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May I make a suggestion? Instead of using all that wire, why don't you use Microcontrollers to get the readings and use wireless to communicate with the pi? you can buy an arduino and an nRF24 transceiver for less than one 30m cat5 cable. Plus it really cuts down on the amount of wiring. there are tutorials online and shouldn't be a problem to set up.

Not sure if this would work but it's smaller.

http://www.amazon.com/nRF24L01-Wireless-Transceiver-Arduino-Compatible/dp/B00E594ZX0/ref=sr_1_1?ie=UTF8&qid=1426635199&sr=8-1&keywords=arduino+2.4ghz

Not sure what exactly is possible out of the box but the thought would be having the pursuer transmit a beacon packet and have the evaders echo back the packets and calculate the round trip time?

probably if you're a wizard, I think it's more common to use something like this that just plugs into the GPIO ports. then you need to figure out which commands to send to make the drone do what

How is the servo motor related to the power setting on the fan? Maybe you have a system where it does the switching, but anyway I just amazon searched "arduino wireless" and this is what I got:

I actually bought these, haven't used em yet.

Wifi Sheild

Bluetooth

I think it should be formatted right. For me, ardiuno has so much stuff, equipment is the easy stuff, programming gets tough lol.

I don't know how many Hobby Electronics people we have in here but typically speaking when you develop a product you use someone else's transition tech. They make it super easy to integrate into electronics. You can do any of this with an Arduino now if you want to see how easy it is. And there are tons of options out there and just a super quick search on amazon shows they carry quite a few. Bellow is a few links to some kits you can buy off amazon right now. These kits let you link over Bluetooth or RF or even Wi-fi. So I don't really think valve would waist the time to make a completely new method of wireless communication for their hardware when so much is readily available that is reliable. Also when it comes to wireless transmission you only have a certain band of radio waves you can use commercially and they are all already used. I took apart a wireless Wi-Mote and it had one of these chips soldered right into the board. You can also see these chips soldering into the sixense as well. It is super common to do this. Also I think everyone here knows the PS3 and PS4 both use Bluetooth for their controller, you can even pair them with the Gear VR. So it is highly unlikely that valve has anything special here.

Low Power Bluetooth

RF-Transmitter

Normal Bluetooth

Wi-Fi connection


So In Short;
I don't think valve would waist their time making a custom wireless system. I would think they want this to be as universal as possible.

Why not use the quadcopter one?

They are usually 4 channel, and one channel is typically set up to allow for a "fixed speed" (for hovering) - meaning you can stick the joystick in one position, and it doesn't "spring return".

That channel/stick (up/down - non-spring return) will be the one you should use for the blade control.

The other stick (2 channels - left/right, up/down) will be "spring-return to center" - where "center" is considered "zero speed". You would use those two channels to control the differential (left/right) wheel motors to control where you want to go.

Now you're probably asking yourself "how the heck will that work" - so I'll tell ya:

You didn't mention what you were using for motor control (nor what kind of motors you have). So I am going to assume this is a full-sized mower using wheelchair motors. If you haven't gotten a controller yet, you will need one. It would be best to get something from Vantec if you have the cash:

http://www.vantec.com/

Their controllers can take the signals from your receiver - two channels as an x/y joystick - and properly "mix" them to output the right signals for your dual-wheel motor setup - you'll want something from this page to match your motor specs of course:

http://www.vantec.com/acatalog/spdcat.html

Note how expensive they are - but they are super-robust. Nearly indestructible. I have a friend who uses them on robots we build together out of old wheelchair parts and such (he has a non-profit to repair wheelchairs to donate to people in need - as such, he has a ton of "junk parts" that we then use to make other stuff out of).

An alternative to an expensive controller would be to use a "bang-bang" controller: Basically, hook servos to control DPDT switches (or use them to control switches that control high-power automotive relays wired as an h-bridge). Unfortunately, you'll get "full speed" all the time, so you'll want to run the motors on a lower voltage and/or gear them down (use a chain drive or something) to keep the speed reasonable.

A low-cost alternative non-quadcopter setup would be to get yourself an older 4-6 channel FM transmitter/receiver pair. They are el-cheapo on Ebay most of the time (if they aren't one of the collectible sets - stay away from those) - heck, sometimes they even come with servos! Anyhow, most of them are set up for aircraft frequencies, so you'll want to get a crystal set for ground frequencies (look this info up if you don't know about this). That will make you legal, and keep the FCC off yer butt.

