概览

对指南针的磁性干扰会严重影响导航 所有类型的机体。

这篇文章解释了你可进行哪些硬件改造以降低成本 罗盘上的磁性干扰以及辅助理论 讨论。 关于如何设置指南针的信息可以在 ** 高级指南设置**。

[站点维基="copter"]. 在科普特磁性干扰上 会导致旋转 (又称"拖拉机") 在Loiter,RTL,AUTO飞行 模式。[/站

另见磁力下降(维基百科).

硬件变化以减少罗盘上的磁干扰

1. 最佳方法是使用**外部指南针** 或**GPS+组件** 安装在桅杆上并远离磁源的模块 干扰包括动力分配板(PDB).
2. 保持PDB、ESC和电池之间的电线短如 也许吧 从ESC到马达的电线不太重要 提供培训 因为它们是空调 既然是空调 产生较少的干扰
3. 将PDB、ESC和电池之间的电线转接并禁用看看这个 尽可能屏蔽
4. Replace the PDB and ESCs with a 4-in-1 ESC because they tend to produce less interference probably because their wires are shorter and closer together and they also have an aluminum plate on top which may help reduce the interference.
5. Add aluminum shielding (even gutter tape) around the wires from the ESC to the motors may reduce the AC interference. Aluminum will not help reduce the primary DC interference from the PDB, ESCs and the wires connecting them.

Maxwell's Equations - The Magnetic Field on the Axis of a Current Loop

There are 3 things to get from this drawing and the equation for the magnetic field B as you move away from a current loop along the Z axis:

1. The magnetic field increases as a function of the enclosed loop area Pi R^2
   • Big loop = big magnetic field
   • Reduce the magnetic field by twisting the loop to close it. aka twist the wires together and keep your return path close to the source
   • In the case where you have a PDB and 4 ESCs you have 4 loops that start at the Deans connector on the PDB, go out to the ESC and return back to the Deans connector. In the case of the 4 in 1 ESC the current flow is much more concentrated in one area and you don't have the big loops so consequently you decrease the magnetic field.
2. The magnetic field increases as a function of current
   • Where there is the option, you can deliver the same power and decrease the magnetic field by increasing the voltage and decreasing the current.
3. The magnetic field decreases as a function of the cube of the distance
   • It is more complicated when you are close to the loop but when z >> R the denominator goes to z^3

There is one more thing and that is that the direction of the magnetic field depends on the direction that the current flows so when you rotate a battery it changes the magnetic field produced by the current flowing in the battery.

It can't be stated enough that minimizing the enclosed loop areas and moving the compass away from the current will help things work better and "yes", power distribution boards with big circular thick high current PC traces on them produce significant semi-spherical fields as large or larger than their diameter.

Natural and Artificial Magnetic Anomalies Warning

1. Many things can distort the earth's magnetic field in the area you are flying:

   • Steel framed or reinforced concrete buildings, bridges and roadways, iron pipes and culverts, high power electric lines, heavy equipment, trucks and automobiles, steel tanks, electric motors and even computers.
   • Flying between steel framed or reinforced high rise buildings will distort the magnetic field in addition to causing GPS multi-pathing.

2. Safe distances for compass calibration

   • 6" (15 cm) minimum: Metal rim glasses, pen/pencil, metal watch band, pocket knife, metal zipper/buttons, belt buckle, batteries, binoculars, cell phone, keys, camera, camcorder, survey nails, metal tape measure.

   • 18" (50 cm) minimum: Clipboard, data collector, computer, GPS antenna, 2-way radio, hand gun, hatchet, cell phone case with magnetic closure.

   • 6 ft (2 m) minimum: Bicycle, fire hydrant, road signs, sewer cap or drain, steel pole, ATV, guy wire, magnets, chain-link fence, bar-wire fence, data collectors

     that use a magnet to hold the stylus.

   • 15 ft (5 m) minimum: Electrical box, small car/truck, powerline, building with concrete & steel.

   • 30 ft (10 m) minimum: Large truck, metal building, heavy machinery.

GPS for yaw

ArduPilot supports the use of GPS heading information to reduce malfunctions caused by changes in the magnetic field in certain environments.

• Configure GPS for yaw

https://youtu.be/Kh_6TynYqEI

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