does measuring distance between two components with Arduino is realistic?

Projects Programming
1

Hey guys.
I wondered if that is the right place to post my question. I assumed it is.

My goal is creating two different but syncronized components, which able to measure the exact distance between them.

I thought about "radio waves". Using "radio waves" I can send a single character between the two components, and by some formula of speed of light (also the speed of radio waves) - assume the distance.

But I wonder wether the Arduino's hardware is fast enough to provide me this purpose, or not.

Guys. I will appreciate if you will help me with the lack of knowledge of mine.

Thank you very much, and have a best day...

3

No, the Arduino UNO hardware is not fast enough to measure light speed for reasonable distances. You can use a radio signal to trigger a remote ultrasonic pulse and measure the time of flight to get a fairly accurate distance over a range of several meters. See the Ben Heck Show episode about Robotic Luggage which not only measures distance but direction.

4

Delta_G:
How far apart are we talking about? inches? feet? miles?

100 feet top.
more then that, I dont care about deviations.

5

johnwasser:
No, the Arduino UNO hardware is not fast enough to measure light speed for reasonable distances. You can use a radio signal to trigger a remote ultrasonic pulse and measure the time of flight to get a fairly accurate distance over a range of several meters. See the Ben Heck Show episode about Robotic Luggage which not only measures distance but direction.

So it will be accurate enough if I want to measure accurate and fast enough a distance of 100 meters?

If it doesnt, so what hardware I can use for achive my target?

6

If it doesnt, so what hardware I can use for achive my target?

A 100 foot tape measure.

7

Or maybe a length of string.
With a couple of tin cans, it could double as a communications device.

8

PaulS:
A 100 foot tape measure.

What?

9

michaelbuzorgi:
What?

A tape measure that is 100 feet long

10

What?

Tape measure

11

jremington:
Tape measure

Yhea Yhea... haha..:slight_smile:
now seriously. It can be accurate for measuring 100 metter distance?

12

michaelbuzorgi:
Yhea Yhea... haha..:slight_smile:
now seriously. It can be accurate for measuring 100 metter distance?

Yes, if you've got a peg or nail you can stick in the ground to anchor the tape. You may also need a calculator (to convert feet to metres) and a pencil and paper to count how many lots of 100 feet plus remainder you've measured.

13

Check out LIDAR Lite v3, made by Garmin and offered at Garmin.com, or resellers such as Sparkfun.com and Robotshop.com for $149 USD.
Good to at least 40 meters with 1cm resolution.
100 meters? Resolution may drop, or it just may not work.
Product site, manual, Arduino library software on Github are here
Garmin LIDAR-Lite v3 | GPS Sensors
Page 9, looks like it has 2 bytes for High Range and Low Range in cm. I don't know how that is interpreted, as 65535 cm = 655.35m = 2150 feet

"The LIDAR-Lite 3 Laser Rangefinder by Garmin is an essential, powerful, scalable and economical laser based measurement solution supporting a wide variety of applications (ex. drones, general robotics, industrial sensing and more). Measures distance, velocity and signal strength of cooperative and non cooperative targets at distances from zero to more than 40 meters. Offering the highest performance available in a single beam ranging sensor in its class.

The new LIDAR-Lite has all of the same specifications as the legacy sensor: Up to 40-meter range capability with 1cm resolution, small size, low power consumption and light weight. There have been a number of upgrades:

Signal Processing Improvements offer 5X Faster Measurement Speeds
•With the implementation of a new signal processing architecture, LIDAR-Lite will now operate at measurement speeds of up to 500 readings per second offering greater resolution for scanning applications."

If you could find a way to get a reading from a golf laser range finder, you could measure even farther, in tenths of yards, out to 650+ yards.
These are advertised numbers for some Leupold range finders (the brand I use - I forget which model).
Maximum Range – Reflective Target/Prism
800 y /731 m
700 y /640 m
650 y /594 m

I regularly use mine (almost daily when the weather is nice, I play on the way home after work) to confirm the flag is over 200 yards away, farther than I can hit with anything except a driver. Some flags have a reflective prism in them, you get a good reading on these from quite far out if you can hold the unit steady enough to pick out the flag.
There are plenty of other brands as well, Bushnell is a big one.
The other big thing in golf is GPS distance, with more general numbers like front, center, and back of green or to some obstacles, even units that will speak the distance for you.

Is the thing you are measuring to a known location? You could program that into a GPS and have the unit tell you how far you are from it.

14

CrossRoads:
Check out LIDAR Lite v3, made by Garmin and offered at Garmin.com, or resellers such as Sparkfun.com and Robotshop.com for $149 USD.
Good to at least 40 meters with 1cm resolution.
100 meters? Resolution may drop, or it just may not work.
Product site, manual, Arduino library software on Github are here
Garmin LIDAR-Lite v3 | GPS Sensors
Page 9, looks like it has 2 bytes for High Range and Low Range in cm. I don't know how that is interpreted, as 65535 cm = 655.35m = 2150 feet

"The LIDAR-Lite 3 Laser Rangefinder by Garmin is an essential, powerful, scalable and economical laser based measurement solution supporting a wide variety of applications (ex. drones, general robotics, industrial sensing and more). Measures distance, velocity and signal strength of cooperative and non cooperative targets at distances from zero to more than 40 meters. Offering the highest performance available in a single beam ranging sensor in its class.

