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1、精选优质文档-倾情为你奉上Title：CALIBRATING METHOD FOR ELECTRONIC COMPASSElectronic compass is an electronic compass by measuring the Earths magnetic field to achieve directional navigation device, it is an important navigational tool that can provide real-time data objects heading and attitude, and has a small
2、size, low cost, fast response , no accumulated error, etc., are widely used in mobile robots, vehicles, aircraft and other orientation subsystem; However, due to the electronic compass is based on magnetic principles calculations magnetic bearings, their work environment, in addition to other extern
3、al magnetic field Earths magnetic field will inevitably affect the output of the electronic compass, resulting in errors affect measurement accuracy. Therefore, how to reduce outside interference precision of its output is engineering applications must be addressed.Electronic compass the existing li
4、terature has proposed several possible compass error compensation method. Yuen Chee Wing paper, three-axis magnetic heading sensors full attitude error compensation proposed compass error into quadrature error, zero and sensitivity errors were compensated, high compensation accuracy of the method, b
5、ut in the compensation process requires non-magnetic turntable , but also the computer automatically when the measured rotation compass X and Y-axis sensor output maximum, minimum, the calibration process is complex and requires high equipment; HIGHWAY AND TRANSPORTATION Wang Jiaxin paper Developmen
6、t of high-precision electronic compass and Shao Tingting, ROCKETS paper electronic compass tilt and Luo slip compensation algorithm research, the least square method to compensate for the electronic compass, the method requires Compass 0 360 rotation average sampling, operation is relatively cumbers
7、ome and The amount of data samples of different sizes will have a greater impact fitting result, the amount of data is too small, the compensation effect is not good, too much data can cause performance degradation fitting; Yangxin Yong, Huang Shengguo paper magnetic heading measurement system Error
8、 Correction Method and Qi Zhang, Liang-shui Lei, Jiang Fan, Song Lius paper Autocalibration of a magnetic compasswithout heading reference error ellipse hypothesis is proposed based on the model compensation method, because only a hypothetical model ellipse based on the experimental experience sugge
9、sted that the lack of theoretical deduction, the compensation effect is not very satisfactory; Chao Min, Jiang Oriental, Wen rainbow paper, magnetic compass error analysis and calibration using an analytical method to establish the direction of the magnetic measurement system is more accurate models
10、, and electronic compass compensation in the horizontal conditions, but the compensation process to identify more parameters (up 9), and the results show the compensation effect is similar to oval hypothetical model; Hao Zhenhai, Huang Shengguo paper, based on a combination of differential magnetic
11、compass heading system. proposed a differential magnetic compass (DMC, Differential Magnetic Compasses) design program, which uses two identical magnetic compass to determine whether the system is a combination of low-frequency interference occurs, if the system glitches did not happen, then the use
12、 of magnetic compass navigation, low-frequency interference will occur if the system switches to the gyroscope system navigation. The program does not substantially improve the magnetic compass measurement accuracy, and the navigation program consists of a plurality of magnetic compass and gyroscope
13、 structure, will lead to greatly increase the cost; Lu Wang, Zhao Zhong and other paper Magnetic Compass Error Analysis and Compensation using BP neural network error model, and use LM learning algorithm to train the network, the method need not 0 360 within the average sampling, with a neural netwo
14、rk can be approximated function with arbitrary precision characteristics, with high compensation accuracy, but the BP neural network convergence is slow, the right to set initial values need to be very careful, and easy to fall into local minimum.In summary, the current electronic compass calibratio
15、n methods are the main method of least squares, oval assumption France, BP neural network method, etc. These methods are more cumbersome calibration procedure or the existence of the necessary instruments for demanding calibration or calibration issues such as lack of precision. It is an electronic
16、compass by measuring the Earths magnetic field to achieve directional navigation device, it is an important navigational tool that can provide real-time data objects heading and attitude, and has a small size, low cost, fast response , no accumulated error, etc., are widely used in mobile robots, ve
