Position Tracking Devices

[Al Skierkiewicz]

Bob,
If you remember back a few years, the TV networks began using a tracking system to follow the puck in a hockey game. That system used IR LEDs around the perimeter of the puck. Each venue was wired with receptors to determine where the puck was in a grid like fashion. With that data in hand, pan, tilt and zoom data were then extracted from each camera and processed by a computer that then positioned a "hole" in the video output of the system which was then filled and "streaked" to make the puck more visible. That system has gone on to produce the now famous "green" first down mark on football coverage. If you watch football you will notice that not all cameras will show the first down marker since all cameras are not wired to send data to the position computers.

[Mike]

On a FRC robot, since you don't have access to modify the playing field, you must use encoders/gyros. As I understand this project, you would be allowed to place objects around the perimeter of the field.

Here is how I would do this project...

The player would wear a necklace, wristband, or something of that nature that contains a small IR transmitter. I believe these can be purchased/built in the sub-$20 range. I would also place 3 IR receivers at 3 corners of the court. These shouldn't cost more than $20 a piece as well.

By reading in data seperately from those receivers, you can know the distance from that specific receiver to the transmitter. By using some basic trigonometry you can figure out where the transmitter is.

Feel free to ask for clarifications.

[yongkimleng]

Are you tracking 1 player or many players?

In a simple situation of tracking 1 player, you can use the abovementioned idea. You may need multiple receivers since the IR light can be blocked by the person's body, etc.

Where the person is can be calculated by the intensity of the IR received (since your IR transmit signal isn't pulsed)

IF your IR transmit signal IS pulsed, you can use time-difference in recieving the pulses to calculate the position.

However it gets more complicated if you have multiple players on the field. Mary have to result to using time-synchronised microprocessors on each IR transmitter on each player.

[Hieb]

Another thought--active RFID. I don't know much about implementation--just brainstorming--but reading the wikipedia entry on active RFID mentions a range of up to 300 feet, can be the size of a coin, and cost a couple of dollars for the tags. Something like that could be sewn into the uniform so it wouldn't present an injury risk like a braclet or necklace, and each player on the floor could have a unique ID for tracking the entire team or both teams.