lightweight, inexpensive speed controllers

[tilky]

I deleted my post about the brushless motors because i looked it up and realized that I definitely do not have brushless motors

[tilky]

what type of capacitor would you recommend?

[yash101]

Originally Posted by tilky

yea I'm stupid with the voltage thing. wanted to only have one power source, but that wouldn't work too well.

Please elaborate. What is your power source?

Also, you were wondering about the capacitor: any capacitor will work. In this case, you probably would like a Electrolytic Capacitor. Make sure the voltage ratings are 3 TIMES the max voltage of the qc. 1000uF - 5000uF should be good enough for a filter cap. Also, don't forget the protection diode. Make sure the diode is set up to only allow current in one direction, to prevent reverse current!

[tilky]

I didn't do anything yet, still in planning stage, so I wasn't exactly sure how to power it yet. I wanted everything to be run off of the same batteries, but it is now apparent that I would need to have 1 set for the controller and 1 for the motors, etc.

[yash101]

Originally Posted by tilky

I didn't do anything yet, still in planning stage, so I wasn't exactly sure how to power it yet. I wanted everything to be run off of the same batteries, but it is now apparent that I would need to have 1 set for the controller and 1 for the motors, etc.

NO. You need an UBEC. That will reduce the voltage of the main battery to 5V for your Arduino. This is what you are looking for! Otherwise, you can always hook up ye olde' 7805 or LM2940 to power up the controls! I am not an Arduino user. I've been taken by Parallax. However, if Arduino has the regulator built in, it would be horribly inefficient. Make sure to use VDD, not VIN, if using a UBEC!

[AlexH]

nah man you don't need multiple batteries, you need a BEC
it steps voltage down to 5v


if you are looking at loads under 7a you can hack the vex motor controllers


guide to hack

[efoote868]

Originally Posted by tilky

I didn't do anything yet, still in planning stage, so I wasn't exactly sure how to power it yet. I wanted everything to be run off of the same batteries, but it is now apparent that I would need to have 1 set for the controller and 1 for the motors, etc.

Well, if you're still in the planning stage, you need to first figure out what you want as the end product, and then you can begin to fill in the details of how to get the end product.

So, let's start with the quadrocopter itself. How big of a quadrocopter do you intend to build? How long do you want to fly it in one go? How much are you looking to spend? Those three questions aren't mutually exclusive, but if you can answer them it'll definitely help us determine the scope of your project.

Once you answer those questions, we can move on to something like the power source. Based on how light these things need to be, you'll probably be using some sort of Lithium Polymer battery. Based on that chemistry, there are several voltages you can pick be it 3.7v, 7.4v etc.

You'll be using unregulated voltage (directly from the battery) to power the motors. Which are also important. Based on the size of your quadrocopter, what motors do you need to power it? The motors you pick will determine what kind of motor controller you can use.

Once you know these things, you can start to focus on what's controlling it. It's fairly straight forward to design a power supply for the rest of the circuit (micro, sensors, etc), but you'll need to pick each one of those components out.


As you can see, there is a lot of thought that goes into a project like this, and it's better if you first understand and describe the basics (such as size) before asking for help on a minor detail (motor controller).
Unless you're trying to guestimate the cost, which asking for prices of motor controllers might be appropriate.


____
EDIT:
I'm not trying to discourage you! This sounds like an awesome project, and I'd love to see you follow through with it. We just need a bit more information to be more helpful

[yash101]

Originally Posted by efoote868

Well, if you're still in the planning stage, you need to first figure out what you want as the end product, and then you can begin to fill in the details of how to get the end product.

So, let's start with the quadrocopter itself. How big of a quadrocopter do you intend to build? How long do you want to fly it in one go? How much are you looking to spend? Those three questions aren't mutually exclusive, but if you can answer them it'll definitely help us determine the scope of your project.

Once you answer those questions, we can move on to something like the power source. Based on how light these things need to be, you'll probably be using some sort of Lithium Polymer battery. Based on that chemistry, there are several voltages you can pick be it 3.7v, 7.4v etc.

You'll be using unregulated voltage (directly from the battery) to power the motors. Which are also important. Based on the size of your quadrocopter, what motors do you need to power it? The motors you pick will determine what kind of motor controller you can use.

Once you know these things, you can start to focus on what's controlling it. It's fairly straight forward to design a power supply for the rest of the circuit (micro, sensors, etc), but you'll need to pick each one of those components out.


