horizontal accuracy levels, two levels of DGPS horizontal accuracy, two DGPS sampling frequencies and two machine delay times. Two integrated models were developed which documented the effects of the parameters. Machine delay time was the most important factor and GPS horizontal accuracy was the second most important. 相似文献
14.
大马力拖拉机作业机组故障的调查分析 总被引：4，自引：0，他引：4
为了减少大马力拖拉机机组故障,提高农业作业效率,在调查测试播种和收获作业中大马力拖拉机机组故障的基础上,对机组故障时间、故障时间比率、故障时间分布和故障率等进行了分析。结果表明,个别大马力拖拉机机组的故障次数较多、故障时间比率较高;存在机具性能差、机具与拖拉机不匹配、作业管理水平低等问题。为更好的发挥大马力拖拉机机组作业能力提出了建议。 相似文献
15.
采用16位单片机的拖拉机电液悬挂控制系统 总被引：4，自引：1，他引：4
将原有机械式液压悬挂控制系统改装为电液式悬挂控制系统,其控制核心采用了MCS96系列16位单片机系统;对电液悬挂控制系统进行了硬件和软件设计,并在室内仿真试验台上进行了试验验证。试验结果表明,系统具有较好的调节性能,能够满足对拖拉机悬挂控制系统的静动态要求。 相似文献
16.
DGPS数据分析及定位精度研究 总被引：1，自引：0，他引：1
本文进行了DGPS数据分析及定位精度研究。通过试验分析表明，Ag132GPS接收机接收到的卫星信号数可以满足使用卫星数量的要求。采用伪距差分纠偏后，Ag132GPS接收机的DGPS单点定位精度可以达到0．232m，满足亚米级的定位精度。 相似文献
17.
Gerhards R. Sökefeld M. Timmermann C. Kühbauch W. Williams M. M. 《Precision Agriculture》2002,3(1):25-35
A four-year study of site-specific weed control is presented in this paper. Weed seedling distribution was sampled and mapped prior to and after post-emergence herbicide application in four fields planted with maize, sugar beets, winter wheat and winter barley, rotating on one site. Herbicides and other weed control strategies were applied site-specifically according to the spatial variation of weed populations. Different decision algorithms were used for chemical weed control methods in each crop. A weed treatment map was created to direct location and dosage of herbicide application. The sprayer was coupled with a differential Global Positioning System (DGPS). The solenoid valves of the sprayer were opened automatically when the tractor entered a weed patch characterized in the weed treatment map. For site specific herbicide application, a patch sprayer was developed that allowed variable rate application and the selective control of each section of the spray boom. 相似文献
18.
拖拉机作业机组智能化技术的研究现状及发展趋势 总被引：8，自引：1，他引：8
庞昌乐 《中国农业大学学报》2001,6(4):71-75
介绍了国内外拖拉机作业机组智能化技术的应用水平和研究现状，分析了目前国内该研究领域存在的问题，提出了加快我国拖拉机作业机组智能化研究和应用进程的建议，预测了拖拉机作业机组智能化技术的发展趋势。 相似文献
19.
拖拉机作业负荷仿真装置 总被引：1，自引：0，他引：1
为将拖拉机作业机组室内仿真控制研究中模拟的作业阻力转化为拖拉机作业负荷，设计了一种拖拉机作业负荷仿真装置，由拖拉机动力输出轴、万向节传动轴、增速箱和电涡流测功机、模拟犁架和液压加载器几部分组成。试验结果表明，阻力模拟加载系统中牵引力和电涡流测功机产生的制动转矩变化规律与耕深阶跃信号变化规律相同。测功机产生的制动转矩实测值与设定值变化趋势一致。该装置能在计算机控制下实现拖拉机作业负荷的实时模拟和对机组进行各种加载试验研究。 相似文献
20.
B. KolatorI. Bia?obrzewski 《Computers and Electronics in Agriculture》2011,76(2):231-239
The aim of this study was to develop a model that can accurately simulate the performance of a 2WD tractor with a suspended working implement (cultivator) on various types of soil. The following performance indicators were assessed with the use of the developed model: tractor's overall efficiency, tractive efficiency, specific fuel consumption and soil productivity. The proposed model supports the determination of performance indicators accounting for the overall loss of energy during machine operation. Overall efficiency is such an indicator. The value of this parameter varies significantly subject to changes in tractive force from 0 to 7 kN for the analyzed values of the fuel injector control signal and the total transmission ratio in the third (3L), fourth (4L) and fifth (1H) gear. For this reason, the above indicator may be used to determine the optimal parameters of tractor performance. The above variability was not reported in respect of the coefficient of tractive efficiency. 相似文献