我正在修补一个简单的Arduino草图,它使用超声波传感器探测距离。根据我的理解,触发器发送ping。回声侦听回来计算距离的回声。这是以微秒为单位测量的。
如果这是正确的,问题是,如何确定该ping的英寸和厘米(以微秒为单位)?这只是基本的数学/物理,并且只有一个基本的公式吗?
void loop() {
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin, HIGH);
这是我遇到问题的部分。我想将ping时间从微秒分为几英寸然后cm:
distance_in = duration ????;
distance_cm = duration ????;
Serial.print(distance_in);
Serial.print(" in, ");
Serial.print(distance_cm);
Serial.print(" cm");
Serial.println();
delay(1500);
}
任何帮助,尽可能多的解释将不胜感激。我是Arduino的新手(而不是数学方面的重量级人物)
答案 0 :(得分:1)
distance_cm = duration / 29 / 2;
distance_in = distance_cm * 0,393701;
声音以每秒343米的速度传播,这意味着每厘米需要29.155微秒。因此,我们必须将持续时间除以29,然后除以2,因为声音必须两次传播距离。它移动到物体然后返回传感器。
1 cm = 0,393701 in
答案 1 :(得分:1)
我在这个问题上找到的最好的文章实际上是在Arduino。 https://www.arduino.cc/en/Tutorial/Ping
/* Ping))) Sensor
This sketch reads a PING))) ultrasonic rangefinder and returns the
distance to the closest object in range. To do this, it sends a pulse
to the sensor to initiate a reading, then listens for a pulse
to return. The length of the returning pulse is proportional to
the distance of the object from the sensor.
The circuit:
* +V connection of the PING))) attached to +5V
* GND connection of the PING))) attached to ground
* SIG connection of the PING))) attached to digital pin 7
http://www.arduino.cc/en/Tutorial/Ping
created 3 Nov 2008
by David A. Mellis
modified 30 Aug 2011
by Tom Igoe
This example code is in the public domain.
*/
// this constant won't change. It's the pin number
// of the sensor's output:
const int pingPin = 7;
void setup() {
// initialize serial communication:
Serial.begin(9600);
}
void loop() {
// establish variables for duration of the ping,
// and the distance result in inches and centimeters:
long duration, inches, cm;
// The PING))) is triggered by a HIGH pulse of 2 or more microseconds.
// Give a short LOW pulse beforehand to ensure a clean HIGH pulse:
pinMode(pingPin, OUTPUT);
digitalWrite(pingPin, LOW);
delayMicroseconds(2);
digitalWrite(pingPin, HIGH);
delayMicroseconds(5);
digitalWrite(pingPin, LOW);
// The same pin is used to read the signal from the PING))): a HIGH
// pulse whose duration is the time (in microseconds) from the sending
// of the ping to the reception of its echo off of an object.
pinMode(pingPin, INPUT);
duration = pulseIn(pingPin, HIGH);
// convert the time into a distance
inches = microsecondsToInches(duration);
cm = microsecondsToCentimeters(duration);
Serial.print(inches);
Serial.print("in, ");
Serial.print(cm);
Serial.print("cm");
Serial.println();
delay(100);
}
long microsecondsToInches(long microseconds) {
// According to Parallax's datasheet for the PING))), there are
// 73.746 microseconds per inch (i.e. sound travels at 1130 feet per
// second). This gives the distance travelled by the ping, outbound
// and return, so we divide by 2 to get the distance of the obstacle.
// See: http://www.parallax.com/dl/docs/prod/acc/28015-PING-v1.3.pdf
return microseconds / 74 / 2;
}
long microsecondsToCentimeters(long microseconds) {
// The speed of sound is 340 m/s or 29 microseconds per centimeter.
// The ping travels out and back, so to find the distance of the
// object we take half of the distance travelled.
return microseconds / 29 / 2;
}