What you need to know before hacking toy RC cars into combat robots
Now this is a very tempting idea. Obviously, because an RC car comes with wheels and motors and a controller, but as somebody who has a whole box of well an overflowing box of us toy RC cars and has been pulling these things apart. Since I was about 10 years old, I can tell you that there is like three categories to these: the regular RC cars, which are bad, the stunt RC cars which are good and then these two little guys down the front here which are almost perfect. But to get into that we’re gon na have to talk about the actual chassis of the vehicles first and then we’ll talk about controllers after that, so let’s get started with the conventional RC cars. The kind of cheap run of the mill bulk car style that you will get pretty much everywhere so here we’ve got our conventional RC cars that are kind of in various states of disassembly and also in curraghs, a kind of broad ish range of prices. These ones in the middle I got secondhand, so they were quite cheap and then the ones on the edges are a little more expensive and then the big guy is even more expensive again, but all of these here are functionally the same thing and we’ll pull them All apart in a second and I’ll show you what I’m talking about, but most importantly, is their steering system, so the steering system, if I grab hold of this guy you can see, I can pick up and grab hold of the front, wheels and turn them.
This is the steering mechanism on this car it’s called Ackermann steering, and it means that these front these wheels at the back here are locked together. They go at the same speed forwards or backwards and to turn the car. You turn the wheels one way or the other now. This is bad for a combat robot, because let’s say you want to take this car and drive back towards me. To do that, you need to lock the steering one direction drive forwards. Then you need to lock the steer in the other direction and drive backwards, which is all very hard to do with my hands. But you end up like that facing back in the direction you want to go, which it’s a two point: maneuver. It takes time and energy to do that, and it takes a lot of coordination to do that. Compare that to the typical steering mechanism used in a combat robot, which is skid and or tank steering, depending on how, where you want to do it. Sorry, how you want to say it because it’s the same thing: you have two wheels that are independent of each other and you literally turn one in the opposite direction to the one to the other one and you manage to spin round on the spot. This you can do just by flicking a switch sideways and you spin around on the spot and you’re immediately facing the direction you want to go so Ackermann steering itself is quite bad.
You don’t want a combat robot to have a command steering because you will be outpaced and outmatched every single flight. Your opponent is going to be able to drive circles around you quite literally, and if your opponent has a weapon, that is very, very bad news for you, so Ackermann steering is just bad in general, but this thing does have two motors in it, so you might Be thinking that you can just rip these two motors out and then use these two motors in some kind of skid steering style, but you also can’t do that so. But to look at that, we need to actually look at how they’ve implemented the Ackermann steering inside these cars, and it is exactly the same for all of these, regardless of the price point which is kind of crazy. So here is the inside of that mechanism. You can see on this side, you’ve got a motor attached to the top plate and the top plate sits on the top and gets screwed down and then on the inside in here you see that we have the two wheels on there little pivots, and then we Have an arm that runs between the two wheels and up into this kind of geared to section up here, so what’s actually happening here and I’m just going to put this down so that the car doesn’t break. When I put it all down, we have a single regular standard, boring DC motor, so this has got two wires coming off the back of it, which means you can put power in one side and get it to spin one direct and then put power on the Other side and you get it to spin the other direction.
So how does the car get an angle going? Well, it literally put power into one of these wires and then that will turn this gear on the end here and then that turns on this pinion that’s down here and then it’s going to go until it hits a hard locking point there’s. Actually, a piece of plastic in underneath this pinion that hits a piece of the chassis and it just stops, but there’s still power going to this motor. So while the Ackermann steering is full lock like this, this motor is drawing a lot of power, it’s drawing it’s full stall currents, keeping the wheels in this position. This is really really bad for your battery and it’s why these motors themselves are often different. So you see this guy has a little red cap on the back of him. If we look at the back of this guy, so this is the other one. You can see the red cap mode right in the back here where this is necessary in the front here. This is where the steering is then in the back. You see there’s another motor, but it has a black cap on the back of it. So because these things are being manufactured in China, nothing is different for no reason, because something being different means it’s, costly, so things being different means that they are physically. There has to be a physical reason for this difference, so this motor is going to be wound differently, so that it is more talky or slower speed or draws less power, something along those lines, which means that if you try and pull both of these motors out Of here and use them to drive two different wheels, a not only you’re, not going to have the same, gearing stack up, because this guy has a single gear and then opinion which you can’t use to drive a wheel, but also be these motors are going to Be different power levels in some some way or form like this steering motor is probably going to be slower and more talky and also draw less power, and then the motor at the back.
