FPV ground vehicle

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Schlauncha
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FPV ground vehicle

Post by Schlauncha » 06 Aug 2013, 11:46

So, just wanted to start this thread here to get it out of the General AR Drone (salute!) section, from the FPV Scavenger Hunt thread. As you may have read from there, the story is this: I picked up some wifi-controlled webcam robots, which can be accessed to be driven over the internet from any browser. I set one up that could drive around my house, and it worked pretty well. Still does work well, and you can test it out by going to tinyurl.com/drivemyrobot and logging in with username robot1, password robot1.

One thing it would really be nice to do though, is to be able to drive around outdoors. This would require a more offroad-capable vehicle, longer wifi range, and building a charging station that works with the new chassis. I plan on using an Arduino to read the voltages of the three motors (the stock robot has omni wheels) and translating the motor outputs into new PWM outputs for ESC's to run electric wheelchair motors for track drive units off of a snowblower. Since it would no longer move omni-style, I would be remapping it to read forward back as normal, strafe right or strafe left as pivot right or pivot left, combination forward/back and strafe left/right as combination forward/back and turning, and then the pivoting command (which stops any forward/back driving on the robot) would turn into two momentary outputs for each direction, so you would gain two "channels" on the robot. This could run an air horn, and possibly an air-powered belt fed machine gun (which is legal). It would be used for fun out in the countryside anyways and would have other safety interlocks built in - mostly it's just for a proof of concept that it can be done.

This Sunday I will be picking up the snowblower to use the track drive from. Here is what it looks like:
Image

I have experience with building Battlebots before, so using wheelchair motors to make something this size is pretty normal stuff. Anyways, I'll try to post updates and stuff here as it goes. I'll probably have a few wiring questions about how to use the Arduino to read voltages from the motor wires which will be reversing polarity, so hopefully the right people read this section who can help answer those things when we get to them.

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appelm
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Re: FPV ground vehicle

Post by appelm » 06 Aug 2013, 16:05

Online Snow Blowing service! first of its kind! Have someone on another continent manage your snow clearing needs! Prompt service, day or night - there's always someone awake somewhere. Please keep small children off the snow blower at all times.

Kyrt
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Re: FPV ground vehicle

Post by Kyrt » 07 Aug 2013, 00:06

I guess autonomous "go to dock" navigation won't end so well if you've remapped some of its movement to a ballistic weapon ;)

Schlauncha
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Re: FPV ground vehicle

Post by Schlauncha » 07 Aug 2013, 01:21

Outdoor operation means no ceiling for the dock's IR beacons to shine on, and without seeing them (no Nav signal) it won't initiate a docking sequence.

I spent some time talking with a few engineers earlier this evening, and I think I've got it figured out how I'll need to wire up the Arduino, and how the program will work.

Pawelsky, you up for another PWM output converter? This one should be easy! No serial stuff to need to read, just good old IF/THEN conditions based on voltage inputs on a few pins, controlling simple forward/neutral/reverse on two PWM outputs, and high/low on another two PWM outputs.

We are hooking the Arduino to a common ground with the Rovio, and using resistors as voltage dividers coming off the positive and negative wires of the three motors, to run to pins 0-5 (six pins, since 0 is a pin). So then the program loops to watch the inputs, and according do the outputs to two PWM pins.

For example then

Front left motor forward is voltage to pin 0, rev pin 1
Right right motor forward is voltage to pin 2, rev pin 3
Rear motor CW is voltage to pin 4, CCW pin 5
PWM1 is left motor, PWM2 is right motor, high is forward, low is reverse
PWM3 is a simple high/low that can run a servo-based relay. Needs to start low. This will run accessories (horn, flamethrower, etc)
PWM4, ditto.

