Quadcopter Parts - Page 1
Forum section: electronics / beginners

author: skillz21
author_rank: Frequent Contributor
timestamp: September 23, 2017, 03:22:33 am
content: Hi, I want to hopefully try and build a quadcopter in the future, I want to learn more about the parts. what flight controller should I use? Could I use an Arduino? (because it's open source) if so, what other modules would I need to use with the Arduino? (Gyroscope, accelerometer etc.) what about the motors and the ESC's? could I just use any cheap ESC? (likethis, orthis?) Also, what about the motors? once again, could i just use any cheap old brushless motor for this? (likethisorthis?) What about controllers? I have seen really cheap flight controllers for under $20.... but the controllers for them are seventy or eighty dollars... for arduino, what method would you recommend for controls? bluetooth, rc, or what?Thanks!

author: FreddyVictor
author_rank: Regular Contributor
timestamp: September 23, 2017, 08:27:17 am
content: Arduino is an easy way to mess around creating your own flight controllerThere's already one's available such asthiswhich is effectively an arduino with MPU6050 6 axis gyro/accelerometer and all the right pin connectionsNote this has minimal facilities so you have to actually fly it yourself (no GPS etc) !Speed controllers (ESC's) usually need PWM signals to control them but the ATmega (8bit) chip has limited PWM options but can still be used OKMost flight controllers now use 32bit processors which are faster and can hold larger control programs with better hardware facilitiesFor control, it's probably best to start with standard rc Tx and Rx unitsAs for choosing actual components such as ESC + motors/props, alot of this depends on the size of the quad you're wanting to buildMaybe best to look intoRCGroupsforum for info/helpThe 2200Kv (Kv is 1000rpm per volt) motors are typically used on small drones, now often used for racing.Hobbykingis a good place to get cheap rc kit.It's useful if you should break a part you can replace it with an identical part which may be difficult if you buy random bits off ebayThere's lots of things you'll need, power connectors, suitable wire, and don't forget LiPo's (batterys), they will also need a chargerAnd buy spares of breakables, especially propellorsIf you're unlucky, a crash will break the motors quite easily and sometimes can cause the ESC's to go up in smokeThis lot can add up to quite a bit, hence the cheap Ready-to-fly drones are an easy option

author: skillz21
author_rank: Frequent Contributor
timestamp: September 23, 2017, 08:33:41 am
content: But what about the controller, you know, the user side of things? And willthisandthiswork?

author: Rerouter
author_rank: Super Contributor
timestamp: September 23, 2017, 08:53:24 am
content: Controller wise, the first thing is, are you confident to learn to fly it, or do you want it to fly itself,This will divide between GPS controllers and non GPS controllers, the non will still have a stability mode where they will return to a hover, but on a windy day or due to you not calibrating the accelerometers dead level it can still go running off at a few kmph, Ideally you should learn how to atleast hover a quad in Acro mode, just to recover if something goes wrong, but you build up to it,For command, it comes down to the size of the quad and the distances you want it to respond within, Inside a house with a little 200g mini, bluetooth could work, for around 800g and outdoors i would say go proper RC, the amount of times i have been furthur away than it looked, and had to recover it from 200m away near trees, I've been glad i could trust the control link.The ESC's and Motors will strongly come down to your mass, flytime and top speed, many RC groups have calculators for them.Personally i ended up going with a prebuilt - Walkera F210, It has hit the ground atleast 100 times with minimal injury, (the feet are fragile, but a 3D printer cranks out replacements), The main thing i clued in to early on was expect that you will hit the ground hard, and learn how to slow it down, and reduce the risk of damage,

author: skillz21
author_rank: Frequent Contributor
timestamp: September 23, 2017, 09:28:04 am
content: Quote from: Rerouter on September 23, 2017, 08:53:24 amWhat do you mean by this? I don't have a lot of experience flying drones, but I am confident that I could learn how to.

author: Brumby
author_rank: Unknown
timestamp: September 23, 2017, 09:39:29 am
content: Do you want to have a drone that:- only goes up, down, left and right when you command it to- OR -- you program a course or a "follow me" or some other "smart" operation and it navigates itself?