That does the gear driving, because it’s actually got a gear train on it. It will be faster and a little bit less talky, but it will probably draw more power, so, overall, this whole thing is junk. You just ha do anything with it for a combat robot, because, even if you do kind of, if you are okay with this Ackermann steering everything else about this is bad. This. The way this Ackermann steering setup is running means that as you’re turning your drawing significant amounts of power out of your system and, unfortunately, all of the cars, even this massive massive ones, that cost me a lot more than these tiny little ones all use the same System they all use just a regular brushed DC motor slamming into a hard end, stop to do the turning. In fact, if you look right here, you can actually see that this turning motor, that is in the be more expensive, larger car, actually looks to be exactly the same as the motor that is driving one of these tiny little cars, and I am honestly not surprised By that, the factories that are making these would probably be making a bunch of different RC cars for a bunch of different brands and just reusing whatever parts they have around the place there. All of these cars, even the big ones that are kind of expensive or more expensive they’re made as cheaply as they possibly can make them so yeah, there’s lots of corners, cut and lots of duplicate parts and all of that kind of stuff like these boards.
That are in here these are from different eras, so this guy is from I don’t know, 10 or so years ago, and this one is more modern, but the boards themselves are functionally the same thing that verbally just replaced some of the more expensive parts on this Board with cheaper parts on this board, as the years have gone on alright anyway, let’s actually now move over and have a look at the stunt cars. So the next group is stunt cars, and I don’t have quite as many of these because they keep getting hacked and used for other different bits and pieces that’s, because things that are sold as stunt cars are often a lot more usable than the things that are Just regular old RC cars, now not everything in this category is actually going to be usable. Some of it is still going to have that commence tearing and still do exactly the same as the cars that we just saw and still have that really terrible terrible steering mechanism in there with the single motor and everything but cars like this well, this one has Been already hacked and turned into a beta weight, which happened a very very long time ago, I tried to build a beta weight in 24 hours that didn’t quite work as well as I’d planned because it was also my first beetle weight so yeah, but you can See here that this here has a native tank, skid steering mechanism right, you’ve got one wheel, motor on either side and they turn independently of each other.
So you can then do a conventional tank steer set up with this, which means you can actually get a decently controlled, combat robot out of it and that’s the same with this thing here. So if I pulled this up off the ground, these two wheels on this side move together, but they move independently of the other side. So that means that we can turn these two forwards and these two backwards at the same time and spin on the spot, which is exactly what we want out of this thing now, like I said some of them, you will find don’t do this and do have A cumin searing, but what you need to look out for when you’re looking for a stunt car is the ability or the the lack of ability to do a command steering. Basically, if you see very large, very strong axles like this one or if you see our thing, where it’s got two massive wheels at the back and then tiny little wheels at the front, and especially if it claims that it can still spin around on the spot. When those tiny wheels are off the ground, then you’ve got yourself something that will do tank steering natively, and that is going to help you a lot in getting a car like this to actually convert into a combat robot. This one here is a little bit big. So we could probably convert this into like a u.s. ant. This guy, I, like I said I converted into a beetle this mining stunt cars low enough or small enough to convert into 150 gram.
Ants is a little bit hit and miss there’s, some that I’ve found but they’re more suited for that almost be more suited for flea weights than they would be for 150 gram and weights. So let me pop the hood on this thing and we can have a look at the gear train inside of it, and you can see that it is exactly the same as this one. Okay, here we go so yeah there you go, you can now see. There are two motors in here. There is also that same circuit board as everywhere else. This one might actually be a lot closer to some of the ones that were in the Ackermann steering cars, but you can see. We’Ve got two different motors in here. One Simpson facing this way into this gearing stack up and one Simpson facing that way into this. Carrying stack up most likely. The gearing in through here is all plastic, which is a little bit dicey for combat robots, but I mean, if you’re looking to do a budget combat robot. Then plastic gears probably aren’t the most of your worries in this case, so it should be okay to do that, but you know you probably will have to replace your gearing sets more often than people with a metal geared motor of some description but yeah. So there you go this, these are the good type. This is the type of thing you want to be able to find.
