Hello all,

I am a newbie to this board and hands-on electronics in general. I am trying to identify a kit which can help me build a system which can do proximity measurement along with direction.

Just to provide a little more info.

Parameters: A sensor system which when deployed can measure the distance between a mother node and children nodes and the relative direction of the children nodes with respect to mother node.

should be able to work with distances of 5-20 ft, accuracy ~90+%

technology: ultrasonic, bluetooth, zigbee, ir, ...

I was looking at Senix ultrasonic products, but the problem I can't seem to get my mind wrapped around is how to figure out relative orientation.

example: I can have 4 ultrasonic sensors, 3 placed like the ends of a triangle and one in the centroid. Then I make each one of the sensors placed at the vertices, emit a pulse which will be picked up by the one in the centroid, but I can't figure out how to determine relative direction.

any ideas/comments/pointers are greatly appreciated.

PS: a wild thought .. I have heard about directional antennae arrays..can anyone suggest if this is a decent possibility or a wild goose chase

Thanks again

 

TheBiggestBangTheory... The August issue of the hobbyist magazine, "Nuts and Volts" contains plans for a "Solar Tracker!"

Of particular interest to me was the development of a Pointing Vector.

(My apologizes to those finding the "V-Word" abhorrent!)

Regards, Phil Corso (cepsicon [at]aol.com)

 

I think that ultrasonic sensors could be applied with triangulation techniques to solve your problem.

Your mother node would need three ultrasonic receivers separated from each other by some distance, the child nodes would transmit a burst of sound which the mother node would detect at each (all) of its receivers. Because the receivers are separated, the sound will generally arrive at different times at each receiver. The mother node then knows the distance between the child node and each receiver, the intersection of the circles (or spheres if you are working in three dimensions) drawn about the three receivers with radii of the detected distances provides the position of the child node.

This is actually how human hearing works to know the direction of a sound source (although with only two ears, some directions are ambiguous; equidistant positions can be interpreted incorrectly).

Ultrasonic range measurement usually is distance determined using time of flight of sound bursts, your mother node will need to know when the child node started transmitting to determine the distances. This could be achieved by having the mother node command the child nodes to transmit, or the child node could potentially just transmit at a constant rate (e.g., one burst [precisely] every second). Handling multiple child nodes may be best achieved by having the mother node command each child to transmit separately (eliminating collisions).

Regards,
Chris Turcotte

 

I have used the Senix sensors in a very tough application, and found them to work great. You should propose your project to tech support at Senix, and I am sure they can guide you. I know that there are times that sensors can get "confused" about which sensor sent out the signal when multiple US sensors are used in close proximity. The Senix sensors have a wire that allows you to connect the sensors to one another to avoid that problem.

Other methods of sensing will require more accurate timing. I think that ultrasonic might be your best choice.

 

We use to use DME 200 measuring lasers that seemed to work real well. I know they had RS 232 with other kinds of outputs. But your looking for a package deal right? Not interested in using pulse tach to determine direction and using logic for the rest