G+_Joel Belton Posted February 7, 2017 Share Posted February 7, 2017 Good morning kitas from boiler maker city. (Boiler up) I am currently designing a robotic (ugv) system that I would like to transmit video as well as commands via computer.i choose this option for in future to encrypt signal. I found a robot system that communicates via two routers. I am curious if someone can explain to me how this is done or point me in right direction for how to do it. Link to comment Share on other sites More sharing options...
G+_Benjamin Webb Posted February 8, 2017 Share Posted February 8, 2017 Well control and video are probably completely separate systems. With a router they probably just connected a web cam on the lan side for visuals then a linux computer you can SSH into for control. Abviously the linux computer needs IO to control the robot (that's the hard part). Have the router broadcast wifi with wpa2 AES cipher and a descently long password. That is cleared for top secret documents. You can use a preshaired key instead of password for SSH if your paranoid and pretty sure it is easy to pick up a camera with built in encryption. And for super paranoid wrap the whole thing with a VPN with a preshaired key. So for this to fail they would need WiFi password, camera password, and both preshaired keys for VPN and SSH. Just need to be in wifi range to control. Be pretty cool to add a LTE modem to the router for long distance remote control but setting up the stuff above will take a while. I would use a router running open source software like openwrt (hope someone can suggest something easier to work with openwrt has steep learning curve but can do what you need to do). You could use a regular stock router but probably won't be able to firewall off the wifi and set up a VPN to the lan side of the router. Up to you how much security you want. Link to comment Share on other sites More sharing options...
G+_Joel Belton Posted February 8, 2017 Author Share Posted February 8, 2017 Thank you Benjamin Webb. I am curious of openwrt and how to set up. I am simple electronic engineer and unsure about network stuff. Any assistance would be greatly appreciated. Link to comment Share on other sites More sharing options...
G+_Ben Reese Posted February 8, 2017 Share Posted February 8, 2017 I would think a Raspberry Pi would be great for controlling the robot. I don't know how good the on-board wifi is on the Pi 3, but a USB WiFi adapter should give longer range if needed. It will support the OpenVPN option that Webb mentioned if you want to go that route. There are already tutorials on setting up USB cameras or using the Pi Cam modules. For the other router, most will do fine. One with external antennas will probably give farther range or at least let you put a better antenna on it. Buffalo (and probably others too) makes some routers that come preloaded with DD-WRT. If you want something with more options, I think the WiFi Pineapple from Hak5 is pretty decent ($100-$250 and runs OpenWRT I think). Beyond that, I don't know of any robot tutorials. Link to comment Share on other sites More sharing options...
G+_Joel Belton Posted February 8, 2017 Author Share Posted February 8, 2017 Ben Reese would pi allow for transmit hd video. I am worried about broadband.. Link to comment Share on other sites More sharing options...
G+_Joel Belton Posted February 8, 2017 Author Share Posted February 8, 2017 Bandwidth Link to comment Share on other sites More sharing options...
G+_Benjamin Webb Posted February 8, 2017 Share Posted February 8, 2017 Yeah not a fan of the PI when dealing with anything with serious control (LED Christmas lights is fine). The voltage of the GPIO is extremely low voltage (3.3V) and the flux from motors will probably drive the PI crazy. In an ideal world you want higher voltage digital/analog signals for control (0-10V 0-5V in a pinch) or 4-20 ma. If you go low voltage to save money be weary of shielding. I'd probably do RS232 from a small form factor x86 computer to an arduino and control everything from that. I know this is more hardware and more cost but I find it is the minimum for a truly reliable system. Speak up if your a master of controlling motors with a PI. I've seen them controlling 3D printers but they are usually far away from the action and those motors are tiny. I also burned up about 4 SD cards running my Gen I PI and it would often lock up after about a week but I think they fixed some of that. The PI 3 is miles above the one I used and software way more mature. Link to comment Share on other sites More sharing options...
G+_Ben Reese Posted February 8, 2017 Share Posted February 8, 2017 I'm far from an expert in the field, but I also don't know how much Joel is wanting to spend on this or how big of a robot he's building. It would definitely be unwise to try driving motors off the Pi directly, but in my mind it would just send commands to the actual controller. I don't see why it couldn't also do RS232 with a USB adapter (I think most modern x86 motherboards would have to as well). I haven't done much with it, but my OG Pi is still working strong. I've had one SD card fail in it, but it actually broke physically. So, I don't disagree... Better hardware should make for a much better system. I'm just REALLY cheap and would probably try the $50 system before I spent money on an x86. Would you use a NUC for that? As for the bandwidth, the Pi shouldn't have any problems pushing 1080 video. Your milage may vary depending in your chosen codec and bitrate, but YouTube has a basic guide for live streaming video. https://support.google.com/youtube/answer/2853702?hl=en For 1080p, 30 FPS they recommend 3 to 6 Mbps. That should be well within the bounds of most WiFi connections (and even a lot of LTE connections). Link to comment Share on other sites More sharing options...
G+_Benjamin Webb Posted February 8, 2017 Share Posted February 8, 2017 Yeah definitely need more info on budget and what he needs for control. I know from this Alexa Teddy Ruxbin Hack at Ars that the PI serial drivers are not the greatest with Arduino. Small form factor PC with a serial connector probably run you around $200. Anybody into beagleboards? Their new one with wifi might be the way to go if price and configuration reasonable. arstechnica.com - You can’t unsee Tedlexa, the Internet of Things/AI bear of your nightmares Link to comment Share on other sites More sharing options...
G+_Joel Belton Posted February 8, 2017 Author Share Posted February 8, 2017 I trying to power 12-24v dc motors for a rideable tank I'm building Link to comment Share on other sites More sharing options...
G+_Joel Belton Posted February 8, 2017 Author Share Posted February 8, 2017 That has an option to send video data back via encrypted Link to comment Share on other sites More sharing options...
G+_Golden Retriever Posted February 9, 2017 Share Posted February 9, 2017 Actually a cheap security DVR could have the ability to pan tilt and zoom a camera that should be able to be quite easily converted into a control interface, mini DVRs have the ability to log in remotely for monitoring if you connected it to a small router and set up a cell phone as your WAN connection , you could piggyback off the cellular system instead of having to worry about powerful radio transceivers Link to comment Share on other sites More sharing options...
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