You want something that has native tank, steering or skin, steering whatever you want to call it involve, because then we can hook up our own ESC s and receive it into this and then make a new body. Shell and bing bam boom. We have ourselves a u.s. ant weight, combat robot, so let’s move on to the final category here, which was the ones that are considered to be perfect. Actually, No before we do that, we’re going to talk about controllers, because controllers are a big part of why those other ones were so very. Nearly perfect I’ve been saying this whole time that RC cars are made rather cheaply and controllers are where this kind of really really shines through. Now it used to be a couple of years ago that you would have controllers like these, so you would have them on 24 megahertz or on 48 megahertz and the control scheme or the the data that they send down. That 28 megahertz was exactly the same. So this control – I saw a 27 megahertz. It literally says that on the top of this one, so this control of this control control of this controller, all of them, sent the same data on the same channel and you can interfere with each other. So this controller, despite looking very different to this one they’ve, worked functionally the same way. One stick would control one motor and the other stick would control a different motor. This one is for a stunt car, so you can see that it’s got two sticks that go forwards and backwards, so pulling up would send both the motors forwards and pulling back would send both the motors backwards, whereas this one is done for an acumen steering car.
So you’ve got a throttle for the back wheels and then a turn control for the Ackermann steering but functionally they send the same data. So if you turned on an acumen steering car with this and then turn this on as well, this would be your forwards and backwards, and then this would be a left and right turning which would be really confusing, but you could definitely do it. The other thing that’s worth noting in here is that how this thing works is quite unusual in that these sticks they look like they should give you a nice amount of control right. It looks like if I pull the stick to here. It should go a certain speed and if I pull the stick all the way, it will go faster speed, but that’s not the case. If you look all the way down at the very bottom, you see metal plates in under here, and these are basically Springs and when I pull one way it connects the contact and now probably the other way it connects a different contact. So these are switches. It means you pull all the way up and it turns the motor on and you let go and it turns the motor off you push the other way. It turns a motor on in the other direction. There is no speed control in this at all and it’s. The same with all of these, in fact, this controller even goes so far as having literal push buttons in here that’s.
If we can focus on this, there’s literally push buttons in here to control the speeds of the motors or it’s, not really a speed, control right. It’S literally just turn the motor on release the motor turn and, while they’re on in the other way that’s it and, like I said all of these interfere each other and the only one didn’t was this 48 49 megahertz one because it was on a different frequency. So all of this stuff is not useful for combat robots at all, because this stuff is the old analog radio style, and this is just not competition, illegal in any way, shape or form. However, in the last couple of years, 24 gigahertz digital radios have started to come into the the RC space like this guy. Now, you would immediately think that this is a lot better, because this is a digital radio. So therefore it is technically competition legal. However, this thing is exactly the same inside as these, so while it’s got a different chip in it, you can hear if I put this up to a microphone its clicky, which means that this doesn’t have that proportional to control either it’s literally pull until it clicks That turns your motor on pull until it clicks the other way that turns a motor on in Reverse and the same with the wheel. We’Ve got clicks, which means that we don’t get any proportional control, which means that the robot is going to be going at full speed in any given direction at any given time now this one and this one are both 2.
4 gigahertz radios for Ackermann steering, which means That the control board on the car side literally just says alright turn the mote turn the drive motors on turn. The drive motors on then reverse turn the steering motors on one way turn the steering wheel on the other way, and the same thing happens with this control of it. Of course, this one is a lot more obvious than it’s just buttons, because that’s literally all these are they’re just clicky buttons. Now, if you compare and contrast that to a real radio that people very typically used for combat robots, we have proportional control on everything here. These sticks, don’t, have any click to them, and if you stick the stick here, it’s going to move at a different speed than if you spoil the stick all the way over to one side. So this is the type of thing that you want to be emulating when your rang controllers. Now this brings us to those final two RC cars that I said were very very close. Okay, so here are our two final cars, which are so some very close to being the ideal base for a combat robot. Now these you might look at them in a minute think, oh, no! These have got Ackermann steering in them, but if we look at the underside of these, they actually don’t. One of these wheels is raised up and can’t actually move at all the other side, can’t that’s, what got a gear inside it and a gear ratio, and then this one’s also Drive.