As you can see, there is a lot of thought that goes into a project like this, and it's better if you first understand and describe the basics (such as size) before asking for help on a minor detail (motor controller).
Unless you're trying to guestimate the cost, which asking for prices of motor controllers might be appropriate.

Let's go with some more details!:
-How much do you want to haul?
-*Flight Time per charge
-Size
-Weight
-Power Rating (~200w/KG)
-*Price range
-other features

*=Mentioned by E. Foote

[Redo91]

I just finished up my senior design project and it was based around a quadcopter. There is quite a steep learning curve when you get into it all.

First and foremost, what do you currently have on your list of parts for the quadcopter you want to build?

[yash101]

I'll have to say, for the QC, here's what you will need, minimally:
-Frame (can build yourself)
-Motors(4) (Brushed/brushless. brushless if prefered because brushes wear out quickly at that RPM)
-Battery
-ESCs(4) (one for your motor)
-Control system (Arduino, with gyro)
-Propellers(4) (Depends on size of frame and weight)
-BEC (5V for Control System)


-And, don't forget those blinkies
-You put those together and you have a UFO when flying at night!

[Redo91]

Originally Posted by yash101

I'll have to say, for the QC, here's what you will need, minimally:
-Frame (can build yourself)
-Motors(4) (Brushed/brushless. brushless if prefered because brushes wear out quickly at that RPM)
-Battery
-ESCs(4) (one for your motor)
-Control system (Arduino, with gyro)
-Propellers(4) (Depends on size of frame and weight)
-BEC (5V for Control System)


-And, don't forget those blinkies
-You put those together and you have a UFO when flying at night!

I'm going to add that brushless motors are a must. The way a brushless motor operates makes their speed much more controllable than a brushed DC motor.
There are also ESCs with a BEC built in that provide power to your flight controller.

[ILAMtitan]

Before moving too far ahead with your project using FRC based knowledge, I strongly recomend boning up on modern RC build practices. I've built several quads and RC planes, and the difference to FRC is night and day.

If you're doing this on a budget, HobbyKing is going to be your best friend. Their forums have a great write up to get started in quads: http://www.hobbyking.com/hobbyking/f....asp?TID=38561

After that, there is a rather lengthy post about building your first quad here: http://www.hobbyking.com/hobbyking/f....asp?TID=18772

A few last minute tips from my own experience:
Always fly in an open area, since trees suck to crash into.
Don't go as big as possible for your first quad. These things are tough to learn to tune and fly; starting on a smaller platform is much easier.
And last but not least, be very safe. Always treat it like it will turn the rotors on at any moment.

Best of luck.

[efoote868]

Originally Posted by Redo91

I'm going to add that brushless motors are a must. The way a brushless motor operates makes their speed much more controllable than a brushed DC motor.
There are also ESCs with a BEC built in that provide power to your flight controller.

If I were to approach this problem, I might start by looking at what's available to the average consumer / near hobbyist level. I believe brushed DC motors are used on the popular Syma S107G model and knockoffs, and searching Ebay I can get a pair of them from China for $6 (including shipping).

One could also try to cannibalize more of that helicopter to get appropriate (and proven) gear ratios, as well as mounting hardware.

Controlling a brushless DC motor is not trivial, which is to say that as a hobbyist you wouldn't build one from scratch as you might an H-bridge or other brushed DC motor controller.

[Andrew Schreiber]

Originally Posted by ILAMtitan

Always treat it like it will turn the rotors on at any moment.

Best of luck.

One of the guys at my local space has a series of nasty scars up his right side from when his quad turned on and the blade caught him. Turns out CF blade vs skin… the CF wins by a lot.

Don't forget these are machines with a simply crazy amount of power.

When working with your batteries be careful not to short them. Be careful flying near people, even a small quad dropping at someone can hurt.

[nuttle]

Bottom line is there's a ton of stuff already done for this particular application and you probably want to at least start with what is readily available and in widespread use. The underlying technology is similar, but you most likely do not want to try to build your own controller -- lots of optimization has already been done, just as for motors for this application. The terminology is different and seems to come from the RC plane/heli world. You want an "ESC" where you ask about motor controller and yes, these use PWM -- same RC background, which is really where PWM came into FRC I suspect. This is how most traditional RC systems send control signals over the air. And the motors need to run directly from the batteries, with the "battery eliminator" to supply power to other electronics that needs different voltage(s).

BTW, the reason for this is the same reason you don't try to regulate the voltage except by turning it on and off very quickly: trying to control voltage other than just on/off means turning power into heat / lower efficiency. You don't want low efficiency in anything that is battery powered, not that you ever really want this in anything besides a heater.