Robot is driving forward: Pins 0 and 2 read voltage above 2v, but no others do. Result: PWM1 and PWM2 are high value
Robot is driving backward: Pins 1 and 3 read voltage above 2v, but no others do. Result: PWM1 and PWM2 are low value

Robot is stopped: No pins are voltage above 2v. Result: PWM1 and PWM2 are neutral (at medium value)

Robot is strafing left: Pins 1 2 and 5 read voltage above 2v, but no others. Result: PWM1 is low, PWM2 is high
Robot is strafing right: Pins 0 3 and 4 read voltage above 2v, but no others. Result: PWM1 is right, PWM2 is low

Robot is driving forward while strafing left: Pins 2 and 5 read voltage above 2v, but no others. Result: PWM1 is neutral, PWM2 is high
Robot is driving forward while strafing right: Pins 0 and 4 read voltage above 2v, but no others. Result: PWM1 is high, PWM2 is neutral
Robot is driving backward while strafing left: Pins 1 and 5 read voltage above 2v, but no others. Result: PWM1 is neutral, PWM2 is low
Robot is driving backward while strafing right: Pins 3 and 4 read voltage above 2v, but no others. Result: PWM1 is low, PWM2 is neutral

Robot is pivoting left: Pins 1 2 and 4 read voltage above 2v, but no others. Result: PWM3 is high (in any other situation, it is low)
Robot is pivoting left: Pins 0 3 and 5 read voltage above 2v, but no others. Result: PWM4 is high (in any other situation, it is low)

Schlauncha
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Re: FPV ground vehicle

Post by Schlauncha » 08 Aug 2013, 05:32

Okay, I think I have my first attempt here at the Arduino program. I picked up an Arduino Uno to use for this. I also retrieved one of my old Battlebots and borrowed the drive motors from it, so I can start figuring out how to adapt them to drive the track pods. These are NPC-01280 24VDC 0.7HP 4700rpm brushed motors, and I have some IFI Victor 884's to run them with. They currently gear drive a jackshaft which has 5" diameter tires on it, which was probably even a bit too fast (I'd rather have more torque). Initial observations make it appear that the track pods mount to an single-hung axle, so that may present some challenges compared to this double-hung gearing currently in use with this NPC motor. I found my bigger wheelchair motors but they were still mounted in another Battlebot (I care more about). I'll probably just use two SLA 12v batteries for now and worry about recharging systems much later.

Anyways, super tired but I am able to compile this program (haven't actually tried downloading it or wiring it up yet). We'll see if Pawelsky or anyone else has some thoughts on how well it looks like this will work, and/or if I've ham-fistedly written something far more bulky and repetitive than what it really needs to be, such that it can be slimmed down to work better. But I got my motor power ramping built into the code easy enough, I think! That way it isn't 100% throttle the first moment you hit Forward, but instead, takes a second or two to scale up from 0 to 100% throttle (and doesn't go past 100%). Talking 0 to 100 on a -100 to 0 to 100 scale, but in the program we're actually talking a 0 to 90 to 180 scale. Having a high refresh rate isn't a big deal, we don't need super precise super fast updating like we did on the AR Drone PWM conversion - this thing is free to clunk around a little bit, doesn't need to react lightning fast.
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AR.Tommy
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Re: FPV ground vehicle

Post by AR.Tommy » 08 Aug 2013, 08:01

Nice project, too bad you are on Android since I did a sweet app to control Rovio. :D
http://www.digitalsirup.com

Sweet and delicious apps for your drones.

Schlauncha
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Re: FPV ground vehicle

Post by Schlauncha » 08 Aug 2013, 12:30

I tried using an Android App to control the Rovio, and even on very very low video quality settings I could never get a decent framerate or a small enough control delay to make it a viable method of driving. Even when put onto the same wifi network. I don't know where the bottleneck is, but an AR Drone works better and isn't too different of a thing. Maybe it's an app problem after all.

Once you connect to it through the link of tinyurl.com/drivemyrobot you will see the IP address and port which it is connecting to. With those numbers and the username and password (robot1 and robot1) you should be able to connect with your app and see whether your video and controls are fast enough. Of course, trying it out from a PC first to establish a baseline for your connection speed. Firefox and Google Chrome seem to work better with it than Internet Explorer does.

Kyrt
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Re: FPV ground vehicle

Post by Kyrt » 08 Aug 2013, 16:52

I figured out my earlier issues with video from the rovio were simply due to using safari, using Firefox just now was fine. Your dog must be bored of this thing by now as he didn't bat an eyelid when I discovered your bedroom.