author: Novgorod
author_rank: Contributor
timestamp: September 23, 2017, 10:14:04 am
content: Quote from: skillz21 on September 23, 2017, 08:33:41 amThe RC flight controller hardware and software matured greatly since the old days of Arduino and Multiwii. Today, virtually all DIY quadcopters (and even the cheap-ish Chinesepre-assembled kits) use STM32 based controllers for their superior performance and features. There are different versions of the chip (F1, F3, F4), which differ in speed, flash size, number of UARTs and of course prize (the STM32 F3 is currently the de-facto standard for DIY quads). There are lots of different controller boards based on this chip. All of them have an accelerometer onboard and they only differ in the amount of other flight-related features, e.g. magnetometer, barometer, on-screen display, BEC, power distribution, or even integrated ESCs.The bare minimum for a flight controller is this:- Accelerometer (all STM32 based controllers have one onboard)- input for your radio receiver (n PWM pins for n channels or just 1 pin for PPM or serial communication)- 4 outputs for the ESCs (either PWM or serial)- USB/UART for setupIf you want to add more devices (e.g. GPS receiver, sonar, bluetooth, OSD module), the controller chip must provide the respective communication ports (usually UART or I²C). The "old" analog PWM/PPM stuff is currently being replaced by digital serial communication. All major radio manufacturers provide receiver modules with some sort of serial data communication protocol and even the ESCs started to use digital communication (called Dshot) for faster and more precise response than the usual 1kHz PWM.The final component is the software. There are several choices for the STM32 flight controller, most of them open source. The most popular are Cleanflight and Betaflight, which are easy to set up and configure through a fancy GUI. They support all sorts of receivers (old PWM style and modern serial ones), ESC configurations and all kinds of gadgets (additional sensors like sonar and GPS, programmable LED lights etc.). However, you will have to read/watch some tutorials to correctly set up your radio and the flight modes, it doesn't work out-of-the-box unless you buy a full kit including the radio. The link to RCgroups was posted already, they have great resources for beginners, but there are also tons of youtube tutorials...

author: skillz21
author_rank: Frequent Contributor
timestamp: September 23, 2017, 11:17:30 am
content: Quote from: Brumby on September 23, 2017, 09:39:29 amOh, I wasn't planning on anything advanced like that, if i do build this, it'd be my first Quadcopter build, so I just want it to move when I tell it to.

author: BenKenobi
author_rank: Regular Contributor
timestamp: September 23, 2017, 11:21:51 am
content: So as one that does this a word of warning - learn to fly first - you cannot program a flight controller unless you do, you need to be sure that the problem you have (and you will have them) is not down to you. I'm not poking you here but the question tells me you don't know much and that's a good thing - you're asking - but be under no illusion things that fly can be darn dangerous. Step 1 learn to fly with a known entity before you try to DIY.Checkout ArduCopter -http://www.arducopter.co.ukTake a read of this place toohttp://diydrones.com/forum/topics/differences-between-apm-px4-pixhawkI mix and match boards to suit the needs because I can but if I were you I'd buy a Pixhawk and figure out how it all works in depth before going hip deep down your own path. You only need this board, it handles all the ESC communication, gyro etc, adding a GPS is easy but then the fun starts.The ESC must be matched to the motor / rating, and the battery, the more weight you add the more lift you need, the more lift you need the more power you need, the more power you need the bigger the battery you need and up goes the weight, and then you need more power than the ESC or motor can deliver so you start all over again - so then you get into matching motors to the propellers you need more power to turn larger propellers ... and so on and so forth.https://pixhawk.org/modules/pixhawkThat said you can use almost any processor board if you know what you're doing but you may need to port code or write specific code - my advice is don't - you will find it incredibly difficult to tune for stable flight if you can't fly in the first place - because these things are not plug and play, every multirotor behaves differently (we DON'T call them drones !!!) and you need to react to things instinctively whilst tuning 'stuff'

author: skillz21
author_rank: Frequent Contributor
timestamp: September 23, 2017, 11:22:48 am
content: Quote from: Novgorod on September 23, 2017, 10:14:04 amSo, an atmega 328 wouldn't cut it?