So this does do that skin steering tank steering it just does it with offset wheels, which is a little bit interesting, and I think that just comes down to the fact that these things are designed to drive on the wall. So the minimal contact points helps and they’ve just kind of done it this way. Now. This is interesting because it means that this controller, you can see this controller, has an up and down stick and a left and right stick. So this controller is pre mixed to do tank, steering just straight for you, which is awesome. None of those other controllers that I showed you would have mixed your sticks for you, so you would have to kind of do that on the fly or run an Arduino in the mix. Some way to do some stick mixing for you, but this controller does that all in one go, the other thing it does is. If we have a look in here, we don’t have buttons in here. We actually have potentiometers that’s. What this little green thing is down here, and that means that this has proportional control, so this much is going to be a like a little bit and then this much is going to be a lot more turns. So that is actually awesome and, like I said this, this this here is why these were so so close. They have the software to do the proportional, sorry, the or yes, they have software and hardware to do proportional, skin, steering or tank steering whatever you want to call it, which is awesome.
This is so so close. The only problem is, they are running the 2.4 gigahertz. I talked about which is competition. Legal kind of the big problem with these is that the 2.4 gigahertz you need to bind, so you need to bind the controller to the receiver inside the robot now in combat robot stuff. This is done with a bind button, so I’ve got a bind button down here and then there’s a binds plug that you put into your receiver. You put power them both up with the bind thing done and it’s a one time bind and you’re done that’s it. It would just the receiver will remember the controller, remember everything’s done and every time you power up from that point on these two things will just bind with each other automatically and won’t try and bind with anything else. So you know that when you power your controller up, it’s going to talk to just your robot, the problem with these is these are running a toy protocol, a toy 2.4 gigahertz protocol, and that means that they do the binding. They forget binding every single time. Every time you turn them off, they forget binding and every time you turn the back on the first few seconds forces of bind which means that, even though this controller came with the orange vehicle and this controller came with the blue vehicle, I have no way of Having them locked in to bind so I can turn this control on and this car on and drive those turn everything back off.
Turn this controller on and this car on and that will drive and obviously that’s a scary thought when you’re doing combat robot stuff and it’s most likely going to mean that these controllers would not be competition illegal. Unfortunately, just because you don’t want a situation where two people rock up with these same controllers and are fighting each other and then turn their robots on and then turn their controllers. On only for the controllers to bind crossed and have one person Drive, your opponent Obot and your opponent driving your robot that’s, just that’s, a scary, scary thought and just would not help anybody out at all so, like I said these are so so so close if They just bow correctly, then everything would be fine and everything would work exactly as it is now. I’Ve been looking at trying to hack these so that they do bind correctly. The problem is that these are cheaply made or as cheaply made as they can be, and that means that all of the electrical components in the air have all of their identifying marks, just scraped off of them. So there’s no way to find any real information about the insides of these. I could potentially build a new ID. We know system to go into an RC car that go into a combat robot that responds to this. But that means that I’m not getting the full advantage out of my equipment here, so unfortunately yeah we’re kind of getting to a conclusion point here, and that conclusion is this.
Unfortunately, you can’t really use any of the electronics inside of any of these RC cars. Even the ones that have 2.4 gigahertz enabled don’t have a good bind system that’s going to keep you and everybody around you safe in a competition setting, so you’re going to need some form of actual RC electronics that you’re gon na have to put into any of Your RC cars, but having said that, something like this that has that skid steering setup in it could make a decent base a fairly cheap, decent base. As long as you’re willing to accept the fact that you’re gon na have plastic gears in here which are going to be potentially a little bit weaker than the gears in your opponent’s vehicles and things like that, the tiny little cars I mean these things, they were So so close and I’ll probably use the parts out of these to make flea weights at some point in the future. But once again I need to put in my own electronics into that because yeah the receivers and the transmitters and everything while this, Oh nearly there, they have that big, glaring issue with binding, which makes them a safety issue. So you, like, I said you might be able to use one of these at an event, maybe at a stretch you would definitely have to be talking to the event organizer about it and explaining everything that I’ve just kind of gone through in this video, and you Know letting them know that it doesn’t bind automat, sorry that it doesn’t hold bind and it has to bind every single time to power it up, which yeah, I think, most event.
Organizers are probably going to tell you you can’t use at their event, because yeah the potential for crosstalk and controlling somebody, else’s robot, is a very scary prospect anyway. Unfortunately, I think that’s going to be the end of this video. I have tried for a long long time to find RC cars that are good and hackable and usable as combat robots, just throw them straight into the arena with a wedge slapped on the front, but unfortunately that just doesn’t seem to be anything out there. At this point in time, if I find something at some point that has all of the boxes ticked, I will be making a new video. I will be showing you guys how to hack an RC car into a combat robot, but for the moment, stick with traditional, conventional RC equipment and yeah.