Another option would be to build the transmitter and receiver your own self. Picture something like an Arduino (or other microcontroller - just using an Arduino here because it is popular), coupled to a transmitter on one side, and a receiver on the other. Now, add code on each end to take the input of a joystick and buttons and transmit that to the receiver, and then output the proper PWM and such for the motors. Honestly, it is that simple. For instance - something like this as a transmitter:

1x Joystick for Nano and NRF24L01: https://www.amazon.com/SunFounder-Mobile-Controller-Arduino-NRF24L01

2x NRF24L01: https://www.amazon.com/gp/product/B00E594ZX0/

2x Nano: https://www.amazon.com/dp/B01DBV1UE4

So - you plug in a Nano and NRF24L01 into the joystick board - that's your transmitter. You'll need to write code that reads the joystick (analog pins), then converts those values (0-1023 on both axes) into a byte stream to be transmitted by the NRF24L01. There's plenty of example code out there to show you how to do this. Note that is only for driving the wheels - if you want to control the blade motor, you can also detect the press of the top of the joystick (it's a pushbutton - like all those small stick are), and transmit that, too.

Now - on the other end, take the other Nano and hook it up to the other NRF24L01 and read the data stream from the transmitter; use that to output PWM to your motor controllers, which could be anything - but for wheelchair motors you could try a couple of these if budget isn't big for a Vantec:

https://www.amazon.com/SainSmart-BTS7960B-Stepper-H-Bridge-Arduino/dp/B01H2XEEWM

Of course, you'll have to write your own code to take the x/y position of the joystick and convert it to drive the wheels properly (this isn't easy, but it is doable - check the Arduino forums for info - there have been threads about it).

That's basically it. Oh - one other thing: You have thought about safety cutouts, dead-man switches, etc - right? If you haven't - stop - and start thinking about what-if scenarios:

There you are happily mowing the lawn - and the unthinkable happens: The robot goes out of range and a channel gets stuck, a servo stops responding to inputs, a control linkage breaks, a relay gets stuck, etc - and now the robot is traveling forward, blades spinning, and heading towards the neighbor's cat being played with by their 2-year old daughter.

How do you stop the robot?

You need to think up how you would handle such a situation. You should give your robot a means to be shut-off manually on the robot (one of those big red non-resettable override buttons would be perfect) - some way anyone could figure out in a hurry. You should add some kind of emergency strobe light on the robot to warn people. You should also add some means to remotely shut the system down from your controller. Also, if you can, a way for the robot to know when something has gone wrong and to shut itself down would be a good thing, too.

Lastly (seriously!) - when you test your robot - test it "wheels off the ground" - because you don't want to attempt to try to stop a fully loaded wheelchair robot from running away from you (guess what - you really can't - those things weigh a couple hundred pounds loaded with the batteries, motors, frame, etc - and the motors have no f's left to give and won't stop just because you hold on to the frame - they will just happily drag you along - trust me on this).

Hope this helps, and good luck with the project (heh - it's actually something on my todo list myself - though my plan is to convert an old Friendly Robotic robo-mower that I have lying around).

http://www.amazon.com/nRF24L01-Wireless-Transceiver-Arduino-Compatible/dp/B00E594ZX0/ref=sr_1_1?s=electronics&ie=UTF8&qid=1417728219&sr=1-1&keywords=arduino+wireless

Where do you find those at $1 apiece? Sparkfun has them about $20 a pop and Amazon sells them for $7 for 2

Unless you want to build one to learn from it might be chaper to just buy one:

http://www.amazon.com/Wireless-Transmitter-Receiver-Module-Arduino/dp/B00INTI8R2

This is in the 400mhz range area. but you'll need two sets for both ends to transmit and receive. (or one set to just send commands)

If you can wait for shipping then:
http://www.gearbest.com/development-boards/pp_142069.html

OR

http://www.amazon.com/nRF24L01-Wireless-Transceiver-Antistatic-Compatible/dp/B00E594ZX0/

This will allow sending and receiving at both ends, but works in the highly cluttered 2.4Ghz range.

Then go with IR? As long as it's in line of sight it's a decent option. Otherwise these little guys are pretty convenient.

$40? Man, that's a bit steep. Would it be a lot harder using an arduino nano clone and maybe one of these small wifi receiver modules?

> Do you need a wireless link the whole way, or would two short WiFi links to the internet work?

That's what I'm looking to do. Others have suggested something like this. I'll probably end up going with that.

I am not sure about your application, but these $6 wireless transceivers might be of interest. http://www.amazon.com/dp/B00E594ZX0/ref=cm_sw_r_tw_awdm_coFetb0931RQF