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Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
The XV-11 lidar use some brushes to transfer power and serial coms at 115.2k baud while rotating 10 times a second.
But I may need a similar capability, spinning a high speed circuit board with A/D at 300k. Is this posible? Or did they restrict it due to noise from motion on the contacts?
I don't really want to have a blue tooth type communication, for hand shake, device population and discovery reasons.
Registered Member #65
Joined: Thu Feb 09 2006, 06:43AM
Location:
Posts: 1155
Make sure to use parity checking in the communication lines if you are going to use the mechanical method.
Note, almost every LIDAR manufacturer uses a variation of the optics methods shown.
At one time, I had considered adapting a modified UT390B for a precision kit. However, at 3 samples per second it did not meet to minimum refresh rate.
Registered Member #2463
Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546
There is a child toy that has a spinning ring with LEDs. I makes various patterns. Uses a gang of four slip rings. Uses AAA Batteries. Cost about $6. I bought a few a couple of years ago to specifically hack the ship ring system. They were sold in the Dollar stores.
Registered Member #2431
Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639
radiotech wrote ...
There is a child toy that has a spinning ring with LEDs. I makes various patterns. Uses a gang of four slip rings. Uses AAA Batteries. Cost about $6. I bought a few a couple of years ago to specifically hack the ship ring system. They were sold in the Dollar stores.
what quality were the slip rings?
often, ive seen in 80's and 90s tech, thin copper strips pressed into plastic, making it inseperable from the original body.
Registered Member #3414
Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245
Concentric rings cut from different diameters of copper pipe is one way, the other way is to use rings cut from the same diameter copper pipe, and fit them onto a shaft, like the sliprings on a car alternator, for example.
I have repaired/modified alternators in this way before. I've even mounted the rotor and stator from a car alternator on motorcycle crankshafts in the past.
A lathe and some epoxy will be your 'best friends' here.
Registered Member #72
Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659
Electroholic wrote ...
Would this work?
That's a really clever use of a cheap readily available product. You can get them far smaller than those huge things he was demonstrating, I've just bought some 4mm bore 4mm thick 8mm O/D races for another project, that's not a lot of weight to add, even to a flyer. While it's moving metal on metal, the multiple contact points may make it more secure than just a rubbing slip-ring. Now if you can design the mechanics to accept purchased ball races, that's going to be as cheap and more robust as any other solution.
I would suggest using a good forward error error correcting code with burst correction capability for the data link, so an inner and outer code with block interleave between, that will correct data over a long mechanical outage. You should be able to find CD readback chips for decoding, or FOSS IP for uCs or FPGAs.
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help! serial communication across moving contacts.