Schlauncha
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Re: FPV ground vehicle

Post by Schlauncha » 08 Aug 2013, 18:28

Kyrt wrote:Your dog must be bored of this thing by now as he didn't bat an eyelid when I discovered your bedroom.
He's smart enough, it didn't take him very long to figure out that 1) the Rovio was not going to compete for alpha dog status, 2) the Rovio was not going to give him food, and 3) he can climb up onto the bed and not have to worry about the Rovio reaching him. At this point, it is of little interest to him. I think I will see if there's something I can build from Legos and hot glue on top of the Rovio, to carry treats and incrementally dispense them when the Rovio's camera is cycled up/down. Picturing being in the Rovio's viewpoint, when Ein gets the first treat and begins seeing if he can forcefully get more from the Rovio by trying to nudge or flip or bite it. It would look much like the footage from being inside a shark cage.

I have some more work to do with rearranging my place now that my brother moved out, so that should be interesting. I plan on moving the Rovio base into my bedroom so that it has a better (flat) ceiling to shine its IR beacons on, to do better at docking.

Once I get the big robot working and come up with a charging station for it (or just solar panels on it maybe?) then I could always chain it in the yard at my brother's house out in the country, and continue making that publicly available, so people could have fun driving that around. It might have to be downgraded to an airsoft rifle for when we're doing that, though.

I already have some ideas on how to make gauges and other HUD features... by physically putting indicators in the path of the camera so they show up on the edges of the frame. Things like LED's indicating drive system voltage, which accessory is currently active (I figured out a way to toggle through multiple ones) and so on.

I think there may even be a way to have an AR Drone controlled through it, with a landing dock on top of the robot which would recharge the Drone. For when you need to send out the recon Drone to scout targets! You can fly an AR Drone from a PC, you can put a laptop in the robot to do that, you can have the Rovio camera look at the laptop, you can have the Arduino (when toggled into the right mode) translate all the Rovio movements into AR Drone movements, etc etc.

Kyrt
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Re: FPV ground vehicle

Post by Kyrt » 08 Aug 2013, 23:49

Flying a drone remotely via a rovio might just cause a few exploding heads. I doubt the drone would last long though! Especially if someone gets the bright idea to use it as target practice...

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Re: FPV ground vehicle

Post by DroneFreakFPV » 09 Aug 2013, 01:17

This build is gonna be epic huh

Samsung Galaxy S3 using Tapatalk HD
ARD2/MiruMod/Miru GPS/Spektrum DX6I/ HogMod/GoPro Custom Mount/808 #16/ Wi-Fi Less FPV System
Tarot FY450/Turnigy Motors/I86L FC, HK Blue 30a ESCS/R610 Micro DSM 2.4ghz Reciever, GAUI Props

Schlauncha
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Re: FPV ground vehicle

Post by Schlauncha » 09 Aug 2013, 02:55

I got the program working, and all the functions work pretty much how I want. I have attached the program, and it seems to be working well with the Arduino Uno I bought for it. I took some resistors and soldered them up as voltage dividers, and hooked one to each motor's positive and negative wires (well, I mean, the motor runs both directions so these roles change), and then in between the resistors I have wires coming out to the Arduino, so it can use its pins 0-5 to listen in to what the Rovio is trying to do. I say trying, because I pulled the wheels off. The motors still have to be running inside the Rovio, since each one has an encoder on it that the Rovio uses to keep wheel rotations synchronized.

This video should really clarify things.

Direct link: http://www.youtube.com/v/MzN8_8rZBS0

Doing some calculating on the motor gearing and power, it looks like if I have this pair of 0.7hp motors rated at 4700 rpm, then with a 16:1 reduction and 9" diameter on the track, the result (and this is no-load, no frictional losses, so of course real world numbers will be less) should be around 8mph speed and 66 pounds of pushing force. That seems to me like it should be enough. I don't want it too fast given the control lag, so it will be better to gear lower than needed, than to risk getting stuck on terrain somewhere due to a lack of torque to drive its way out. The robot will probably weigh somewhere around 70 to 100 pounds by the time it is done. I will probably design up a chain reduction using flange-mount bearings in a plate-constructed chassis, such that once I have it modeled up in 3D I can just have a local shop CNC plasma-cut the chassis out of 1/4" steel plates that will slot-and-tab together, allowing for an amazingly strong structure once it's welded up. Just so if it happens to go tumbling down a hill, it won't bend and deform. I'll have to figure out where the Rovio is going inside of this, because with the camera on there, the camera position is determined by where the Rovio is at unless I can wire an extension on the camera.
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Schlauncha
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Re: FPV ground vehicle

Post by Schlauncha » 10 Aug 2013, 04:47

More progress. I came up with what I feel is a pretty nifty piece of code that uses Q to cycle the servo up and down for vertical aiming of the (cupcake dispenser) which will probably have a laser sight mounted on it, and the camera will probably end up mounted looking down the barrel as well. As long as Q is held, it slowly cycles, until you let off and it will stay there even as you drive around.