author: BenKenobi
author_rank: Regular Contributor
timestamp: September 23, 2017, 11:26:54 am
content: Technically it could but it would be crazy basic.Remember that you need to get your signals from the RC transmitter, then to the receiver and from there to the CPU, whilst this sounds straightforward it isn't - you are into a real time system relying on communications as a critical path. I tend to stick to Futaba SBUS because it is readily available but I've been playing with my own protocol 'stuff', I have a number of FrSky transmitters because they too are open source and I can program pretty much anything I can imagine.

author: skillz21
author_rank: Frequent Contributor
timestamp: September 23, 2017, 11:28:46 am
content: Oh, and also a quick question, why brushless motors? I know all that about how it's more durable and all because the brushes in brushed motors can wear out and everything, but why? If you wanted a Quadcopter, and you aren't really too fussed about longevity, could you use a brushed motor?

author: skillz21
author_rank: Frequent Contributor
timestamp: September 23, 2017, 11:33:05 am
content: Quote from: BenKenobi on September 23, 2017, 11:26:54 amBut what about the MultiWii FreddyVictor mentioned earlier (here) It has an atmega.... does that mean that it is not good?

author: Rerouter
author_rank: Super Contributor
timestamp: September 23, 2017, 11:34:46 am
content: It struggles to cut it, there are a few cascaded PID loops going on inside a normal controller, which up till now most people have just used floating point for, unless you had a fixed point varient you run out of processing cycles very quickly when you add in talking to the sensors,Whereas the STM32's pack in hardware floating point which means before you even get to the 32 bit architecture leaves you with far more free time.Brushless motors are common because the speed is controlled (you are activley setting the RPM), whereas with brushed motors, while there is a relationship between voltage and speed, there is not one between PWM% and speed with a varying load, your left without an easy way to read back the speed so your relying on your PID loop to compensate every motor under varying loads, vs the brushless approach where the ESC's are self adjusting to maintain the requested speed.

author: skillz21
author_rank: Frequent Contributor
timestamp: September 23, 2017, 11:36:25 am
content: Just curious, is there an ESC equivalent for a brushed DC motor?

author: Rerouter
author_rank: Super Contributor
timestamp: September 23, 2017, 11:37:43 am
content: That would effectivly be called a continuous rotation servo, It requires a rotation encoder of some form to extract the speed.

author: BenKenobi
author_rank: Regular Contributor
timestamp: September 23, 2017, 01:29:46 pm
content: You don't use brushed motors in multirotors or aeroplanes, insufficient power, too large and too much interference to deal with.

author: Brumby
author_rank: Unknown
timestamp: September 23, 2017, 01:42:40 pm
content: Quote from: skillz21 on September 23, 2017, 11:36:25 amI think you should do a bit more browsing an RC forum and generally looking around at what is already in use.You sound like you are trying to re-invent the wheel using what is on hand. While such thingsmayproduce something that flies, it is going to be far less impressive than learning from those who have done the hard yards - unless you want to repeat all their failures to arrive at the same conclusions.

author: Novgorod
author_rank: Contributor
timestamp: September 23, 2017, 02:20:51 pm
content: Quote from: skillz21 on September 23, 2017, 11:28:46 amOf course -here you go!A ready-to-fly kit for 14 freedom-bucks...Besides the toy-grade stuff, there are some brushed enthusiasts using "professional" controllers and quality motors but it only makes sense for micro quads (below ~100mm diagonal). There are also flight controllers specially designed for brushed based on the STM32 and compatible with the great flight software available for these chips. Instead of driving the ESCs, the PWM outputs drive FETs and the brushed motors are directly connected to the LiPo through the FETs. This is of course much simpler and cheaper than 3-phase ESCs and the reason why those Chinese toy quads are so cheap. Frankly speaking, it doesn't make much of a difference to the flight controller whether it drives a brushed or a brushless motor, at least not to a degree that a beginner would ever notice (besides the less available power of course). So if you're really on a budget, you can build a brushed micro with a brushed controller, no problem. Just be prepared to replace the motors every couple of hours of operation...

