lightweight, inexpensive speed controllers

[tilky]

I was interested in building a quadrocopter, the classic robot enthusiast project. I know generally what to do, except when it comes to speed controllers. The speed controllers used in FRC are way too heavy, too expensive, and require the wrong amount of voltage. I am looking for a light, inexpensive speed controller that can support a 5v input, as well as PWM functioning. Anyone have any ideas?

[Andrew Schreiber]

I'm using http://www.hobbyking.com/hobbyking/s...ontroller.html for mine.

It's not running yet so I can't attest to it's quality but they came highly recommended to me by various sources. Plus, they were cheap enough.

[AlexH]

Originally Posted by Andrew Schreiber

I'm using http://www.hobbyking.com/hobbyking/s...ontroller.html for mine.

It's not running yet so I can't attest to it's quality but they came highly recommended to me by various sources. Plus, they were cheap enough.

i've run that esc on a battlebot. they do pretty much exactly what the descriptions says.

soft start is annoying if you are trying to start with a heavy load on the motor and go full throttle but otherwise i can't complain.

yes they are pwm based.

[Andrew Schreiber]

Originally Posted by AlexH

i've run that esc on a battlebot. they do pretty much exactly what the descriptions says.

soft start is annoying if you are trying to start with a heavy load on the motor and go full throttle but otherwise i can't complain.

yes they are pwm based.

They are programmable, perhaps it's an option to turn off soft start? It's not really an issue for me, I shouldn't ever be going to full throttle suddenly.

[AlexH]

Originally Posted by Andrew Schreiber

They are programmable, perhaps it's an option to turn off soft start? It's not really an issue for me, I shouldn't ever be going to full throttle suddenly.

yeah there is way to turn it off. i just wanted to point out that soft start is a thing because i was having cogging issues and thought it was the motor for the longest time before i tried disabling soft start.

[tilky]

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

[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?

[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.