17、hicles, aircraft and other orientation subsystem; However, due to the electronic compass is based on magnetic principles calculations magnetic bearings, their work environment, in addition to other external magnetic field Earths magnetic field will inevitably affect the output of the electronic comp
18、ass, resulting in errors affect measurement accuracy. Therefore, how to reduce outside interference precision of its output is engineering applications must be addressed.In order to simplify the calibration procedure, reducing the requirements for the necessary equipment and to improve calibration a
19、ccuracy, the present invention designed an electronic compass calibration method, the calibration method based on adaptive differential evolution method and Fourier neural network (Adaptive Differential Evolution and Fourier Neural Network, ADE-FNN), by means of Fourier neural network modeling of th
20、e electronic compass error, the neural network using orthogonal Fourier series excitation function as a network, and uses adaptive differential evolution algorithm to train the network weights, get more precise The error model to compensate for the measured values of the compass, so as to improve th
21、e precision of the compass.Differential evolution method based on adaptive neural networks and Fourier electronic compass calibration methods, including access to training samples, the use of Fourier neural network (FNN) build error compensation model and the use of adaptive differential evolution a
22、lgorithm (ADE) to train the neural network weight value of three parts, to achieve the specific steps are as follows:Step one, get training samples;Step two, identified neural network structure;Step three, to create an electronic compass error model and choose the training targets;Step four: Accordi
23、ng to the training sample using an improved adaptive differential evolution algorithm for training the neural network;Step Five, will optimize the neural network weights obtained values into the neural network to obtain a more accurate compensation models;Step Six, the electronic compass output meas
24、urement values into compensate for neural network input and output compensation value.The invention took into account the impact of measurement precision electronic compass, proposes a differential evolution method based on adaptive neural networks and Fourier concentration calibration method to com
25、pensate, on the one hand to simplify the calibration process, that is just the turntable rotate (no uniform rotation) electronic compass one week for training samples and the corresponding true value; hand with better results, ie, more precisely offset outside interference, improve measurement accur
26、acy.The compensation method with neural network structure is simple, easy to implement, and can approximate nonlinear functions with arbitrary precision, and has good generalization capability advantages.Orthogonal Fourier function as the excitation function neural network, the nonlinear optimizatio
27、n problem into a linear optimization problem, which greatly improve the convergence speed, avoid falling into local minimum.Using adaptive differential evolution algorithm to train the neural network, relying on a system to avoid the initial value problem of a priori knowledge is difficult to choose
28、; while the improved differential evolution algorithm in the initial stages of a strong global search ability, as much as possible to find the global optimum, but at a later stage there is a strong local search ability to improve convergence rate and solution accuracy; therefore the algorithm has st
29、rong global search ability, can effectively prevent premature convergence, and algorithms good stability.How Does a Digital Compass Work? An electronic compass such as the Wayfinder uses a patented magnetic sensor technology that was first developed by PNI, Inc. for the U.S. military. This technolog
30、y is called magneto-inductive and is the largest advancement in compass technology since the fulxgate was invented 60 years ago. The magneto-inductive technology is able to electronically sense the difference in the earths magnetic field from a disturbance caused by external elements such as ferro-m
31、agnetic materials and the magnetic field generated by automobile electrical systems. WayFinder digital compass has an embedded micro controller that subtracts the automobile magnetic field (the distortion) from the stronger earth magnetic fields resulting in a highly accurate compass reading. Compas
32、s InstallationThe performance of a compass will greatly depend on its installation location. A compass relies on the earths magnetic field to provide heading. Any distortions of earth magnetic field by other sources such as a car massive iron components should be compensated for in order to determin
33、e an accurate heading. Sources of magnetic fields in any automobile include permanent magnets mostly in its audio speakers, motors, electric currents flowing in its wiringeither dc or ac, and ferro-magnetic metals such as steel or iron. The influence of these sources of interference on an electronic