The new LIDAR-Lite has all of the same specifications as the legacy sensor: Up to 40-meter range capability with 1cm resolution, small size, low power consumption and light weight. There have been a number of upgrades:

Signal Processing Improvements offer 5X Faster Measurement Speeds
•With the implementation of a new signal processing architecture, LIDAR-Lite will now operate at measurement speeds of up to 500 readings per second offering greater resolution for scanning applications."

If you could find a way to get a reading from a golf laser range finder, you could measure even farther, in tenths of yards, out to 650+ yards.
These are advertised numbers for some Leupold range finders (the brand I use - I forget which model).
Maximum Range – Reflective Target/Prism
800 y /731 m
700 y /640 m
650 y /594 m

I regularly use mine (almost daily when the weather is nice, I play on the way home after work) to confirm the flag is over 200 yards away, farther than I can hit with anything except a driver. Some flags have a reflective prism in them, you get a good reading on these from quite far out if you can hold the unit steady enough to pick out the flag.
There are plenty of other brands as well, Bushnell is a big one.
The other big thing in golf is GPS distance, with more general numbers like front, center, and back of green or to some obstacles, even units that will speak the distance for you.

Is the thing you are measuring to a known location? You could program that into a GPS and have the unit tell you how far you are from it.

But I need a clean view for using this kind of technology (right? I can use it through buildings for example..).

I want to use radio wavws for a reason, but I need a way to make it be fast enough, which will give me the ability to measure 100 metters in high accuracy with a transmitor and a reciever.

15

In that case, have the other end equipped with GPS and broadcast its position via radio waves, your end receives and do the calculations based on your position.

16

CrossRoads:
In that case, have the other end equipped with GPS and broadcast its position via radio waves, your end receives and do the calculations based on your position.

I will clear my question :slight_smile:
In what problems I will head with, when I will connect a transmitor and a reciever to two Arduinos, and put each one 50 metters away from the other, and then transmit signal from Arduino A to Arduino B, and then measure the exact distance when I know the time past until a signal came back to Arduino A?

How much accurate I can get (In m\cm) with this methos?

17

How much accurate I can get (In m\cm) with this methos?

probably no worse than about 10-20 km

18

AWOL:
probably no worse than about 10-20 km

If that is the situation so I will buy one right now!

Are u telling me for sure that I can with Arduino and to radio "transmit and recive" technology measure 10KM precisely? without any cm deviation?
What is the hardware speed of Arduino anyway? nanosecond cycles?

19

No, I wrote no such thing - I wrote that if you wanted to measure a distance of 100 metres, it would be reasonable to expect an error of up to 10 to 20 km using an Arduino for the timing.

20

AWOL:
No, I wrote no such thing - I wrote that if you wanted to measure a distance of 100 metres, it would be reasonable to expect an error of up to 10 to 20 km using an Arduino for the timing.

Ohh.. and why is that? If the radio waves moving the speed of light, shouldnt it be more accurate? Shat prevent it from be good enough?

And...do you know about another hardware that will help me to achive my target?

21

If the Arduino tells a radio to transmit a value, and another Arduino with receiver receives the value, and sends a reply to the first Arduino, there are several things that have to happen.

The first Arduino needs to record the time and tell the radio to send some data. Does it record the time first? Or does it tell the radio to send the data first? The time will be different in each case.

What is the resolution of the time that it records?

The signal needs to travel from one radio to the other. That is the time that you are interested in. How will you KNOW that the signal made it to the other radio? You only know that because the other radio receives the signal, passes it to the Arduino, which notices that there is data to read, reads, it, decides what it means, and tells the radio to send a response. How long does all THAT take to happen? Is that amount of time consistent? With what accuracy can you measure that time?

The second signal needs to travel back to the first radio. The first radio collects the data, and makes it available to the Arduino, which, sooner or later, notices that there is data to be obtained from the radio. Only when the first Arduino notices that there is data to be read can it stop measuring time.

So, now, you have some unknown period of time that it took for the signal to be sent, some time of interest that it took the radio signal to go from one radio to the other, some unknown period of time between the first radio receiving a signal and it sending a signal, some time of interest that it took the signal to get from the second radio to the first, and some unknown period of time that it took for the Arduino to recognize that the signal had returned.

So, you now have an equation: TotalTime = TimeOfInterest * 2 - UnknownTime1 - UnknownTime2 - UnknownTime3.

One equation, three unknowns.

Now, you need to figure out how long it takes a radio wave to travel 200 meters - 100 out and 100 back. Given the magnitude of that value and the resolution of the times you can measure, how accurately can you measure the time of flight? You could bury your head in the sand, and claim that the three unknown amounts of time are negligible, but we'd laugh at you if you did.

So, you can't really do that. You have to assign some magnitude to the known times. What value(s) will you estimate? What are the magnitudes of th(os)e value(s) relative to the total time?