Does the distance sensor I need exist yet (at low cost)?

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1

Hi. I’m working on a unique project and need distance sensors to the following requirements:

  • - Small (width doesn’t matter but length does)

  • - About 10 metres max range (I could settle for 5)
  • - Millimeter precise / reading-to-reading (preferably sub-mm if possible!)
  • - At least 20 Hz sample rate, preferably 60 Hz
  • - Low cost (less than $30 per sensor in an order of 6 or 12)
    • I don't care about accuracy, just precision. If it's wrong, but consistent (precise), then it's great for me. It could literally read 2 metres as 1 meter and I wouldn't care as long as it's still mm or sub-mm precise and the readings are accurate *relative to the initial reading*.

    Does the sensor I need exist yet? Would it exist if I were a large company? Does it exist, but just at too high a price?

    If not, anyone hazard a guess to the number of years until it does exist (at the price I need it at)?

    2

    Maybe you can hack one of those laser “measuring tapes.”

    Besides that, not a snowball’s chance of doing it for $30 unless you can make it a contact measurement.

    3

    Millimeter precise / reading-to-reading (preferably sub-mm if possible!)

    Very difficult for a laser in any case, and not even possible for $30.

    4

    Thanks for the answer. How many years in the future do you expect it to be possible at $30?

    Also I don’t need it to be a laser. It could be sonar, lidar, ToF, anything. As long as it meets the requirements above.

    5

    Any noncontact distance measurement, with 1 mm precision and accuracy, will be very expensive.

    Do some googling to learn why.

    6

    Heaney555:
    Thanks for the answer. How many years in the future do you expect it to be possible at $30?

    Also I don’t need it to be a laser. It could be sonar, lidar, ToF, anything. As long as it meets the requirements above.

    Stuff doesn’t just magically decrease in price for no reason. It does so primarily because economies of scale allow manufacturers to drop prices when building things in large volumes. Before that happens, there has to be a market to make the investment worthwhile.

    What’s your proposed market for these sensors?

    7

    Okay, so what would the actual price be? Do the above exist at even <$150?

    8

    Here is a laser rangefinder with 1 mm accuracy. http://www.acuitylaser.com/products/ite … ance-meter

    Contact the company to get the price, and let us know what you find out.

    9

    I think ultrasonic seems like a better idea: https://www.sparkfun.com/products/11724

    The only issue is price (but that’s understandable) and sample rate.

    7.5Hz is just too low. Does anyone know if I could modify this to operate at a higher rate?

    10

    Consumer grade ultrasonic rangers cannot possibly achieve 1 mm precision and accuracy. You are lucky if you get +/- 1 cm.

    There are two problems: the wavelength limitation and the fact that a train of pulses is sent, so you don’t know which pulse was returned.

    11

    Just submitted a price request, just out of curiosity.

    12

    The one I linked claimed 1 mm precision. As I said in the OP, accuracy doesn’t matter at all.

    This actually seems even better: https://www.sparkfun.com/products/11309

    But again only 10 Hz :frowning:

    13

    From the datasheet: Filtered Operation - Free-Run The HRLV-MaxSonar-EZ uses an internal 2Hz bandwidth filter to process range data; which reports the latest range every 100mS or 10Hz. This improves the sensor’s performance for accuracy, noise rejection, and reading to reading stability.

    14

    As a point of reference, a [Sick DT20 laser sensor with a measuring range of 1 meter and a resolution of 1.5mm, is going for $700 at an industrial distributor and $950 on eBay.

    You’re not going to get anything remotely near $30 without at least partially building it yourself.

    Here’s a project: research what it takes to build a laser or ultrasonic displacement sensor with 1mm resolution. I’m fairly sure you can build one for under $50 in parts (combination of TOF ranging and phase measurement should get you there) However, once you’ve built it, you now have a device with a BOM cost of $50 that normally sells for $700+ on the open market. What’s your incentive to lower that price when you can sell what you built for 10x what it cost you to build it?

    If you’re going to be that philantropic, hobbyists will love you for it!

    However, if you actually tell us what you’re trying to accomplish, perhaps we can offer other solutions.](SICK | Sensor Intelligence)

    15

    Yes, a description of the actual goal would be interesting.

    I can see how the Maxbotix folks could claim 1 mm “stability” in the distance readings – if they are targeting a large flat surface a meter or so away. But if you are interested to detect a mm-scale feature on that surface with 1mm resolution using ultrasonics, it is hopeless. You could do so with a suitable (expensive) laser scanner, though.