I wired up the two ESC's, and I'm lucky to have TWO, since one of them came amazingly close to death - the killsaw had come through the aluminum chassis and even the plastic casing on the bottom of the ESC, but stopped maybe 1mm or 2mm away from hitting the board inside, based on the cut marks to the ESC's case. I know the wiring is way too thin at the moment, this was just for testing porpoises right now. The ESC's have a button to hold for calibrating their range, but by just using the normal Arduino servo commands as shown in their examples, I didn't need to mess with the exact frequencies - just a number 0 to 180 (90 neutral). Stuff looks slow, but that is a combination of the thin wiring, programmed slow ramp-up of throttle, and running this 24v motor on 12v for this test.

Just waiting for the test chassis to arrive ("Tarantula" r/c tank my brother is dropping off tonight). Then begins the task of soldering up everything into a neat shape that can be mounted in a project box, along with the Rovio, on top of the Tarantula tank. Although... just remembered, I have to actually scrounge up another ESC and come up with an alternate program for the Tarantula, so I can run its arm motors (it has arms with tracks too, like EOD robots do). My friend wants one so I may just get this one all working, sell it to him that way, and pick up another for my big robot build.


Direct link: http://www.youtube.com/v/-Z2s0QaMWeE
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Schlauncha
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Re: FPV ground vehicle

Post by Schlauncha » 12 Aug 2013, 12:24

Well, we got the snowblower picked up and it looks to be in great shape. It even started on the first revolution of the first pull and ran like a champ - a shame I don't just simply need this as a snowblower, and won't be using the motor. I'm sure the 5hp motor can find a useful porpoise somewhere else on my dad's farm, running a water pump or something.

But what a trip to get it... My friend borrowed his dad's truck and trailer so we were picking up the Lancer Evo project car that he had sold a guy and was now buying back in a more rebuilt form. The snowblower happened to be along the way, so I came with for that. Everything was going fine until the way back when (and we were in Illinois at the time, hours away from home in Iowa) a police officer began tailing us. He came up alongside our trailer (2 lane each-way divided highway) like he was going past... but then just stayed there next to the trailer for a while, but then slowed back behind us again and here come the lights. We pull over, and the cop tells my friend that not only does his trailer not have lights (we kind of knew that) but also: There was no license plate. The trailer had more than 2,000 lbs on it and didn't have its own brakes as required. There was only 1 of the 2 safety chains. We didn't have the registration for the trailer (which a license plate would have shown with its sticker) and since we also didn't have a VIN number on the trailer, it could be subject to seizure on the spot. The car on the trailer, during the rebuilding process, had its dash replaced and the VIN plate had been glued back on, missing the official rivets that held it on, and this makes the car subject to seizure, but luckily the VIN in the door jam matched so he believed the VIN plate on the dash was not any foul play. At least our truck had plates, insurance, registration, but pretty much everything behind the hitch was wrong illegal and subject to seizure.

How we got away with just a huge list of warnings is something I'll never understand. The officer directed us to the nearest Farm & Fleet where we picked up a set of magnetic add-on trailer lights, and we made the rest of the trip home just fine.

In summary, if you take a trailer to another state to pick up a car, it is worth the time to take a glance at the trailer and consider how likely its deficiencies will get you pulled over.

Schlauncha
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Re: FPV ground vehicle

Post by Schlauncha » 13 Aug 2013, 03:25

I wired it all up on the smaller tracked chassis for now, since it will take a little while to build the bigger one with the tracks from the snowblower.

Here is a brief video comparing the stock Rovio to the one that I have modded to use the tank style chassis. This would need more work to put its wiring into enclosures so it would be suited for driving around more than this limited testing.


Direct link: http://www.youtube.com/v/P3rpaU9FmrQ

I kind of wish I knew who was logging in and driving... every now and then people still log in and drive the Rovio around, kind of wish I knew who. I mean, it'd be fun to chat about their experiences with driving it. Earlier somebody was driving it and I fired up this behemoth Rovio and the two robots played together for a bit.

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