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There are certain tracking devices for cameras on the market these days. Here is one example.

The concept is, you wear a tag or a wristband and the tripod knows to track you while you're out surfing or racing around a track or running back and forth on a soccer field. I always assumed these work via GPS. But there is this other very recent question where it's been implied that tracking technology has been around since the 60s. While military GPS has probably been around that long, it also occurred to me that GPS perhaps doesn't have the high level of accuracy one would need to track precisely.

I'm curious to know what sort of technology these personal tripods use? How does it track its target?

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  • $\begingroup$ Yeah, GPS wouldn't work for this - it's got an accuracy of a few metres at best. $\endgroup$ – Philip Kendall May 2 '17 at 17:41
  • $\begingroup$ Migrating to robotics on request by the OP. $\endgroup$ – MikeW May 2 '17 at 18:58
  • $\begingroup$ All of that stuff (like rocket launches) back in the 1960s referenced in the other question was tracked via optical and/or radar contact. $\endgroup$ – Michael C May 3 '17 at 0:44
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On the page you provided (https://soloshot.com/#features-lightbox), the technical characteristics for the tag indicate (the tag is what you need to have on you for the camera to follow you):

SS Link: 2.4 GHz

Wi-Fi: 802.11 b/g/n

And as for the Range:

Range (SS Link): 2,000 ft

Range (Wi-Fi): 30 ft

The 2.4 GHz is probably a data link between the tag and the tripod (Wifi or Zigbee).

It's GPS !

Extract from https://thetechnologyteacher.wordpress.com/2014/05/29/robotic-camera-follow-soloshot-swivl-aime:

First onto the scene was SoloShot. It was designed for surfers to record their practice runs. As such, it works great outdoor, it’s water proof, and it has an incredible range. The technology it is built on is Xigbee [typo: probably Zigbee] wireless communication and GPS. You do not need to maintain line-of-sight with the marker armband. Unfortunately, it does not work indoors, and can’t do anything close range.

For a better accuracy, you can use differential GPS. It will yield an accuracy of about 20 cm. Extract from Wikipedia:

Differential Global Positioning System (DGPS) is an enhancement to Global Positioning System that provides improved location accuracy, from the 15-meter nominal GPS accuracy to about 10 cm in case of the best implementations.

or unlikely Directional antenna

A directional antenna may be used with a small low power emitter in the tag device. The camera then simply try to keep pointed to the emitter with a more or less basic filter to smooth the tracking.

This technology is used to retrieve UAV if something broke in the UAV navigation system (for example when the USA is flying over a desert or over the see, with no visual helpful information, even if you still have the data-link on).

If the accuracy is very good, a big antenna is needed and probably won't fit on the tripod.

or very unlikely WIFI and MIMO

using Wifi's MIMO capability, you could also detect the angle of arrival of the Wifi signal using multiple antennas as receivers... but I doubt that this is a good solution.

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  • $\begingroup$ You say differential GPS is better. By how much? Can you add a reference or info on the accuracy of relative position between two independent GPS units (The naive implementation of a soloshot type system)? Help readers understand how much of the error is (un)related to time of measurement and location of measurement. $\endgroup$ – hauptmech May 3 '17 at 3:24
  • $\begingroup$ @hauptmech The difference in accuracy is in the Wiki extract (15m vs 10cm). Regarding how DGPS works and how the error is (un)related to time of measurement and location of measurement, I am not qualified to answer. Feel free to edit my answer or make your own. $\endgroup$ – Olivier May 3 '17 at 5:17
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Soloshot 2

At the beginning of a session the tag must be collocated with the pan-tilt unit (held over the camera). There is only a GPS receiver in the tag and none on the pan-tilt unit. The system measures the camera position, the starting angle, and is able to calculate the pointing angle from the updated GPS measurements of the tag.

GPS accuracy varies depending on a number of factors between roughly 5-15m. If one only considers absolute measurements, this is almost, but not quite, good enough for tracking when the camera is zoomed in enough for a human subject. However we are not using absolute measurements, but instead using the relative position to calculate the pan-tilt units angle. In this case, some of the factors that cause errors in the absolute measurement cause less error in the differential measurement (Ionospheric effects for instance). So while the absolute accuracy is insufficient, the differential accuracy is good enough.

Soloshot 3

In the soloshot 3, based on the FAQ, it appears the technology is improved and 2 GPS receivers are used, one in the tag and one in the pan-tilt unit. You no longer have to collocate the tag and the pan-tilt unit on startup. And you can reposition the base if you want. With 2 receivers they would be able to further improve the accuracy of the differential measurement by eliminating drift caused by changes in the error (changes in the ionosphere) over time.

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