author: FreddyVictor
author_rank: Regular Contributor
timestamp: September 23, 2017, 02:57:13 pm
content: Quote from: Novgorod on September 23, 2017, 10:14:04 amI think I should point out that you've mixed up accelerometers & gyroscopesI was into copters some years (5+) back and wrote a fair bit of code to control then but have moved onto other things now!

author: Novgorod
author_rank: Contributor
timestamp: September 23, 2017, 03:19:35 pm
content: Fine, if you want to be strict, you only need a gyroscope as a bare minimum, but that's virtually impossible for a beginner to control...All flight controllers include a 6-axis "gyro" nowadays (i.e. a 3-axis accelerometer and a 3-axis gyroscope in one chip) in order to support auto-level.

author: BenKenobi
author_rank: Regular Contributor
timestamp: September 23, 2017, 03:45:20 pm
content: The issue here is what it takes to fly one of these things without the 'gizmos' without the gyro's to assist most beginners won't even get into the air let alone fly. Most pilots tend to start with all the gizmo's and then gradually wind them back, effectively improving performance but relying far more on the pilot. Keeping the orientation with multirotors is extremely challenging - i.e. which way is forwards.All the control is done using motor speeds - yaw, roll and pitch are all dependent on having very responsive motors - brushed motors aren't it. I tend to use what are called pancake motors of up to 23 poles, these provide much better torque than any brushed motor and lower power consumption per gram. I flew and built many multirotors over the last 5 years but I've moved away from that world now because there is just way too much BS involved to put a multirotor in the air (if you stick to the rules that is).My advice is don't even think of going the DIY route unless you can fly first, well you can, but it won't end well. You'd be better off buying something like a DJI F450 with a NAZA V2 flight controller, this will get you into learning to fly and also understanding how these things work - and sometimes don't.I'm not trying to put you off but knocking something up out of the 'parts bin' is full of potential failure points, take brushed motors off the list - trust me on this one, you don't want anything smaller than the 450 - the bigger the bird the more stable it tends to be. If you don't understand the concepts you will never properly code one of these things, if you want to see just how complex it can get you only need to download the ArduCopter code - it's open source - but hey wait somebody has done it - why do you need to re-invent it. Start with something based on the experience of 100's of pilots and engineers, understands it, learn from it.It may be worth getting yourself a simulator too, there are a couple of good ones, I personally use Real Flight 7.5, you don't care what the weather is like nor how often you crash. There are even places in it where you can 'design your own' and see how it flies, it isn't perfect but it is the cheapest place to start - crashes tend to get expensive.

author: Novgorod
author_rank: Contributor
timestamp: September 23, 2017, 04:25:06 pm
content: Well, I really wouldn't advise getting some expensive DJI as thevery firstcopter for learning. Better get some cheap Chinese $20 toy with big prop guards (or a couple of them) and learn the basic movement with self-leveling. After you're familiar with the basic control, you can get a large and expensive outdoor quad and eventually transition from self-leveling to rate mode (that is, if you're into racing). Start with something you can afford to crash - many times...

author: BenKenobi
author_rank: Regular Contributor
timestamp: September 23, 2017, 04:37:31 pm
content: I lot think that but he could have the satisfaction of building the DJI from a kit of parts.The problem with the toys is that they are exactly that, they don't fly well (mostly), I've still got one in the cupboard made from flimsy bounce back plastic with propeller guards that I bought as a trainer and it is a horrid thing to fly. I flew one of these around in my lounge but when I moved so something more 'real' I was truly messed up, the cheaper one had all kinds of geometry issues - it was just too flimsy and the motor mounts were moving around in flight which adds a dynamic that a learner can do without. This needs to be fun experience not a high stress event.I sure wouldn't by the DJI Phantom or anything like that as a beginner though many do. I'd go for something like thishttp://www.buzzflyer.co.uk/DJI-FlameWheel-F450-ARF-or-RTF__p-2165.aspxHe could leave the NAZA V2 off and buy one of the Pixhawk clones (although this is the hard route) the NAZA is a known, tried and trusted controller.