34、 compass accuracy can be greatly reduced by placing the compass far away from them. Some of the field effects can be compensated by way of calibrating the compass for a defined location in terms of magnetic interference. However, it is not always possible to compensate for time varying magnetic fiel
35、ds; for example, disturbances generated by the motion of magnetic metals, or unpredictable electrical current in a nearby power lines. Magnetic shielding can be used for large field disturbances from motors or audio speakers. The best way to reduce disturbances is distance. Also, never enclose the c
36、ompass in a magnetically shielded metallic housing.Compass Tilt ErrorsHeading errors due to a tilt depend somewhat on geographic location. At the equator, tilt errors are less critical since the earths field is strictly in the horizontal plane. This provides larger X and Y readings and little of the
37、 Z component correction near the magnetic poles, tilt errors are extremely importantsince there is less X,Y field and more of the Z component. Tilt errors are also dependent on the heading.Magnetic Field DistortionsNearby Ferrous materials is another consideration for heading inaccuracy. Since headi
38、ng is based on the direction of the earths horizontal field a digital compass must be able to measure this field with lesser influence from other nearby magnetic sources or disturbances.The amount of disturbance depends on the material content of the platform and connectors as well as ferrous object
39、s moving nearby. When a ferrous object is placed in a uniform magnetic field it will exert an influence. This object could be a steel bolt or bracket near the compass or an iron door latch close to the compass. The net result is a characteristic distortion, or anomaly to the earths magnetic field th
40、at is unique to the shape of the object. Magnetic distortions can be categorized as two typeshard iron and soft iron effects. Hard iron distortions arise from permanent magnets and magnetized iron or steel on the compass platform. These distortions will remain constant and in a fixed location relati
41、ve to the compass for all heading orientations. Hard iron effects add a constant magnitude field component along each axes of the sensor output. To compensate for hard iron distortion is usually done by rotating the compass and platform (your car) in a circle and measure enough points on the circle
42、to determine this offset. Once found, the (X,Y) offset can be stored in memory and subtracted from every reading. The net result will be to eliminate the hard iron disturbance from the heading calculation.The soft iron distortion arises from the interaction of the earths magnetic field and any magne
43、tically soft material surrounding the compass. Like the hard iron materials, the soft metals also distort the earths magnetic field lines. The difference is the amount of distortion from the soft iron depends on the compass orientation.What Is True North?It is well known that the earths magnetic pol
44、es and its axis of rotation are not at the same geographical location. They are about 11.5 rotation from each other. This creates a difference between the true north, or grid north, and the magnetic north, or direction a magnetic compass will point. Simply it is the angular difference between the ma
45、gnetic and true north expressed as an Easterly or Westerly variation. This difference is defined as the variation angle and is dependent on the compass short duration, making a magnetic compass a useful navigation tool.Compass CalibrationEach calibration method is associated with a specified physica
46、l movement of the compass platform in order to sample the magnetic space surrounding the compass. The Hard and Soft iron distortions will vary from location to location within the same platform. The compass has to be mounted permanently to its platform to get a valid calibration. A particular calibr
47、ation is only valid for that location of the compass. If the compass is re-oriented in the same location, then a new calibration is required. It is possible to use a compass without any calibration if the need is only for repeatability and not accuracy.题目：校准电子罗盘的方法电子罗盘是一种通过测量地球磁场来实现定向导航功能的装置，它是一种重要的
48、导航工具，能实时提供物体的航向和姿态数据，且具有体积小、成本低、响应速度快、无累积误差等特点，被广泛应用于移动机器人、车辆、飞行器等的定向子系统中；然而，由于电子罗盘是根据地磁原理计算磁方向角，其工作环境中除地球磁场的其他外界磁场不可避免的会对电子罗盘的输出造成影响，从而产生误差影响测量精度。因此，如何降低外界干扰对其输出的精度的影响是工程应用中心必须解决的问题。 现有的文献已经提出了几种可行的罗盘误差补偿方法。袁智荣的论文三轴磁航向传感器的圈子太误差补偿提出将罗盘误差分为正交误差、零位于灵敏度误差分别进行补偿，该方法补偿精度较高，但是在补偿过程中需要无磁转台，而且需要计算及自动测出罗盘旋转一
49、周时X和Y周传感器输出的最大、最小值，其标定过程较复杂，且对设备要求较高；李希胜、王家鑫的论文高精度电子罗盘的研制以及邵婷婷、马建仓的论文电子罗盘的倾斜角及罗差补偿算法研究采用最小二乘法对电子罗盘进行补偿，该方法需要对罗盘在0 360 旋转式平均采样，操作较繁琐，而且采样的数据量的大小不同会对拟合结果长生较大的影响，数据量太小，补偿效果不好，数量太大，会造成性能恶化的拟合；杨新勇、黄圣国的论文磁航向测量系统误差修正方法研究以及Qi Zhang、Liang-shui Lei、Jiang Fan、Song Liu的论文Autocalibration of a magnetic compasswithout heading reference提出一种基于椭圆假设误差模型的补偿方法，由于椭圆假设模型仅是根据实验经验提出，缺乏理论论证，补偿效果并不是很理想；晁敏、将东方、文彩虹的论文磁罗盘误差分析与校准采用分析法建立磁方向测量系统较为精确地模型，并对电子罗盘在水平条件下进行补偿，单补偿