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What is LLT?

asked 2016-05-05 20:13:36 -0600

Rob Mueller gravatar image

updated 2016-05-05 20:14:14 -0600

What is Low Latency Tele-Robotics (LLT)?

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answered 2016-05-07 07:51:26 -0600

Spacerobots gravatar image

Various groups and companies have developed software to help compensate for latency, by giving the operator an image that is projected forward in time. However, since these cannot predict the future (e.g. a thruster firing, a reaction wheel turning) they do not provide any additional margin of safety in a dynamic situation.

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answered 2016-05-06 21:53:47 -0600

Rob Mueller gravatar image

updated 2016-05-07 09:42:28 -0600

When robots are tele-operated by human operators, the time delay (called latency) of the radio frequency (RF) communications signal can be a problem in terms of the disruption it causes to the operator's perception and control. Most tele-operators can tolerate about 200 milli-seconds of latency. Some very talented people can tolerate as much as 600 milli-seconds of latency, but that is rare.

Since the latency for operating robots on the Moon is about 1.3 seconds each way or 2,600 milli-seconds total round trip, then it makes it difficult to do real time tele-operations of robots. Not all operations require real time control, but for those that do, it is an issue.

The latency for Mars communication varies from 6-42 minutes depending on orbital phasing with the Earth, making tele-operations from Earth impossible.

One proposed solution is to control these robots from a closer distance to the Moon or Mars, from orbit, or in the case of Mars it could also be from from Phobos. An innovative solution for Mars was proposed by the NASA HERRO study, where a 12 hour highly elliptical Mars Molniya orbit is used to tele-operate surface robots for science and exploration.

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Asked: 2016-05-05 20:13:36 -0600

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Last updated: May 07 '16