蓝牙LE RSSI用于接近检测iOS [英] Bluetooth LE RSSI for proximity detection iOS

问题描述

我将从问题开始。

BTLE RSSI是指示两个设备彼此接近的好方法吗？它只适用于像Fobs等小型设备吗？

Is the BTLE RSSI a good way to indicate two devices proximity to each other or not? does it only work with small devices like fobs etc?

问题：

我目前正在制作一款将使用BTLE并允许基于邻近度的连接的应用。在这方面，它很像苹果在高级核心蓝牙主题演示中展示的演示应用程序（当两个设备几乎触摸它们然后连接时）。

I am currently looking at making an app that will use BTLE and allow connections based on proximity. In this regard it is much like the demo app that apple show in the Advanced Core Bluetooth keynote (When two devices are almost touching they then connect).

据我所知当中心发现外围设备时，基于RSSI值确定接近度。然而，当我尝试使用两个iPad时，信号看起来太强了，它也太不一致，因为它没有显示与设备接近度的非常大的相关性，因此它与接近处没有显示出很大的相关性。

As I understand it the proximity is determined based on the RSSI value when the central discovers the peripheral. When I try this however with two iPads the signal seems too strong for this it is also too inconsistent to have an accurate stab at the proximity as it doesn't show very much correlation to the devices proximity.

我已经尝试了Apple示例代码，类似的是设备不必完全关闭，以便信息从一个传递到另一个。

I have tried the Apple sample code and that is similar in that the devices don't have to be close at all for the information to pass from one to another.

如果只有一种方法可以降低外围设备广告的信号强度....

If only there was a way to reduce the signal strength of the peripheral devices advertisement....

提前感谢您的帮助。

推荐答案

Matthew Griffin的经历与我的相遇。然而 - 当我们可以测量相当长的一段时间时，有两件事情帮助我们更好地校准。

The experience of Matthew Griffin matches mine. However - when we can measure for a fair period of time two things have helped us calibrate this better.

我们必须在天线上包裹一个简单的（kalman）滤波器方向和IMU得到一个粗略的运行评论 - 这不是CPU或电池灯。

We did have to wrap a simple (kalman) filter on the antenna orientation and the IMU to get a rough running commentary though - and this is not very CPU or battery light.

• 使用IMU你会得到一个对距离/行进方向的公平想法 - 如果这是在很短的时间内 - 我们假设另一个'侧'是静止的。这有助于获得当前方向的值和调用当前环境噪声。


• 同样 - 对旋转/位置更改执行相同操作。

我们发现，一般来说，重新定位设备是获得方向的更好方法;并且该距离仅在移动校准后大约30至600秒内可靠，并且仅在设备没有旋转太多时才可靠。而在实践中，曾经需要一些4-5个其他设备;理想情况下不要过于动态，以保持自己的动态校准。

We've found that in general a re-orientation of the device is a better way to get direction; and that distance is only reliable some up to some 30 to 600 seconds after a 'move' calibration' and only if the device is not too much rotated. And in practice once needs some 4-5 'other' devices; ideally not too mobile, to keep oneself dynamically calibrated.

然而反过来相当可靠 - 即我们知道什么时候不测量。最终的结果是，人们可以很好地确定诸如在键盘上和重新定位/通过特定的门/开放或方向移动的东西。同样通过在房间里随机跳舞来测量场地;改变方向很多 - 一旦接收器天线波瓣在静止一段时间后有所改善，它确实能正常工作。

However the converse is quite reliable - i.e. we know when not to measure. And the net result is that one can fairly well ascertain things like 'at the keyboard' and 'relocated'/moved away through a specific door/openning or direction. Likewise measuring a field by randomly dancing through the room; changing orientation a lot - does work well once the receiver antenna lobes got somewhat worked out after a stationary period.

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