author: FreddyVictor
author_rank: Regular Contributor
timestamp: September 23, 2017, 09:40:54 pm
content: Quote from: Novgorod on September 23, 2017, 03:19:35 pmSeems to me alot of people started with these 'virtually impossible' drones and coped quite well consideringQuote from: Novgorod on September 23, 2017, 03:19:35 pmgyros have 3-axis, accelerometers have 3-axis, doesn't make it a 6-axis 'gyro'best use the phrase IMU instead ...

author: BenKenobi
author_rank: Regular Contributor
timestamp: September 23, 2017, 10:04:49 pm
content: Yes many do just jump in, and learn the hard way, it's a valid way of learning but can be somewhat expensive and in some cases dangerous.As for the 6 axis bit I agreee but that just seems to be how they get named in countless forums and before you know it the world repeats it, but you're correct the terminology is inappropriate but most know what it means in the RC circles. The true term would be 6 axis inertial motion sensor.There is another version used a lot too and that's a 9 axis, this adds a 3 axis magnetometer into the device, the 9 axis can be combined to make highly accurate decisions about where the device is and what it is doing using a mathematical process called sensor fusion - but this is pretty complex.Almost everyone uses the latter but doesn't even realise it - they're in most smart phones and tablets. These are complex beasts, they don't work out of the box - in fact nor do the 6 axis - they have to be taught about the world that they are in - you can mount them in any orientation as long as you tell them about it - but if you don't do this you won't be flying level. Even slight errors in 'level' would see the multirotor drifting.

author: FreddyVictor
author_rank: Regular Contributor
timestamp: September 23, 2017, 10:31:10 pm
content: Quote from: BenKenobi on September 23, 2017, 10:04:49 pmYea, I was looking at the other persons problem with his propel quad on this forum & noticed the box claimed '6-axis gyro' to which I figuratively sighedQuote from: BenKenobi on September 23, 2017, 10:04:49 pmCurrently been messing around with an ST LSM9DS1 9-axis sensor, but not for dronesFor sensor calibration, the real pain is the magnetometer, they need calibrating to remove hard iron offsets and then the data must be tilt-compensated (for use in phones where it's not level)I'm quite curious as to how they get them to work with little or no calibration - anyone ever calibrated their phone ?I gave up writing my own code for drones as the maths was too complex, also, there was other freely available code which easily outperformed most other available softwares@OP, just buy a cheap drone to see if you like it or not, you'll save a heap of money !

author: Novgorod
author_rank: Contributor
timestamp: September 24, 2017, 07:13:46 am
content: Quote from: BenKenobi on September 23, 2017, 04:37:31 pmThen he could go straight for one of the countless mini quad kits and it should be a lot cheaper. DJI stuff are luxury toys, which are great if you're into drone photography rather than actual flying...QuoteDefinitely true - you need to find the right one, but when you find it, you'll save yourself a lot of money and pain. I recommend beginners to get a Syma X11 or X13 (or clones), which have large (and geared) props for their size making them remarkably stable. They're neither fast nor powerful but very precise to control and easy to hands-off hover. Once you've learned how to fly circles, funnels and figure-8s without crashing, you can progress to something more serious, but until then you do absolutely nothing wrong with (the right!) toy-grade quads.Quote from: FreddyVictor on September 23, 2017, 09:40:54 pmI did't come up with the nomenclature and I know it's technically wrong but that's how most brands lable these sensors

author: Rerouter
author_rank: Super Contributor
timestamp: September 24, 2017, 08:19:39 am
content: the gyro is the only superfluous bit of information, it is a 6 or a 9 axis, 3 rotational axis's, 3 translating axis's, and 3 orientation axis's, technically GPS would be an additional 3 spacial axis's, which do not correlate to the translating axis's until a translation / rotation of the matrix is performed, then you have other sensors which are derived but not the same as an axis like optical flow sensors that measure air speed,I would replace the "gyro" with IMU, or INU, or even sensor, but i suppose at the end of the day it conveys the same message.