Question

如何在JavaScript函数中计算传感器的方向？我在3d Accelerometer calculate the orientation中看到了示例，但不确定如何在计算中应用msg.payload.xAxis / yAxis / zAxis的值。如果可能，我需要以新字段的形式将其应用于以下示例有效负载。

{
"device":"368640",
"deviceType":"Sigfox-Tracker",
"version":3,
"timestamp":"1535121228",
"rssi":"-113.00",
"battery":3.28,
"temp":21.5,
"soil":2107,
"xAxis":61,
"yAxis":-26,
"zAxis":994
}

Answer 1

您粘贴的是一个javascript对象，访问其属性的方法之一是使用dot notation，例如下面的data.xAxis。

我创建了2个函数来根据您链接中的the answer进行计算。然后，我将内置的Math object用于所提供的公式。

这里是例子：

let data = {
  "device": "368640",
  "deviceType": "Sigfox-Tracker",
  "version": 3,
  "timestamp": "1535121228",
  "rssi": "-113.00",
  "battery": 3.28,
  "temp": 21.5,
  "soil": 2107,
  "xAxis": 61,
  "yAxis": -26,
  "zAxis": 994
}

function calcRoll(y, z){
  return Math.atan2(y, z) * 180/Math.PI;
}

function calcPitch(x, y, z){
  return Math.atan2(-x, Math.sqrt(y*y + z*z)) * 180/Math.PI;
}

let dataX = data.xAxis;
let dataY = data.yAxis;
let dataZ = data.zAxis;

let roll = calcRoll(dataY, dataZ);
let pitch = calcPitch(dataX, dataY, dataZ);

console.log(`roll is: ${roll} and pitch is ${pitch}`);

Answer 2

谢谢安德鲁，这是在msg.payload中采用的正确语法，因为每个有效载荷报告的值都不相同？

let data = msg.payload

function calcRoll(y, z){
  return Math.atan2(y, z) * 180/Math.PI;
}

function calcPitch(x, y, z){
  return Math.atan2(-x, Math.sqrt(y*y + z*z)) * 180/Math.PI;
}

let dataX = data.xAxis;
let dataY = data.yAxis;
let dataZ = data.zAxis;

let roll = calcRoll(dataY, dataZ);
let pitch = calcPitch(dataX, dataY, dataZ);

msg.payload.roll = roll;
msg.payload.pitch = pitch;
return msg;

这是当新修改的有效负载到达时我在Node-RED中查看的调试消息：

{"device":"368640","deviceType":"Sigfox-Tracker","version":3,"timestamp":"1535136195","rssi":"-109.00","battery":3.28,"temp":19.5,"soil":2105,"xAxis":71,"yAxis":-32,"zAxis":1002,"roll":-1.8291836314227448,"pitch":-4.05104777734416}

在JavaScript函数（节点RED）中计算加速度计方向

2 个答案: