Re: Relative Positioning

In case you are attempting to use this for motion capture, probably the
best place to start is the wide variety of technical articles regarding
motion capture systems used for such things as movie special effects,
medical research, etc.

Maybe you need all these transceivers, or maybe what you can really use
is a jogging suit with (for example) triggered LEDs or fluorescent pads
embedded in it, and shot by a high-resolution digital camera. Motion
capture software translates the markers into distance and movement, and
can export that data for such things as integration with Maya or another
character animation program. You get what you are looking for (distance
between two objects) but of course this system only works for objects
visible to the camera.

John mentions magnetic AC trackers, but there's also acoustic and
several other technologies in regular use. Depending on the resolution
you need you might be able to use inertial tracking, like what a Wii
controller does. The solution really depends on how accurate you need to
be, how many frames per second of motion you need to record, and how
many markers you need to monitor.

-- Gordon



mattrapoport@xxxxxxxxx wrote:

Is it possible to build the following scenario, and if so, can anyone
point me on the right track?

I have a person and I want to place small transceivers in various
places on his body. The transceivers would all be able to detect
their distances from each other using some sort of wireless
transmission and then send those distances to a small wireless
processor attached to the person's hip. The processor would then use
the distance variables to determine the relative positions of each
transceiver in 3-dimensions.

I've tried to research this and I've found a lot of sensors that can
determine distances to a random object in its field of vision. But I
would like to know the distance between 2 discrete objects that both
move around. I was thinking maybe I can send a wireless transmission
with a timestamp and a serial number and then the receiving device
would record that information along with the current time stamp.
Maybe the transmission time could then be used to calculate the
distance?

Are there currently transceiving devices that can do this? I am less
concerned about the processing and mostly concerned about the data
capturing.
.

Relevant Pages

  • Re: Long distance comms
    ... where the distance between them is approximately 3km. ... transceivers & connecting the Rx/Tx pins to UARTs at either end. ... The DC resistance of the wire pair is critical. ...
    (comp.arch.embedded)
  • Re: Long distance comms
    ... where the distance between them is approximately 3km. ... transceivers & connecting the Rx/Tx pins to UARTs at either end. ... (the CAN transceiver advantage is that their slew rate can be "programmed" ...
    (comp.arch.embedded)