I want to build a measuring device, preferably using sensors to be integrated with RaspberryPi or Arduino, to measure distances between 30cm and 30meter with an accuracy of 5 cm or less.
Currently I'm thinking of a device which can have two modes: a master- (transmitter) and a receiver-mode. The other device should be identical and can also be in one of the two modes. With at least two of these devices/robots I should be able to arrange any setup and let the two 'measuring' robots communicate (or measure) with each other. I would also like to attach a display and logging facility such that while using the devices one can see the measured distance and the results being transferred to an iPad.
If the above requirements can be met I'ld love to make a measuring solution with which I'm able to measure at least three or more position in a large area. For this I need to have for each measuring point in the field an identical measuring-device (which again can be set into master/receiver mode) and create a triangular measuring setup where each device can measure its distance to each of the other positions.
Using Google and looking into some discussions in this forums a see quite a lot of projects where the MaxBotix sensors are being used and connected to either a RaspberryPi or Arduino. However the measured ranges do not fit within the 30cm-30meter requirements I've to fulfill. I really would like some guides in selecting building a sensor setup to meet the above requirements.
Ideas or suggestions, e.g. are ultrasonic sensors the right type of sensors, are very welcome. Thanks in advance!
More info on universal rangefinder device I’ld like to build
Hey guys, thanks very much for the feedback. My apologies for wasting bandwidth due to giving too less or vague information.
Below I try to give more info regarding the device requirements/setup I’ve in mind. Actually I was inspired by an iOS app with which one can measure distances between two iPhones/iPads using the built-in speaker and sound generator. For more info regarding this app see:
https://itunes.apple.com/nl/app/acoustic-ruler-pro/id475081963?mt=8
http://techcrunch.com/2011/11/15/the-acoustic-ruler-iphone-app-is-more-useful-than-the-sonic-screwdriver/
The general area of measurement and requirements can be described as follows:
I would like to measure distances between any positions or objects in an area of maximum 30 x 30 meters with a preferred accuracy of say 5 cm (or about 0.25%). For each position I’ld like to have a measuring device which is able to use e.g. ultrasonic sensors (or any other ‘cheap’ sensors) to measure its distance to all the other positions, which have the same measuring device. Each measuring device should be able to detect at least two other devices (if they’re not out-of-range) and show its distance to them. Every measuring device has a unique id, for example an increasing number in the order they’ve been placed on the area. Depending on the positions of objects one wants to measure the user can layout any area (e.g. a rectangular, triangular or any other grid). Since every measuring device must be able to measure and record the distances to other positions (which are in line-of-sight) all recordings should be transferred preferably to an iPad. To gather all data I would like to be able to do that using one of the placed measuring devices, which should communicate with all other ‘networked’ measuring devices. This means that at any position in the area the nearest measuring device can be used for this data collection process.
Finally the user should see on the iPads screen all measured positions and distances between them.
In the measurement area I’ve at least 1 reference position with known coordinates, and using the other positions I should be able to calculate the distances and positions from the (starting) reference position.
The measuring protocol should be very easy for anybody and consist of the following steps:
1. Determine coordinates of the reference position and place the first measuring-device.
2. For each (object)position to be determined place a measuring-device which should give an instant reading of distance to a previous position (or placed measuring-device). If the newly placed measuring-device is out-of-range an appropriate error should be shown to the user, who has to select another position within the measurement-range.
3. Finally when all positions to be measured are ‘marked’ with a measuring-device all data can be gathered and shown on the iPad.
By reading a number of very inspiring projects on LMR I came up with some thoughts and questions which I’ll summarize below:
a. Although laser sensors seem to have better accuracy and longer-range, the setup may be time consuming and every object/position must be in line-of-sight to other objects/positions. For this reason I was thinking about a RADAR/LIDAR like setup.
b. The MaxBotix ultrasonic sensors seem to be intereseting but have a limited range of maximum 1068 cm! An advantage may be that for example a bush between two objects/positions do not affect the measured distance as much as the laser-method.
c. Infrared does IMHO not have the required accuracy and range I’m looking for.
d. A radio-wave measuring technique is interesting since radio-wave travel through objects but seems not to be appropriate due to its inaccuracy of measurement.
e. Maybe I should combine a number of different measuring sensor techniques and hook them onto 1 RaspberryPI or Arduino board, since looking at the number of project I think it must be do-able to meet the above requirements and measurement-protocol.
I hope the above information is not too much and may be the start of a very interesting (first) project for me and the LMR community.
Thanks again very much for your time and the feedback!
